Name

OHKI, Yoshimichi

Official Title

Professor

Affiliation

(School of Advanced Science and Engineering)

Contact Information

Mail Address

Mail Address
yohki@waseda.jp

URL

Web Page URL

http://www.f.waseda.jp/yohki/

Grant-in-aids for Scientific Researcher Number
70103611

Sub-affiliation

Sub-affiliation

Faculty of Science and Engineering(Graduate School of Advanced Science and Engineering)

Affiliated Institutes

循環型環境経済共創システム研究所

研究所員 2010-2013

理工学総合研究センター

兼任研究員 1989-2006

環境調和電気電子材料研究所

プロジェクト研究所所長 2010-2012

理工学術院総合研究所(理工学研究所)

兼任研究員 2006-2018

理工学術院総合研究所(理工学研究所)

兼任研究員 2018-

Educational background・Degree

Degree

Doctor of Engineering Coursework Waseda University

Master of Engineering Coursework

Academic Society Joined

Japanese Electrotechnical Committee President

Institute of Engineers on Electrical Discharges in Janpan President

Institute of Electrical and Electronics Engineers

Institute of Electrical and Electronics Engineers

Award

Prize for Science and Technology, The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology

2015/04

Materials Life Society Best Paper Award

2015/07

IEEJ Technical Development Award

2014/05

IEEJ Book of the Year Award

2013/05

IEEJ Fellow

2012/05

Honorable Professor of Xi'an Jiaotong University

2011/02

M. Ieda Memorial Lecture Award, IEEE International Conference on Properties and Applications of Dielectric Materials

2009/07

Whitehead Memorial Award, IEEE DEIS

2007/10

E. O. Forster Award, IEEE DEIS

2002/10

Fellow, Institute of Electrical and Electronics Engineers

2000/01

Research Field

Keywords

dielectrics, electrical insulating materials, optical fiber

Grants-in-Aid for Scientific Research classification

Engineering / Electrical and electronic engineering / Electronic materials/Electric materials

Engineering / Electrical and electronic engineering / Power engineering/Power conversion/Electric machinery

Cooperative Research Theme Desire

Optical Properties of Silica Glasses

Institution:Cooperative research with other research organization including private (industrial) sectors

Purpose:Collaboration research

Dielectric Properties of Organic Polymers

Institution:Cooperative research with other research organization including private (industrial) sectors

Purpose:Collaboration research

Development of New Materials for High Voltage Insulation

Institution:Cooperative research with other research organization including private (industrial) sectors

Purpose:Collaboration research

Development of functional optical fiber

Institution:Cooperative research with other research organization including private (industrial) sectors

Purpose:Collaboration research

Research interests Career

2005-2008Development of Nanocomposite Insulating Matetrials for Eco-friendly Power Apparatus

Current Research Theme Keywords:Nanocomposite, Insulating Matetrial, Eco-friendly, Power Apparatus

Cooperative Research within Japan

2004-2006Structure and Formation Mechanism of Point Defects in High-k Dielectric Films for Next Generation LSIs

Cooperative Research within institute

2000-2004Optical Properties of Silica Glasses

Current Research Theme Keywords:Silica glass,SiO<sub>2</sub>,Point defect

Cooperative Research within institute

Dielectric Properties of Organic Polymers

Current Research Theme Keywords:Organic polymer,Electrical Insulation,dielectric phenomena

Cooperative Research within Japan

Development of new materials for high voltage insulation

Current Research Theme Keywords:insulating solid,high Voltage,electrical insulation

Cooperative Research within Japan

Electrical and Electronic Insulating Materials

Individual research allowance

Silica Glass and Optical Transmission Materials

Individual research allowance

Dielectric Materials for Power Apparatus and Semiconductor Devices

Individual research allowance

Paper

Identification of antioxidants in polymeric insulating materials by terahertz absorption spectroscopy

Kozai, Takuya; Kaneko, Takuya; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi

Polymer Degradation and Stability 147p.284 - 2902018/01-2018/01

DOIScopus

Detail

ISSN:01413910

Outline:© 2017 The Authors For the purpose of using organic polymeric materials for electrical insulation, various additives such as antioxidants are added to prevent degradation or oxidative decomposition of the polymers. Therefore, it is desirable that we can identify antioxidants added in polymers by instrument analyses. In this research, terahertz absorption spectroscopy was conducted for nine kinds of antioxidants. The spectroscopy was also conducted for sheets of low-density polyethylene, to which each antioxidant had been added with different contents. As a result, it has become clear that each antioxidant has its own specific spectrum. In addition, for most antioxidants, the absorption intensity is proportional to the content of antioxidant added in LDPE. However, several absorption peaks change their spectral shapes when the antioxidant is in LDPE.

Degradation of silicone rubber analyzed by instrumental analyses and dielectric spectroscopy

Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi; Hirai, Naoshi; Min, Daomin; Min, Daomin; Yang, Liuqing; Yang, Liuqing; Li, Shengtao

Minerals, Metals and Materials Series Part F11p.107 - 1162018/01-2018/01

DOIScopus

Detail

ISSN:23671181

Outline:© The Minerals, Metals & Materials Society 2018. Silicone rubber (SiR) was gamma irradiated at 125, 145 and 185 °C or thermally aged at 220, 250 and 280 °C and the resultant changes in performance were evaluated. It has become clear from instrumental analyses that crosslinking via oxidation of silicon atoms and chain scission are induced by gamma rays. Furthermore, from the temperature dependence of real relative permittivity at high frequencies, the thermal expansion coefficient was found to become smaller with the increase in dose. These results can be understood well by the chemical and structural changes in SiR induced by the degradation.

Successful detection of insulation degradation in cables by frequency domain reflectometry

Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi; Hirai, Naoshi

Minerals, Metals and Materials Series Part F11p.77 - 852018/01-2018/01

DOIScopus

Detail

ISSN:23671181

Outline:© The Minerals, Metals & Materials Society 2018. We have succeeded in detecting the degradation of cable’s polymeric insulation well before its continual use becomes risky. Degradation of organic polymers is mainly caused by oxidation if the ambience around the cable contains oxygen. When organic polymers are oxidized, polar carbonyl groups are formed, by which the permittivity is increased. This in turn decreases the characteristic impedance of a polymer-insulated cable. If we inject electromagnetic waves in a very wide frequency range into the cable and measure the ratio of reflected power to injected power, the information on the effects of the characteristic impedance changes is included in the frequency spectra of the ratio. If we do inverse Fourier transform, we can convert the data to a time domain. Therefore, we can know the degraded portion by multiplying the velocity of electromagnetic waves in the cable.

Enhanced conductivity of polyaniline in the presence of nonionic amphiphilic polymers and their diverse morphologies

Yang, Liuqing; Yang, Liuqing; Yang, Liuqing; Wu, Wenling; Ohki, Yoshimichi; Feng, Yang; Li, Shengtao

Journal of Applied Polymer Science 134(47) 2017/12-2017/12

DOIScopus

Detail

ISSN:00218995

Outline:© 2017 Wiley Periodicals, Inc. Poly(ethylene oxide) (PEO) and its copolymers have excellent affinity for protons and contribute to proton transfer. In the present study, PEO and its copolymers, poly[(ethylene oxide) 20 -(propylene oxide) 70 -(ethylene oxide) 20 ] (EO 20 PO 70 EO 20 , P123) and poly[(ethylene oxide) 106 -(propylene oxide) 70 -(ethylene oxide) 106 ] (EO 106 PO 70 EO 106 , F127), have been found to significantly enhance the conductivity of polyaniline (PANI). After introducing these polymers, the conductivity of PANI is markedly promoted more than two orders of magnitude compared to that of PANI without additives, from 5.2 to 667 S/m. The molecular weight of PEO affects the conductivity of PANI/PEO. The mechanism by which these amphiphilic polymers are beneficial to the conductivity of PANI is studied experimentally and theoretically. The PANI/P123 prepared in the presence of PEO block copolymer shows gradually varying morphologies containing leaflike sheets, rodlike particles, and uniform chestnutlike sphere particles. This is similar to the morphology change of micelles with surfactant concentration. PEO, P123, and F127 are further found to have a positive effect on PANI as a material for sensors or supercapacitors, since high specific capacity and fast response rate are desired qualities in sensors and supercapacitors. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45547.

Far-Infrared Absorption of Deoxyribonucleic Acid with Thymine

Kitamura, Ayano; Komatsu, Marina; Mizuno, Maya; Kojima, Hiroaki; Ohki, Yoshimichi; Ohki, Yoshimichi

Electronics and Communications in Japan 100(12) p.53 - 602017/12-2017/12

DOIScopus

Detail

ISSN:19429533

Outline:© 2017 Wiley Periodicals, Inc. Recently, attempts to use deoxyribonucleic acid (DNA) as an industrially important substance have been emerging. For that purpose, easy and convenient determination of the high-order structure of DNA is desirable. In this research, we measured far-infrared absorption spectra of various synthetic single-stranded DNAs, each with an identical base in its nucleotides, and found that DNAs with different bases exhibit different spectra. We also demonstrated that the number of thymine bases on a single-stranded DNA can be estimated from the spectra.

Insulation performance of safety-related cables for nuclear power plants under simulated severe accident conditions

Minakawa, Takefumi; Minakawa, Takefumi; Ikeda, Masaaki; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi

Proceedings of the International Symposium on Electrical Insulating Materials 2p.716 - 7192017/12-2017/12

DOIScopus

Detail

Outline:© 2017 Institute of Electrical Engineers of Japan. All rights reserved. To examine electrical insulation behavior of cables under severe accident environmental conditions, safety-related low voltage cables used as severe accident management equipment were subjected to two tests that simulated two environments: 1) at 155 oC, which is the simulated highest assumed temperature when proper accident management measures are taken, 2) at 200 oC, which is the maximum durable temperature of a primary containment vessel. In addition, electrical insulation resistance was measured for the cables during steam exposure in the two tests. As a result, all the cables passed the acceptance criteria of the tests. The minimum volume resistivity of the cables during the test at 155 oC was around 10 8 Ωm, confirming that the cables have a sufficient insulation performance. On the other hand, the minimum volume resistivity during the severer test at 200 oC was around 10 5 Ωm due to the increase in leak current.

Correlation between indenter modulus and elongation-at-break observed for four electrical insulating polymers

Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi

Proceedings of the International Symposium on Electrical Insulating Materials 2p.753 - 7562017/12-2017/12

DOIScopus

Detail

Outline:© 2017 Institute of Electrical Engineers of Japan. All rights reserved. The correlation between degradation-induced changes in two important indicators of mechanical properties, namely elongation at break (EAB) and indenter modulus (IM), is examined for flame-retardant ethylene propylene rubber (FR-EPR), silicone rubber (SiR), flame-retardant crosslinked polyethylene (FR-XLPE), and XLPE. The samples were degraded by heat or concurrently by heat and radiation. In the case that the polymers become hard after they were degraded, the two indicators show a good correlation. However, if they become brittle, their correlation is not good. Regarding this, their correlation is good in SiR, while it is not good in FR-XLPE and XLPE. In FR-EPR, the correlativity changes, depending on the aging condition and presumably its additives.

Terahertz absorption spectroscopy of poly(ether ether ketone)

Kaneko, Takuya; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi

Proceedings of the International Symposium on Electrical Insulating Materials 2p.539 - 5422017/12-2017/12

DOIScopus

Detail

Outline:© 2017 Institute of Electrical Engineers of Japan. All rights reserved. The crystallinity of sheets of poly(ether ether ketone) (PEEK) was changed by thermal treatments conducted at 295 oC for various periods and their terahertz (THz) and Fouriertransform infrared absorption (FT-IR) spectra were obtained. As a result, it has been confirmed that an absorption peak appears at around 3.5 THz in the sheet samples that exhibit clear X-ray diffraction patterns at 20= 18.8, 20.8, 22.8, and 28.8o. In contrast, no obvious sample-dependent changes were observed in FT-IR spectra. The absorption at around 3.5 THz shows a shift in frequency to a degree proportional to the crystallinity. Its maximum intensity is also in proportion to the crystallinity. These results indicate that the absorption at 3.62 THz has a close relation with the crystallinity of PEEK This in turn means that the THz absorption spectroscopy can be used for estimating the crystallinity of PEEK.

Effects of addition of MgO fillers with various sizes and co-addition of nano-sized SiO2fillers on the dielectric properties of epoxy resin

Yanashima, Ryosuke; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi

Proceedings of the International Symposium on Electrical Insulating Materials 2p.650 - 6532017/12-2017/12

DOIScopus

Detail

Outline:© 2017 Institute of Electrical Engineers of Japan. All rights reserved. Complex permittivity (ϵ r ' and ϵ r "), conductivity (σ), and glass transition temperature (T g ) were measured for composites of epoxy resin and MgO fillers with various sizes in a wide temperature and frequency range. The effect of coaddition of nano-sized SiO 2 was also examined. It has become clean that T g decreases by the addition of MgO fillers, and its decrement becomes more with a decrease in filler size. Moreover, T g decreases if the silica nanofillers are co-added. However, all the three important parameters for electrical insulation ability of polymers, namely ϵ r ', ϵ r ", and σ, decrease with the decrease in size of MgO fillers or by the addition of silica nanofillers at high temperatures and low frequencies. This is a very astonishing result, since it seems reasonable that a polymer with a high T g should have a better insulating ability. Probably, the above-mentioned results indicate that the charge transport becomes more difficult, presumably resulting from the suppression of molecular motion with the decrease in size of MgO fillers and by the co-addition of SiO 2 nanofillers. This indicates that the suppression of molecular motion becomes very strong if the filler size is small, making the carrier transport difficult even in polymers with low T g .

Dielectric absorption behavior of YAlO3at terahertz frequencies

Morimoto, Takaaki; Kuroda, Yasuhiro; Ohki, Yoshimichi; Ohki, Yoshimichi

Japanese Journal of Applied Physics 56(10) 2017/10-2017/10

DOIScopus

Detail

ISSN:00214922

Outline:© 2017 The Japan Society of Applied Physics. Using THz time-domain spectroscopy, optical or dielectric absorption spectra were obtained for YAlO 3 (100) single crystals. A sharp absorption peak appears at around 3.4 THz only when the THz electric field is parallel to the sample's [011] axis. This peak should be due to a normal mode of vibration, to which Y largely contributes.

Optimization of a waveguide-mode sensing chip for an ultraviolet near-field illumination biosensor

Kuroda, Chiaki; Ohki, Yoshimichi; Ohki, Yoshimichi; Fujimaki, Makoto; Fujimaki, Makoto

Optics Express 25(21) p.26011 - 260192017/10-2017/10

PubMedDOIScopus

Detail

Outline:© 2017 Optical Society of America. A waveguide-mode sensor with a planar sensing chip, consisting of two waveguiding layers and a glass substrate, is a promising candidate for a near-field illumination biosensor. Aiming at using fluorescent labeling induced by ultraviolet light, we optimize the structure of a waveguide-mode sensing chip, based on the mechanism for enhancing ultraviolet near-field light revealed by numerical calculations. Candidates of optimal materials are also presented. The chip optimized as above should be able to enhance the intensity of ultraviolet near-field light 25 times as high as an Al surface plasmon resonance sensing chip.

Dielectric and carrier transport properties of silicone rubber degraded by gamma irradiation

Min, Daomin; Min, Daomin; Yan, Chenyu; Huang, Yin; Li, Shengtao; Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi

Polymers 9(10) 2017/10-2017/10

DOIScopus

Detail

Outline:© 2017 by the authors. Silicone rubber (SiR) is used as an insulating material for cables installed in a nuclear power plant. Gamma rays irradiated SiR sheets for various periods at temperatures of 145 and 185 °C, and the resultant changes were analyzed by examining complex permittivity spectra and surface potential decay characteristics. Three different processes, namely, instantaneous polarization, electrode polarization due to the accumulation of ions to form double charge layers at dielectric/electrode interfaces, and DC conduction caused by directional hopping of ions, contribute to the complex permittivity. By fitting the spectra to theoretical equations, we can obtain the dielectric constant at high frequencies, concentration and diffusion coeffcient of ions and DC conductivity for the pristine and degraded samples. The instantaneous polarization becomes active with an increase of dose and ageing temperature. The thermal expansion coeffcient estimated from the temperature dependence of dielectric constant at high frequencies becomes smaller with an increase in dose, which is in good agreement with the experimental results of the swelling ratio. Additionally, trap distributions are calculated from surface potential decay measurements and analyzed to explain the variation in conductivity. Trap energy increases firstly, and then decreases with an increase in dose, leading to a similar change in DC conductivity. It is concluded that generations of both oxidative products and mobile ions, as well as the occurrence of chain scission and crosslinking are simultaneously induced by gamma rays.

Terahertz absorption spectra of antioxidants in insulating polymers

Kozai, Takuya; Kaneko, Takuya; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi

Proceedings of the International Symposium on Electrical Insulating Materials 1p.61 - 642017/10-2017/10

Scopus

Detail

Outline:Terahertz absorption spectra were measured for nine kinds of antioxidants. The spectra were also measured for lowdensity polyethylene sheets that contain each antioxidant with different contents. As a result, a fingerprint spectrum appears for each antioxidant, from which the antioxidants become distinguishable and their contents can be estimated.

Dielectric absorption behavior of YAlO

Morimoto Takaaki;Kuroda Yasuhiro;Ohki Yoshimichi

Jpn. J. Appl. Phys. 56(10) 2017/09-2017/09

CiNii

Detail

ISSN:0021-4922

Outline:Using THz time-domain spectroscopy, optical or dielectric absorption spectra were obtained for YAlO3(100) single crystals. A sharp absorption peak appears at around 3.4 THz only when the THz electric field is parallel to the sample’s [011] axis. This peak should be due to a normal mode of vibration, to which Y largely contributes.

Aging of poly(ether ether ketone) by heat and gamma rays — Its degradation mechanism and effects on mechanical, dielectric and thermal properties

Yang, Liuqing; Yang, Liuqing; Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi; Hirai, Naoshi; Hanada, Shugo

Polymer Degradation and Stability 142p.117 - 1282017/08-2017/08

DOIScopus

Detail

ISSN:01413910

Outline:© 2017 Elsevier Ltd In radiation research facility, where heat and radiation are two crucial factors inducing material degradation, highly stable materials are required. In the present work, various properties of poly(ether ether ketone) (PEEK) exposed to heat and gamma rays in air are instrumentally investigated. If PEEK is aged by heat and gamma irradiation in air, chemical bond scission, oxidation, crosslinking, and char formation occur as competing mechanisms. The temperature plays a decisive role in degradation, while the irradiation accelerates it. The mechanical properties deteriorate much earlier than the dielectric properties with the progress of aging. This means that the mechanical properties can be an important condition monitoring factor compared to the dielectric properties for PEEK-insulated apparatus or cables. If PEEK is aged severely, its electrical conductivity increases dramatically, whereas both real and imaginary parts of complex dielectric permittivity decrease, showing a marked contrast to many industrially important polymeric insulating materials.

Detection of norovirus virus-like particles using a surface plasmon resonance-assisted fluoroimmunosensor optimized for quantum dot fluorescent labels

Ashiba, Hiroki; Sugiyama, Yuki; Wang, Xiaomin; Shirato, Haruko; Higo-Moriguchi, Kyoko; Taniguchi, Koki; Ohki, Yoshimichi; Fujimaki, Makoto

Biosensors and Bioelectronics 93p.260 - 2662017/07-2017/07

PubMedDOIScopus

Detail

ISSN:09565663

Outline:© 2016 The Authors A highly sensitive biosensor to detect norovirus in environment is desired to prevent the spread of infection. In this study, we investigated a design of surface plasmon resonance (SPR)-assisted fluoroimmunosensor to increase its sensitivity and performed detection of norovirus virus-like particles (VLPs). A quantum dot fluorescent dye was employed because of its large Stokes shift. The sensor design was optimized for the CdSe-ZnS-based quantum dots. The optimal design was applied to a simple SPR-assisted fluoroimmunosensor that uses a sensor chip equipped with a V-shaped trench. Excitation efficiency of the quantum dots, degree of electric field enhancement by SPR, and intensity of autofluorescence of a substrate of the sensor chip were theoretically and experimentally evaluated to maximize the signal-to-noise ratio. As the result, an excitation wavelength of 390 nm was selected to excite SPR on an Al film of the sensor chip. The sandwich assay of norovirus VLPs was performed using the designed sensor. Minimum detectable concentration of 0.01 ng/mL, which corresponds to 100 virus-like particles included in the detection region of the V-trench, was demonstrated.

Terahertz spectroscopic analysis of crystal growth in poly(ethylene naphthalate)

Odaka, Daisuke; Ohki, Yoshimichi; Ohki, Yoshimichi

Japanese Journal of Applied Physics 56(7) 2017/07-2017/07

DOIScopus

Detail

ISSN:00214922

Outline:© 2017 The Japan Society of Applied Physics. Terahertz absorption spectra and X-ray diffraction patterns were measured for amorphous poly(ethylene naphthalate) (PEN) while the sample temperature was elevated from 25 to 230°C then lowered back to 25 °C. Before the elevation of the temperature, PEN exhibited broad absorption with a maximum at around 2.6 THz. This absorption seems to originate from amorphous regions. As the sample temperature increases, PEN becomes crystallized in the form of α crystal. With this change in crystallinity, the 2.6 THz absorption becomes smaller, while another absorption peak at 2.05 THz, originating from crystalline regions, becomes larger. Furthermore, in the cooling process to 25°C, the 2.05 THz absorption shifts to 2.15 THz and the lattice constants associated with this absorption become smaller. Therefore, intermolecular vibrations closely related to the crystal growth in PEN at high temperatures seem to be responsible for the THz absorption.

Terahertz spectroscopic analysis of crystal growth in poly(ethylene naphthalate)

Odaka Daisuke;Ohki Yoshimichi

Jpn. J. Appl. Phys. 56(7) 2017/06-2017/06

CiNii

Detail

ISSN:0021-4922

Outline:Terahertz absorption spectra and X-ray diffraction patterns were measured for amorphous poly(ethylene naphthalate) (PEN) while the sample temperature was elevated from 25 to 230 °C then lowered back to 25 °C. Before the elevation of the temperature, PEN exhibited broad absorption with a maximum at around 2.6 THz. This absorption seems to originate from amorphous regions. As the sample temperature increases, PEN becomes crystallized in the form of α crystal. With this change in crystallinity, the 2.6 THz absorption becomes smaller, while another absorption peak at 2.05 THz, originating from crystalline regions, becomes larger. Furthermore, in the cooling process to 25 °C, the 2.05 THz absorption shifts to 2.15 THz and the lattice constants associated with this absorption become smaller. Therefore, intermolecular vibrations closely related to the crystal growth in PEN at high temperatures seem to be responsible for the THz absorption.

Comparison between poly(ethylene naphthalate) and poly(ethylene terephthalate) in terms of gamma-ray irradiation on their dielectric properties

Miyamoto, Maki; Ohki, Yoshimichi; Ohki, Yoshimichi

Japanese Journal of Applied Physics 56(6) 2017/06-2017/06

DOIScopus

Detail

ISSN:00214922

Outline:© 2017 The Japan Society of Applied Physics. The effects of gamma-rays on the complex permittivity (ϵr' and ϵr'') and electrical conductivity were compared between poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET). Although both ϵ'r and ϵ''r increase in PET with an increase in the total dose of gamma irradiation, such increases are hardly observed in PEN. The conductivity is always smaller in PEN than in PET. Therefore, it has been confirmed that charge transport is less activated by gamma irradiation in PEN than in PET. Together with experimental results obtained by ultraviolet-visible absorption spectroscopy and thermogravimetric analysis, it can be concluded that PEN has a superior anti-gamma-ray dielectric property to PET.

Comparison between poly(ethylene naphthalate) and poly(ethylene terephthalate) in terms of gamma-ray irradiation on their dielectric properties

Miyamoto Maki;Ohki Yoshimichi

Jpn. J. Appl. Phys. 56(6) 2017/05-2017/05

CiNii

Detail

ISSN:0021-4922

Outline:The effects of gamma-rays on the complex permittivity ([Formula: see text] and [Formula: see text]) and electrical conductivity were compared between poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET). Although both [Formula: see text] and [Formula: see text] increase in PET with an increase in the total dose of gamma irradiation, such increases are hardly observed in PEN. The conductivity is always smaller in PEN than in PET. Therefore, it has been confirmed that charge transport is less activated by gamma irradiation in PEN than in PET. Together with experimental results obtained by ultraviolet–visible absorption spectroscopy and thermogravimetric analysis, it can be concluded that PEN has a superior anti-gamma-ray dielectric property to PET.

Blue-laser scanned imaging system using positioning marks formed on an optical disk substrate

Shima, Takayuki; Wang, Xiaomin; Wang, Xiaomin; Shiramizu, Hideyuki; Fujimaki, Makoto; Fujimaki, Makoto; Awazu, Koichi; Ohki, Yoshimichi

Japanese Journal of Applied Physics 56(5) 2017/05-2017/05

DOIScopus

Detail

ISSN:00214922

Outline:© 2017 The Japan Society of Applied Physics. We improved the optical disk-based imaging system to make more precise images at low cost for safety enhancement applications to observe and detect micrometer-order hazardous substances collected on a large-area surface. An optical disk substrate with positioning marks is prepared, and a signal processor is developed to automatically construct an image using the marks. We successfully obtained an image of Escherichia coli dispersed on an optical disk sample surface with a laser-scanning interval of 0.40μm in the optical disk's radial direction; this interval is reduced from the 0.74 and 1.36μm intervals demonstrated in our previous papers.

Improved high-temperature dielectric property of epoxy resin composites with nano- and micro-sized magnesia fillers

Xie, Q.; Ohki, Y.; Hirai, N.; Cheng, Y. H.

2017 IEEE International Workshop on Integrated Power Packaging, IWIPP 2017 2017/05-2017/05

DOIScopus

Detail

Outline:© 2017 IEEE. Nano-sized magnesium oxide or magnesia has been reported to be useful for suppressing the space charge accumulation when it is added in epoxy resin. However, the addition of nano-magnesia to epoxy resin decreases the glass transition temperature (Tg) signficantly, which may limit industrial applications of magnesia/epoxy nanocomposites. In this work, nanomagnesia particles with an average size of 52 nm and micro-magnesia with an average size of 3.1 pm were mixed in a commercially available bisphenol-A epoxy resin. The weight ratio of nano- and micro-fillers in each composite was changed, while the total content of the two fillers was fixed at 5 weight%. As a result, it has become clear that the addition of micro-sized magnesia fillers to magnesia/epoxy nanocomposites recovers Tg back to its original high temperature. Then, a dc electric field of 30 kV/mm was applied to the samples for 20 minutes at various temperatures from 40 to 200 °C and space charge distributions were measured by the pulsed electro-Acoustic method. The results show that space charge accumulates in both vicinities of the cathode and the anode with the same polarities as those of the nearby electrodes when the temperature is 80 °C or below. However, space charges become hetero and are observed only in the vicinity of the cathode at 140 °C and above. These homocharges and heterocharges become very small when the weight content of nano-sized fillers increases, which is industrially very important. Both complex dielectric permittivity and electrical conductivity also decrease with the increase in the content of nanofillers.

Crystallinity of poly(ethylene naphthalate) and its relation to terahertz absorption

Odaka, Daisuke; Ohki, Yoshimichi; Ohki, Yoshimichi; Mizuno, Maya

Japanese Journal of Applied Physics 56(3) 2017/03-2017/03

DOIScopus

Detail

ISSN:00214922

Outline:© 2017 The Japan Society of Applied Physics. The crystallinity of poly(ethylene naphthalate) (PEN) was changed by thermal annealing and its effects on terahertz absorption spectra and X-ray diffraction patterns were examined. As a result, the intensity of a relatively sharp absorption peak at around 2.2 THz was found to be proportional to the crystallinity. As a plausible cause of this absorption, a lattice vibration, a torsional vibration, or their combination mode associated with (010) planes in crystal α of PEN is proposed. Therefore, the crystallinity of PEN can be estimated from the intensity of this absorption.

Design of a sedimentation hole in a microfluidic channel to remove blood cells from diluted whole blood

Kuroda, Chiaki; Ohki, Yoshimichi; Ohki, Yoshimichi; Ashiba, Hiroki; Fujimaki, Makoto; Fujimaki, Makoto; Awazu, Koichi; Makishima, Makoto

Japanese Journal of Applied Physics 56(3) 2017/03-2017/03

DOIScopus

Detail

ISSN:00214922

Outline:© 2017 The Japan Society of Applied Physics. With the aim of developing a sensor for rapidly detecting viruses in a drop of blood, in this study, we analyze the shape of a hole in a microfluidic channel in relation to the efficiency of sedimentation of blood cells. The efficiency of sedimentation is examined on the basis of our calculation and experimental results for two types of sedimentation hole, cylindrical and truncated conical holes, focusing on the Boycott effect, which can promote the sedimentation of blood cells from a downward-facing wall. As a result, we demonstrated that blood cells can be eliminated with an efficiency of 99% or higher by retaining a diluted blood sample of about 30 μL in the conical hole for only 2 min. Moreover, we succeeded in detecting the antihepatitis B surface antigen antibody in blood using a waveguide-mode sensor equipped with a microfluidic channel having the conical sedimentation hole.

Design of a sedimentation hole in a microfluidic channel to remove blood cells from diluted whole blood

Kuroda Chiaki;Ohki Yoshimichi;Ashiba Hiroki;Fujimaki Makoto;Awazu Koichi;Makishima Makoto

Jpn. J. Appl. Phys. 56(3) 2017/02-2017/02

CiNii

Detail

ISSN:0021-4922

Outline:With the aim of developing a sensor for rapidly detecting viruses in a drop of blood, in this study, we analyze the shape of a hole in a microfluidic channel in relation to the efficiency of sedimentation of blood cells. The efficiency of sedimentation is examined on the basis of our calculation and experimental results for two types of sedimentation hole, cylindrical and truncated conical holes, focusing on the Boycott effect, which can promote the sedimentation of blood cells from a downward-facing wall. As a result, we demonstrated that blood cells can be eliminated with an efficiency of 99% or higher by retaining a diluted blood sample of about 30 µL in the conical hole for only 2 min. Moreover, we succeeded in detecting the anti-hepatitis B surface antigen antibody in blood using a waveguide-mode sensor equipped with a microfluidic channel having the conical sedimentation hole.

Crystallinity of poly(ethylene naphthalate) and its relation to terahertz absorption

Odaka Daisuke;Ohki Yoshimichi;Mizuno Maya

Jpn. J. Appl. Phys. 56(3) 2017/02-2017/02

CiNii

Detail

ISSN:0021-4922

Outline:The crystallinity of poly(ethylene naphthalate) (PEN) was changed by thermal annealing and its effects on terahertz absorption spectra and X-ray diffraction patterns were examined. As a result, the intensity of a relatively sharp absorption peak at around 2.2 THz was found to be proportional to the crystallinity. As a plausible cause of this absorption, a lattice vibration, a torsional vibration, or their combination mode associated with (010) planes in crystal α of PEN is proposed. Therefore, the crystallinity of PEN can be estimated from the intensity of this absorption.

Complex Permittivity Spectra of Various Insulating Polymers at Ultrawide-Band Frequencies

Hasegawa, Yuka; Ohki, Yoshimichi; Ohki, Yoshimichi; Fukunaga, Kaori; Mizuno, Maya; Sasaki, Kensuke

Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) 198(3) p.11 - 182017/02-2017/02

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ISSN:04247760

Outline:© 2016 Wiley Periodicals, Inc. Nowadays, trials to use even higher frequencies are pursued to realize high-speed wireless communications. In order to respond to such a trend, dielectric properties of insulating polymers at high frequencies have to be clarified, although the importance of clarifying low-frequency properties is still very high, especially for use as high-voltage insulators. In this regard, complex permittivity spectra from 10 mHz to 4.0 THz were obtained for various insulating polymers. The spectra obtained in the very wide frequency range are important, because they can be a valuable database and they provide various pieces of important information on dielectric characteristics.

Far-infrared absorption of deoxyribonucleic acid with thymine

Kitamura, Ayano; Komatsu, Marina; Mizuno, Maya; Kojima, Hiroaki; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEJ Transactions on Fundamentals and Materials 137(1) p.88 - 942017/01-2017/01

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ISSN:03854205

Outline:© 2017 The Institute of Electrical Engineers of Japan.Recently, attempts to use deoxyribonucleic acid (DNA) as an industrially important substance have been emerging. For that purpose, easy and convenient determination of the higher-order structure of DNA is desirable. In this research, we measured far-infrared absorption spectra of various synthetic single stranded DNAs, each with an identical base in its nucleotides, and found that DNAs with different bases exhibit different spectra. We also demonstrated that the number of thymine bases on a single stranded DNA can be estimated from the spectra.

Comparison between far-IR and IR absorption spectroscopy for estimating vinyl acetate content in ethylene-vinyl acetate copolymer

Odaka, Daisuke; Izutsu, Tomoyuki; Komatsu, Marina; Ohki, Yoshimichi; Ohki, Yoshimichi; Mizuno, Maya

IEEJ Transactions on Fundamentals and Materials 137(3) p.171 - 1772017/01-2017/01

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ISSN:03854205

Outline:© 2017 The Institute of Electrical Engineers of Japan.Far-IR absorption spectra at frequencies from 0.5 to 21.0 THz were obtained for sheets of ethylene-vinyl acetate copolymer (EVA) containing different contents of vinyl acetate (VA) from 12 to 60% with different thicknesses from 1.0 to 3.0 mm. As a result, EVA exhibits absorption at 2.5, 6.7, 10.5, 11-17, and 17-20 THz. Especially, the 2.5-THz intensity with a good proportionality up to 60% of VA content exhibits comparable accuracy to the IR method and is applicable for estimating the VA content in EVA sheets 2.0 or 3.0 mm thick, for which IR method is difficult to be applied.

Terahertz imaging of iron powder in low density polyethylene sheets

Kozai, Takuya; Odaka, Daisuke; Ohki, Yoshimichi; Ohki, Yoshimichi; Saitou, Takashi; Yamazaki, Takanori

IEEJ Transactions on Fundamentals and Materials 137(5) p.311 - 3122017/01-2017/01

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ISSN:03854205

Outline:© 2017 The Institute of Electrical Engineers of Japan.If powder of iron is included in the insulation of a polymer-insulated cable during its manufacturing process, breakdown or a water tree would be triggered from there. In this study, we mixed powder of iron into a sheet of low-density polyethylene and measured spatial distributions of absorption at terahertz (THz) frequencies. As a result, it has become clear that the absorption increases in the whole range from 0.5 to 5.0 THz at the places where the powder exists, even if the sheet is covered with an opaque carbon-black-loaded polyethylene sheet.

Complex Permittivity Spectra of Various Insulating Polymers at Ultrawide-Band Frequencies

Hasegawa, Yuka;Ohki, Yoshimichi;Fukunaga, Kaori;Mizuno, Maya;Sasaki, Kensuke

ELECTRICAL ENGINEERING IN JAPAN 198(3) p.11 - 182017-2017

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ISSN:0424-7760

Far-infrared Absorption of Deoxyribonucleic Acid with Thymine

Kitamura Ayano;Komatsu Marina;Mizuno Maya;Kojima Hiroaki;Ohki Yoshimichi

IEEJ Transactions on Fundamentals and Materials 137(1) p.88 - 942017-2017

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Detail

ISSN:0385-4205

Outline:

Recently, attempts to use deoxyribonucleic acid (DNA) as an industrially important substance have been emerging. For that purpose, easy and convenient determination of the higher-order structure of DNA is desirable. In this research, we measured far-infrared absorption spectra of various synthetic single stranded DNAs, each with an identical base in its nucleotides, and found that DNAs with different bases exhibit different spectra. We also demonstrated that the number of thymine bases on a single stranded DNA can be estimated from the spectra.

Comparison between Far-IR and IR Absorption Spectroscopy for Estimating Vinyl Acetate Content in Ethylene-vinyl Acetate Copolymer

Odaka Daisuke;Izutsu Tomoyuki;Komatsu Marina;Ohki Yoshimichi;Mizuno Maya

IEEJ Transactions on Fundamentals and Materials 137(3) p.171 - 1772017-2017

CiNii

Detail

ISSN:0385-4205

Outline:

Far-IR absorption spectra at frequencies from 0.5 to 21.0 THz were obtained for sheets of ethylene-vinyl acetate copolymer (EVA) containing different contents of vinyl acetate (VA) from 12 to 60% with different thicknesses from 1.0 to 3.0 mm. As a result, EVA exhibits absorption at 2.5, 6.7, 10.5, 11-17, and 17-20 THz. Especially, the 2.5-THz intensity with a good proportionality up to 60% of VA content exhibits comparable accuracy to the IR method and is applicable for estimating the VA content in EVA sheets 2.0 or 3.0 mm thick, for which IR method is difficult to be applied.

Terahertz Imaging of Iron Powder in Low Density Polyethylene Sheets

Kozai Takuya;Odaka Daisuke;Ohki Yoshimichi;Saitou Takashi;Yamazaki Takanori

IEEJ Transactions on Fundamentals and Materials 137(5) p.311 - 3122017-2017

CiNii

Detail

Outline:

If powder of iron is included in the insulation of a polymer-insulated cable during its manufacturing process, breakdown or a water tree would be triggered from there. In this study, we mixed powder of iron into a sheet of low-density polyethylene and measured spatial distributions of absorption at terahertz (THz) frequencies. As a result, it has become clear that the absorption increases in the whole range from 0.5 to 5.0 THz at the places where the powder exists, even if the sheet is covered with an opaque carbon-black-loaded polyethylene sheet.

Chemiluminescence characteristics of FR-EPDM and SiR aged by concurrently-given heat and radiation

Ikeno, Risa; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi

Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2016-Decemberp.853 - 8562016/12-2016/12

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ISSN:00849162

Outline:© 2016 IEEE.Flame-retardant ethylene propylene diene copolymer (FR-EPDM) and silicone rubber (SiR) were aged by heat with or without concurrent irradiation of gamma rays. For these samples, chemiluminescence (CL) and infrared absorption spectra were measured. Although the CL intensity decreases with an increase in total dose of gamma rays both in FR-EPDM and SiR, this negative dose-dependence is weaker in FR-EPDM than in SiR. This is reasonable, since CL appears when a substance is oxidized. Namely, the CL intensity becomes weak if the sample was already oxidized. While FR-EPDM is an organic polymer that can be oxidized easily, SiR is an inorganic polymer with siloxane bonds. Moreover, carbonyl groups appear when FR-EPDM is degraded, while SiR forms mainly a crosslinked structure by bridging two silicons by one oxygen when it is irradiated by gamma rays. Such differences in degradation mechanism between two insulating polymers are reflected on their CL properties.

Aging mechanism of silicone rubber by heat and gamma-rays

Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi; Hanada, Shugo; Miyamoto, Maki; Hirai, Naoshi; Yang, Liuqing; Yang, Liuqing

Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2016-Decemberp.869 - 8722016/12-2016/12

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ISSN:00849162

Outline:© 2016 IEEE.The aging mechanism of silicone rubber, which is important for electrical insulation of cables, is examined from many aspects such as instrumental, chemical, electrical, and mechanical analyses. As a result, it has become clear that silicone rubber degrades by forming crosslinked structures via the formation of abundant siloxane bonds.

Space charge distributions in epoxy/MgO nanocomposites at various temperatures

Xie, Q.; Xie, Q.; Cheng, Y. H.; Hirai, N.; Ohki, Y.; Ohki, Y.; Ohki, Y.

ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application 2016/12-2016/12

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Outline:© 2016 IEEE.The effect of addition of nano-sized magnesia fillers to epoxy resin on the distribution of space charges is examined at various temperatures from 40 to 200 °C. Although the spatial distribution of space charges in the sample varies depending on temperature and filler content, magnesia nanocomposites exhibit a smaller amount of homocharge near the cathode than the unfilled epoxy resin at 40 and 80 °C. At 120 and 140 °C, although the polarity of space charge in the vicinity of the cathode becomes positive or hetero, its amount becomes smaller with the increase in content of magnesia nanofillers. This finding agrees well with the fact that magnesia nanofillers effectively suppress the formation of space charge in low-density or crosslinked polyethylene. As another distinctive feature, it has become clear that the addition of magnesia nanofillers effectively suppresses carrier transport, especially at high temperatures.

Comparison of location abilities of degradation in a polymer-insulated cable between frequency domain reflectometry and line resonance analysis

Ohki, Yoshimichi; Ohki, Yoshimichi; Hirai, Naoshi

ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application 2016/12-2016/12

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Outline:© 2016 IEEE.The ability of locating a degraded portion in a double-core cable insulated with silicone rubber (SiR) or in a coaxial cable insulated with low-density polyethylene (LDPE) was compared between a system based on frequency domain reflectometry (FDR) being developed by the authors and a commercially available system called line resonance analysis (LIRA). Both the FDR and the LIRA methods cannot detect the degradation of SiR before its further use becomes uncommend-able in a nuclear power plant. However, for location trials of the degraded portion in the LDPE coaxial cable, the FDR method showed a higher sensitivity and a better resolution than LIRA.

Dielectric spectroscopic analysis of degradation in ethylene-propylene-diene copolymer

Min, Daomin; Min, Daomin; Li, Shengtao; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEE Transactions on Dielectrics and Electrical Insulation 23(6) p.3620 - 36302016/12-2016/12

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ISSN:10709878

Outline:© 2016 IEEE.Gamma-ray induced changes occurring in ethylene-propylene-diene copolymer (EPDM) were analyzed through its complex permittivity spectra. First, four different processes, namely, instantaneous polarization, hopping of ions, segmental relaxation, and dc conduction are found to contribute to the complex permittivity. By fitting the spectra to theoretical equations, it has become clear that the instantaneous polarization and ionic hopping become active by the irradiation, indicating that generation of oxidative products and mobile ions and occurrence of chain scission are induced by gamma rays. Furthermore, since both the thermal expansion and the contribution of the segmental relaxation to the permittivity become less with an increase in dose, it is assumed that crosslinking is induced by the gamma irradiation.

Fault location in a cable for a nuclear power plant by frequency domain reflectometry

Ohki, Yoshimichi; Ohki, Yoshimichi; Hirai, Naoshi

CMD 2016 - International Conference on Condition Monitoring and Diagnosis p.36 - 392016/11-2016/11

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Outline:© 2016 IEEE.Cables installed in nuclear power plants are subjected to thermal burden and radioactive rays. Regarding this, if we want to monitor the integrity of a cable in a nuclear power plant continuously, we have to do measurements while the cable is heated and irradiated. In this research, we obtained frequency domain reflectometry signals for a 50-m long cable insulated with flame-retardant ethylene propylene diene copolymer (FR-EPDM) installed in an environment where heat and radiation were given simultaneously. Then, we separated signals originating in the degradation of the insulation from those due to heat and radiation. This result indicates that the separation of the signal arising from the degradation of insulation from other signals due to heat and radiation is in principle possible at least as far as FR-EPDM insulated cables are concerned.

Non-destructive diagnosis of degradation of silicone rubber by indenter modulus and scanning probe microscopy

Hanada, Shugo; Odaka, Daisuke; Yang, Liuqing; Yang, Liuqing; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi

CMD 2016 - International Conference on Condition Monitoring and Diagnosis p.123 - 1262016/11-2016/11

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Outline:© 2016 IEEE.We aged silicone rubber, which is widely used for electrical insulation of cables in nuclear power plants under various conditions. The surface of each sample was measured by an indenter and a scanning probe microscope (SPM) for non-destructive diagnosis. As a result, it has become clear that the surface of silicone rubber becomes hard with the progress of degradation in both cases of thermal aging and simultaneous aging by heat and radiation. The indenter modulus shows a good correlation with the elongation at break (EAB). On the other hand, the delay of phase angle measured by SPM exhibits a rather low correlation with EAB. Through the results of thermal analyses, it seems that the thermal aging without radiation induces cross-linking first, which is followed by bond break. However, bond breakage seems predominant over cross-linking in the simultaneous aging with heat and radiation.

Electronic excitation and relaxation processes of oxygen vacancies in YSZ and their involvement in photoluminescence

Morimoto, Takaaki; Kuroda, Yasuhiro; Ohki, Yoshimichi; Ohki, Yoshimichi

Applied Physics A: Materials Science and Processing 122(9) 2016/09-2016/09

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ISSN:09478396

Outline:© 2016, Springer-Verlag Berlin Heidelberg.Yttria-stabilized zirconia (YSZ) consists of zirconia and yttria and oxygen vacancies appear in accordance with the ratio of yttria. The oxygen vacancy would sometimes give annoyance, but it would be beneficial on other occasions, depending on its applications. Photoluminescence (PL) due to oxygen vacancies induced by photons with energies around 5.5 eV exhibits two decay time constants. As a possible reason for this, an oxygen vacancy changes its charging state from neutral to positive monovalent by losing an electron when YSZ is irradiated by ultraviolet photons. The PL decays either in a ms range or in a ns range, depending on whether the oxygen vacancies are neutral or positive monovalent.

Comparison of gamma-ray resistance between dicyclopentadiene resin and epoxy resin

Miyamoto, M.; Tomite, N.; Ohki, Y.; Ohki, Y.

IEEE Transactions on Dielectrics and Electrical Insulation 23(4) p.2270 - 22772016/08-2016/08

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ISSN:10709878

Outline:© 1994-2012 IEEE.Radiation resistance was compared between dicyclopentadiene (DCP) resin (P) and epoxy resin (E) by analyzing mainly their complex permittivity ( ϵr' and ϵr«) and electrical conductivity. While both ϵr' and ϵr» increase significantly in E with an increase in total dose of the gamma irradiation, no such increases are observed in P. The conductivity is always smaller in P than in E and the difference becomes larger with the increase in total dose. This difference becomes very obvious if we pay attention to electric modulus spectra. These results indicate clearly that P has a better gamma resistance than E.

Observation of crystal growth in polyethylene naphthalate by terahertz spectroscopy

Odaka, D.; Komatsu, M.; Ohki, Y.; Ohki, Y.

Proceedings of the 2016 IEEE International Conference on Dielectrics, ICD 2016 1p.593 - 5962016/08-2016/08

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Outline:© 2016 IEEE.Various properties of polyethylene naphthalate (PEN) are affected by its crystallinity. In this paper, the possibility of using terahertz (THz) spectroscopy as a tool to examine the crystallinity of PEN is studied. When THz absorption is measured while the sample temperature is being raised, an absorption peak suddenly appears at around 2.10 THz at 180 °C. By analyzing the THz spectra together with XRD patterns, we found that the 2.10-THz absorption has a close relation with the crystal form α of PEN and its intensity increases with the progress of crystallization. Therefore, THz absorption spectroscopy can be used for monitoring the crystallization of PEN.

Terahertz spectroscopic diagnosis of degradation of ethylene-propylene-diene copolymer

Ohki, Yoshimichi; Ohki, Yoshimichi; Kozai, Takuya; Komatsu, Marina; Hirai, Naoshi

Proceedings of the 2016 IEEE International Conference on Dielectrics, ICD 2016 2p.646 - 6492016/08-2016/08

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Outline:© 2016 IEEE.Flame-retardant ethylene-propylene-diene copolymer (FR-EPDM) with the same additives as those used in nuclear power plants was analyzed by terahertz (THz) and infrared (IR) absorption spectroscopy, before and after the irradiation by γ-rays. As a result, it has become clear that THz spectroscopy can indicate the degradation of the FR-EPDM samples better than IR spectroscopy. Namely, the THz spectroscopy can indicate the oxidation of the samples, which is difficult by IR spectroscopy.

A new method for estimating the content of vinyl acetate in ethylene-vinyl acetate copolymer

Izutsu, Tomoyuki; Odaka, Daisuke; Komatsu, Marina; Ohki, Yoshimichi; Ohki, Yoshimichi; Mizuno, Maya; Nakamura, Yoshiaki; Chiwata, Naofumi

IEEE Transactions on Dielectrics and Electrical Insulation 23(3) p.1260 - 12652016/06-2016/06

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ISSN:10709878

Outline:© 2016 IEEE.A new method for estimating the content of vinyl acetate (VA) in ethylene-vinyl acetate copolymer (EVA) is proposed. It is a kind of optical absorption spectroscopy in a frequency range from 0.5 to 21.0 THz. Comparison of absorption spectra among sheets of EVA with differing contents of VA from 12 to 60% by weight and a sheet of low-density polyethylene containing no VA revealed that the EVA sheets exhibit relatively sharp absorption at 2.5, 6.7, and 10.5 THz and rather broad absorption at 11 to 17 THz and 17 to 20 THz. All these absorption intensities are in proportion to the content of VA, up to certain contents, which enables us to estimate the content of VA in EVA quantitatively. Among them, the absorption at 2.5 THz measured by THz time-domain spectroscopy shows the best accuracy.

Estimation of gel fraction of polyethylene cross-linked with silane by far-infrared absorption spectroscopy

Takihana, Junya; Komatsu, Marina; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEE Transactions on Dielectrics and Electrical Insulation 23(3) p.1500 - 15052016/06-2016/06

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ISSN:10709878

Outline:© 2016 IEEE.Far-infrared absorption spectra were measured for low density polyethylene in a frequency range from 3.0 to 120 THz. When the polyethylene was cross-linked using vinyl silane, the absorption was found to increase in proportion to the cross-linking degree at 13.2, 30.9, and 32.7 THz, where absorption attributable to Si-O bonds appears. Therefore, the degree of cross-linking of polyethylene by vinyl silane can be estimated by far-infrared absorption spectroscopy.

Erratum: Modeling of oxidation process and property changes of ethylene-propylene-diene copolymer( IEEE Transactions on Dielectrics and Electrical Insulation (2016) 23:1 (537-546))

Min, Daomin; Min, Daomin; Li, Shengtao; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEE Transactions on Dielectrics and Electrical Insulation 23(2) 2016/04-2016/04

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ISSN:10709878

Numerical simulation on molecular displacement and DC breakdown of LDPE

Min, Daomin; Min, Daomin; Li, Shengtao; Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEE Transactions on Dielectrics and Electrical Insulation 23(1) p.507 - 5162016/02-2016/02

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ISSN:10709878

Outline:© 1994-2012 IEEE. It is generally known that the dc breakdown strength of low density polyethylene (LDPE) decreases with as the thickness and temperature of the sample increase. The breakdown strength is influenced by the charge transport and electric field distortion, and is also related to the molecular chain displacement and fracture. This paper investigates mutual relations among the charge transport, molecular chain displacement, and thickness dependent dc breakdown of LDPE. A model that combines the dynamics of charge transport and molecular displacement (CTMD) is used to calculate the space charge accumulation, molecular chain displacement, and dc breakdown properties of LDPE with various thicknesses at various constant voltage ramping rates. It is assumed that breakdown occurs when the molecular chain displacement reaches a critical value. The simulation results show that the breakdown field as a function of sample thickness satisfies an inverse power law with a power index of about 0.43 for various voltage ramping rates. This is consistent with experimental results. The CTMD model considers both the distortion of electric field and the displacement kinetics of molecular chains, resulting in a power index closer to the experiment than that calculated only from the electric field distortion. Adopted a Williams-Landel-Ferry type molecular chain mobility in the CTMD model, the simulation results are consistent with the results calculated by applying experimental results on polyisobutylene and polymethyl methacrylate to the free volume breakdown theory. It is also found that the CTMD model with temperature-dependent molecular chain mobility controlled by piecewise Arrhenius equations can explain well the temperature dependent breakdown experimental results of LDPE.

Effects of the structure and insulation material of a cable on the ability of a location method by FDR

Ohki, Yoshimichi; Ohki, Yoshimichi; Hirai, Naoshi

IEEE Transactions on Dielectrics and Electrical Insulation 23(1) p.77 - 842016/02-2016/02

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ISSN:10709878

Outline:© 1994-2012 IEEE. The authors have demonstrated that the estimation of the precise locations of points in cables aged thermally or mechanically or by the irradiation of gamma rays is possible by a combination of frequency domain reflectometry and inverse fast Fourier transform. This paper examines how this ability of fault location depends on the type, structure, and insulation material of the cable, using several kinds of polymer insulated cables such as a triple core cable insulated with flame-retardant ethylene propylene diene copolymer, a dual core cable insulated with silicone rubber, a dual core cable insulated with crosslinked polyolefin (XLPO), a coaxial cylindrical cable insulated with low density polyethylene, and a flat cord insulated by polyvinyl chloride (PVC). As a result, for cables with lengths from 16 to 72 m, the maximum sensitivity is attained when the highest frequency of the inputted electromagnetic waves is 1.0 GHz or higher for coaxial cables, but around 300 to 800 MHz for dual or triple core cables. For the location attempt of the position heated by a heater, cables insulated with PVC give higher signal intensities than those insulated with XLPO.

Modeling of oxidation process and property changes of ethylene-propylene-diene copolymer

Min, Daomin; Min, Daomin; Li, Shengtao; Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEE Transactions on Dielectrics and Electrical Insulation 23(1) p.537 - 5462016/02-2016/02

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ISSN:10709878

Outline:© 1994-2012 IEEE. The oxidation process induced in ethylene-propylene-diene (EPDM) copolymer by gamma irradiation was simulated by solving equations on chemical reactions and gas diffusion rates. As a result, distributions of oxidative products and gases and changes in material properties were clarified. All the oxidative products such as ketones, alcohols, and carboxylic acids, crosslinks between molecular chains, and chain scissions in EPDM increase with irradiation and they show concave spatial distributions inside the sample sheets. The simulation results demonstrates that EPDM becomes hard when it was irradiated by gamma rays and the increase in hardness is more significant at the surface of the sample sheet than its inside. Moreover, it was found that a low diffusion coefficient of oxygen in EPDM leads to the appearance of a clearer diffusion-limited regime of degradation. These simulation results are in good agreement with experimental results.

Rapid detection of hemagglutination using restrictive microfluidic channels equipped with waveguide-mode sensors

Ashiba, Hiroki; Fujimaki, Makoto; Awazu, Koichi; Fu, Mengying; Ohki, Yoshimichi; Tanaka, Torahiko; Makishima, Makoto

Japanese Journal of Applied Physics 55(2) 2016/02-2016/02

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ISSN:00214922

Outline:© 2016 The Japan Society of Applied Physics.Hemagglutination is utilized for various immunological assays, including blood typing and virus detection. Herein, we describe a method of rapid hemagglutination detection based on a microfluidic channel installed on an optical waveguide-mode sensor. Human blood samples mixed with hemagglutinating antibodies associated with different blood groups were injected into the microfluidic channel, and reflectance spectra of the samples were measured after stopping the flow. The agglutinated and nonagglutinated samples were distinguishable by the alterations in their reflectance spectra with time; the microfluidic channels worked as spatial restraints for agglutinated red blood cells. The demonstrated system allowed rapid hemagglutination detection within 1 min. The suitable height of the channels was also discussed.

Structural Change Induced in LaAlO3 by Ion Implantation

IEEJ Transactions on Electrical and Electronic Engineering 11(1) p.5 - 92016/01-

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Publish Classification:Research paper (scientific journal)

Involvement of crystallinity in various luminescent bands in yttrium aluminate

Takaaki Morimotoa, Masayuki Harimaa, Yosuke Horiia, Yoshimichi Ohki

Nuclear Instruments and Methods in Physics Research B 366p.198 - 2052016/01-

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Publish Classification:Research paper (scientific journal)

Electronic transition process of fluorescence appearing in various organic polymers

Nishikawa, Seiya; Tonoi, Masashi; Yoshikawa, Takeshi; Hirai, Naoshi; Nakai, Hiromi; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEJ Transactions on Fundamentals and Materials 136(4) p.205 - 2112016/01-2016/01

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ISSN:03854205

Outline:© 2016 The Institute of Electrical Engineers of Japan. Low density polyethylene (LDPE) and polypropylene (PP) exhibit a photoluminescence (PL) band, which emits photons with an energy of around 4.3 eV when excited by photons with energies around 6.4 eV. The origin of this PL band has been assigned to α, β -unsaturated carbonyl. In this paper, the appearance of PL was examined for four kinds of polyolefin and four kinds of biodegradable polymers. As a result, it has become clear that all the polymers show a PL band with a PL excitation spectrum and a PL spectrum similar to those of the above-mentioned PL band in LDPE and PP. The decay profiles observed for these PL bands indicate that they are fluorescence. Furthermore, the intensity of the PL becomes weak for all the four polyolefin samples and the polylatic acid sample if ultraviolet photons were irradiated to the sample. Quantum chemical calculations carried out by assuming a model of α, β -unsaturated carbonyl have revealed that the PL originates in the π∗to π transition of electrons in the carbon-carbon double bond.

Estimation of talc contents in ethylene-propylene-diene copolymer by terahertz absorption spectroscopy

Izutsu, Tomoyuki; Komatsu, Marina; Ohki, Yoshimichi; Ohki, Yoshimichi; Mizuno, Maya; Nakamura, Yoshiaki; Chiwata, Naofumi

IEEJ Transactions on Fundamentals and Materials 136(2) p.81 - 852016/01-2016/01

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ISSN:03854205

Outline:© 2016 The Institute of Electrical Engineers of Japan.The authors examined the possibility of terahertz (THz) absorption spectroscopy whether it can be used as a tool to estimate the content of talc in ethylene-propylene-diene copolymer (EPDM), an important factor determining the electrical insulation properties of EPDM-insulated power cables. For this purpose, absorption spectra were measured in a frequency range from 0.3 to 10.0 THz for EPDM sheets containing different contents of talc, a disk-shaped sample made of talc powder, and a similar disk-shaped sample made of a mixture of talc and high-density polyethylene. As a result, the whole absorption in the frequency range from 0.3 to 10.0 THz is increased by the addition of talc into EPDM sheets. More specifically, it has become clear that talc in EPDM induces absorption peaks at 3.05, 4.8, 5.1, 5.3, 6.9, and 7.8 THz. The integrated absorption coefficients calculated for these absorption peaks show a good linearity with respect to the content of talc. Therefore, by watching the increments of these absorption peaks, the content of talc can be quantitatively estimated.

Detection of overheated parts in low-density polyethylene by terahertz absorption spectroscopy and imaging

Izutsu, Tomoyuki; Odaka, Daisuke; Kozai, Takuya; Komatsu, Marina; Ohki, Yoshimichi; Ohki, Yoshimichi; Saitou, Takashi; Yamazaki, Takanori

IEEJ Transactions on Fundamentals and Materials 136(9) p.603 - 6082016/01-2016/01

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ISSN:03854205

Outline:© 2016 The Institute of Electrical Engineers of Japan.Overheating during the manufacturing process of a cross-linked polyethylene-insulated cable often induces brownish resin, which may become a starting point of breakdown and water trees. In this study, an XLPE sheet was overheated and cut to many pieces of squares with various sizes from 0.5×0.5 to 10×10 mm2. Then, each piece was sandwiched between two sheets of low-density polyethylene and its absorption intensity was measured at terahertz (THz) frequencies. Furthermore, the spatial distribution of absorption was measured in the form of a two-dimensional image by scanning the sample. As a result, it has become clear that the whole absorption increases in a range from 0.5 to 5.0 THz when the volume of overheated part becomes bigger. Moreover, the distribution of overheated parts can be visualized by the THz absorption imaging.

Effects of ion implantation on oxygen vacancies in YSZ

Kuroda, Yasuhiro; Morimoto, Takaaki; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEJ Transactions on Fundamentals and Materials 136(9) p.592 - 5932016/01-2016/01

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ISSN:03854205

Outline:© 2016 The Institute of Electrical Engineers of Japan.Photoluminescence (PL) due to oxygen vacancies appearing in yttria-stabilized zirconia (YSZ) decreases clearly by ion implantation in both bulky single crystal plates and thin multicrystal films. This indicates that segregation into Y2O3 and ZrO2 and change in charging state of oxygen vacancy occur similarly in the two substances despite big differences in their thicknesses and morphologies.

Location attempts of a heated and irradiated portion in a silicone rubber insulated cable by frequency domain reflectometry and line resonance analysis

Hirai, Naoshi; Ohki, Yoshimichi; Ohki, Yoshimichi

IEEJ Transactions on Fundamentals and Materials 136(9) p.553 - 5602016/01-2016/01

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ISSN:03854205

Outline:© 2016 The Institute of Electrical Engineers of Japan.Electric cables play important roles for supplying power and for transmitting information and control signals. Therefore, their degradation may cause a serious problem. Silicone rubber (SiR) is widely used for electrical insulation in safety-related cables in nuclear power plants. In this paper, the ability of locating a degraded portion in a duplex cable insulated with SiR was compared between a system based on frequency domain reflectometry (FDR) being developed by the authors and a commercially available system called line resonance analysis (LIRA). Reflecting the fact that the FDR system can expand the measurement frequency range, FDR shows a higher sensitivity and a better resolution than LIRA. However, both methods cannot detect the degradation of SiR before its further use becomes uncommendable.

Diagnosis of surface degradation of flame-retardant ethylene propylene diene copolymer by scanning probe microscopy

Niki, Takayuki;Hirai, Naoshi;Ohki, Yoshimichi

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 53(1) p.82 - 882016-2016

DOI

Detail

ISSN:0022-3131

Electronic Transition Process of Fluorescence Appearing in Various Organic Polymers

Nishikawa Seiya;Tonoi Masashi;Yoshikawa Takeshi;Hirai Naoshi;Nakai Hiromi;Ohki Yoshimichi

The transactions of the Institute of Electrical Engineers of Japan.A 136(4) p.205 - 2112016-2016

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Detail

ISSN:0385-4205

Outline:Low density polyethylene (LDPE) and polypropylene (PP) exhibit a photoluminescence (PL) band, which emits photons with an energy of around 4.3 eV when excited by photons with energies around 6.4 eV. The origin of this PL band has been assigned to α, β-unsaturated carbonyl. In this paper, the appearance of PL was examined for four kinds of polyolefin and four kinds of biodegradable polymers. As a result, it has become clear that all the polymers show a PL band with a PL excitation spectrum and a PL spectrum similar to those of the above-mentioned PL band in LDPE and PP. The decay profiles observed for these PL bands indicate that they are fluorescence. Furthermore, the intensity of the PL becomes weak for all the four polyolefin samples and the polylatic acid sample if ultraviolet photons were irradiated to the sample. Quantum chemical calculations carried out by assuming a model of α, β-unsaturated carbonyl have revealed that the PL originates in the π* to π transition of electrons in the carbon-carbon double bond.

Electronic excitation and relaxation processes of oxygen vacancies in YSZ and their involvement in photoluminescence

Morimoto, Takaaki;Kuroda, Yasuhiro;Ohki, Yoshimichi

APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 122(9) 2016-2016

DOIWoS

Detail

ISSN:0947-8396

Superior High-temperature Dielectric Properties of Dicyclopentadiene Resin

Masuzaki, Y.;Suzuki, Y.;Ohki, Y.

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 23(5) p.3078 - 30852016-2016

DOIWoS

Detail

ISSN:1070-9878

Estimation of Talc Contents in Ethylene-Propylene-Diene Copolymer by Terahertz Absorption Spectroscopy

Izutsu Tomoyuki;Komatsu Marina;Ohki Yoshimichi;Mizuno Maya;Nakamura Yoshiaki;Chiwata Naofumi

The transactions of the Institute of Electrical Engineers of Japan.A 136(2) p.81 - 852016-2016

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Detail

ISSN:0385-4205

Outline:The authors examined the possibility of terahertz (THz) absorption spectroscopy whether it can be used as a tool to estimate the content of talc in ethylene-propylene-diene copolymer (EPDM), an important factor determining the electrical insulation properties of EPDM-insulated power cables. For this purpose, absorption spectra were measured in a frequency range from 0.3 to 10.0 THz for EPDM sheets containing different contents of talc, a disk-shaped sample made of talc powder, and a similar disk-shaped sample made of a mixture of talc and high-density polyethylene. As a result, the whole absorption in the frequency range from 0.3 to 10.0 THz is increased by the addition of talc into EPDM sheets. More specifically, it has become clear that talc in EPDM induces absorption peaks at 3.05, 4.8, 5.1, 5.3, 6.9, and 7.8 THz. The integrated absorption coefficients calculated for these absorption peaks show a good linearity with respect to the content of talc. Therefore, by watching the increments of these absorption peaks, the content of talc can be quantitatively estimated.

Location Attempts of a Heated and Irradiated Portion in a Silicone Rubber Insulated Cable by Frequency Domain Reflectometry and Line Resonance Analysis

Hirai Naoshi;Ohki Yoshimichi

IEEJ Transactions on Fundamentals and Materials 136(9) p.553 - 5602016-2016

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Detail

ISSN:0385-4205

Outline:

Electric cables play important roles for supplying power and for transmitting information and control signals. Therefore, their degradation may cause a serious problem. Silicone rubber (SiR) is widely used for electrical insulation in safety-related cables in nuclear power plants. In this paper, the ability of locating a degraded portion in a duplex cable insulated with SiR was compared between a system based on frequency domain reflectometry (FDR) being developed by the authors and a commercially available system called line resonance analysis (LIRA). Reflecting the fact that the FDR system can expand the measurement frequency range, FDR shows a higher sensitivity and a better resolution than LIRA. However, both methods cannot detect the degradation of SiR before its further use becomes uncommendable.

Effects of Ion Implantation on Oxygen Vacancies in YSZ

Kuroda Yasuhiro;Morimoto Takaaki;Ohki Yoshimichi

IEEJ Transactions on Fundamentals and Materials 136(9) p.592 - 5932016-2016

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Outline:

Photoluminescence (PL) due to oxygen vacancies appearing in yttria-stabilized zirconia (YSZ) decreases clearly by ion implantation in both bulky single crystal plates and thin multicrystal films. This indicates that segregation into Y2O3 and ZrO2 and change in charging state of oxygen vacancy occur similarly in the two substances despite big differences in their thicknesses and morphologies.

Detection of Overheated Parts in Low-density Polyethylene by Terahertz Absorption Spectroscopy and Imaging

Izutsu Tomoyuki;Odaka Daisuke;Kozai Takuya;Komatsu Marina;Ohki Yoshimichi;Saitou Takashi;Yamazaki Takanori

IEEJ Transactions on Fundamentals and Materials 136(9) p.603 - 6082016-2016

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ISSN:0385-4205

Outline:

Overheating during the manufacturing process of a cross-linked polyethylene-insulated cable often induces brownish resin, which may become a starting point of breakdown and water trees. In this study, an XLPE sheet was overheated and cut to many pieces of squares with various sizes from 0.5×0.5 to 10×10 mm2. Then, each piece was sandwiched between two sheets of low-density polyethylene and its absorption intensity was measured at terahertz (THz) frequencies. Furthermore, the spatial distribution of absorption was measured in the form of a two-dimensional image by scanning the sample. As a result, it has become clear that the whole absorption increases in a range from 0.5 to 5.0 THz when the volume of overheated part becomes bigger. Moreover, the distribution of overheated parts can be visualized by the THz absorption imaging.

A Monitoring Method of Additives in a Copper Sulfate Plating Solution Using a Near-Field Optical Sensor

FUJIMAKI Makoto;SATO Koutaro;OHKI Yoshimichi

Journal of the Surface Finishing Society of Japan 67(11) p.575 - 5802016-2016

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Estimation of the number of nucleotides with thymine in deoxyribonucleic acid by far-infrared absorption

Kitamura, Ayano; Komatsu, Marina; Ohki, Yoshimichi; Ohki, Yoshimichi; Mizuno, Maya; Hirabayashi, Miki; Kojima, Hiroaki

Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2015-Decemberp.617 - 6202015/12-2015/12

DOIScopus

Detail

ISSN:00849162

Outline:© 2015 IEEE.A new research trend that regards deoxyribonucleic acid (DNA) as a new dielectric polymeric material has been emerging in recent years. Especially for such application purposes, a simple easy-to-use method for determining the higher-order structure of synthetic DNA is desirable. From this viewpoint, we demonstrated in this research that far-infrared absorption spectroscopy can be a tool to determine the DNA higher-order structure and we calculated experimentally the integrated molar absorption coefficients per nucleotide with thymine at various frequencies. Therefore, using these coefficients, the number of thymine base on a single stranded DNA can be estimated by far-infrared spectroscopy.

Terahertz and far-infrared spectroscopic estimation of vinyl acetate content in ethylene-vinyl acetate copolymer

Izutsu, Tomoyuki; Odaka, Daisuke; Komatsu, Marina; Ohki, Yoshimichi; Ohki, Yoshimichi; Mizuno, Maya; Nakamura, Yoshiaki; Chiwata, Naofumi

Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2015-Decemberp.39 - 422015/12-2015/12

DOIScopus

Detail

ISSN:00849162

Outline:© 2015 IEEE.For the purpose of estimating the content of vinyl acetate (VA) in ethylene-vinyl acetate copolymer (EVA), optical absorption spectra were measured in a frequency range from 0.5 to 21.0 THz for sheets of EVA containing different contents of VA from 12 to 60 % by weight and a sheet of low-density polyethylene containing no VA. As a result, it has become clear that EVA exhibits relatively sharp absorption at 2.5, 6.7, and 10.5 THz and rather broad absorption at 11 to 17 THz and 17 to 20 THz. All these absorption peaks and bands are in proportion to the content of VA, up to certain frequency-dependent contents. Using these proportionalities, the content of VA in EVA can be estimated quantitatively. Especially, the absorption at 2.5 THz shows a good accuracy similar to the method recommended by an international standard.

Influence of cable structure on the fault location by frequency domain reflectometry

Ohki, Yoshimichi; Hirai, Naoshi

Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2015-Decemberp.274 - 2772015/12-2015/12

DOIScopus

Detail

ISSN:00849162

Outline:© 2015 IEEE.The authors have demonstrated that the estimation of the precise locations of points in cables aged thermally or mechanically or by the irradiation of gamma rays is possible by a combination of frequency domain reflectometry (FDR) and inverse fast Fourier transform (IFFT). This paper examines how this ability of fault location depends on the type and structure of the cable, using several kinds of polymer insulated cables such as triple core cables insulated with flame-retardant ethylene propylene diene copolymer (FR-EPDM), dual core cables insulated with silicone rubber (SiR) or crosslinked polyolefin (XLPO), and coaxial cylindrical cables insulated with low density polyethylene (LDPE). As a result, for cables with lengths of 16 to 72 m, the maximum sensitivity is attained when the highest frequency of the inputted electromagnetic waves is 1.0 GHz or higher for coaxial cables, but around 600 to 800 MHz for dual or triple core cables.

THz absorption of adenine base in single-stranded deoxyribonucleic acid

Komatsu, Marina; Ohki, Yoshimichi; Ohki, Yoshimichi; Mizuno, Maya

IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves 2015/11-2015/11

DOIScopus

Detail

Outline:© 2015 IEEE.Absorption spectra were measured in a frequency range from 3 to 18 THz for various single-stranded deoxyribonucleic acids (DNAs) containing adenine as their bases. Nine absorption components in total, most of which can be assigned to either phosphoric acid or adenine, appear in the range observed. From the dependence of each absorption on the number of nucleotides in one DNA, the integrated molar absorption coefficient per nucleotide with adenine was estimated.

Charging States of Oxygen Vacancies in Yttria-Stabilized Zirconia Analyzed by the Decay of Photoluminescence

S. Kaneko, T. Morimoto and Y. Ohki

UVSOR Activity Report 2014 UVSOR-42p.59 - 592015/07-

Cause of the appearance of oxygen vacancies in yttria-stabilized zirconia and its relation to 2.8 eV photoluminescence

Kaneko Shoji;Morimoto Takaaki;Ohki Yoshimichi

Jpn. J. Appl. Phys. 54(6) 2015/06-

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Detail

ISSN:0021-4922

Outline:When we implanted P+or B+ions into yttria-stabilized zirconia (YSZ), its crystallinity was degraded. Concurrently, the photoluminescence at around 2.8 eV originating from two types of oxygen vacancies with one or two captured electrons became weak, indicating a decrease in the number of oxygen vacancies. Oxygen vacancies appear in YSZ as a result of the replacement of Zr4+by Y3+in ZrO2. Therefore, it seems that the separation of YSZ into ZrO2and Y2O3induced by the ion implantation is responsible for the decrease in the number of oxygen vacancies. Moreover, the intensity of the 2.8 eV photoluminescence returns to the value before the ion implantation if the sample is annealed thermally after the implantation at temperatures higher than the crystallization temperature of YSZ. The reaction opposite to the above seems to be induced by the thermal annealing.

Development of a Plasma Separation System for a Portable Blood Test Device

Kuroda Chiaki;Ohki Yoshimichi;Ashiba Hiroki;Fujimaki Makoto;Awazu Koichi;Tanaka Torahiko;Makishima Makoto

The Journal of the Institute of Electrical Engineers of Japan 135(5) p.152 - 1572015/05-

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Detail

ISSN:1341-8939

Outline:Aiming at developing a portable and speedy blood test device, a microfluidic system is designed and developed. Blood is injected into a hole with a diameter of 3.0 mm and a height of 3.0 mm. When the blood sample is transported from the bottom to the top of the hole, blood cells sediment at the bottom and plasma is separated at the upper side. Using this system, approximately 1 µL pure plasma can be obtained when blood is injected at a flow rate of 0.70 µL/min for 15 minutes. Moreover, by retaining the blood in the hole for seven minutes, pure plasma can be obtained 11 minutes later.

Terahertz spectral change associated with glass transition of poly-epsilon-caprolactone

Komatsu, Marina;Mizuno, Maya;Saito, Shingo;Fukunaga, Kaori;Ohki, Yoshimichi

JOURNAL OF APPLIED PHYSICS 117(13) p.133102(1) - 133102(7)2015/04-

DOI

Detail

ISSN:0021-8979

Parallel-incidence-type waveguide-mode sensor with spectral-readout setup

Fujimaki, Makoto;Wang, Xiaomin;Kato, Takafumi;Awazu, Koichi;Ohki, Yoshimichi

OPTICS EXPRESS 23(9) p.10925 - 109372015/04-

DOI

Detail

ISSN:1094-4087

Diagnosis of surface degradation of flame-retardant ethylene propylene diene copolymer by scanning probe microscopy

Takayuki Niki, Naoshi Hirai, Yoshimichi Ohki

Journal of Nuclear Science and Technology 2015/03-

DOI

Hemagglutination detection for blood typing based on waveguide-mode sensors

Hiroki Ashiba, Makoto Fujimaki, Koichi Awazu, Mengying Fu, Yoshimichi Ohki, Torahiko Tanaka, Makoto Makishima

Sensing and BioSensing Research 3(3) p.59 - 642015/03-

DOI

Experimental observations on the crystalline structures of YAlO3 single crystal at high temperatures

Inoue, Takahiro;Morimoto, Takaaki;Ohki, Yoshimichi

APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 119(4) p.1423 - 14292015/03-

DOI

Detail

ISSN:0947-8396

Space Charges Remaining in Polymers after Electron Beam Irradiation and the Role of Conductivity in Their Decay Profiles

Tomite, Naoto;Arai, Yukitaka;Ohki, Yoshimichi;Hinata, Toru;Washio, Masakazu

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 10(3) p.237 - 2412015/02-

DOI

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ISSN:1931-4973

Comparison of Dielectric Properties of Olefin Thermosetting Polydicyclopentadiene and Epoxy Resin

Masuzaki Yuki;Ohki Yoshimichi;Tian Fuqiang;Kozako Masahiro;Kamei Nobuhito

IEEJ Transactions on Fundamentals and Materials 135(2) p.82 - 872015/02-

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ISSN:0385-4205

Outline:Complex permittivity spectra were obtained in a wide temperature and frequency range from 20 to 200°C and from 10-2 to 105 Hz for polydicyclopentadiene resin (PDCPD). For comparison, two epoxy resins, one with a similar glass transition temperature (Tg) to PDCPD and the other with a lower Tg, were used. As a result, PDCPD shows much smaller values of εr and εr than the two epoxy resins in nearly the whole temperature and frequency range. The differences of εr and εr between PDCPD and the epoxy resin with a similar Tg are also significant at low frequencies and at high temperatures. The increase in εr is attributable to the accumulation of hetero space charges in front of the electrodes. On the other hand, the increase in εr is an indication of the increase in Joule heat caused by the enhanced charge transport. Therefore, the experiental results indicate that PDCPD possesses better electrical insulating properties than epoxy resin. Furthermore, analysis using complex electric modulus, which is the inverse of the complex permittivity, has revealed very clearly that both charge transport and dipolar orientation are much more difficult in PDCPD than the two epoxy resins.

Space Charge Formation and Charge Transport in Epoxy Resin at Varied Temperatures

Li Xiuting;Masuzaki Yuki;Tian Fuqiang;Ohki Yoshimichi

IEEJ Transactions on Fundamentals and Materials 135(2) p.88 - 932015/02-

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ISSN:0385-4205

Outline:In order to investigate space charge behavior and charge transport characteristics of epoxy resin, complex dielectric permittivity and conduction current were measured at various temperatures from 20 to 200°C. Space charge distributions polarized at these temperatures were measured at room temperature. At temperatures above 100°C, significant accumulation of heteropolar space charges, most likely due to ions, is seen around the cathode/sample interface. Furthermore, both the real and imaginary parts of complex permittivity increase to remarkably high values at these high temperatures. It seems that such increase in permittivity is ascribable to the electrode polarization due to the hetero-charge accumulation. These results indicate that the dielectric behavior in epoxy resin is mainly governed by the electronic charge injection at relatively low temperatures below 100°C and by the transport of ionic carriers at high temperatures above 100°C.

Complex Permittivity Spectra of Various Insulating Polymers at Ultrawide-band Frequencies

Hasegawa Yuka;Ohki Yoshimichi;Fukunaga Kaori;Mizuno Maya;Sasaki Kensuke

IEEJ Transactions on Fundamentals and Materials 135(2) p.63 - 682015/02-

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ISSN:0385-4205

Outline:Nowadays, trials to use even higher frequencies are pursued to realize high-speed wireless communications. In order to respond to such a trend, dielectric properties of insulating polymers at high frequencies have to be clarified, although the importance of clarifying low-frequency properties is still very high, especially for use as high voltage insulators. In this regard, complex permittivity spectra from 10 mHz to 4.0 THz were obtained for various insulating polymers. The spectra obtained in the very wide frequency range are important, because they can be a valuable database and they provide various pieces of important information on dielectric characteristics.

Development of Low Loss Magnetodielectric Nanocomposites of Epoxy Resin and Iron Nanoparticles

Hirose, Yuichi;Hasegawa, Daiji;Ohki, Yoshimichi

ELECTRICAL ENGINEERING IN JAPAN 190(2) p.17 - 232015/01-

DOI

Detail

ISSN:0424-7760

Dielectric Properties of Three Liquid Crystal Polymers

Yang, Peng;Ohki, Yoshimichi

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 10(6) p.609 - 6132015-

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ISSN:1931-4973

特集 高分子絶縁体の劣化 [解説]有機高分子の絶縁劣化とその検出

大木義路

マテリアルライフ学会誌 26(3) p.36 - 412014/10-

Dielectric Properties of Poly(ethylene terephthalate) and Poly(ethylene 2,6-naphthalate)

Yang, Peng;Tian, Fuqiang;Ohki, Yoshimichi

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 21(5) p.2310 - 23172014/10-

DOI

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ISSN:1070-9878

特別企画 放熱・絶縁破壊の評価技術 高分子絶縁体の絶縁破壊メカニズムと評価

大木義路

Polyfile 51(607) p.46 - 532014/09-

特集 新しい光技術とその利用 電力分野でのテラヘルツ波の利用

大木義路

電気評論 99(9) p.32 - 372014/09-

解説 テラヘルツ波利用材料検査技術の現状 進展著しい我が国のテラヘルツ非破壊検査・材料評価技術

大木義路

検査技術 19(8) p.1 - 72014/08-

Terahertz absorption spectra of oxidized polyethylene and their analysis by quantum chemical calculations

Komatsu, Marina;Hosobuchi, Masashi;Xie, Xiaojun;Cheng, Yonghong;Furukawa, Yukio;Mizuno, Maya;Fukunaga, Kaori;Ohki, Yoshimichi

JAPANESE JOURNAL OF APPLIED PHYSICS 53(9) p.092402(1) - 092402(9)2014/08-

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ISSN:0021-4922

半導体高誘電率材料LaAlO3 とYAlO3 中の点欠陥 〜その種類と構造、光・熱・イオンの影響〜

森本貴明,堀井陽介,井上貴博,金子昇司,針間正幸,大木義路

放電学会誌 放電研究 57(2) p.3 - 122014/06-

Electric Modulus Powerful Tool for Analyzing Dielectric Behavior

Tian, Fuqiang;Ohki, Yoshimichi

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 21(3) p.929 - 9312014/06-

DOI

Detail

ISSN:1070-9878

Estimation of thermal expansion coefficients of polymeric insulating films from temperature dependence of dielectric permittivity

Hasegawa, Yuka;Takihana, Junya;Ohki, Yoshimichi

JAPANESE JOURNAL OF APPLIED PHYSICS 53(7) p.071501(1) - 071501(4)2014/06-

DOI

Detail

ISSN:0021-4922

Optical Characterization and Computational Chemical Evaluation of Electronic Localized States in Polyolefin

Arai, Tomoyuki;Hosobuchi, Masashi;Fuse, Norikazu;Takeda, Kyozaburo;Ohki, Yoshimichi

ELECTRICAL ENGINEERING IN JAPAN 188(1) p.1 - 82014/04-

DOI

Detail

ISSN:0424-7760

高分子絶縁ケーブルの放射線による劣化とその検出

大木義路

現代化学 (516) p.48 - 542014/03-

Charge transport and electrode polarization in epoxy resin at high temperatures

Tian, Fuqiang;Ohki, Yoshimichi

JOURNAL OF PHYSICS D-APPLIED PHYSICS 47(4) p.045311 (1) - 045311 (9)2014/01-

DOI

Detail

ISSN:0022-3727

Precise Location of the Excessive Temperature Points in Polymer Insulated Cables

Ohki, Yoshimichi;Yamada, Takayuki;Hirai, Naoshi

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 20(6) p.2099 - 21062013/12-

DOI

Detail

ISSN:1070-9878

Development of Low Loss Magneto-Dielectric Nanocomposites of Epoxy Resin and Iron Nanoparticles

Hirose Yuichi;Hasegawa Daiji;Ohki Yoshimichi

IEEJ Transactions on Fundamentals and Materials 133(12) p.668 - 6732013/12-

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ISSN:0385-4205

Outline:To achieve the aim of developing a new insulating substrate that can exhibit both high permittivity and high permeability, ferromagnetic iron nanoparticles were dispersed uniformly in epoxy resin. Measurements of the electrical conductivity, permittivity, and permeability indicate that the composite can be a good candidate for an insulating substrate with negligibly small eddy-current loss and sufficiently high permittivity.

わが国電力産業および関連分野におけるテラヘルツ波利用材料評価技術の現状

大木義路

化学工業 64(11) p.27[835] - 34[842]2013/11-

Effect of Ion Implantation on the Crystallinity of YAlO3 Single Crystal

Y. Horii, T. Morimoto and Y. Ohki

UVSOR Activity Report 2012 p.131 - 1312013/08-

Roles of Point Defects in Thermally Enhanced Generation and Transfer of Electrons and Holes in LaAlO3

Yamasaka, Daiki;Horii, Yosuke;Morimoto, Takaaki*;Ohki, Yoshimichi

JAPANESE JOURNAL OF APPLIED PHYSICS 52(7) p.071501(1) - 071501(5)2013/06-

DOI

Detail

ISSN:0021-4922

Detection of influenza viruses attached to an optical disk

Takayuki Shima, Makoto Fujimaki, Akihiro Yoshida, Subash C. B. Gopinath, Masashi Kuwahara, Yoshimichi Ohki and Koichi Awazu

Journal of Biomaterials and Nanobiotechnology 4(2) p.145 - 1502013/04-

DOI

放電学会年次大会 特別講演 テラヘルツ分光とイメージングの放電・絶縁分野への応用Applications of THz Spectroscopy and Imaging to the Fields of Electrical Discharges and Dielectric Insulation

大木義路

放電学会誌 放電研究 56(1) p.7 - 162013/03-

Factors Determining the Partial Discharge Resistance of Polymers

Isamu Ikeda, Yuka Hasegawa, and Yoshimichi Ohki

IEEJ Transactions on Fundamentals and Materials 133(3) p.75 - 802013/03-

DOI

Effects of Nanofiller Materials on the Dielectric Properties of Epoxy Nanocomposites

J. Katayama, Y. Ohki, N. Fuse, M. Kozako, and T. Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 20(1) p.157 - 1652013/02-

DOI

Comparisons of Partial Discharge Resistance and Dielectric Properties after Water Absorption between Polyetherimide and Aramid Insulating Papers

KATAYAMA Jun;OHKI Yoshimichi

IEEJ Transactions on Fundamentals and Materials 133(2) p.51 - 562013/02-

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ISSN:03854205

Outline:Partial discharge resistance was compared between newly developed polyetherimide insulating paper and conventional aramid insulating paper. Effects of water absorption on dielectric properties were also compared. The time to breakdown via partial discharges observed for the polyetherimide paper by applying a constant voltage was found to be about twice as long as that observed for the aramid paper, while the partial discharge charge amount per unit time is similar in the two papers. Moreover, the average area of degraded portions induced by partial discharges is smaller in the polyetherimide paper than in the aramid paper. The polyetherimide paper absorbs less water than does the aramid paper, when they are immersed in water at 27 and 80°C for the same period. Because of this, complex permittivity and conductivity increase more significantly in the aramid paper than in the polyetherimide paper. Therefore, especially in a humid condition, the polyetherimide paper is superior to the aramid paper.

Location of the Position with an Extraordinary Temperature in a Cable by Frequency Domain Reflectometry

YAMADA Takayuki;HIRAI Naoshi;OHKI Yoshimichi;KUMAGAI Susumu

2013(1,29) p.39 - 442013/02-

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Control of Refractive Index of Fluorinated Polyimide by Proton Beam Irradiation

Arai, Yukitaka;Ohki, Yoshimichi;Saito, Keisuke;Nishikawa, Hiroyuki

JAPANESE JOURNAL OF APPLIED PHYSICS 52(1) p.012601(1) - 012601(5)2013/01-

DOI

Detail

ISSN:0021-4922

Location feasibility of degradation in cable through Fourier transform analysis of broadband impedance spectra

Ohki, Yoshimichi;Hirai, Naoshi

ELECTRICAL ENGINEERING IN JAPAN 183(1) p.1 - 82013/01-

DOI

Detail

ISSN:0424-7760

Comparison of Behavior of Alumina Plate-like Particles in an Uncured Epoxy Resin among Several Conditions of Applied Electric Field

KINOSHITA Satoshi;KOZAKO Masahiro;HIKITA Masayuki;OHKI Yoshimichi

2013(20,11,52) p.37 - 422013/01-

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Space Charge Distributions in Polymers Induced by Electron Beam Irradiation and Their Determining Factor

ARAI Yukitaka;TOMITE Naoto;NAKAMURA Hirotaka;HINATA Toru;WASHIO Masakazu;OHKI Yoshimichi

2012(93) p.1 - 62012/12-

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Space Charge Behavior of Polymer Nanocomposites toward the Application to Power Semiconductor Modules

KAWANO Shohei;ITO Koji;MIYAKE Hiroaki;TANAKA Yasuhiro;HIROSE Yuichi;OHKI Yoshimichi;KOZAKO Masahiro

2012(93) p.13 - 182012/12-

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Thermal Conductivity and Dielectric Properties of Epoxy Resin Co-added with Nano- and Micro-Fillers

HIROSE Yuichi;MASUZAKI Yuki;TIAN Fuqiang;OHKI Yoshimichi;KOZAKO Masahiro

2012(93) p.19 - 242012/12-

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Charge Behavior of Epoxy/Silica Nanocomposites under AC High Field

WATANABE Yutaro;TOHYAMA Kazuyuki;HIROSE Yuichi;OHKI Yoshimichi;KOZAKO Masahiro

2012(93) p.25 - 302012/12-

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Feasibility Study on Terahertz Imaging of Corrosion on a Cable Metal Shield

Komatsu, Marina;Sato, Ryo;Mizuno, Maya;Fukunaga, Kaori;Ohki, Yoshimichi

JAPANESE JOURNAL OF APPLIED PHYSICS 51(12) p.122405(1) - 122405(5)2012/11-

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Detail

ISSN:0021-4922

Correlation between mechanical and dielectric relaxation processes in epoxy resin composites with nano- and micro-fillers

Hyuga, Mayumi;Tanaka, Toshikatsu;Ohki, Yoshimichi;Imai, Takahiro;Harada, Miyuki;Ochi, Mitsukazu

ELECTRONICS AND COMMUNICATIONS IN JAPAN 95(9) p.1 - 92012/09-

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ISSN:1942-9533

Optical Characterization and Computational Chemical Evaluation of Electronic Localized States in Polyolefin

ARAI Tomoyuki;HOSOBUCHI Masashi;FUSE Norikazu;TAKEDA Kyozaburo;OHKI Yoshimichi

IEEJ Transactions on Fundamentals and Materials 132(9) p.760 - 7662012/09-

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ISSN:03854205

Outline:Optical absorption spectra and photoluminescence spectra were obtained for eight kinds of polyolefin sheet samples using photons in a range from visible to vacuum ultraviolet. Almost all samples were found to exhibit an absorption peak at around 6.5 eV and a luminescence band at around 4.3 eV. The luminescence was found to be induced by the absorption. Furthermore, it was found that successive absorption of ultraviolet photons weakened the luminescence intensity. It is assumed from these results that α, β-unsaturated carbonyls are luminous and that the carbonyls are decomposed through the Norrish type II reaction by absorbing ultraviolet photons. Quantum chemical calculations were carried out using polyethylene models with and without an unsaturated carbonyl to verify the above-mentioned assumption. As a result, the model with an unsaturated carbonyl was found to have localized electronic states in the forbidden band. One of the differential energies between the states is close to the photon energy, by which the luminescence is induced. The bond length of a double bond, which is next to the carbonyl, was found to be longer at the excited singlet state than at the ground state. These results obtained by computation support the above-mentioned assumption of the luminescence center and its decomposition.

Frequency Dependence of Breakdown Performance of XLPE with Different Artificial Defects

Li, Weiwei;Li, Jianying;Yin, Guilai;Li, Shengtao;Zhao, Jiankang;Ouyang, Benhong;Ohki, Yoshimichi

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 19(4) p.1351 - 13592012/08-

Detail

ISSN:1070-9878

Role of Interface on the Thermal Conductivity of Highly Filled Dielectric Epoxy/AlN Composites

Huang, Xingyi;Iizuka, Tomonori;Jiang, Pingkai;Ohki, Yoshimichi;Tanaka, Toshikatsu

JOURNAL OF PHYSICAL CHEMISTRY C 116(25) p.13629 - 136392012/06-

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ISSN:1932-7447

高誘電率ゲート絶縁膜材料LaAlO3およびYAlO3における点欠陥の原因

山坂大樹, 中原和也, 堀井陽介, 大木義路

放電学会誌 55(1) p.27 - 312012/03-

Dielectric properties of poly(phenylene sulfide) as a function of temperature and frequency

Hikosaka, Saki;Ohki, Yoshimichi

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 7(2) p.116 - 1202012/03-

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ISSN:1931-4973

First-Principles Study on Intrinsic Point Defects in Rhombohedral LaAlO3 and Their Effects on Electrical Properties

Xie, Xiaojun;Cheng, Yonghong;Xiao, Bing;Ohki, Yoshimichi

JAPANESE JOURNAL OF APPLIED PHYSICS 51(4) p.041103(1) - 041103(9)2012/03-

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ISSN:0021-4922

A study of the critical factor determining the size of etched latent tracks formed on SiO2 glass by swift-Cl-ion irradiation

Nomura, Ken-ichi;Ohki, Yoshimichi;Fujimaki, Makoto;Wang, Xiaomin;Awazu, Koichi;Komatsubara, Tetsuro

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 272p.1 - 42012/02-

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ISSN:0168-583X

Location Feasibility of Degradation in Cable through Fourier Transform Analysis of Broadband Impedance Spectra

OHKI Yoshimichi;HIRAI Naoshi

IEEJ Transactions on Fundamentals and Materials 132(2) p.122 - 1282012/02-

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ISSN:03854205

Outline:Since electric cables play important roles such as power supply and information transmission, their degradation may cause a serious problem. We have been trying to monitor the degradation of cable insulation by measuring the magnitude and phase angle of impedance as a function of frequency in a very wide frequency range. The cables tested were insulated with flame-retardant ethylene propylene rubber or special heat-resistant polyvinyl chloride. They were damaged partially by peeling off their insulation layers, or aged partially by heat and γ-rays. Impedance and phase angle were measured from a terminal of the cable. The difference in impedance between the damaged and sound cables becomes clear by fast Fourier transform analyses, from which the damaged portion can be located. It can be clearly shown that this method has a potential ability to detect the degradation of cable insulation induced by physical damage, γ-ray irradiation, and thermal aging.

Terahertz Imaging of Water Trees Generated in Low-density Polyethylene

SATO Ryo;KOMATSU Marina;FUSE Norikazu;NAKAMICHI Yoshinobu;MIZUNO Maya;FUKUNAGA Kaori;OHKI Yoshimichi

IEEJ Transactions on Fundamentals and Materials 132(2) p.148 - 1492012/02-

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ISSN:03854205

Outline:Research was carried out whether it is possible to detect water trees in a low density polyethylene sheet by terahertz light. The attenuation of the reflected intensity of THz light was observed on several points in the sample under a polyvinylchloride sheet. The intensity distribution of the reflected light agrees with the distribution of water trees in the sample. Therefore, the distribution of water trees would be detectable even if the trees are invisible to naked eyes.

Sensitivity of Broadband Impedance Spectroscopy as a Location Method of Cable Degradation

YAMADA Takayuki;HIRAI Naoshi;OHKI Yoshimichi

2012(53) p.11 - 162012/02-

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Terahertz Spectroscopic Diagnosis of Thermal Degradation Induced in Cross-linked Polyethylene for Cable Insulation

KOMATSU Marina;YAMADA Toshita;SATO Ryo;OHKI Yoshimichi;MIZUNO Maya;FUKUNAGA Kaori

2012(53) p.23 - 272012/02-

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Correlation between Mechanical and Dielectric Relaxation Processes in Epoxy Resin Composites with Nano- and Micro-fillers

HYUGA Mayumi;TANAKA Toshikatsu;OHKI Yoshimichi;IMAI Takahiro;HARADA Miyuki;OCHI Mitsukazu

IEEJ Transactions on Fundamentals and Materials 131(12) p.1041 - 10472011/12-

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ISSN:03854205

Outline:Effects of addition of nano-sized and micro-sized fillers into epoxy resin on its mechanical and dielectric relaxation phenomena were examined. The glass transition temperature (Tg) decreases when a small content of nanoclay modified by octadecylamine was added, while the decrease in Tg is suppressed when the nanoclay was modified by dimethyldodecylamine. On the other hand, Tg increases when microsilica was added abundantly. At temperatures above Tg, both mechanical and dielectric relaxations are accelerated in samples with octadecylamine-modified nanoclay, while the acceleration does not occur in samples with nanoclay modified by dimethyldodecylamine. Both relaxations are restricted in composites with abundant microsilica. Therefore, co-addition of dimethyldodecylamine-modified nanoclay and abundant microsilica is adequate in order to make an epoxy resin composite with a high Tg and low dielectric loss.

Several Pieces of Knowledge on Electrochemical Migration Resistance of Printed Wiring Boards Obtained by Space Charge Distribution Measurements

OHKI Yoshimichi;ASAKAWA Hiroki;WADA Genta;HIROSE Yuichi;TANAKA Toshikatsu;MAENO Takashi;OKAMOTO Kenji

2011(77) p.13 - 182011/12-

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Factors Contributing to the Generation of Packet-like Space Charge in Polyethylene

ARAI Yukitaka;KANEGAE Etsu;TANAKA Toshikatsu;OHKI Yoshimichi;INOUE Yoshiyuki;MURATA Yoshinao;REDDY C. C.

2011(77) p.29 - 342011/12-

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Development of Low Loss Magneto-Dielectric Nanocomposites of Epoxy Resin and Fe Nanoparticles

HIROSE Yuichi;HASEGAWA Daiji;OHKI Yoshimichi

2011(77) p.77 - 822011/12-

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Development of Epoxy/BN Composites with High Thermal Conductivity and Sufficient Dielectric Breakdown Strength Part I -Sample Preparations and Thermal Conductivity

Wang, Zengbin;Iizuka, Tomonori;Kozako, Masahiro;Ohki, Yoshimichi;Tanaka, Toshikatsu

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 18(6) p.1963 - 19722011/12-

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ISSN:1070-9878

Development of Epoxy/BN Composites with High Thermal Conductivity and Sufficient Dielectric Breakdown Strength Part II - Breakdown Strength

Wang, Zengbin;Iizuka, Tomonori;Kozako, Masahiro;Ohki, Yoshimichi;Tanaka, Toshikatsu

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 18(6) p.1973 - 19832011/12-

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ISSN:1070-9878

Optimal design of a spectral readout type planar waveguide-mode sensor with a monolithic structure

Xiaomin Wang, Makoto Fujimaki, Takafumi Kato, Ken-ichi Nomura, Koichi Awazu, and Yoshimichi Ohki

OPTICS EXPRESS 19(21) p.20205 - 202132011/10-

Dielectric Properties of XLPE/SiO2 Nanocomposites Based on CIGRE WG D1.24 Cooperative Test Results

Tanaka, Toshikatsu;Bulinski, Alexander;Castellon, Jerome;Frechette, Michel;Gubanski, Stanislaw;Kindersberger, Josef;Montanari, Gian Carlo;Nagao, Masayuki;Morshuis, Peter;Tanaka, Yasuhiro;Pelissou, Serge;Vaughan, Alun;Ohki, Yoshimichi;Reed, Clive W.;Sutton, Simon;Han, Suh Joon

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 18(5) p.1484 - 15172011/10-

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ISSN:1070-9878

Observation of Water Trees Using Terahertz Spectroscopy and Time-domain Imaging

Sato, Ryo;Komatsu, Marina;Ohki, Yoshimichi;Fuse, Norikazu;Nakamichi, Yoshinobu;Mizuno, Maya;Fukunaga, Kaori

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 18(5) p.1570 - 15772011/10-

Detail

ISSN:1070-9878

Effects of ultraviolet photon irradiation on the transition metal impurities in LaAlO3

Yamasaka, Daiki;Tamagawa, Kenta;Ohki, Yoshimichi

JOURNAL OF APPLIED PHYSICS 110(7) p.074103(1) - 074103(5)2011/10-

DOI

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ISSN:0021-8979

Detection of Electrochemical Migration Grown in a Two-layered Dielectric by the Pulsed Electroacoustic Method and Numerical Analysis of the Signals

ASAKAWA Hiroki;NATSUI Masashi;TANAKA Toshikatsu;OHKI Yoshimichi;MAENO Takashi;OKAMOTO Kenji

IEEJ Transactions on Fundamentals and Materials 131(9) p.771 - 7772011/09-

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ISSN:03854205

Outline:Electrochemical migration growth along the thickness direction in a two-layered dielectric, consisting of an Al cathode, paper/phenol-resin composite, epoxy resin, and a Cu anode that simulates a laminated structure of a printed wiring board, was detected by the pulsed electroacoustic (PEA) method. The PEA signals obtained were analyzed using a numerical model on the generation and propagation of acoustic waves. Accumulation of positive charge appears in front of the Cu anode of the sample, in which the growth of electrochemical migration was observed by SEM-EDS. At the same time, the signal due to negative charge at the interface between the resin and the composite decreases significantly. This is ascribable to the progress of electrochemical migration in the thickness direction. The numerical analysis done by assuming that the conductivity of the epoxy resin layer near the anode was increased gives a good agreement with the PEA spectra. As for the charge on the anode, the PEA signal appears at the correct position when the anode material is semi-conductive polymer, while it appears as if the anode were inside the real anode when the material is Cu. In order to solve this puzzle, numerical calculations were carried out by the finite difference method. As a result, it has become clear that the discontinuity in the acoustic impedance between the epoxy resin and Cu electrode is responsible.

Thermally Stimulated Current in Low-Density Polyethylene/MgO Nanocomposite. On the Mechanism of Its Superior Dielectric Properties

Kazuyuki Ishimoto, Toshikatsu Tanaka, Yoshimichi Ohki, Yoitsu Sekiguchi, and Yoshinao Murata

Electrical Engineering in Japan 176(3) p.1 - 72011/08-

Effect of Tacticity on the Dielectric Properties of Polystyrene

Hikosaka, Saki;Ohki, Yoshimichi

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 6(4) p.299 - 3032011/07-

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ISSN:1931-4973

Effects of Crystallinity on Dielectric Properties of Poly(L-lactide)

Hikosaka, Saki;Ishikawa, Hiroto;Ohki, Yoshimichi

ELECTRONICS AND COMMUNICATIONS IN JAPAN 94(7) p.1 - 82011/07-

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ISSN:1942-9533

Terahertz Spectroscopy as a New Tool for Insulating Material Analysis and Condition Monitoring

Norikazu Fuse, Tsuguhiro Takahashi, Yoshimichi Ohki, Ryo Sato, Maya Mizuno and Kaori Fukunaga

IEEE Electrical Insulation Magazine 27(3) p.26 - 352011/06-

DOI

The Role of Nano and Micro Particles on Partial Discharge and Breakdown Strength in Epoxy Composites

Li, Zhe;Okamoto, Kenji;Ohki, Yoshimichi;Tanaka, Toshikatsu

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 18(3) p.675 - 6812011/06-

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ISSN:1070-9878

Generation Mechanism of Electrochemical Migration in Printed Wiring Board Insulation

M. Natsui, H. Asakawa, T. Tanaka, Y. Ohki, T. Maeno, and K. Okamoto

IEEJ Transactions on Electrical and Electronic Engineering 6(3) p.200 - 2062011/05-

Shape-sensitive reflectance by nanostructured metal attached on an optical waveguide-mode sensor

Sato, Kazuki;Ohki, Yoshimichi;Nomura, Ken-ichi;Fujimaki, Makoto;Awazu, Koichi

NANOTECHNOLOGY 22(24) p.245503(1) - 245503(6)2011/04-

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ISSN:0957-4484

Importance of Insulation Diagnosis in Nuclear Power Plants and Evaluation of Oxidation by Chemiluminescence

OHKI Yoshimichi;HIRAI Naoshi

Journal of Materials Life Society 23(1) p.1 - 92011/02-

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ISSN:13460633

Effect of Annealing on Optical Absorption of LaAlO3 at Terahertz Frequencies

Nomura, Ken-ichi;Okami, Shimpei;Xie, Xiaojun;Mizuno, Maya;Fukunaga, Kaori;Ohki, Yoshimichi

JAPANESE JOURNAL OF APPLIED PHYSICS 50(2) p.021502(1) - 021502(3)2011/02-

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ISSN:0021-4922

Effects of Nanofiller Materials on the Dielectric Properties of Epoxy Nanocomposites

KATAYAMA Jun;TANAKA Toshikatsu;OHKI Yoshimichi;FUSE Norikazu;KOZAKO Masahiro

2010(74) p.19 - 242010/12-

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Effect of Water Absorption Temperature on Space Charge Profiles in Paper/Phenol-Resin Composites for Printed Circuit Boards

Echigo, Yasutsune;Natsui, Masashi;Maeno, Takashi;Ohki, Yoshimichi

ELECTRICAL ENGINEERING IN JAPAN 173(2) p.1 - 72010/11-

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ISSN:0424-7760

Tree Initiation Phenomena in Nanostructured Epoxy Composites

Yu Chen, Takahiro Imai, Yoshimichi Ohki, Toshikatsu Tanaka

IEEJ Transactions on Dielectrics and Electrical Insulation 17(5) p.1509 - 15152010/10-

Observation and Analysis of Molecular Vibration Modes in Polylactide at Terahertz Frequencies

Norikazu Fuse, Ryo Sato, Maya Mizuno, Kaori Fukunaga, Koichi Itoh, and Yoshimichi Ohki

Jpn. J. Appl. Phys. 49(10) p.102402(1) - 102402(8)2010/10-

Cr3+ Impurities and Photoluminescence in LaAlO3

Eiji Hirata, Kenta Tamagawa, and Yoshimichi Ohki

Jpn. J. Appl. Phys. 49(9) p.091102(1) - 091102(6)2010/09-

Contribution to Green Power Technology Through Electrical Insulating Materials Research

Yoshimichi Ohki

Transactions on Electrical and Electronic Materials 11(4) p.149 - 1542010/08-

Detection of colored nanomaterials using evanescent field-based waveguide sensors

Makoto Fujimaki, Ken-ichi Nomura, Kazuki Sato, Takafumi Kato, Subash C.B.Gopinath, Xiaomin Wang, Koichi Awazu, and Yoshimichi Ohki

OPTICS EXPRESS 18(15) p.15733 - 157402010/07-

Comparison of Nano-structuration Effects in Polypropylene among Four Typical Dielectric Properties

N. Fuse, Y. Ohki, and T. Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 17(3) p.671 - 6772010/06-

Effect of Nano-filler Addition on Partial Discharge Resistance and Dielectric Breakdown Strength of Micro-Al2O3/Epoxy Composite

Zhe Li, Kenji Okamoto, Yoshimichi Ohki, and Toshikatsu Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 17(3) p.653 - 6612010/06-

Effect of Temperature and Crystallinity on Partial Discharge Resistance of Poly-L-lactic Acid

Yoshimichi Ohki, Kazuhiro Miyata

IEEJ Transactions on Electrical and Electronic Engineering 5(3) p.323 - 3272010/05-

Space Charge Distributions in Two-layered LDPE/MgO Nanocomposites Exhibiting Superior Insulation Performance

KANEGAE Etsu;ISHIMOTO Kazuyuki;TANAKA Toshikatsu;OHKI Yoshimichi;SEKIGUCHI Yoitsu;MURATA Yoshinao;REDDY Chandupatla Chakradhar

IEEJ Transactions on Fundamentals and Materials 130(4) p.349 - 3542010/04-

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ISSN:03854205

Outline:Recently polymer nanocomposite has been attracting much attention as an emerging insulating material. In this paper, we measured space charge distributions for two-layered dielectric films consisting of certain combination of low-density polyethylene (LDPE) and its nanocomposite with magnesia nano-fillers during the application of dc electric field of 25 kV/mm or 100 kV/mm. Both at room temperature and 50°C, space charge is formed at the interface of two different materials to maintain the continuity of current when the electric field is 25 kV/mm, while packet-like charge appears only in the LDPE when the electric field is 100 kV/mm. These phenomena are explained by assuming that the nano-fillers effectively suppress the increase in conductivity induced by the high electric field.

Electrical Conduction and Dielectric Relaxation in Polyethylene Terephthalate Succinate

Kato, Fukutaro;Ohki, Yoshimichi

ELECTRICAL ENGINEERING IN JAPAN 170(4) p.1 - 82010/03-

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ISSN:0424-7760

Comparison of Dielectric Properties between Epoxy Composites with Nanosized Clay Fillers Modified by Primary Amine and Tertiary Amine

N. Tagami, M. Hyuga, Y. Ohki, T. Tanaka, T. Imai, M. Harada, and M. Ochi

IEEE Transactions on Dielectrics and Electrical Insulation 17(1) p.214 - 2202010/02-

Improving Epoxy-based Insulating Materials with Nano-fillers toward Practical Use in Heavy Electric Apparatuses

Imai Takahiro;Komiya Gen;Murayama Kiyoko;Ozaki Tamon;Sawa Fumio;Shimizu Toshio;Harada Kiyoko;Ochi Mitsukazu;Ohki Yoshimichi;Tanaka Toshikatsu

Proceedings of Symposium on Network Polymer 31(1) p.36 - 422010-

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ISSN:1342-0577

Outline:SynopsisNanotechnology has been attracting much attention in recent research on insulating materials to realize environmentally-conscious heavy electric apparatuses such as switchgear using solid insulation systems. The apparatuses without gas insulation systems using of sulfur hexafluoride(SF6), which has been designated as a greenhouse gas, can reduce environmental impact. This paper shows development in the application of epoxy-based nanocomposite with clayspractical solid insulating systems, which would lead to environmental harmony, downsizing, and higher efficiency in heavy electric apparatus.

Superiority of Dielectric Properties of LDPE/MgO Nanocomposites over Microcomposites

K. Ishimoto, E. Kanegae, T. Tanaka, Y. Ohki, Y. Sekiguchi, Y. Murata, C. C. Reddy

IEEE Transactions on Dielectrics and Electrical Insulation 16(6) p.1735 - 17422009/12-

Plasmonic Activity on Gold Nanoparticles Embedded in Nanopores Formed in a Surface Layer of Silica Glass by Swift-heavy-ion Irradiation

K. Nomura, Y. Ohki, M. Fujimaki, X. Wang, K. Awazu, and T. Komatsubara

Nanotechnology 20p.475306(1) - 475306(7)2009/10-

Control of Coupling Ratio by Proton Implantation for a Directional Coupler of Planar-Lightwave-Circuit Type

S. J. Yu, M. Suzuki, Y. Ohki, M. Fujimaki, and K. Awazu

Japanese Journal of Applied Physics 48p.102405(1) - 102405(5)2009/10-

Tree Initiation Characteristics of Epoxy Resin and Epoxy/Clay Nanocomoposite

Stephanie Raetzke, Yoshimichi Ohki, Takahiro Imai, Toshikatsu Tanaka, Josef Kindersberger

IEEE Transactions on Dielectrics and Electrical Insulation 16(5) p.1473 - 14802009/10-

Proposal of a Grating-based Optical Reflection Switch using Phase Change Materials

X. Wang, M. Kuwahara, K. Awazu, P. Fons, J. Tominaga, and Y. Ohki

Optics Express 17(19) p.16947 - 169562009/09-

Effect of Crystallization on the Photoluminescence in LaAlO3 Induced by Ultraviolet Photons

T. Iikura, E. Hirata and Y. Ohki

UVSOR ACTIVITY REPORT 2008 p.81 - 812009/06-

Solution Conductivity as a Key Factor for Thin Silica Coating on Colloidal Silver

Kenichi-Nomura, Shinji Fujii, Yoshimichi Ohki, Koichi Awazu, Makoto Fujimaki, Nobuko Fukuda, and Tsutomu Hirakawa

Japanese Journal of Applied Physics 48p.06FE042009/06-

Monitoring surface-assisted biomolecular assembly by means of evanescent-field-coupled waveguide-mode nanobiosensors

S. C. B. Gopinath, K. Awazu, M. Fujimaki, K. Sugimoto, Y. Ohki, T. Komatsubara, J. Tominaga, P. K. R. Kumar

Analytical and Bioanalytical Chemistry 394p.481 - 4882009/05-

Partial discharge degradation of several biodegradable polymers

Norikazu Fuse, Shinjiro Fujita, Naoshi Hirai, Toshikatsu Tanaka, Masahiro Kozako, Masanori Kohtoh, Shigemitsu Okabe, Yoshimichi Ohki

Electrical Engineering in Japan 168(2) p.1 - 102009/04-

Effects of Nanofiller Loading on the Molecular Motion and Carrier Transport in Polyamide

Norikazu Fuse, Hiroki Sato, Yoshimichi Ohki, and Toshikatsu Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 16(2) p.524 - 5302009/04-

L型ポリ乳酸の結晶化度が誘電特性に与える影響 Effects of Crystallinity on Dielectric Properties of Poly (L-lactide)

彦坂早紀、石川裕人、大木義路

電気学会論文誌A 129(4) p.217 - 2222009/04-

Mechanism of elongation of gold or silver nanoparticles in silica by irradiation with swift heavy ions

Koichi Awazu, Xiamin Wang, Makoto Fujimaki, Junji Tominaga, Shinji Fujii, Hirohiko Aiba, Yoshimichi Ohki, and Tetsuro Komatsubara

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 267(6) p.941 - 9432009/03-

Optical Fiber Depolarizer Using Birefringence Induced by Proton Implantation

S. J. Yu, Y. Ohki, M. Fujimaki, K. Awazu, and J. Tominaga

Japanese Journal of Applied Physics 48p.032404(1) - 032404(3)2009/03-

LDPE/MgOナノコンポジットの熱刺激電流 -良好な絶縁性能の原因について-Thermally Stimulated Current in Low-density Polyethylene/MgO Nanocomposite -On the Mechanism of its SuperDielectric Properties-

石本和之、田中祀捷、大木義路、関口洋逸、村田義直

電気学会論文誌A 129(2) p.97 - 1022009/02-

Terahertz Time-domain Spectroscopic Analysis of Molecular Behavior in Polyamide Nanocomposites

Yoshimichi Ohki, Masahide Okada, Norikazu Fuse, Kentaro Iwai, Maya Mizuno, and Kaori Fukunaga

Applied Physics Express 1(12) p.122401(1) - 122401(3)2008/12-

MgOナノフィラー添加によるLDPEへの電荷注入の抑制Suppression of Charge Injection into LDPE by Addition of MgO Nanofillers

石本和之、田中祀捷、大木義路、関口洋逸、村田義直

電気学会論文誌A 128(12) p.742 - 7432008/12-

Reduction in polarization dependent loss of a planar lightwave circuit by ion-implantation-induced birefringence

Seung Jun Yu, Yoshimichi Ohki, Makoto Fujimaki, Koichi Awazu, Junji Tominaga, Kimikazu Sasa, and Tetsuro Komatsubara

Nuclear Instruments and Methods in Physics Research B 266p.4762 - 47652008/11-

Fabrication of inert silver nanoparticles with a thin silica coating

Ken-ichi Nomura, Shinji Fujii, Yoshimichi Ohki, Koichi Awazu, Makoto Fujimaki, Junji Tominaga, Nobuko Fukuda, Tsutomu Hirakawa, Carsten Rockstuhl

Japanese Journal of Applied Physics 47(11) p.8641 - 86432008/11-

Photoluminescence Analysis of Czochralski-Grown Lathanum Aluminate Single Crystals

Kotaro Kanai, Eiji Hirata, and Yoshimichi Ohki

Japanese Journal of Applied Physics 47(10) p.7980 - 79822008/10-

Photoluminescencein Polyamide/mica and Polyethylene/MgO Nanocomposites Induced by Ultraviolet Photons

Norikazu Fuse, Masahide Okada, Yoshimichi Ohki, Yoshinao Murata, Yoitsu Sekiguchi, and Toshikatsu Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 15(5) p.1215 - 12232008/10-

Whitehead Memorial Lecture Aiming at a More Rigorous Understanding in Electrical Insulating Materials Research

Yoshimichi Ohki

IEEE Transactions on Dielectrics and Electrical Insulation 15(5) p.1201 - 12142008/10-

Temperature Dependence of Complex Permittivity in Biodegradable Polybutylene Succinate

Hiroto Ishikawa, Yoshimichi Ohki

IEEJ Trans. FM 128(10) p.647 - 6512008/10-

Influence of Nanometric Holes on the Sensitivity of a Waveguide-Mode Sensor: Label-Free Nanosensor for the Analysis of RNA Aptamer-Ligand Interactions

Subash C. B. Gopinath, Koichi Awazu, Makoto Fujimaki, Katsuaki Sugimoto, Yoshimichi

Analytical Chemistry 80p.6602 - 66092008/09-

プリント基板用紙/フェノール樹脂複合絶縁体の空間電荷挙動に与える吸水温度の影響Effect of Water Absorption Temperature on Space Charge Profiles in Paper/phenol-resin Composites for Printed Circuit Boards

越後易恒、夏井正嗣、前野恭、大木義路

電気学会論文誌A 128(9) p.585 - 5902008/09-

Defects in yttria-stabilized zirconia induced by irradiation of ultraviolet photons

Takaaki Morimoto, Masayuki Takase, Toshihide Ito,Hiromitsu Kato, and Yoshimichi Ohki

Japanese Journal of Applied Physics 47(8) p.6858 - 68622008/08-

Elongation of gold nanoparticles in silica glass by irradiation with swift heavy ions

Koichi Awazu, Xiaomin Wang, Makoto Fujimaki, Junji Tominaga, Hirohiko Aiba, Yoshimichi Ohki, and Tetsuro Komatsubara

Physical Review B 78(5) p.054102(1) - 054102(8)2008/08-

ポリエチレンテレフタレートサクシネートにおける電気伝導と誘電緩和Electrical conduction and dielectric relaxation in polyethylene terephthalate succinate

加藤福太郎、大木義路

電学論A 128(7) p.490 - 4962008/07-

Photoluminescence in LaAlO3 Single Crystals

Kotaro Kanai, Eiji Hirata, and Yoshimichi Ohki

UVSOR ACTIVITY REPORT 2007 p.772008/06-

Silica-based monolithic sensing plates for waveguide-mode sensors

Makoto Fujimaki, Carsten Rockstuhl, Xiaomin Wang, Koichi Awazu, Junji Tominaga, Yuuki Koganezawa, Yoshimichi Ohki, and Tetsuro Komatsubara

Optics Express 16(9) p.6408 - 64162008/04-

The design of evanescent-field-coupled waveguide-mode sensors

Makoto Fujimaki, Carsten Rockstuhl, Xiaomin Wang, Koichi Awazu, Junji Tominaga, Nobuko Fukuda, Yuuki Koganezawa and Yoshimichi Ohki

Nanotechnology (19) p.95503(1) - 95503(7)2008/02-

Possible Mechanisms of Superior Resistance of Polyamide Nanocomposites to Partial Discharges and Plasmas

Norikazu Fuse, Yoshimichi Ohki, Masahiro Kozako, and Toshikatsu Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 15(1) p.161 - 1692008/02-

Dielectric Properties of Epoxy/Clay Nanocomposites -Effects of Curing Agent and Clay Dispersion Method-

N. Tagami, M. Okada, N. Hirai, Y. Ohki, T. Tanaka, T. Imai, M. Harada and M. Ochi

IEEE Transactions on Dielectrics and Electrical Insulation 15(1) p.24 - 322008/02-

Enhanced Partial Discharge Resistance of Epoxy/Clay Nanocomposite Prepared by Newly Developed Organic Modification and Solubilization Methods

Toshikatsu Tanaka, Yoshimichi Ohki, Mitsukazu Ochi, Miyuki Harada, and Takahiro Imai

IEEE Transactions on Dielectrics and Electrical Insulation 15(1) p.81 - 892008/02-

Biomolecular sensors utilizing waveguide modes excited by evanescent fields

M. Fujimaki, C. Rockstuhl, X. Wang, K. Awazu, J. Tominaga, T. Ikeda, Y. Koganezawa, and Y. Ohki

Journal of Microscopy 229(2) p.320 - 3262008/02-

A Plasmonic Photocatalyst Consisting of Silver Nanoparticles Embedded in Titanium Dioxide

Koichi Awazu, Makoto Fujimaki, Carsten Rockstuhl, Junji Tominaga, Hirotaka Murakami, Yoshimichi Ohki, Naoya Yoshida, and Toshiya Watanabe

Journal of the American Chemical Society 130(5) p.1676 - 16802008/01-

Electrical Conduction and Breakdown Properties of Several Biodegradable Polymers

Y. Ohki and N. Hirai

IEEE Trans. Dielectrics and Electrical Insulation 14(6) p.1559 - 15672007/12-

Comparison of Partial Discharge Resistance among Several Biodegradable Polymers

K. Miyata, S. Fujita and Y. Ohki

IEEE Trans. Dielectrics and Electrical Insulation 14(6) p.1474 - 14762007/12-

Birefringence in optical fibers formed by proton implantation

Seung Jun Yu, Masahiro Suzuki, Yoshimichi Ohki, Makoto Fujimaki, Koichi Awazu, Eisuke Yamaguchi, and Satoshi Okude

Nuclear Instruments and Methods in Physics Research B 265p.490 - 4942007/12-

Control of the properties of directional couplers using proton irradiation

Makoto Fujimaki, Keita Kawabe, Masahiro Suzuki, Koichi Awazu, Yoshimichi Ohki, and Junji Tominaga

Nuclear Instruments and Methods in Physics Research B 264p.267 - 2712007/11-

Modification of structural and optical properties of silica glass induced by ion microbeam

H. Nishikawa, M. Murai, T. Nakamura, Y. Ohki, M. Oikawa, T. Sato, T. Sakai, Y. Ishii, M. Fukuda

Surface and Coatings Technology 201(19?20) p.8185 - 81892007/08-

いくつかの生分解性高分子の部分放電劣化Partial Discharge Degradation of Several Biodegradable Polymers

布施則一、藤田慎二郎、平井直志、田中祀捷、小迫雅裕、向當政典、岡部成光、大木義路

体裁 127(8) p.459 - 4662007/08-

Effect of Crystallinity on Electrical Conduction Characteristics of Poly(L-lactic Acid)

Shingo Omori, Makoto Matsushita, Fukutaro Kato, and Yoshimichi Ohki

Japanese Journal of Applied Physics 46(6A) p.3501 - 35032007/06-

Effect of Endothermic Reaction Associated with Glass Transition on the Breakdown Strength of Biodegradable Polymer Films

F. Kato, M. Matsushita, S. Omori, and Y. Ohki

IEEE Transactions on Dielectrics and Electrical Insulation 14(3) p.653 - 6552007/06-

Effects of Curing and Filler Dispersion Methods on Dilelctric Properties of Epoxy Nanocompositesh

M. Okada, N. Hirai, T. Tanaka, Y. Ohki, T. Imai, M. Harada, M. Ochi

UVSOR ACTIVITY REPORT 2006 2007/06-

High sensitivity sensors made of perforated waveguides

Koichi Awazu, Carsten Rockstuhl, Makoto Fujimaki, Nobuko Fukuda, Junji Tominaga, Tetsuro Komatsubara, Takahiro Ikeda and Yoshimichi Ohki

Optics Express 15(5) p.2592 - 25972007/05-

Micro-photoluminescence study on defects induced by ion microbeam in silica glass

Masato Murai, Hiroyuki Nishikawa, Tomoharu Nakamura, Hirohiko Aiba, Yoshimichi Ohki, Masakazu Oikawa, Takahiro Sato, Tomihiro Kamiya

Journal of Non-Crystalline Solids 353(5?7) p.537 - 5412007/04-

プリント配線板用絶縁材料の空間電荷挙動に対する湿度と温度の影響Effect of Humidity and Temperature on Space Charge Distribution Profiles in Printed Circuit Board Insulations

越後易恒、田中秀郷、福永香、岡本健次、前野恭、大木義路

エレクトロニクス実装学会誌 10(2) p.148 - 1512007/03-

生分解性高分子の誘電特性におよぼす紫外光照射の影響Effects of Ultraviolet Photon Irradiation on the Dielectric Properties of Biodegradable Polymers

山口雄也、内堀直、大木義路

電気学会論文誌A 127(2) p.115 - 1202007/02-

Nanoscale pore fabrication for high sensitivity waveguide-mode biosensors

Makoto Fujimaki , Carsten Rockstuhl, Xiaomin Wang, Koichi Awazu, Junji Tominaga, Takahiro Ikeda, Yoshimichi Ohki, Tetsuro Komatsubara

Microelectronic Engineering 84p.1685 - 16892007/02-

Space charge distributions in glass fibre/epoxy resin composites under dc 10 kV/mm electric field

Hidesato Tanaka, Yoshimichi Ohki, Kaori Fukunaga, Takashi Maeno and Kenji Okamoto

Journal of Physics D: Applied Physics 40p.1489 - 14962007/02-

Thermal stability of Deformation and Refractive Index Change in Silica Glass Induced by Ion Microbeam

H. Aiba, T. Nakamura, Y. Ohki, M. Murai, H. Nishikawa, M. Oikawa, T. Satoh

JAEA Takasaki Annual Report 2005 JAEA-Review2006(42) p.175 - 1752007/02-

High sensitive biosensors based on perforated waveguide structure

K. Awazu, M. Fujimaki, T. Komatsubara, Y. Ohki

Tandem Accelerator Center University of Tsukuba Annual Report (2006) p.46 - 472007-

Preparation and Various Characteristics of Epoxy/alumina Nanocomposites

Masahiro Kozako, Yoshimichi Ohki, Masanori Kohtoh, Shigemitsu Okabe, Toshikatsu Tanaka

IEEJ Trans. FM 126(11) p.1121 - 11272006/11-

Treeing Phenomena in Epoxy/Alumina Nanocomposite and Interpretation by a Multi-core Model

Toshikatsu Tanaka, Akira Matsunawa, Yoshimichi Ohki, Masahiro Kozako, Masanori Kohtoh, Shigemitsu Okabe

IEEJ Trans. FM 126(11) p.1128 - 11352006/11-

Filler-content Dependence of Dielectric Properties of Low-Density Polyethylene/MgO Nanocomposites

Toshiaki Kikuma, Norikazu Fuse, Toshikatsu Tanaka, Yoshinao Murata, Yoshimichi Ohki

IEEJ Trans. FM 126(11) p.1072 - 10772006/11-

Dielectric Properties of BaTiO3, Thin Films Prepared by Laser Ablation

Junya Fujita, Keigo Suzuki, Nobuyuki Wada, Yukio Sakabe, Kazuo Takeuchi, and Yoshimichi Ohki

Japanese Journal of Applied Physics 45(10A) p.7806 - 78122006/10-

Core/shell ZrTiO4/LiAlSi2O6 nanocrystals: A synchrotron X-ray diffraction study of high-pressure compression

Kristina E. Lipinska-Kalita, Michael Pravica, Gino Mariotto, Patricia E. Kalita and Yoshimichi Ohki

Journal of Physics and Chemistry of Solids 67(9月10日) p.2072 - 20762006/09-

Structure of latent tracks in rutile single crystal of titanium dioxide induced by swift heavy ions

Koichi Awazu, Xiaomin Wang, Makoto Fujimaki, Tetsuo Komatsubara, Takahiro Ikeda, and Yoshimichi Ohki

Journal of Applied Physics 100p.44308(1) - 44308(5)2006/08-

プリント回路基板用絶縁材料の空間電荷挙動に対する水処理温度の影響Effect of Water Treatment Temperature on Space Charge Profiles in Printed Circuit Board Insulations

田中秀郷、福永香、前野恭、岡本健次、大木義路

電学論A 126(7) p.709 - 7152006/07-

Photoluminescence in Polyamide-6/Mica Nanocomposite

Norikazu Fuse, Masahide Okada, Toshikatsu Tanaka, and Yoshimichi Ohki

UVSOR Activity Report 2005p.68 - 682006/07-

Improvement in electrical properties of hafnium and zirconium silicates by postnitriding

T. Ito, H. Kato, T. Nango, and Y. Ohki

Journal of Physics: Condensed Matter 18(26) p.6009 - 60162006/06-

Mechanisms of several photoluminescence bands in hafnium and zirconium silicates induced by ultraviolet photons

Toshihide Ito, Hiromitsu Kato, and Yoshimichi Ohki

J. Appl. Phys 99p.94106(1) - 94106(9)2006/05-

プラズマ化学気相堆積により成膜したhigh-k膜のX線光電子分光X-ray photoelectron spectroscopy of high-k dielectric films synthesized by plasma-enhanced chemical-vapor deposition

及川圭太、伊藤俊秀、高瀬雅之、大木義路、加藤宙光

放電研究 49(1) p.39 - 422006/03-

高分解能三次元空間電荷分布測定装置High Resolution Three-dimensional Space Charge Distribution Measurement System

前田和哉、大木義路、西方敦博、前野恭

電学論A 126(3) p.185 - 1902006/03-

Enhanced Crystallization of Strontium Bismuth Tantalate Thin Films by Irradiation of Elongated Pulses of KrF Excimer Laser

Masashi Tsubuku, Kwang Soo Seol, In-Hoon Choi, and Yoshimichi Ohki

Jpn. J. Appl. Phys. 45(3A) p.1689 - 16932006/03-

Spectroscopic properties of Cr3+ ions in nanocrystalline glass-ceramic compostes

Kristina E. Lipinska-Kalita, Patricia E. Kalita, Dnise M. Krol, Russel J. Hemley, Cedric L. Gobin, Yoshimichi Ohki

Journal of Non-Crystalline Solids 352p.524 - 5272006/02-

ポリ乳酸の電気特性

大木義路

月刊エコインダストリー 11(2) p.15 - 202006/01-

Spatial distribution of irradiation effects on silica glass induced by 15-MeV oxygen ion microbeam

H. Nishikawa, K. Fukagawa, T. Nakamura, Y. Ohki, M. Oikawa

Nuclear Instruments and Methods in Physics Research B242p.437 - 4402006-

Evaluation of Three-dimensional Microstructures on Silica Glass Fabricated by Ion Microbeam

T. Nakamura, Y. Ohki, K. Fukagawa, M. Murai, H. Nishikawa, M. Oikawa, T. Sato and K. Arakawa

TIARA Annual Report 2004, JAERI-Review2005 1p.259 - 2612005/11-

Photonic crystals of titanium dioxide fabricated by swift heavy ions

Koichi Awazu, Makoto Fujimaki, Yoshimichi Ohki, Tetsuro Komatsubara

Radiation Measurements 40p.722 - 7292005/11-

Properties of Polyethylene Blend Tested as a Non-cross-linked Insulating Material for Power Cable

Hiroki Tamura, Hironaga Ono, Masaaki Ikeda, Yoshimi Yamamoto, and Yoshimichi Ohki

Electrical Engineering in Japan 153(1) p.1 - 82005/10-

Electrical Engineering Education in Waseda University

Y. Ohki

The Proceedings of The Korean Institute of Electrical Engineering 54(10) p.48 - 512005/10-

Synthesis of Size- and Structure-Controlled Ge2Sb2Te5 Nanoparticles

Hoon Sang Choi, Kwang Soo Seol, Kazuo Takeuchi, Junya Fujita, and Yoshimichi Ohki

Jpn. J. Appl. Phys. 44(10) p.7720 - 77222005/10-

Temperature effects on luminescence properties of Cr3+ ions in alkali gallium silicate nanostructured media

Kristina E. Lipinska-Kalita, Denise M. Krol, Russell J. Hemley, Patricia E. Kalita, Cedric L. Gobin, and Yoshimichi Ohki

J. Appl. Phys 98(5) p.54302(1) - 54302(6)2005/09-

Synthesis and characterization of metal-dielectric composites with copper nanoparticles embedded in a glass matrix:A multitechnique approach

Kristina E. Lipinska-Kalita, Denise M. Krol, Russell J. Hemley, Gino Mariotto, Patricia E. Kalita, and Yoshimichi Ohki

J. Appl. Phys 98p.54301(1) - 54301(6)2005/09-

Effects of High Pressure on Stability of the Nanocrystalline LiAlSi2O6 Phase of a Glass-Ceramic Composite: a Synchrotron X-Ray Diffraction Study

Kristina E. Lipinska-Kalita, Gino Mariotto, Patricia E. Kalita and Yoshimichi Ohki

Physica B 365p.155 - 1622005/08-

Breakdown Strength at the Interface between Epoxy Resin and Silicone Rubber -A Basic Study for the Development of All Solid Insulation-

Toshihiro Takahashi, Tatsuki Okamoto, Yoshimichi Ohki, and Kohei Shibata

IEEE Trans. Dielectrics and Electrical Insulation 12(4) p.719 - 7242005/08-

Proposal of a Multi-core Model for Polymer Nanocomposite Dielectrics

Toshikatsu Tanaka, Masahiro Kozako, Norikazu Fuse, and Yoshimichi Ohki

IEEE Trans. Dielectrics and Electrical Insulation 12(4) p.669 - 6812005/08-

Characterization of Partial Discharge Degradation of Polyamide-6 Nanocomposites by a Photoluminescence Analysis

N. Fuse, M. Kozako, T. Tanaka, and Y. Ohki

UVSOR Activity Report 2004 32p.68 - 682005/06-

Fabrication of two- and three-dimensional photonic crystals of titania with submicrometer resolution by deep X-ray lithography

Koichi Awazu, Xiaomin Wang, Makoto Fujimaki, Taketo Kuriyama, Akihide Sai, Yoshimichi Ohki, and Hiroaki Imai

J. Vacuum Science and Technology B 23(3) p.934 - 9392005/05-

L型ポリ乳酸の電気伝導特性に及ぼすガラス転移の影響Effect of Glass Transition on Electrical Conduction Characteristics of Poly-L-lactic Acid

前野、山口、平井、田中、大木、田實、向當、岡部

電学論A 125(3) p.254 - 2602005/03-

Similarities in photoluminescence in hafnia and zirconia induced by ultraviolet photons

T. Ito, M. Maeda, K. Nakamura, H. Kato, and Y. Ohki

J. Appl. Phys. 97(5) p.54104(1) - 54104(7)2005/02-

Effects of Crosslinking Byproducts on Space Charge Formation in Crosslinked Polyethylene

Y. Maeno, N. Hirai, Y. Ohki, T. Tanaka, M. Okashita, and T. Maeno

IEEE Trans. Dielectrics and Electrical Insulation, 12(1) p.90 - 972005/02-

Voltage Zero-crossing as a Factor Inducing Water trees

T. Maeda, D. Kaneko, Y. Ohki, T. Konishi, Y. Nakamichi and M. Okashita

IEEJ Trans. FM 125(1) p.51 - 562005/01-

Development of a Sub-micron Processing Method with Ion Implantation

S.J. Yu, M. Fujimaki, K. Kawabe, H. Ohkubo, M. Hattori, Y. Ohki, M. Saito and Y. Wada

IEEJ Trans. FM 125(1) p.69 - 702005/01-

ポリ乳酸およびいくつかの生分解性高分子材料の電気特性Electrical Properties of Polylactic Acid and Other Biodegradable Polymers

大木義路

MATERIAL STAGE 4(9) p.69 - 732004/12-

Energy Band Profile of Hafnium Silicates Estimated by X-Ray Photoelectron Spectroscopy

T. Ito, H. Kato, T. Nango and Y. Ohki

Japanese Journal of Applied Physics 43(12) p.8199 - 82022004/12-

固体絶縁材料研究の最近の課題と展開(その2)〜環境に優しい材料の模索(1)〜生分解性高分子の電気機器絶縁への適用可能性Recent Research Topics on Solid Dielectrics and Their Progress Part 2: Search for Eco-friendly Materials (1) -Applicability of Biodegradable Polymers to electrical Insulation-

平井直志, 大木義路

放電研究 47(3) p.2 - 82004/11-

Fabrication and Evaluation of Micrometer-scale Optical Elements using Three-dimensional Irradiation Effects Localized in Micro and Nano-scale Regions

H. Nishikawa, K. Fukagawa, T. Yanagi, T. Nakamura, Y. Ohki, E. Watanabe, M. Oikawa, K. Arakawa, and T. Kamiya

TIARA Annual Report 2003, JAERI-Review 2004-025p.234 - 2362004/11-

Surface Degradation of Polyamide Nanocomposites Caused by Partial Discharges Using IEC(b) Electrodes

M. Kozako, N. Fuse, Y. Ohki, T. Okamoto, T. Tanaka

IEEE Trans. Dielectrics and Electrical Insulation 11(5) p.833 - 8392004/10-

電力ケーブル用非架橋絶縁材料としてのポリエチレンブレンドの特性Properties of Polyethylene Blend as a Non-crosslinked Insulating Material for Power Cable

田村弘毅、小野裕永、池田雅昭、山本良美、大木義路

電気学会論文誌A 124-A(9) p.817 - 8222004/09-

Ferroelectricity of single-crystalline, monodispersed lead zirconate titanate nanoparticles of 9 nm in diameter

Kwang Soo Seol, Kazuo Takeuchi, and Yoshimichi Ohki

Appl. Phys. Lett. 85(12) p.2325 - 23272004/09-

Role of Number of Consecutive Voltage Zero-crossings in Propagation of Water Trees in Polyethylene

D. Kaneko, T. Maeda, T. Ito, Y. Ohki, T. Konishi, Y. Nakamichi, M. Okashita

IEEE Trans. Dielectrics and Electrical Insulation 11(4) p.708 - 7142004/08-

絶縁体中の電荷移動とデトラッピングに関する基礎電磁気学Electromagnetism in Charge Transport and Detrapping Phenomena in Dielectrics

平井直志, 大木義路

静電気学会誌 28(4) p.204 - 2072004/07-

Effects of additives, photodegradation, and water-tree degradation on the photoluminescence in polyethylene and polypropylene

T. Ito, N. Fuse, and Y. Ohki

UVSOR Activity Report 2003p.53 - 532004/07-

Crystallization of monodisperse lead zirconate titanate nanoparticles produced by laser ablation

T. Katagiri, K. S. Seol, K. Takeuchi, and Y. Ohk

Jpn. J. Appl. Phys. 43(7A) p.4419 - 44232004/07-

Effects of additives, photodegradation, and water-tree degradation on the photoluminescence in polyethylene and polypropylene

T. Ito, N. Fuse, and Y. Ohki

IEEJ Trans. FM 124-A(7) p.624 - 6302004/07-

固体絶縁材料研究の最近の課題と展開 (その1)本特集解説のねらいと国際会議に見る絶縁材料研究の最近の動向Recent Research Topics on Solid Dielectrics and Their Progress Part 1: Scope of This Series and Trend of Recnt R & D Activities

大木義路

JIEED Japan 47(2) p.2 - 112004/05-

Three-Dimensional Lithography for Rutile TiO2 Single Crystals using Swift Heavy Ions

K. Awazu, M. Fujimaki, Y. Ohki, T. Komatsubara

Mat. Res. Soc., Symp. Proc. 797p.69 - 742004/04-

Recent Development of Different Mobility Analyzers for Size-Classification of Nanoparticles and Their Applications to Nanotechnologies

K. S. Seol, Y. Ohki, and K. Takeuchi

KIEE International Transactions on EA 4-C(2) p.39 - 442004/04-

我国における電力機器絶縁監視・診断法の変遷と現状 Status Quo and Trends of Insulation Monitoring and Diagnosis Methods for Electric Power Apparatus in Japan

平井直志、田中祀捷、大木義路、新藤孝敏

電気学会論文誌B 124(3) p.496 - 5032004/03-

研究グループ紹介

大木義路

電気学会論文誌A 124(3) 2004/03-

Technology 2004: Reviews and Forecasts

Y. OHKI

IEEJ Trans., FM 124(1) p.2 - 22004/01-

Effects of Ultraviolet Photon Irradiation on the Dielectric Properties of Polyimide

A. Yamaguchi, Y. Ohki

IEEJ Trans., FM 124(1) p.98 - 1032004/01-

Effects of Ion Microbeam Irradiation on Silica Glass

H. Nishikawa, K. Fukagawa, T. Yanagi, Y. Ohki, E. Watanabe, M. Oikawa, T. Kamiya, and K. Arakawa

Trans. Materials Research Society of Japan 29(2) p.603 - 6062004-

Evaluation of Three Dimensional Microstructures on Silica Glass Fabricated by Ion Microbeam

H. Nishikawa, T. T. Souno, M. Hattori, Y. Ohki, E. Watanabe, M. Oikawa, K. Arakawa, and T. Kamiya

JAERI-Review 2003-033p.254 - 2562004-

平成15年基礎・材料・共通部門大会報告

八井浄、大木義路

電学論A 123(12) p.1147 - 11482003/12-

2002 Conference on Electrical Insulation and Dielectric Phenomena出席報告

大木義路

放電研究 46(3) p.58 - 722003/10-

Structural Change Induced in TiO2 by Swift Heavy Ions and Its Application to Three Dimensional Lithography

Ken-ichi Nomura, Tetsuya Nakanishi, Yoshihiro Nagasawa, Yoshimichi Ohki, Koichi Awazu, Makoto Fujimaki, Naoto Kobayashi, Satoshi Ishii, and Kunihiro Shima

Phys. Rev. B 68(6) p.64106(1) - 64106(8)2003/08-

High-Pressure X-Ray Diffraction Studies of the Nanostructured Transparent Vitroceramic Medium K2O-SiO2-Ga2O3

K.. E. Lipinska-Kalita, B. Chen, M. B. Kruger, Y. Ohki, J. Murowchick, and E. P. Gogol

Phys. Rev. B 68(3) p.352091 - 3520982003/07-

国際情報 Conference on Electrical Insulation and Dielectric Phenomenaの沿革と2003年会議のご案内

大木義路

放電研究 46(1) p.3 - 42003/06-

7th International Conferenceon Properties and Applications of Dielectric Materials -ICPADMの沿革と第7回会議(ICPADM 2003)開催のご案内-

大木義路

放電研究 45(3) p.27 - 292003/06-

Ultraviolet photon-induced absorption bands and paramagnetic centers in Ge and Sn co-doped SiO2 glass

Tetsuya Nakanishi, Makoto Fujimaki, Shin-ichiro Tokuhiro, Ken-ichi Nomura, Yoshimichi Ohki, and Kazuo Imamura

J. Non-Cryst. Solids 318p.87 - 942003/04-

Chemical Group in Crosslinking Byproducts Responsible for Charge Trapping in Polyethylene

Naoshi Hirai, Ryotaro Minami, Toshikatsu Tanaka, Yoshimichi Ohki, Minoru Okashita, and Takashi Maeno

IEEE Trans. Dielectrics and Electrical Insulation 10(2) p.320 - 3302003/04-

Similarities in the electrical conduction process in hydrogenated amorphous silicon oxynitride and silicon nitride

Hiromitsu Kato, Hidefumi Sato, Yoshimichi Ohki, Kwang Soo Seol, and Takashi Noma

J. Phys.: Condens. Matter 15p.2197 - 22052003/03-

Band-tail photoluminescence in hydrogenated amorphous silicon oxynitride and silicon nitride films

Hiromitsu Kato, Norihide Kashio, Yoshimichi Ohki, Kwang Soo Seol, and Takashi Noma

J. Appl. Phys. 93(1) p.239 - 2442003/01-

3D nano-fabrication of rutile TiO2 single crystals with swift heavy ion

K. Awazu, M. Fujimaki, N. Kobayashi, Yoshimichi Ohki, Satoshi Ishii, Kunihiro Shima

Tandem Accelerator Center University of Tsukuba Annual Report 2003p.71 - 722003-

Characterization of refractive index changes of silica glass induced by ion microbeam

M. Hattori, Y. Ohki, M. Fujimaki, T. Souno, H. Nishikawa, E. Watanabe, M. Oikawa, T. Kamiya, and K. Arakawa

Nuclear Instruments and Methods in Physics Research B 210p.272 - 2762003-

Characterization of ion-implanted silica glass by micro-photoluminescence and Raman spectroscopy,

T. Souno, H. Nishikawa, M. Hattori, Y. Ohki, E. Watanabe, M. Oikawa, T. Kamiya, and K. Arakawa

Nuclear Instruments and Methods in Physics Research B 210p.277 - 2802003-

Structural defects in amorphous silicon oxynitride and silicon nitride

H. Kato, and Y. Ohki

Defect and Diffusion Forum 218-220p.39 - 492003-

Evaluation of Three Dimensional Microstructures on Silica Glass Fabricated by Ion Microbeam

H.Nishikawa, T. Souno, M. Hattori, Y. Nishihara, Y. Ohki, T. Yamaguchi, E. Watanabe, M. Oikawa, T. Kamiya, K. Arakawa, and M. Fujimaki

JAERI-Review 2002-035p.240 - 2422002/11-

絶縁性高分子中の電荷分布計測における電磁気学Electromagnetism in Charge Distribution Measurements in Dielectric Polymers

大木義路

静電気学会誌 26(5) p.204 - 2082002/10-

Characteristics of Nanoparticles Formed during Pulsed Laser Ablation of SrBi2 Ta2 O9

Kwang Soo Seol, Kazuo Takeuchi, Takeshi Miyagawa, and Yoshimichi Ohki

Jpn. J. Appl. Phys. 41-Part1(9) p.5654 - 56582002/09-

Gas-phase production of monodisperse lead zirconate titanate nanoparticles

Kwang Soo Seol, Satoshi Tomita, Kazuo Takeuchi, Takeshi Miyagawa, Takahiro Katagiri, and Yoshimichi Ohki

Appl. Phys. Lett. 81(10) p.1893 - 18952002/09-

Factors Influencing the Dielectric Properties of Linear Low-Density Polyethylene

Hironaga Ono, Makoto Araoka, Naoshi Hirai, and Yoshimichi Ohki

Electrical Engineering in Japan 140(3) p.1 - 72002/08-

水トリー劣化架橋ポリエチレンの残留電荷の測定と解釈Measurement and Interpretation of Residual Charge in Crosslinked Polyethylene Degraded by Water Trees

平井直志、小林啓一、大木義路、武田敏尚、岡本達希

電気学会部門誌A 122-A(6) p.597 - 6032002/06-

Photoluminescence properties of hydrogenated amorphous silicon nitride

Norihide Kashio, Hiromitsu Kato, Kwang Soo Seol, Takashi Noma, and Yoshimichi Ohki

UVSOR Activity Report 2001 UVSOR-29p.108 - 1092002/05-

Photo-induced refractive index change in hydrogenated amorphous silicon oxynitride

Hiromitsu Kato, Makoto Fujimaki, Takeshi Noma, Yoshimichi Ohki

J. Appl. Phys. 91(10) p.6350 - 63532002/05-

Plasma-enhanced chemical vapor deposition and characterization of high-permittivity hafnium and zirconium silicate films

Hiromitsu Kato, Tomohiro Nango, Takeshi Miyagawa, Takahiro Katagiri, Kwang Soo Seol, and Yoshimichi Ohki

J. Appl. Phys. 92(2) p.1106 - 11112002/04-

ポリエチレン中の空間電荷分布形成に与える架橋剤分解残渣の影響Effects of Byproducts of Dicumyl Peroxide on Space Charge Formation in Poyethylene

平井直志、南亮太郎、大木義路、岡下稔、前野恭

電学論A 122(3) p.308 - 3142002/03-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 18(2) 2002/03-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 18(1) 2002/01-

Fabrication of microstructures in rutile TiO2 single crystal using structural change induced by swift heavy-ion bombardment

M. Fujimaki, K. Awazu, N. Kobayashi, T. Nakanishi, K. Nomura, Y. Ohki, S. Ishii, K. Shima

University of Tsukuba Tandem Accelerator Center (UTTAC) Annual Report UTTAC-70, 2002p.60 - 612002-

Evaluation of Silica Glasses Implanted by High-energy Ions Using a UV-excited microspectroscopy

T. Yamaguchi, E. Watanabe, T. Souno, H. Nishikawa, M. Hattori, Y. Ohki, T. Kamiya, and K. Arakawa

Nuclear Instruments and Methods in Physics Research B 191p.371 - 3742002-

Characterization of Ion-implanted Silica Glass by Vacuum Ultraviolet Absorption Spectroscopy

M. Hattori, Y. Nishihara, Y. Ohki, M. Fujimaki, T. Souno, H. Nishikawa, T. Yamaguchi, E. Watanabe, M. Oikawa, T. Kamiya, and K. Arakawa

Nuclear Instruments and Methods in Physics Research B 191p.362 - 3652002-

Radiation Effects and Surface Deformation of Silica by Ion Microbeam

H. Nishikawa, T. Souno, M. Hattori, Y. Nishihara, Y. Ohki, E. Watanabe, M. Oikawa, T. Kamiya, K. Arakawa

Nuclear Instruments and Methods in Physics Research B 191p.342 - 3452002-

ポリイミドの耐水・耐アルカリ性—残留電圧等電気的測定による評価—Anti-water and Anti-alkali Properties of Polyimide -Evaluation by Recovery Voltage and Other Electrical Measurement

山口晃、Wei Wei、平井直志、大木義路、財満英一、岡部成光

電学論A 121-A(12) p.1117 - 11242001/12-

Evaluation of Three Dimensional Microstructures on Silica Glass Fabricated by Ion Microbeam

H. Nishikawa, T. Souno, M. Hattori, Y. Nishihara, Y. Ohki, T. Yamaguchi, E. Watanabe, M. Oikawa, T. Kamiya, K. Arakawa, and M. Fujimaki

TIARA Annual Report 2000, JAERI-Review 2001-039p.235 - 2372001/11-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 17(6) 2001/11-

ポリプロピレンの紫外光励起フォトルミネセンスPhotoluminescence in Polypropylene Induced by Ultraviolet Photons

伊藤俊秀、豊田毅彦、平井直志、大木義路

電気学会部門誌A 121-A(9) p.865 - 8712001/09-

直鎖状低密度ポリエチレンの絶縁特性に影響を与える因子Influencing Factors on the Dielectric Properties of Linear Low-density Polyethylene

小野裕永、荒岡誠、平井直志、大木義路

電気学会部門誌A 121-A(9) p.854 - 8592001/09-

Visible Electroluminescence in Hydrogenated Amorphous Silicon Oxynitride

Hiromitsu Kato, Akira Masuzawa, Hidefumi sato, Takashi Noma, Kwang Soo Seol, Makoto Fujimaki, and Yoshimichi Ohki

J. Appl. Phys. 90(5) p.2216 - 22202001/09-

Nucleation of Ga2 O3 Nanocrystals in the K2 O-Ga2 O3 0-SiO2 Glass System

R. Ceccato, R. Dai Maschio, S. Gialanella, G. Mariott, M. Montagna, F. Rossi, M. Ferrari, K. E. Lipinska-Kalita, and Y. Ohki

J. Appl. Phys. 90(2) p.2522 - 25272001/09-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 17(5) 2001/09-

Origin of photoluminescence around 2.6 - 2.9 eV in silicon oxynitride

Takashi Noma, Kwang Soo Seol, Hiromitsu Kato, Makoto Fujimaki, and Yoshimichi Ohki

Applied Physics Letter 79(13) p.1995 - 19972001/09-

シリカ系フォトニクスガラスの高機能化

西川宏之、大木義路

電気学会部門誌A 121-A(8) p.721 - 7242001/08-

Low-wavenumber Raman Scattering Spectroscopy in the Studies of New Gallium-doped Silica Glass-based Transparent Vitroceramic Medium

R. Ceccato, R. Dai Maschio, M. Ferrari, S. Gialanella, K. E. Lipinska-Kalita, G. Mariotto, M. Montagna, Y. Ohki, and F. Rossi

J. Raman Spectroscopy 32p.643 - 6472001/08-

Thermally induced photoluminescence quenching center in hydrogenated amorphous silicon oxynitride

Hiromitsu Kato, Akira Masuzawa, Takashi Noma, Kwang Soo Seol, and Yoshimichi Ohki

J. Phys. Condens. Matter 13(30) p.6541 - 65492001/07-

Low-temperature crystallization induced by excimer laser irradiation of SrBi2 Ta2 O9 films

Kwang Soo Seol, Hiranao Hiramatsu, Yoshimichi Ohki, In-Hoon Choi, and Yong-Tea Kim

J. Mater. Res. 16(7) p.1883 - 18862001/07-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 17(4) 2001/07-

プラズマ化学気相堆積法によるハフニウムシリケート膜の堆積Deposition of hafnium silicate films by plasma-enhanced chemical vapor deposition

加藤宙光、宮川武、南向智広、大木義路、薛光洙、滝山真功

放電研究 44(1, 2) p.69 - 732001/06-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 17(3) 2001/05-

Photoluminescence in Polypropylene Induced by Ultraviolet Laser Irradiation

Takehiko Toyoda, Hiromitsu Kato, Toshihide Ito, Naoshi Hirai, and Yoshimichi Ohki

UVSOR Activity Report 2000p.110 - 1112001/04-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 17(2) 2001/03-

Correlation between Space Charge Distribution in Aged XLPE Cable and Location of Water Tree

K. Suzuki, Y. Tanaka, T. Takada, Y. Ohki, and C. Takeya

IEEE Trans. Dielectrics and Electrical Insulation 8(1) p.78 - 812001/02-

Estimation of Conductivity and Permittivity of Water Trees in Polyethylene from Space Charge Distribution Measurements

T. Toyoda, S. Mukai, Y. Ohki, Y. Li, and T. Maeno

IEEE Trans. Dielectrics and Electrical Insulation 8(1) p.111 - 1162001/02-

特集 21世紀へ向けての技術展望—1 21世紀へ向けた新材料の展望

荒井賢一、大木義路

電学誌 121(1) p.31 - 352001/01-

水トリー劣化した絶縁材料のPEA法による空間電荷分布測定

大木義路、高田達雄、田中康寛、鈴木健太郎、竹谷千加士

タツタ電線技報 16p.46 - 552001/01-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 17(1) 2001/01-

Photoluminescence Analysis of Plasma-deposited Oxygen-rich Silicon Oxynitride Films

Takashi Noma, Kwang Soo Seol, Makoto Fujimaki, Hiromitsu Kato, Takashi Watanabe, and Yoshimichi Ohki

Jpn. J. Appl. Phys. 39 Part 1(12A) p.6587 - 65932000/12-

Ion-implantation-induced densification in silica-based glass for fabrication of optical fiber gratings

Makoto Fujimaki, Yoshitaka Nishihara, Yoshimichi Ohki, John L. Brebner, and Sjoerd Roordaf

J. Appl. Phys. 88(10) p.5534 - 55372000/11-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 16(6) 2000/11-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 16(5) 2000/09-

ポリエチレン中の水トリーの導電率と誘電率Conductivity and Permittivity of Water Tree in Polyethylene

豊田毅彦、向井茂雄、大木義路、李英、前野恭

電学論A 121-A(7) p.750 - 7542000/07-

Time-resolved photoluminescence study of hydrogenated amorphous silicon nitride

Kwang Soo Seol, Takashi Watanabe, Makoto Fujimaki, Hiromitsu Kato, Yoshimichi Ohki, and Makoto Takiyama

Phys. Rev. B 62(3) p.1532 - 15352000/07-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 16(4) 2000/07-

Application of Infrared Attenuated Total Reflection Spectroscopy to In situ Analysis of Atheromatous Plaques in Aorta

Atsushi Nakamura, Takchiro Koga, Makoto Fujimaki, Yoshimichi Ohki, Takayuki Sota, Kristina Lipinska-Kalita, Tsuneyuki Nagae, Shin Ishimaru, and Katsuo Aizawa

Jap. J. Appl. Phys. 39(6A) p.L490 - L4922000/06-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 16(3) 2000/05-

学会情報 第31回電気電子絶縁材料システムシンポジウム

電気学会論文誌A 120-A(4) p.5172000/04-

熱可塑性ポリイミドの電気伝導Electrical Conduction in Thermoplastic Polyimide

武井精一、田邊泰広、大木義路

電学論A 120-A(4) p.478 - 4832000/04-

Photoluminescence in amorphous silicon oxynitride grown by plasma-enhanced chemical vapor deposition

Hiromitsu Kato, Kwang Soo Seol, Makoto Fujimaki, Takashi Noma, Takashi Watanabe, and Yoshimichi Ohki

UVSOR Activity Report 1999 UVSOR-27p.74 - 752000/04-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 16(2) 2000/03-

Effects of internal postoxidation on the oxygen deficiency and dielectric strength of buried oxide formed by the separation-by-implanted-oxygen (SIMOX) process

Kwang Soo Seol, Hidemi Koike, Tsuyoshi Futami, Yoshimichi Ohki

Electrical Engineering in Japan 130(1) p.15 - 202000/02-

Fabrication of long-period optical fiber gratings by use of ion implantation

Makoto Fujimaki, Yoshimichi Ohki, John L. Brebner, and Sjoerd Toorda

Optics Letters 25(2) p.88 - 892000/01-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 16(1) 2000/01-

アセトフェノンがポリエチレンの空間電荷形成に与える影響Effect of Acetophenone on Space Charge Formation in Polyethylene

小林啓一、大原尚、大木義路、前野恭

電学論A 119-A(12) p.1465 - 14711999/12-

Effect of ozone annealing on the charge trapping property of Ta2 O5 -Si3 N4 -p-Si capacitor grown by low-pressure chemical vapor deposition

Hiromitsu Kato, Kwang Soo Seol, Makoto Fujimaki, Takehiko Toyoda, Yoshimichi Ohki, and Makoto Takiyama

Japanese Journal of Applied Physics 38-Part 1(12A) p.6791 - 67961999/12-

Experimental Investigation on the Cause of Harmfulness of the Blue Water Tree to XLPE Cable Insulation

G. Katsuta, A. Toya, Ying Li, M. Okashita, F. Aida, Y. Ebinuma, and Y. Ohki

IEEE Trans. Dielectrics and E. I. 6(6) p.887 - 8911999/12-

高調波電圧がCV電力ケーブルの長期絶縁特性に与える影響—超電導磁気浮上式鉄道用き電線の基礎的絶縁性能—

中道好信、戸田弘康、池内忍、品川潤一、大木義路

電学論D 119-D(11) p.1327 - 13361999/11-

Insulation characteristics of XLPE cables for high frequency voltage with a PWM inverter

Akio Seki, Shigeki Miyamoto, Yoshimichi Ohki, Toyokazu Hisatsune, Tsutomu Ono and Susumu Sakuma

Electrical Engineering in Japan 129(2) p.31 - 391999/11-

Effect of annealing on Ge-doped SiO2 thin films

Makoto Fujimaki, Shigeyuki Shimoto, Nahoko Miyazaki, Yoshimichi Ohki, Kwang Soo Seol, and Kazuo Imamura

Journal of Applied Physics 86(9) p.5270 - 52731999/11-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 15(6) 1999/11-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 15(5) 1999/09-

Structural changes induced by KrF excimer laser photons in H2-loaded Ge-doped SiO2 glass

Makoto Fujimaki, Toshiaki Kasahara, Shigeyuki Shimoto, Nahoko Miyazaki, Shin-ichi Tokuhiro, Kwang Soo Seol, and Yoshimichi Ohki

Phys. Rev. B 60p.4682 - 46871999/08-

Characteristic red photoluminescence band in oxygen-deficient silica glass

Yuryo Sakurai, Kaya Nagasawa, Hiroyuki Nishikawa, and Yoshimichi Ohki

J. Appl. Phys. 86(1) p.370 - 3731999/07-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 15(4) 1999/07-

Direct deposition of a blanket tungsten layer on SiO2 by preexposure of helium plasma

Takashi Noma, Kwang Soo Seol, Makoto Fujimaki, and Yoshimichi Ohki

J. Appl. Phys. 85(12) p.8423 - 84261999/06-

Dielectric Breakdown of New Type Polymerized Polyethylene Using a Single-site Catalyst

M. Araoka, H. Yoneda, and Y. Ohki

IEEE Trans. Dielectrics and E. I. 6(3) p.326 - 3301999/06-

プラズマCVD堆積SiO2薄膜の絶縁破壊電界におよぼすフッ素添加の効果 Effects of Fluorine Doping on the Dielectric Strength in SiO2 Films Formed by Plasma-enhanced Chemical Vapor Deposition

加藤宙光、高見明宏、酒井真吾、石井啓介、大木義路

電学論A 119(5) p.658 - 6641999/05-

Effects of ion implantation and thermal annealing on the photoluminescence in amorphous silicon nitride

Kwang Soo Seol, Tsuyoshi Futami, Takashi Watanabe, Hiromitsu Kato, and Yoshimichi Ohki

UVSOR ACTIVITY Report 1998 UVSOR-26p.80 - 811999/05-

Effects of ion implantation and thermal annealing on the photoluminescence in amorphous silicon nitride

Kwang Soo Seol, Tsuyoshi Futami, Takashi Watanabe, Yoshimichi Ohki, and Makoto Takiyama

J. Appl. Phys 85(9) p.6746 - 67501999/05-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 15(3) 1999/05-

Paramagnetic centers induced in Ge-doped SiO2 glass with UV irradiation

Makoto Fujimaki, Tetsuya Katoh, Toshiaki Kasahara, Nahoko Miyazaki, and Yoshimichi Ohki

J. Phys. Condensed Matter 11(12) p.2589 - 25941999/03-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 15(2) 1999/03-

実験結果より考察したインバータ電圧に対する電力ケーブルの絶縁設計へのいくつかの指針 Some Hints on the Insulation Design of Power Cables for Inverter Voltages Based on Experimental Results

向井茂雄、大木義路、中道好信、安喰浩司

電学論B 119(1) p.117 - 1221999/01-

プラズマCVD法による希土類添加シリカ薄膜—成膜法の開発と発光の物性研究への応用 Rare-earth-doped SiO2 Films Prepared by Plasma-enhanced Chemical Vapor Deposition -Development of Deposition Method and Application of Its Luminescence to Research in Physics

四元茂之、酒井真吾、大木義路

電学論A 119(1) p.113 - 1171999/01-

鉄蒸気の混入した高温アルゴンの熱力学特性と粘性率 Thermodynamic Properties and Viscosity of High Temperature Argon Mixed with Iron Vapoer

天川正士、足立和郎、大木義路、稲葉次紀

電学論A 119(1) p.75 - 791999/01-

Temperature dependence of the lifetime of 4.3 eV photoluminescence in oxygen-deficient amorphous SiO2

Kwang Soo Seol, Makoto Fujimaki, Yoshimichi Ohki, and Hiroyuki Nishikawa

Phys. Rev. B 59(3) p.1590 - 15931999/01-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 15(1) 1999/01-

Low Temperature Crystallization of SrBi2 Ta2 O9 Film by Excimer Laser Irradiation

K. S. Seol, H. Hiramatsu, Y. Ohki, D.-S. Shin, I.-H. Choi, and Y.-T. Kim

Mat. Res. Soc. Symp. Proc. 541p.293 - 2981999-

Structures and Oprical Properties of Defects Correlated with Photo-induced Refractive Index Changes in Ge-doped SiO2 Glass

Makoto Fujimaki, and Yoshimichi Ohki

Defect and Diffusion Forum 177-178p.43 - 501999-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 14(6) 1998/11-

Space Charge Formation in Water-treed Insulation

Y. Ohki, Y. Ebinuma, S. Katakai

IEEE Trans. On Dielectrics and E. I 5(5) p.707 - 7121998/10-

γ線照射されたポリエーテルスルホンの誘電特性に与える熱処理の影響 Effect of Heat Treatment on the Dielectric Property in gamma-irradiated Polyethersulfone

加藤学、斉尾奈穂子、大木義路

電学論A 118(9) p.1053 - 10541998/09-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 14(5) 1998/09-

内部酸化がSIMOX埋め込み酸化膜の酸素欠乏性と絶縁破壊電界におよぼす影響 Effects of internal oxidation on the oxygen deficiency and dielectric strength of buried oxide formed by the separation-by-implanted-oxygen (SIMOX) process

薛光洙、小池英巳、二見毅、大木義路

電学論A 118(7, 8) p.826 - 8311998/07-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 14(4) 1998/07-

固体絶縁材料中の電荷と電気伝導 Charges and Their Transport in Solid dielectrics

大木義路

静電気学会誌 22(3) p.132 - 1361998/05-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 14(3) 1998/05-

Concentration of neutral oxygen vacancies in buried oxide formed by implantation of oxygen

K.. S. Seol, T. Futami, and Y. Ohki

UVSOR Activity Report 25p.98 - 991998/04-

Water-tree Characteristics in Low-density PE under Simulated Inverter Voltages

H. Suzuki, S. Mukai, Y. Ohki, Y. Nakamichi, and K. Ajiki

IEEE Trans. Dielectrics and Electrical Insulation 5(2) p.256 - 2601998/04-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 14(2) 1998/03-

送変電設備の現地耐電圧試験合理化

大木義路

電気協同研究 53(4) 1998/03-

特別高圧CVケーブル絶縁劣化形態と絶縁診断技術の動向

大木義路

電気学会技術報告 6681998/02-

Concentration of neutral oxygen vacancies in buried oxide formed by implantation of oxygen

Kwang Soo Seol, Tsuyoshi Futami, and Yoshimichi Ohki

J. Appl. Phys. 83(4) p.2357 - 23591998/02-

Structures and generation mechanisms of paramagnetic centers and absorption bands responsible for Ge-doped SiO2 optical-fiber gratings

Makoto Fujimaki, Tomofumi Watanabe, Tetsuya Katoh, Toshiaki Kasahara, Nahoko Miyazaki, and Yoshimichi Ohki, Hiroyuki Nishikawa

Phys. Rev. B 57(7) p.3920 - 39261998/02-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 14(1) 1998/01-

PWMインバータ出力波形に対する架橋ポリエチレンケーブルの絶縁特性 Insulation Characteristics of XLPE Cables for High Frequency Voltage with PWM Inverter

関秋生、宮本茂樹、大木義路、久恒豊一、小野努、佐久間進

電学論B 117(12) p.1553 - 15601997/12-

Effect of Gamma-ray Irradiation on the TSC in Polyethersulfone

E. J. Kim, G. Kato, T. Ohara, Y. Ohki, and S. T. Li

IEEE Transactions on Dielectrics and Electrical Insulation 4(6) p.732 - 7371997/12-

Formation mechanisms of paramagnetic defect centers induced by excimer lasers, gamma rays, and mechanical fracturing in amorphous SiO2

Hiroyuki Nishikawa, Eiki Watanabe, Daisuke Ito and Yoshimichi Ohki

Electrical Engineering in Japan 121(3) p.9 - 191997/11-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 13(6) 1997/11-

Interfacial charge between ZnO varistor ceramics and inorganic insulating materials and its role

Li Shengtao, Liu Fuyi, Li Bo, and Ohki Yoshimichi

Chinese Journal of Materials Research 11(5) p.479 - 4821997/10-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 13(5) 1997/09-

Evaluation of Microscopic Structural Randomness in SiO2 by Analysis of Photoluminescence Decay Profiles

Keisuke Ishii, Kwang Soo Seol, Yoshimichi Ohki, and Hiroyuki Nishikawa

Electrical Engineering in Japan 119(3) p.1 - 61997/08-

Rare-earth-doped SiO2 films prepared by plasma-enhanced chemical vapour deposition

M. Yoshihara, A. Sekiya, T. Morita, K. Ishii, S. Shimoto, S. Sakai, and Y. Ohki

J. Phys. D: Appl. Phys 30(13) p.1908 - 19121997/07-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 13(1月4日) 1997/07-

Thermal annealing behavior of defects induced by ion implantation in thermally grown SiO2 films

Kwang Soo Seol, Toshifumi Karasawa, Yoshimichi Ohki, Hiroyuki Nishikawa, and Makoto Takiyama

Microelectronic Engineering 36(1月4日) p.193 - 1951997/06-

学界情報

電学論A 117(5) 1997/05-

Electrical Conduction in Highly Resistive Polyolefin Films Modified by Polar Groups

Yoshimichi Ohki, Tadashi Asada, Yuka Umeshima, and Masaaki Ikeda

Electrical Engineering in Japan 120(3) p.9 - 161997/05-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 13(3) 1997/05-

Energy states of Ge-doped SiO2 glass estimated through absorption and photoluminescence

Makoto Fujimaki, and Yoshimichi Ohki

UVSOR Activity Report 1996 UVSOR-24p.222 - 2231997/04-

Dielectric Breakdown of Low-density Polyethylene under Simulated Inverter Voltages

Hidenori Suzuki, Shigeo Mukai, Yoshimichi Ohki, Yoshinobu Nakamichi, and Kohji Ajiki

IEEE Transactions on Dielectrics and Electrical Insulation 4(2) p.238 - 2401997/04-

ポリメチルペンテンの熱刺激電流 Thermally Stimulated Current in Polymethylpentene

鈴木英範、黒田博文、朝井壮太郎、大木義路

電学論A 117(3) p.269 - 2751997/03-

Structural stabilization induced by oxygen plasma post-exposure of SiO2 films deposited from tetraethoxysilane

Takashi Noma, Takaharu Sugiura, Keisuke Ishii, Yoshimichi Ohki, and Yoshimasa Hama

J. Phys.D: Appl. Phys. 30(6) p.937 - 9431997/03-

Excited-state absorption measurement in Ge-doped SiO2 glass

Makoto Fujimaki, Kwang Soo Seol, and Yoshimichi Ohki

J. Appl. Phys. 81(6) p.2913 - 29151997/03-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 13(2) 1997/03-

Effects of fluorine addition on the structure and optical properties of SiO2 films formed by plasma-enhanced chemical vapor deposition

K. Ishii, A. Takami, and Y. Ohki

J. Appl. Phys. 81(3) p.1470 - 14741997/02-

Energy states of Ge-doped SiO2 glass estimated through absorption and photoluminescence

Makoto Fujimaki, Yoshimichi Ohki, and Hiroyuki Nishikawa

J. Appl. Phys. 81(3) p.1042 - 10461997/02-

Space Charge Behavior under ac Voltage in Water-treed PE Observed by the PEA Method

Ying Li, Hiro Kawai, Yasumitsu Ebinuma, Yasutaka Fujiwara, Yoshimichi Ohki, Yasuhiro Tanaka, and Tatsuo Takada

IEEE Trans. Dielectrics and E. I. 4(1) p.52 - 571997/02-

Luminescence properties of sol-gel synthesized silica glass induced by an ArF excimer laser

K. Mukasa, M. Ono, R. Wakabayashi, K. Ishii, Y. Ohki, and H. Nishikawa

J. Phys.D: Appl. Phys. 30(2) p.283 - 2851997/01-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 13(1) 1997/01-

Effect of post-oxidation on the oxygen deficiency of buried oxide

Kwang Soo Seol, Toshifumi Karasawa, Hidemi Koike, Yoshimichi Ohki, and Masaharu Tachimori

Mat. Res. Soc. Symp. Proc. 446p.219 - 2231997-

Photoluminescence of oxygen-deficient-type defects in a-SiO2

N. Nishikawa, Y. Miyake, E. Watanabe, D. Ito, K. S. Seol, Y. Ohki, K. Ishii, Y. Sakurai, and K. Nagasawa

J. Non-Cryst. Solids 222p.221 - 2271997-

エキシマレーザ、ガンマ線、および機械的応力による非晶質SiO2中の常磁性中心の生成機構 The formation mechanisms of paramagnetic defect centers induced by excimer lasers, gamma rays, and mechanical fracturing in amorphous SiO2

西川宏之、渡辺英紀、伊藤大佐、大木義路

電学論A 116(12) p.1129 - 11371996/12-

極性基が導入された高抵抗性オレフィン系高分子フィルムの電気伝導 Electrical Conduction in Highly-resistive Polyolefin Films Modified by Polar Groups

浅田規、大木義路、梅島由香、池田雅昭

電学論A 116(12) p.1113 - 11201996/12-

Structural Origin of Dimensional Effect on Dielectric Breakdown Strength of ZnO Vraistors

Shengtao Li, Fuyi Liu, Guangping Jia, and Yoshimichi Ohki

T. IEE Japan 116(12) p.1146 - 11471996/12-

Effect of implanted ion species on the decay kinetics of 2.7 eV Photoluminescence in thermal SiO2 films

Kwang Soo Seol, Yoshimichi Ohki, Hiroyuki Nishikawa, Makoto Takiyama, and Yoshimasa Hama

J. Appl. Phys. 80(11) p.6444 - 64471996/12-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 12(6) 1996/11-

発光減衰曲線の解析によるSiO2の微視的構造の乱雑さの評価 Evaluation of Microscopic Structural Randomness in SiO2 through Analysis of Decay Profile of Photoluminescence

石井啓介、薛光洙、大木義路、西川宏之

電学論A 116(10) p.881 - 8851996/10-

水トリー劣化した架橋ポリエチレンにおける空間電荷の挙動 Space Charge Behavior in Crosslinked Polyethylene Degraded by Water Trees

李英、川井二郎、海老沼康光、藤原靖隆、大木義路

電学論A 116(9) p.818 - 8241996/09-

Visible photoluminescence from Si clusters in gamma-irradiated amorphous SiO2

Hiroyuki Nishikawa, Eiki Watanabe, Daisuke Ito, Yuryo Sakurai, Kaya Nagasawa, and Yoshimichi Ohki

J. Appl. Phys. 80(6) p.3513 - 35171996/09-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 12(5) 1996/09-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 12(4) 1996/07-

ポリメチルペンテンにおける異常放電電流 Anomalous Discharging Current in Polymethylpentene

大木義路、朝井壮太郎

電学論A 116(6) p.545 - 5511996/06-

Origins of Thermally Stimulated Current in Polyethersulfone

E. J. Kim, T. Takeda, and Y. Ohki

IEEE Trans. Dielectrics and E. I 3(3) p.386 - 3911996/06-

シリコン酸化膜中の点欠陥の新しい検出法 A New Detection Method of Point Detects in Silicon Dioxide Thin Films

大木義路、石井啓介、薛光洙、西川宏之

電学論A 116(5) p.387 - 3911996/05-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 12(3) 1996/05-

ポリエーテルスルホンの熱刺激電流と電気伝導 Thermally Stimulated Current and Electrical Conduction in Polyethersulfone

大木義路、金恩住、武田敏尚

電学論A 116(4) p.357 - 3631996/04-

Photoluminescence Study on Point Defects in SIMOX Buried SiO2 Film

UVSOR Activity Report 1996/04-

Laser-power dependence of absorption changes in Ge-doped SiO2 glass induced by a KrF excimer laser

Makoto Fujimaki, Kanta Yagi, Yoshimichi Ohki, Hiroyuki Nishikawa, and Koichi Awazu

Phys. Rev. B 53(15) p.9859 - 98621996/04-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 12(2) 1996/03-

Photoluminescence Study on Point Defects in Buried SiO2 Film Formed by Implantation of Oxygen

Kwang Soo Seol, Akihito Ieki, Yoshimichi Ohki, Hiroyuki Nishikawa, and Masaharu Tachimori

J. Appl. Phys. 79(1) p.412 - 4161996/01-

アモルファスSiO2ならびに希土類ドープガラスの局所構造とその非線形光学効果に及ぼす役割

カシオ科学振興財団平成7年年報 1996/01-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 12(1) 1996/01-

Paramagnetic Defect Centers Induced by Excimer Lasers, γ-rays and Mechanical Fracturing in Amorphous SiO2

H. Nishikawa, and Y. Ohki

Defect and Diffusion Forum/Scitec Publication 123-124(Part A) p.123 - 1241995/12-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 11(6) 1995/11-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 11(5) 1995/09-

Photoluminescence and Electron-spin-resonance Studies of Defects in Ion-implanted Thermal SiO2 Films

H. Nishikawa, H. Fukui, E. Watanabe, D. Ito, M. Takiyama, A. Ieki, and Yo. Ohki

Materials Science Forum/Trans Tech Publications 196-201(Part 1) p.97 - 1021995/07-

Photoluminescence Study on Point Defects in SIMOX Buried SiO2 Film

K. S. Seol, A. Ieki, Y. Ohki, H. Nishikawa, and M. Tachimori

Materials Science Forum/Trans Tech Publications 196-201(Part 4) p.1909 - 19141995/07-

Photoluminescence Study of Defects in Ion-implanted Thermal SiO2 Films

Hiroyuki Niishikawa, Makoto Takiyama, Akihito Ieki, and Yoshimichi Ohki

J. Appl. Phys. 78(2) p.842 - 8461995/07-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 11(4) 1995/07-

パルス静電応力法による空間電荷分布の計測と熱刺激電流により考察したポリエーテルスルホンの自発電流 Sponganeous Current of Polyethersulfone Investigated through the Measurements of Space Charge Distribution by the Pulsed Electroacoustic Method and Thermally Stimulated Current

金恩住、武田敏尚、大木義路

電学論A 115(5) p.437 - 4441995/05-

News from Japan

Yoshimichi Ohki

IEEE Electrical Insulation Magazine 11(3) 1995/05-

Nature of Photoluminescence Involving Transitions from the Ground to 4fn-15d1 States in Rare-earth-doped Glasses

T. Yokokawa, H. Inokuma, Y. Ohki, H. Nishikawa, and Y. Hama

J. Appl. Phys. 77(8) p.4013 - 40171995/04-

直流電圧印加によりガンマ線照射低密度ポリエチレン中に形成される空間電荷分布 Measurement of Space Charge Accumulation in Gamma-irradiated Polyethylene with DC Voltage

小嶋雅之、田中康寛、高田達雄、大木義路

電学論 115-A(2) p.93 - 981995/02-

Ionic Behavior of dc Conduction in Polyetheretherketone

E. J. Kim and Y. Ohki

IEEE Trans. Dielectrics and E. I. 2(1) p.74 - 831995/02-

Role of Point Defects in Dielectric Breakdown of SiO2 Formed by Plasma-Enhanced Chemical Vapor Deposition of Tetraethoxysilane,

Keisuke Ishii, Daisuke Isshiki, Yoshimichi Ohki, Hiroyuki Nishikawa, and Makoto Takiyama

Jpn. J. Appl. Phys. 34-Part 1(1) p.205 - 2111995/01-

Optical characteristics of SiO2 formed by plasma-enchanced chemical-vapor deposition of tetraethoxysilane

Keisuke Ishii, Yoshimichi Ohki, and Hiroyuki Nishikawa

J. Appl. Phys. 76(9) p.5418 - 54221994/11-

Gamma-Ray-Induced Loss of Er3+ Doped Silica-Core Optical Fiber

Takeshi Koyama, Nobuyuki Dohguchi, Yoshimichi Ohki, Hiroyuki Nishikawa, Yasuo Kusama, and Tadao Seguchi

Jpn. J. Appl. Phys. 33(Part 1- 7A) p.3937 - 39411994/07-

Preparation of Cd1-xYxSb2O6 thin film on glass substrate by radio frequency sputtering

Kazuhiko Yanagawa, Yoshimichi Ohki, Takehisa Omata, Hideo Hosono, Naoyuki Ueda, and Hiroshi Kawazoe

Appl. Phys. Lett. 65(4) p.406 - 4081994/07-

Decay kinetics of the 4.4eV photoluminescence associated with the two states of oxygen-deficient-type defect in amorphous SiO2

Hiroyuki Nishikawa, Eiki Watanabe, Daisuke Ito, and Yoshimichi Ohki

Phys. Rev. Lett. 72(13) p.2101 - 21041994/03-

New Oxide Phase Cd2(1-x)Y2xSb2O7 Pyrochlore with a Wide Band Gap and High Electrical Conductivity

Kazuhiko Yanagawa, Yoshimichi Ohki, Takehisa Omata, Hideo Hosono, Naoyuki Ueda, and Hiroshi Kawazoe

Jpn. J. Appl. Phys. 33(Part 2-2B) p.L238 - L2401994/02-

Point defects in high purity silica induced by high-dose gamma irradiation

Yuryo Sakurai, Kaya Nagasawa, Hiroyuki Nishikawa, and Yoshimichi Ohki

J. Appl. Phys. 75(3) p.1372 - 13771994/02-

絶縁材料の期待される方向

大木義路

静電気学会誌 18(3) p.204 - 2051994-

Dielectric Properties of Fluorine-containing Plasma Polymer Films

Keisuke Ishii, Yoshimichi Ohki, and Toshiki Nakano

J. Photopolym. Sci. Technol. 7(2) p.353 - 3601994-

Kinetics of enhanced photogeneration of E' centers in oxygen-deficient silica

Hiroyuki Nishikawa, Eiki Watanabe, Daisuke Ito, and Yoshimichi Ohki

J. Non-cryst. Solids. 179p.179 - 1841994-

Correlation of pre-existing diamagnetic defect centers with induced paramagnetic defect centers by ultra-violet or vacuum-ultra-violet photons in high-purity silica glasses

Hiroyuki Nishikawa, Ryuta Nakamura, Yoshimichi Ohki, and Yoshimasa Hama

Phys. Rev. B 48(21) p.15584 - 155941993/12-

New oxide phase Cd1-xYxSb2O6 with a wide band gap and high electrical conductivity

Kazuhiko Yanagawa, Yoshimichi Ohki, Naoyuki Ueda, Takahisa Omata, Takuoya Hashimoto, and Hiroshi Kawazoe

Appl. Phys. Lett. 63(24) p.3335 - 33371993/12-

Study of defects in silicon dioxide films on Si(100) by a variable-energy positron beam

M. Fujinami, N. B. Chilton, K. Ishii, and Y. Ohki

J. Appl. Phys. 74(9) p.5406 - 54091993/11-

A positron beam study of defects in SiO2

M. Fujinami, N. B. Chilton, K. Ishii, and Y. Ohki

J. de Phys. Ⅳ 3p.169 - 1751993/09-

低密度ポリエチレン中の不純物が空間電荷形成挙動に与える影響 Effect of Impurities on Space Charge Formation in Low-Density Polyethylene

田中康寛、田中貞嗣、大木義路

電学論A 113(8) p.598 - 5991993/08-

Enhanced photogeneration of E'centers from neutral oxygen vacancies in the presence of hydrogen in high-purity silica glass

Hiroyuki Nishikawa, Ryuta Nakamura, Yoshimichi Ohki, and Yoshimasa Hama

Phys. Rev. B 48(5) p.2968 - 29731993/08-

Various bonding forms of OH groups in hydrogen- treated silica

Manabu Kitagawa, Hiroyuki Nishikawa, Yoshimichi Ohki, and Yoshimasa Hama

J. Appl. Phys. 74(4) p.2378 - 23801993/08-

液晶ポリマの電気伝導特性 Conduction Characteristics in Liquid-Crystal Polymer

平井知生、宇田茂晴、田中康寛、大木義路、池田雅昭

電学論A 113(1) p.32 - 381993/01-

Characterization of ClOx radicals in vacuum- ultraviolet-irradiated high-purity silica glass

Hiroaki Nishikawa, Ryuta Nakamura, Yoshimichi Ohki, Kaya Nagasawa, and Yoshimasa Hama

Phys. Rev. B 46(13) p.8073 - 80791992/10-

プラズマ重合エチレン薄膜の光伝導特性 Photoconduction Characteristics of Plasma-polymerized Ethylene Thin Films

石井啓介、大木義路

電学論A 112(9) p.789 - 7961992/09-

Morphology of Ethylene-Styrene Copolymers and its Effect on Dielectric Strength

Yasuhiro Tanaka, Yoshimichi Ohki, and Masaaki Ikeda

IEEE Transactions on Electrical Insulation 27(3) p.432 - 4391992/06-

プラズマ重合エチレンおよびフッ素含有エチレン薄膜の絶縁破壊機構 Breakdown Mechanism of Plasma Polymerized Ethylene and Ethylene-trifluoromethane Films

石井啓介、大木義路

電学論A 112(3) p.188 - 1951992/03-

Photoluminescence from defect centers in high-purity silica glasses observed under 7.9 -eV excitation

Hiroyuki Nishikawakawa, Taiji Shiroyama, Ryuta Nakamura, Yoshimichi Ohki, Kaya Nagasawa, and Yoshimichi Hama

Phys. Rev. B 45(2) p.586 - 5911992/01-

Si-O-Si strained bond and paramagnetic defect centers induced by mechanical fracturing in amorphous SiO2

Shuji Munekuni, Nobuyuki Dohguchi, Hiroyuki Nishikawa, Yoshimichi Ohki, Kaya Nagasawa, and Yoshimasa Hama

J. Appl. Phys. 70(9) p.5054 - 50621991/11-

Effect of high-temperature treatment on optical-absorption bands in amorphous SiO2

Nobuyuki Dohguchi, Shuji Munekuni, Hiroyuki Nishikawa, Yoshimichi Ohki, and Kaya Nagasawa

J. Appl. Phys. 70(5) p.2788 - 27901991/09-

水素プラズマによるYBa2 Cu3 O7の劣化 Degradation of YBa2 Cu3 O7 by Hydrogen Plasma

沓掛孝夫、大木義路

電学論A 111(7) p.684 - 6851991/07-

Effects of Crystallinity Electron Mean-free-path on Dielectric and strength of Low-density Polyethylene

Yasuhiro Tanaka, Norihiro Ohnuma, Kunio Katsunami, and Yoshimichi Ohki

IEEE Trans Electr. Insulation 26(2) p.258 - 2651991/04-

シリカガラスの光吸収・放出と構造欠陥

大木義路

電学論A 111(3) p.223 - 2261991/03-

高純度シリカガラスの放射線・レーザ誘起欠陥 Defects in high purity silica glasses induced by ionizing radiations and lasers.

大木義路、長沢可也

応用物理 60(7) p.708 - 7111991-

Effect of Plasma Surface Modification on Electrical Conduction in Polyethylene

Hisaaki Hayashi, Toshiki Nakano, and Yoshimichi Ohki

Electrical Engineering in Japan 111(6) p.17 - 231991-

エチレンースチレン共重合体の機械的練込みによる高次構造の変化と絶縁破壊特性 Relation between Morphology Change due to Mechanical Kneading and Dielectric Breakdown Characteristics in Ethylene-Styrene Copolymers

田中康寛、尾坪利信、大木義路、池田雅昭、矢崎文彦

電学論A 110(12) p.919 - 9261990/12-

プラズマによるポリエチレンの表面構造の変化と電気伝導 Effect of Plasma Surface-Modification on the Electrical Conduction in Polyethylene

林央晶、中野俊樹、大木義路

電学論A 110(12) p.913 - 9181990/12-

Effect of Polar Groups on the Electrical Breakdown Strength of Plasma-polymerized films

Toshiki Nakano, Masao Fukuyama, Hisaaki Hayashi, Keisuke Ishii, and Yoshimichi Ohki

IEEE Transactions on Electrical Insulation 125(6) p.1085 - 10911990/12-

Various Types of non-bridging oxygen hole center in high-purity silica glass

Shuji Munekuni, Toshihisa Yamanaka, Yasushi Shimogaichi, Ryoichi Tohmon, Yoshimichi Ohki, Kaya Nagasawa, and Yoshimasa Hama

J. Appl. Phys. 68(3) p.1212 - 12171990/08-

Generation mechanism of photoinduced paramagnetic centers from pre-existing precursors in high-purity silicas

Hiroyuki Nishikawa, Ryuta Nakamura, Ryoichi Tohmon, Yoshimichi Ohki, Yuryo Sakurai, Kaya Nagasawa, and Yoshimasa Hama

Phys. Rev. B 41(11) p.7828 - 78341990/04-

Triplet-state defect in high-purity silica glass

Ryoichi Tohmon, Yasushi Shimogaichi, Yoshiki Tsuta, Shuji Munekuni, Yoshimichi Ohki, Yoshimasa Hama, and Kaya Nagasawa

Phys. Rev. B 41(10) p.7258 - 72601990/04-

Spatial distribution of defects in high-purity silica glasses

Ryoichi Tohmon, Akihiro Ikeda, Yasushi Shimogaichi, Shuji Munekuni, Yoshimichi Ohki, Kaya Nagasawa, and Yoshimasa Hama

J. Appl. Phys. 67(3) p.1302 - 13061990/02-

Space charges in ethylene-styrene copolymers irradiated by low-dose gamma rays

Yasuhiro Tanaka, Yuuichi Mita, Yoshimichi Ohki, Hiroshi Yoshioka, Massaki Ikeda, and Fumihiro Yazaki

J. Phys. D: Appl. Phys. 23(12) p.1491 - 14961990-

Electrical properties of nitrogen-containing plasma polymer films

Toshiki Nakano, Shunichi Koike, and Yoshimichi Ohki

J. Phys. D: Appl. Phys. 23(6) p.711 - 7181990-

エチレン-スチレン共重合体の耐水トリー性 Water-Tree Resistance of Ethylene-Styrene Copolymers.

秋山敬一郎、大木義路、矢崎文彦、池田雅昭

電学論A 109(10) p.4641989/10-

プラズマ重合ポリマの絶縁破壊特性に及ぼすフッ素の影響 Effect of Introduced Fluorine on Electrical Breakdown Characteristics of Plasma Polymer Films.

中野俊樹、福山正雄、大木義路

電学論A 109(8) p.343 - 3501989/08-

純粋石英ガラスに誘起される欠陥の生成機構ーイオンビームとガンマ線の比較ー Growth mechanism of defects induced in pure-silica glass -Comparison between ion beams and gamma rays-

東門領一、長沢可也、大木義路、浜義昌

早稲田大学理工学研究所報告 124p.15 - 191989/08-

Gamma-Irradiation Effect on High-Tc Super-conductor Yba2Cu3O7-x

Takao Kutsukake, Hiromichi Somei, Yoshimichi Ohki, Kaya Nagasawa, and Fumitaka Kaneko

Japanese Journal of Applied Physics 28(8) p.L1393 - L13941989/08-

エチレンースチレン共重合体のキャリアトラップ Carrier Traps in Ethylene-Styrene Copolymer.

田中康寛、大木義路、池田雅昭

電学論A 109(7) p.295 - 3021989/07-

Defects and optical absorption bands induced by surplus oxygen in high-purity synthetic silica

Hiroyuki Nishikawa,Ryoichi Tohmon, Yoshmichi Ohki, Kaya Nagasawa, and Yoshimasa Hama

J. Appl. Phys. 65(12) p.4672 - 46781989/06-

Relation between the 1.9 eV luminescence and 4.8eV absorption bands in high-purity synthetic silica

Ryoichi Tohmon, Yasushi Shimogaichi, Shuji Munekuni, Yoshimichi Ohki, Yoshimasa Hama, and Kaya Nagasawa

Appl. Phys. Lett. 54(17) p.1650 - 16521989/04-

2.7eV Luminescence in As-Manufactured High Purity Silica Glass

Ryoichi Tohmon, Yasushi Shimogaichi, Hiroyasu Mizuno, Yoshimichi Ohki, Kaya Nagasawa, and Yoshimasa Hama

Phys. Rev. Lett. 62(12) p.1388 - 13911989/03-

Correlation of the 5.0-eV absorption and 7.6-eV bands in SiO2 with oxygen vacancy

Ryoichi Tohmon, Hiroyasu Mizuno, Yoshimichi Ohki, Kotoku Sasagane, Kaya Nagasawa, and Yoshimasa Hama

Phys. Rev. B 39(2) p.1337 - 13451989/01-

エチレンースチレン共重合体の耐放射線性 Radiation Resistance of Ethylene-Styrene Copolymers.

松本薫、池田雅昭、大木義路、日馬康雄、原重雅浩、矢崎文彦

電学論A 108(8) p.335 - 3421988/08-

エチレンースチレン共重合体の高次構造が絶縁破壊特性に及ぼす影響 Influence of Morphology on Electrical Breakdown Characteristics of Ethylene-Styrene Copolymers.

池田雅昭、松尾克也、大木義路、穂積直裕、原重雅浩

電学論A 108(8) p.321 - 3281988/08-

Dielectric Properties of Plasma-Polymerized Tetrafluoroethylene Films.

Toshiki Nakano, Masao Fukuyama, and Yoshimichi Ohki

Japanese Journal of Applied Physics 27(6) p.1042 - 10461988/06-

プラズマ共重合アリルアミンーエチレン薄膜の絶縁破壊特性 Electrical Breakdown Characteristics of Plasma-Copolymerized Thin Films from Allylamine and Ethylene

中野俊樹、中村理、柴山直幹、大木義路

電学論A 108(3) p.103 - 1101988/03-

Relation between Ge(2) Center and 11.9mT Hyperfine Structure of ESR Spectra in Ge-Silica Fibers

Kaya Nagasawa, Takashi Fujii, Yoshimichi Ohki, and Yoshimasa Hama

Japanese Journal of Applied Physics 27(2) p.L240 - L2431988/02-

Electrical Breakdown Characteristics of Co-polymers of Ethylene and Various Aromatic Monomers

Masaaki Ikeda, Yoshimichi Ohki, and Hideo Kawabada

Electrical Engineering in Japan 108(2) p.1 - 151988-

Electrical Breakdown Characteristics of Plasma-Copolymerized Thin Films from Allylamine and Ethylene

Toshiki Nakano, Osamu Nakamura, Naoki Shibayama, and Yoshimichi Ohki

Electrical Engineering in Japan 18(4) p.8 - 191988-

Plasma Polymer Surface Layer for Suppression of Charge Injection into Polyethylene

Toshiki Nakano, Tohru Kihira, and Yoshimichi Ohki

Electrical Engineering in Japan 108(2) p.24 - 301988-

Hydrogen bond of OH-groups in silica glass and its relation to the 1.39 μm absorption

Yukihiro Yokomachi, Ryoichi Tohmon, Kaya Nagasawa, and Yoshimichi Ohki

Journal of Non-Crystalline Solids 95-96(PART2) p.663 - 6701987/12-

プラズマ重合ポリマ表面のポリエチレンへの電荷注入抑制効果

中野俊樹、大木義路、紀平徹

電学論A 107(11) p.511 - 5161987/11-

Plasma Polymer Surface Layer for Suppression of Charge Injection into Polyethylene.

Toshiki Nakano, Tohru Kihira, and Yoshimichi Ohki

T. IEE Japan 107-A(11) p.511 - 5161987/11-

エチレンー芳香族モノマー共重合体の絶縁破壊特性

池田雅昭、大木義路、川端秀雄

電学論A 107(9) p.415 - 4221987/09-

Electrical Breakdown Characteristics of Copolymers of Ethylene and Various Aromatic MeasureMonomers.

Masaaki Ikeda, Yoshimichi Ohki, and Hideo Kawarada

T. IEE Japan 107-A(9) p.415 - 4221987/09-

エチレンースチレン共重合体の電力ケーブル絶縁体への応用の可能性

池田雅昭、大木義路

電学論A 107(8) p.4041987/08-

Possibility of Ethylene-styrene Copolymer Applying to Power Cable Insulator.

Masaaki Ikeda, Yoshimichi Ohki, and Naohiro Hozumi

T. IEE Japan 107-A(8) p.4041987/08-

Gamma-Ray Induced 2 eV Optical Absorption Band in Pure-Silica Core Fibers

Kaya Nagasawa, Yoshimichi Ohki and Yoshimasa Hama

Japanese Journal of Applied Physics, Part2 26(6) p.L1009 - L10111987/06-

Effect of Oxygen Content on Defect Formation in Pure-Silica Core Fibers

Kaya Nagasawa, Yutaka Hoshi, and Yoshimichi Ohki

Japanese Journal of Applied Physics, Part2 26(5) p.L554 - L5571987/05-

Plasma-Polymerized Films as Orientating Layers for Liquid Crystals

Ryoichi Watanabe, Toshiki Nakano, Taketoshi Satoh, Hitoshi Hatoh, and Yoshimichi Ohki

Japanese Journal of Applied Physics, Part1 26(3) p.373 - 3761987/03-

High Energy Electron Transport in Hydrocarbons

Istvan Racz

Japanese Journal of Applied Physics, Part1 26(2) p.209 - 2151987/02-

Effect of Gold Black on UV Photoelectron Spectra

Istvan Racz

Bulletin of Science and Engineering Research Laboratory, Waseda University 117p.1 - 61987/02-

Cause of Higher Breakdown Strength in Ethylene Styrene Copolymer, a New Insulating Material

Istvan Racz

Japanese Journal of Applied Physics, Part2 26(1) p.L32 - L341987/01-

Effect of Cladding Material on 2-eV Optical Absorption in Pure-Silica Core Fibers and method to Suppress the Absorption

Kaya Nagasawa, Ryoichi Tohmon, and Yoshimichi Ohki

Japanese Journal of Applied Physics, Part1 26(1) p.148 - 1511987/01-

Cause of The 5.0 eV Absorption Band in Pure Silica Glass

Ryoichi Tohmon, Yoshiya Yamasaka, Kaya Nagasawa, Yoshimichi Ohki, and Yoshimasa Hama

Journal of Non-Crystalline Solids 95- 96p.671 - 6781987-

Radiation Effects on Polymers

Yoshimichi Ohki

IEEE Transactions on Electrical Insulation EI-21(6) p.919 - 9221986/12-

エチレンースチレン共重合体の絶縁破壊特性 Electrical Breakdown Characteristics of Ethylene-Styrene Co-polymers.

池田雅昭、大木義路

電学論 106-A(10) p.473 - 4791986/10-

The 1.52 mm Absorption Band in Optical Fibers Induced by Hydrogen Treatment, Japanese Journal of Applied Physics

Kaya Nagasawa, Tsuyoshi Todoriki, Takashi Fujii, Yoshimichi Ohki, and Yoshimasa Hama

Japanese Journal of Applied Physics, Part2 25(10) p.L853 - L8551986/10-

Dielectric Properties of Water and Water/Ethylene Glycol Mixtures for Use in Pulsed Power System Design

Markus Zahn, Yoshimichi Ohki, David B. Fenneman, Ronald J. Gripshover, and Victor H. Gehman, Jr

Proceedings of the IEEE 74(9) p.1182 - 12201986/09-

Structural Inhomogeneity in Ge-Doped Silica Core of Optical Fibers Made by the VAD Method

Kaya Nagasawa, and Yoshimichi Ohki

Japanese Journal of Applied Physics, Part2 25(8) p.L682 - L6831986/08-

圧延ポリテトラフルオロエチレンフィルムの絶縁破壊特性 Dielectric Breakdown Characteristics of Polytetra-fluoroethylene Films Made by Hot-rolling

飯田俊一、大木義路

早稲田大学理工学研究所報告 (114) p.17 - 231986/05-

Radiation Effects on Pure Silica Core Optical Fibers by g-Rays: Relation between 2 eV Band and Non-bridging Oxygen Hole Centers

Kaya Nagasawa, Yutaka Hoshi, Yoshimichi Ohki, and Kichinosuke Yahagi

Japanese Journal of Applied Physics, Part1 25(3) p.464 - 4681986/03-

原子力施設における光ファイバ利用の現状と今後の展望 Fiber Optics and Their Applications in Nuclear Power Plants

矢作吉之助編、大木義路他執筆者35名

日本原子力学会誌 27(9) p.768 - 8031985/09-

Improvement of Radiation Resistance of Pure Silica Core Fibers by Hydrogen Treatment

Kaya Nagasawa, Yutaka Hoshi, Yoshimichi Ohki, and Kichinosuke Yahagi

Japanese Journal of Applied Physics, Part1 24(9) p.1224 - 12281985/09-

Electro-Optic Charge Injection and Transport Measurements in Highly Purified Water and Water/Ethylene Glycol Mixtures

M. Zahn, Y. Ohki, K. Rhoads, M. LaGasse, and H. Matsuzawa

IEEE Transactions on Electrical Insulation EI-20(2) p.199 - 2121985/04-

Effect of Carrier Gas on Structure of Plasma Polymerized Tetrafluoroethylene Films

Toshiki Nakano, Yasuhiro Kasama, Yoshimichi Ohki, and Kichinosuke Yahagi

Japanese Journal of Applied Physics 24(1) p.83 - 861985/01-

Effect of Atmosphere on Dielectric Properties of Plasma Polymerized Ethylene

Naohiro Hozumi, Toshiyuki Takao, Yasuhiro Kasama, and Yoshimichi Ohki

Japanese Journal of Applied Physics 22(4) p.636 - 6391983/04-

真空中における不平等電界下の沿面放電 Surface Flashover Along a Polycarbonate Plate in Vacuum Under a Non-Uniform Electric Field

西田徹二、相沢隆之、新川吉彦、大木義路

早稲田大学理工学研究所報告 103p.45 - 501982/02-

Dielectric Loss Measurement of Plasma Polymerized Ethylene Films in Vacuo and Effect of Hydrogen Treatment pp. 195-196 (1982).

Naohiro Hozumi, Toshiyuki Takao, and Yoshimichi Ohki

Jpn. J. Appl. Phys. 21(1) p.195 - 1961982/01-

Empirical Equation of Surface Flashover Voltage in Vacuum

Yoshimichi Ohki

Bulletin of Science and Engineering Research Laboratory, Waseda University (91) p.157 - 1601980/08-

Deformation of Nematic-Positive Liquid Crystals by an Electric Field between Two Co-Axial Cylindrical Electrodes

Norio Aoki, Yoshimichi Ohki, and Kichinosuke Yahagi

Japanese Journal of Applied Physics 18(3) p.523 - 5261979/03-

Impulse Surface Flashover along a Polycarbonate Plate with a Back Electrode in Vacuum

Yoshimichi Ohki, Michio Sakai, and Kichinosuke Yahagi

Japanese Journal of Applied Physics 17(10) p.1739 - 17431978/10-

電荷重畳法による電界計算 Calculation of Electric Field with Charge Superposition Method

大木義路、矢作吉之助

早稲田大学理工学研究報告 78p.19 - 251977/09-

A Modified Charge Superposition Method for the Calculation of Electric Field

Yoshimichi Ohki, and Kichinosuke Yahagi

Japanese Journal of Applied Physics 16(2) p.355 - 3581977/02-

On the Conditioning Phenomena of Surface Flashover of Epoxy Resins in Vacuum

Yoshimichi Ohki, and Kichinosuke Yahagi

Japanese Journal of Applied Physics 15(1) p.177 - 1781976/01-

Temperature Dependence of Surface Flashover Voltage of Polyethylene in Vacuum

Y. Ohki, and K. Yahagi

Journal of Applied Physics 46(8) p.3695 - 36961975/08-

真空中における固体誘電体のインパルス沿面フラッシオーバについて On the Impulse Surface Flashover of Some Solid Dielectrics to Vacuum.

大木義路、大塚重信、矢作吉之助

電学論A 95(1) p.41 - 471975/01-

On the Surface-Flashover Phenomena in Polymer Insulators in Vacuum

M. Akahane, Y. Ohki, D. Ito, and K. Yahagi

Electrical Engineering in Japan 94(1) p.1 - 81974/01-

真空中における高分子誘電体の直流沿面放電について On the Surface-Flashover Phenomena to Polymer Insulators to Vacuum.

赤羽正雄、大木義路、伊藤大佐、矢作吉之助

電学論 94-A(1) p.1 - 81974/01-

Books And Publication

高分子材料・製品の長寿命化・安定化技術 The Stabilization and Long Life Cycling Technology of Polymeric Materials and Products

監修:西澤仁 執筆者:大木義路他多数

シーエムシー出版2015/09-

Detali

ISBN:978-4-7813-1087-9

ナノテク材料 〜ポリマーナノコンポジット絶縁材料の世界〜

先端複合ポリマーナノコンポジット誘電体の応用技術調査専門委員会篇(大木義路他)

電気学会2014/08-

Detali

ISBN:978-4-88686-294-5

先端エレクトロニクス分野における封止・シーリングの 材料設計とプロセス技術

大木義路(第2節[3]担当)他多数

技術情報協会2013/08-

Detali

ISBN:978-4-86104-486-1

電気化学/インピーダンス測定のノウハウと正しいデータ解釈

大木義路(第6章第11節pp.581-584担当)他多数

技術情報協会2013/05-

Detali

ISBN:978-4-86104-482-3

コンポジット材料の混練・コンパウンド技術と分散・界面制御

大木義路(第5章第6節pp.385-391担当)他多数

技術情報協会2013/04-

Detali

ISBN:978-4-86104-477-9

高分子材料の耐久性・信頼性試験ノウハウ集

大木義路ほか多数

技術情報協会2012/01-

Detali

ISBN:978-4-86104-419-9

教えて?わかった!電磁気学

大木義路、田中康寛、若尾真治

オーム社2011/04-

Detali

ISBN:978-4-274-21008-2

高電界現象論 基礎と応用

大久保仁、大木義路、鈴置保雄、匹田政幸、岡部成光、岡本達希

オーム社2011/01-

Detali

ISBN:978-4-274-20964-2

フィルムの機能性向上と成形加工・分析・評価技術

監修 金井俊孝、執筆者 大木義路含む35名

AndTech2010/08-

Detali

ISBN:978-4-9905388-0-4

太陽電池に用いられるフィルム、樹脂の高機能化とその応用

企画編集 藤本登、執筆者 大木義路ほか多数

技術情報協会2010/03-

Detali

ISBN:978-4-86104-313-0

高分子絶縁材料技術とその実例・評価

監修 大木義路、執筆者多数

サイエンス&テクノロジー2010/03-

Detali

ISBN:978-4-903413-81-5

電子/電気製品の発火・不良原因の究明技術と安全対策 第3章第1節[2]

大木義路他多数

技術情報協会2009/03-

Detali

ISBN:978-4-86104-281-2

EEText 電磁気学

大木義路編著

オーム社2007/12-

Detali

ISBN:978-4-274-20484-5

最新 ポリ乳酸の改質・高機能化と成形加工技術 第5節 電気特性

大木義路他多数

技術情報協会2007/02-

Detali

ISBN:978-4-86104-135-8

電気電子材料ー基礎から試験法までー (電気学会大学講座)

大木義路編著

電気学会2006/03-

Detali

ISBN:4-88686-252-7

3D Nanofabrication of Rutile TiO2 Single Crystals with Swift Heavy-Ions (a part of The Nano-Micro Interface)

Koichi Awazu, Ken-ichi Nomura, Makoto Fujimaki, and Yoshimichi Ohki

WILEY-VCH2005/01-

Detali

ISBN:978-3-527-30978-8

誘電体物性 (電気・電子・情報工学系テキストシリーズ11)

大木義路編著

培風館2002/11-

Detali

ISBN:4-563-03691-9

セラミック工学ハンドブック(第2版)

(社)日本セラミックス協会2002/03-

平成13年度「原子力プラントのケーブル経年変化評価技術調査に関する事業報告書

(財)発電設備技術検査協会2002/03-

平成12年度電気設備技術基準機能性化適合調査(電気設備)報告書

日本電気協会(資源エネルギー庁委託)2001/03-

電気絶縁材料の誘電率および誘電正接試験方法通則

電気学会2001/03-

平成12年度高経年化対策関連技術開発事業報告書

発電設備技術検査協会(経産省原子力安全・保安院委託)2001/03-

誘電・絶縁材料の空間電荷分布計測法と標準化

電気学会技術報告2001-

平成11年度電気施設技術基準機能性化適合調査(電気設備)報告書

日本電気協会2000/03-

科学・技術大百科事典

大木義路他

朝倉書店1999/10-

非晶質シリカ材料応用ハンドブック

大木義路ほか

株式会社 リアライズ社1999/05-

平成10年度電気施設技術基準機能性化適合調査(電気設備)報告書

日本電気協会1999/03-

放電ハンドブック

電気学会放電ハンドブック出版委員会編

電気学会1998/08-

Detali

ISBN:4-88686-308-6

平成9年度電気施設技術基準機能性化適合調査(電気設備)報告書

電気協同研究1998/03-

特別高圧(11 kV〜275 kV)架橋ポリエチレンケーブルおよび接続部の高電圧試験法

電気学会電気規格調査会標準規格1998/02-

電気工学教育の歴史

電気学会技術報告1997/10-

誘電・絶縁材料の分析法の新展開

電気学会技術報告1996/11-

CVケーブルおよび接続部の高電圧試験法

電気協同研究 /電気協同研究会1995/06-

電磁気学演習

大木義路

産業図書1982/04-

Detali

ISBN:4-7828-5509-5

基礎 電磁気学

矢作吉之助、大木義路

産業図書1981/02-

Lecture And Oral

Polymer Nanocomposite as a Cutting-edge Dielectric Material

3rd International Conference on Nanosructured Materials and Nanocomposites 2015 (ICNM2015)Invitation Yes2015/12/12

Detail

National conferenceOral presentation(invited, special)

Ion-induced Changes in Refractive Index and Structure of Solid Dielectrics and Their Applications

Invitation Yes2015/12/09

Detail

National conferenceOral presentation(invited, special)

Detection of Agglomeration of Fillers in Epoxy-Resin Based Nano-Microcomposite by Terahertz Imaging

IEEE Japan Annual Meeting 20152015/12/05

Detail

National conferenceOral presentation(general)

Possibility of Observing Filler/Resin Interaction in Epoxy-Resin Based Nano-Microcomposites by Terahertz Spectroscopy

IEEE Japan Annual Meeting 20152015/12/05

Detail

National conferenceOral presentation(general)

Chemiluminescence Appearing in Nitrogen or Air from Gamma-ray-irradiated Polyethylene Naphthalate

IEEE Japan Annual Meeting 20162015/12/05

Detail

National conferenceOral presentation(general)

Detection of Norovirus Virus-Like Particles by a V-Trench Biosensor

IEEE Japan Annual Meeting 20152015/12/05

Detail

National conferenceOral presentation(general)

Precipitation of Talc from EPDM Simultaneously Aged by Heat and Radiation: Its Confirmation by Terahertz and Infrared Absorption in Attenuated Total Reflection

IEEE Japan Annual Meeting 20152015/12/05

Detail

National conferenceOral presentation(general)

Terahertz Spectroscopy as a Powerful Tool for Analyzing Polymers

2015/10/23

Detail

International conferenceOral presentation(general)

Estimation of the Number of Nucleotides with Thymine in Deoxyribonucleic Acid by Far-infrared Absorption

2015 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2015/10/20

Detail

National conferencePoster presentation

Influence of Cable Structure on the Fault Location by Frequency Domain Reflectometry

2015 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2015/10/19

Detail

National conferencePoster presentation

Terahertz and Far-infrared Spectroscopic Estimation of Vinyl Acetate Content in Ethylene-Vinyl Acetate Copolymer

2015 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2015/10/19

Detail

National conferenceOral presentation(general)

Estimation of Crystallinity of Polyethylene Naphthalate by Terahertz Spectroscopy

2015/09/17

Detail

National conferencePoster presentation

Detection of Surface Hardening of Silicone Rubber by Scanning Probe Microscopy and Indenter Modulus

2015/09/17

Detail

National conferencePoster presentation

Decay Characteristics of the Photoluminescence Due to Oxygen Vacancies in YSZ

2015/09/17

Detail

National conferencePoster presentation

Detection of Nrovirus-Like Particles Using a V-Trench Biosensor

2015/09/16

Detail

National conferenceOral presentation(general)

Photoluminescence from Point Defects in YAlO3

2015/09/13

Detail

National conferenceOral presentation(general)

Dielectric Relaxation Phenomena in Epoxy Resin Analyzed by Electric Modulus

2015/09/03

Detail

National conferenceOral presentation(general)

Terahertz Absorption of Polyethylene Naphthalate and Its Relation to Crystallinity

International Symposium on Frontiers in THz Technology (FTT 2015)2015/08/31

Detail

National conferencePoster presentation

THz Absorption Of Adenine Base In Single-stranded Deoxyribonucleic Acid

40th International Conference on Infrared, Millimeter, and Terahertz Waves2015/08/24

Detail

International conferenceOral presentation(general)

Effects of Gamma Irradiation on the Dielectric Properties of Dicyclopentadiene Resin and Epoxy Resin

2015 IEEE 11th International Conference on the Properties and Applications of Diectric Materials2015/07/22

Detail

National conferenceOral presentation(general)

Terahertz Spectroscopic Observation of Oxidation of Ethylene-Propylene-Diene-Copolymer

2015 IEEE 11th International Conference on the Properties and Applications of Diectric Materials2015/07/22

Detail

National conferenceOral presentation(general)

Analysis on the Thickness and Temperature Dependent DC Breakdown of Low Density Polyethylene

2015 IEEE 11th International Conference on the Properties and Applications of Diectric Materials2015/07/21

Detail

National conferenceOral presentation(general)

Dielectric Relaxation Phenomena of Several Insulating Polymers Analyzed by Electgric Modulus Spectra

2015 IEEE 11th International Conference on the Properties and Applications of Diectric Materials2015/07/20

Detail

National conferenceOral presentation(general)

Simulation on Oxidation Process of Ethylene-Propylene-Diene Copolymer

2015/03/24

Detail

National conferenceOral presentation(general)

Modeling of Oxidation Process and Property Changes Induced in Ethylene-Propylene-Diene Copolymer by Gamma Irradiation

2015/03/13

Detail

National conferenceOral presentation(general)

Photoluminescence Appearing Universally in Many Organic Polymers

IEED Japan Annual Meeting 20142014/12/06

Detail

National conferenceOral presentation(general)

Superior High Temperature Properties of Olefin Thermosetting Dicyclopentadiene Resin Estimated by Electric Modulus

IEED Japan Annual Meeting 20142014/12/06

Detail

National conferencePoster presentation

Comparison of Gamma-ray Resistance between Olefin Thermosetting Resin and Epoxy Resin Using Complex Electric Modulus

IEED Japan Annual Meeting 20142014/12/06

Detail

National conferencePoster presentation

Far-infrared Absorption of Deoxyribonucleic Acid with Thymine Base

IEED Japan Annual Meeting 20142014/12/06

Detail

National conferencePoster presentation

Photoluminescence Due to Oxygen Vacancy in High-permittivity Dielectric YSZ

IEED Japan Annual Meeting 20142014/12/06

Detail

National conferencePoster presentation

Measurement of Local Softing Points of Low Density Polyethylene with Various Antioxidants by Scanning Probe Microscopy

IEED Japan Annual Meeting 20142014/12/06

Detail

National conferencePoster presentation

Generation Mechanisms of Photoluminescence Bands Due to Cr3+, Er3+, and Eu3+ in High-permittivity Gate Dielectric YAlO3

IEED Japan Annual Meeting 20142014/12/06

Detail

National conferencePoster presentation

Terahertz Absorption Spectra of Polyethylene Terephthalate and Polyethylene Naphthalate

IEED Japan Annual Meeting 20142014/12/06

Detail

National conferencePoster presentation

Time-resolved Measurements of Photoluminescence from Dielectrics Using SR in a Single-bunch Mode

UVSOR Symposium 20142014/11/15

Detail

National conferenceOral presentation(general)

Microfluidic Sedimentation System for Separation of Plasma from Whole Blood

IEEE SENSORS 20142014/11/05

Detail

International conferencePoster presentation

Chemiluminescence Due to Oxidation of Ethylene Propylene Diene Copolymers

2014 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (2014 CEIDP)2014/10/21

Detail

International conferenceOral presentation(general)

Analyses of Various Insulating Polymers by Broadband Dielectric Spectroscopy

2014 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (2014 CEIDP)2014/10/21

Detail

International conferencePoster presentation

Observation of Degradation of FR-EPDM by Scanning Probe Microscopy

the International Conference on ‘Condition Monitoring and Diagnosis 2014 (CMD2014)’2014/09/24

Detail

International conferencePoster presentation

Condition Monitoring For Predictive Maintenance of Cables Insulated with FR-EPDM by Frequency Domain Reflectometry

the International Conference on ‘Condition Monitoring and Diagnosis 2014 (CMD2014)’2014/09/22

Detail

International conferenceOral presentation(general)

Far-infrared Absorption by Thymine in Deoxyribonucleic Acid

2014 Annual Conference of Fundamentals and Materials Society IEE Japan2014/08/21

Detail

National conferencePoster presentation

Estimation of Cross-linking Degree of Polyethylene Cross-linked with Silane by Far-infrared Absorption Spectroscopy

2014 Annual Conference of Fundamentals and Materials Society IEE Japan2014/08/21

Detail

National conferencePoster presentation

Quantification of Talc in Ethylene-Propylene-Diene Copolymer by Far-Infrared Spectroscopy

2014 Annual Conference of Fundamentals and Materials Society IEE Japan2014/08/21

Detail

National conferencePoster presentation

Possibility of Detecting La Vacancy in LaAlO3, a High-Permittivity Dielectric Crystal, by Photoluminescence

2014 Annual Conference of Fundamentals and Materials Society IEE Japan2014/08/21

Detail

National conferencePoster presentation

Identification of Thymine Base in Nucleotides in DNA by Far-infrared Absorption

International Symposium on Frontier of Terahertz Science (Frontier of THz Science 2014)2014/08/05

Detail

International conferencePoster presentation

Analysis on Thermally Stimulated Currents in Polyethylene-terephthalate and Polyethylene-aphthalate

7th International Symposium on Electrical Insulating Materials2014/06/04

Detail

International conferencePoster presentation

Comparison of Dielectric Properties among Polydicyclopentadiene Resin, Epoxy Resin and Their Composites with Microsized SiO2 Fillers

7th International Symposium on Electrical Insulating Materials2014/06/04

Detail

International conferencePoster presentation

Terahertz Spectroscopic Analysis of Ethylene-Propylene-Diene Copolymer

7th International Symposium on Electrical Insulating Materials2014/06/04

Detail

International conferenceOral presentation(general)

Crystalline Structures of YAlO3 Single Crystal at High Temperatures

7th International Symposium on Electrical Insulating Materials2014/06/03

Detail

International conferencePoster presentation

Structural Change Induced in LaAlO3 by Ion Implantation

7th International Symposium on Electrical Insulating Materials2014/06/03

Detail

International conferencePoster presentation

Highly Sensitive Detection of Distorted Points in a Cable by Frequency Domain Reflectometry

7th International Symposium on Electrical Insulating Materials2014/06/03

Detail

International conferenceOral presentation(general)

A microchannel-integrated waveguide-mode sensor for detecting hemagglutination

Biosensors 20142014/05/28

Detail

International conferencePoster presentation

Microsystem of blood plasma separation for blood typing test

2014 MRS Spring Meeting & Exhibit2014/04/22

Detail

International conferenceOral presentation(general)

Electron beam irradiation effect for poly(vinylidene fluoride/trifluoroethylene) copolymers

12th Biennial Trombay Symposium on Radiation & Photochemistry (TSRP - 2014)2014/01/07

Detail

International conferencePoster presentation

Electric Modulus Revisited -Dielectric Behavior and Charge Transport Characteristics of Epoxy Resin and Its Composites-

2013/12/11

Detail

National conferenceOral presentation(general)

Electric Modulus Spectra of Polyethylene Terephthalate and Polyethylene Naphthalate

2013/11/26

Detail

National conferencePoster presentation

Charge Transport Characteristics in Epoxy Resin at High Temperatures Based on Electrode Polarization Analysis

Conference on Electrical Insulation and Dielectric Phenomena2013/10/23

Detail

International conferenceOral presentation(general)

Measurements of THz Absorption Peaks in Photo-degraded Polyethylene and Their Assignment by Quantum Chemical Calculations

Conference on Electrical Insulation and Dielectric Phenomena2013/10/23

Detail

International conferenceOral presentation(general)

Experimental Study on the Dielectric Behavior of a Liquid Crystal Polymer

Conference on Electrical Insulation and Dielectric Phenomena2013/10/22

Detail

International conferenceOral presentation(general)

Effects of Thermal Annealing on the Point Defects in YAlO3

2013/09/19

Detail

National conferenceOral presentation(general)

Effects of Thermal Annealing on the Surface Crystal Structure of YAlO3

2013/09/19

Detail

National conferenceOral presentation(general)

Effects of Ion Implantation and Following Heat Treatment on YAlO3 Single Crystal

2013/09/19

Detail

National conferenceOral presentation(general)

Difference in Absorption Observed in Thermally-aged and Gamma-ray-aged Ethylene Propylene Rubber

2013/09/18

Detail

National conferenceOral presentation(general)

Detection of Hydrogen Gas Using a Waveguide-Mode Sensor

2013/09/17

Detail

National conferenceOral presentation(general)

Point Defects in IGZO Thin Films Fabricated by a Screen Printing Method

2013/09/17

Detail

National conferenceOral presentation(general)

Polymer Nanocomposite as an Emerging Dielectric Material

The Second International Conference on Materials, Energy and Environments (ICMEE)Invitation Yes2013/08/08

Detail

International conferenceOral presentation(invited, special)

Space Charges Induced in Polymers by Electron Beam Irradiation and Their Decay Profiles

2013 IEEE International Conference on Solid Dielectrics2013/07/04

Detail

International conferencePoster presentation

Charge Behavior of Epoxy/Silica Nanocomposites under AC High Fields

2013 IEEE International Conference on Solid Dielectrics2013/07/04

Detail

International conferencePoster presentation

Experimental and Numerical Analyses on Terahertz Spectra of Oxidized Cross-linked Polyethylene

2013 IEEE International Conference on Solid Dielectrics2013/07/03

Detail

International conferenceOral presentation(general)

Detection of Polymer Degradation and Metal Corrosion by Terahertz Imaging Using a Quantum Cascade Laser and a THz Camera

2013 IEEE International Conference on Solid Dielectrics2013/07/03

Detail

International conferenceOral presentation(general)

Dielectric Properties and Thermal Conductivity of Epoxy/AlN Composites with Several Kinds of Filler-Matrix Interfaces

2013 IEEE International Conference on Solid Dielectrics2013/07/02

Detail

International conferencePoster presentation

Highly Sensitive Location Method of an Abnormal Temperature Point in a Cable by Frequency Domain Reflectometry

2013 IEEE International Conference on Solid Dielectrics2013/07/01

Detail

International conferencePoster presentation

Dielectric Behavior Analysis of Epoxy Resin Using Complex Electric Modulus

2013/03/20

Detail

National conferenceOral presentation(general)

Experimental Study on the Dielectric Behavior of Poly(ethylene 2,6-naphthalate)

2013/03/20

Detail

National conferenceOral presentation(general)

Luminescence and Local Structure Correlation of Er-doped Glasses and Composites

APS(American Physical Society) March Meeting 20132013/03/18

Detail

National conferenceOral presentation(general)

Space Charge Distributions in Polymers Induced by Electron Beam Irradiation and Their Determining Factor

2012/12/18

Detail

National conferenceOral presentation(general)

Charge Behavior of EpoxySlica Nanocomposites under AC High Field

2012/12/18

Detail

National conferenceOral presentation(general)

Thermal Conductivity and Dielectric Properties of Epoxy Resin Co-added with Nano- and Micro-Fillers

2012/12/18

Detail

National conferenceOral presentation(general)

Space Charge Behavior of Polymer Nanocomposites toward the Application to Power Semiconductor Modules

2012/12/18

Detail

National conferenceOral presentation(general)

Investigation on the Dielectric and Electrical Conduction Characteristics of Epoxy Composites with SiO2-Al2O3 Nano-micro Fillers under Varied Temperatures

2012/12/01

Detail

National conferenceOral presentation(general)

Exfoliation of Layered BN Fillers in Epoxy-based Composite Dielectrics to Enhance the Thermal Conductivity

2012/12/01

Detail

National conferencePoster presentation

Analysis of Terahertz Spectra Observed in Oxidized Cross-linked Polyethylene

International Symposium on Frontiers in THz Technology, Pos2_392012/11/29

Detail

International conferencePoster presentation

Thermally Enhanced Electron and Hole Transfers to Point Defects in LaAlO3 Single Crystal

2012 MRS Fall Meeting2012/11/27

Detail

International conferencePoster presentation

Japanese Research Activities on Assurance of Cable Integrity in Nuclear Power Plants

1st International Conference on Maintenance Science and Technology2012/11/14

Detail

International conferenceOral presentation(general)

Terahertz Spectroscopy as a Novel Method for Diagnosing the Integrity of Polymer Insulated Cables

IEEE Conference on Electrical Insulation and Dielectric Phenomena2012/10/15

Detail

International conferencePoster presentation

Mechanism and Application of Refractive Index Increase Induced in Fluorinated Polyimide by Ion Irradiation

IEEE Conference on Electrical Insulation and Dielectric Phenomena2012/10/14

Detail

International conferenceOral presentation(general)

Comparison of Broadband Impedance Spectroscopy and Time Domain Reflectometry for Locating Cable Degradation

2012 IEEE International Conference on Condition Monitoring and Diagnosis2012/09/25

Detail

International conferenceOral presentation(general)

Improvement in Sensitivity of Broadband Impedance Spectroscopy for Locating Degradation in Cable Insulation by Ascending the Measurement Frequency

2012 IEEE International Conference on Condition Monitoring and Diagnosis2012/09/24

Detail

International conferencePoster presentation

Two Methods for Improving Electrochemical Migration Resistance of Printed Wiring Boards

2012 International Conference on High Voltage Engineering and Application (ICHVE 2012)2012/09/18

Detail

International conferenceOral presentation(general)

Improvement of Inspection and Maintenance Procedures of Polymeric Cable Insulation Used in Nuclear Power Plants in Japan

CIGRE 2012/08/29

Detail

International conferenceOral presentation(general)

Chemiluminescence as a Clear Diagnostic Tool of Polymer Oxidation

2012 IEEE 10th International Conference on the Properties and Applications of Dielectric Materials2012/07/26

Detail

International conferenceOral presentation(general)

Experimental Study on the Factors Determining the Partial Discharge Resistance of Polymers

2012 IEEE 10th International Conference on the Properties and Applications of Dielectric Materials2012/07/25

Detail

International conferenceOral presentation(general)

Terahertz Spectroscopic Observation of Cross-linked Polyethylene Aged Simultaneously by Heat and Gamma-rays

2012 IEEE 10th International Conference on the Properties and Applications of Dielectric Materials2012/07/24

Detail

International conferenceOral presentation(general)

Optical and Electrical Sensing application of High-Aspect-Ratio Nanoholes Formed by Etching of Latent Tracks

The 56th International Conference on Electron, Ion, and Photon Beam Technology and Nanofabrication2012/05/29

Detail

International conferencePoster presentation

The Status Quo of Japanese Research on Assurance of Cable Integrity in Nuclear Power Plants

Third International Conference on Nuclear Power Plant Life Management2012/05/15

Detail

International conferenceOral presentation(general)

Experimental and Computational Characterization of Electronic Localized States in Polyethylene

2012/03/23

Detail

National conferenceOral presentation(general)

Quantum Chemical Analysis of Localized States in Oxidized Polyethylene

Annuarl Meeting 2011, Institute of Electrical Discharges in Japan2011/11/26

Detail

National conferencePoster presentation

Factors Determining Partial Discharge Resistance in Polyvinyl Polymers

Annuarl Meeting 2011, Institute of Electrical Discharges in Japan2011/11/26

Detail

National conferenceOral presentation(general)

Possible Causes of Point Defects in High-permittivity Gate Dielectrics LaAlO3 and YAlO3

Annuarl Meeting 2011, Institute of Electrical Discharges in Japan2011/11/26

Detail

National conferenceOral presentation(general)

Effect of the Selection of a Window Function for Fourier Transform on the Location of a Simulated Water Tree by Broadband Impedance Spectroscopy

Annuarl Meeting 2011, Institute of Electrical Discharges in Japan2011/11/26

Detail

National conferencePoster presentation

Quantum Chemical Analysis of the Photo-degradation Mechanism of Polyethylene

Annuarl Meeting 2011, Institute of Electrical Discharges in Japan2011/11/26

Detail

National conferenceOral presentation(general)

Increase in Refractive Index of Fluorinated Polyimide Induced by Ion Irradiation and Its Mechanism

Annuarl Meeting 2011, Institute of Electrical Discharges in Japan2011/11/26

Detail

National conferencePoster presentation

THz Dielectric Spectroscopy as a Tool for Polymer Analyses

TeraNano 2011(Osaka University, Nakanoshima Center, Osaka)Invitation Yes2011/11/25

Detail

International conferenceOral presentation(invited, special)

Possibility of Observation of the Glass Transition in a Polymer by Terahertz Spectroscopy

TeraNano 2011(Osaka University, Nakanoshima Center, Osaka)2011/11/24

Detail

International conferencePoster presentation

Development of Composite of Epoxy Resin and Iron Nanoparticles as a Low Eddy-current Loss Magnetic Material

2011/11/12

Detail

National conferenceOral presentation(general)

Diagnosis of Cable Aging by Broadband Impedance Spectroscopy

2011/11/12

Detail

National conferenceOral presentation(general)

High Thermal Conductivity Epoxy/BN Composites with Sufficient Dielectric Breakdown Strength

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2011/10/21

Detail

International conferencePoster presentation

Comparison of the Effects of Nanofiller Materials on the Dielectric Properties of Epoxy Nanocomposites

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2011/10/17

Detail

International conferencePoster presentation

Feasibility Study on the Detection of Corrosion of a Cable Metal Shield Using Terahertz Imaging

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2011/10/17

Detail

International conferencePoster presentation

Diagnosis of Cable Aging by Broadband Impedance Spectroscopy

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2011/10/17

Detail

International conferenceOral presentation(general)

Effects of Heat Treatment and UV Irradiation on the Transition Metal Impurities in LaAlO3

2011 International Symposium on Electrical Insulating Materials, Doushisha Univ., Kyoto2011/09/08

Detail

International conferencePoster presentation

Development of Composite of Epoxy Resin and Iron Nanoparticles as a Low Eddy-current Loss Magnetic Material

2011 International Symposium on Electrical Insulating Materials, Doushisha Univ., Kyoto2011/09/08

Detail

International conferencePoster presentation

Space Charge Behavior of XLPE/Silica Nanocomposites under High Electric Field

2011 International Symposium on Electrical Insulating Materials, Doushisha Univ., Kyoto2011/09/08

Detail

International conferencePoster presentation

Superiority of Syndiotactic Polystyrene as an Electrical Insulating Polymer

2011 International Symposium on Electrical Insulating Materials, Doushisha Univ., Kyoto2011/09/08

Detail

International conferencePoster presentation

Various Ion-induced Phenomena Appearing in Dielectric Materials and Their Applications to Optical Devices and Biosensors

2011 International Symposium on Electrical Insulating Materials, Doushisha Univ., Kyoto2011/09/07

Detail

International conferenceOral presentation(general)

Experimental and Numerical Analyses of Molecular Vibrations in Poly-e-caprolactone at Terahertz Frequencies

2011 International Symposium on Electrical Insulating Materials, Doushisha Univ., Kyoto2011/09/06

Detail

International conferencePoster presentation

Presence of Metal Impurities in LaAlO3

2011/09/02

Detail

National conferenceOral presentation(general)

Detection of cadmium ions in water using color-sensitive waveguide-mode sensors

10th Workshop on (Bio)sensors and Bioanalytical microtechniques in environmental and clinical analysis (bbmec2011)2011/06/22

Detail

International conferencePoster presentation

Effects of Heat Treatment on Defects in LaAlO3

2011/03/24

Detail

National conferenceOral presentation(general)

Effects of UV-irradiation on Defects in LaAlO3

2011/03/24

Detail

National conferenceOral presentation(general)

Comparison of Packet-like Space Charge Behavior among Five Types of Polyethylene

2011/03/16

Detail

National conferenceOral presentation(general)

Space Charge Behavior of XLPE/Silica Nanocomposite under High Electric Field

2011/03/16

Detail

National conferenceOral presentation(general)

Effects of Boron Nitride Filler Loading to Epoxy Resins on Thermal Conductivity and Dielectric Breakdown Strength

Effects of Boron NitrProc. IEEJ Joint Study Meeting (Miyazaki)2011/01/28

Detail

National conferenceOral presentation(general)

Behavior of Packet-like Space Charge in Four Types of Polyethylene

2010/11/06

Detail

National conferencePoster presentation

Band Gap Energies of Several Insulating Polymers Estimated by Optical Absorption Measurements

IEEE Conference on Electrical Insulation and Dielectric Phenomena2010/10/20

Detail

International conferencePoster presentation

Fabrication of a grating with phase change material and its static optical switching performance

36th international conference on Micro & Nano Engineering (MNE 2010)2010/09/22

Detail

International conferencePoster presentation

Broadband Impedance Spectroscopy as a Tool to Evaluate the Integrity of Cable Insulation

2010 International Conference on Condition Monitoring and Diagnosis2010/09/08

Detail

International conferenceOral presentation(general)

Effects of Gamma-ray Irradiation and Thermal Aging on the Chemiluminescence in Flame-Retardant Ethylene-Propylene Rubber

2010 International Conference on Condition Monitoring and Diagnosis2010/09/08

Detail

International conferenceOral presentation(general)

Observation of Water Trees Using Terahertz Imaging and Time-domain Spectroscopy

2010 International Conference on Condition Monitoring and Diagnosis2010/09/07

Detail

International conferenceOral presentation(general)

Endurance of Polymeric Insulating Materials in Nuclear Power Plants and Needs for Condition Monitoring of Electric Cables

CIGRE(Paris 2010 Aug. 23-27) Session 43, D1-3022010/08/26

Detail

International conferencePoster presentation

Experimental Research on the Feasibility of Biodegradable Polymeric Insulating Materials

CIGRE (Paris 2010 Aug. 23-27) Session 43, D1-1042010/08/26

Detail

International conferencePoster presentation

A Critical Factor Determining the Sizes of Etched Latent Tracks in Silica Glass Formed by Swift Cl Ions

17th International Conference on Ion Beam Modification of Materials2010/08/23

Detail

International conferencePoster presentation

Experimental and Numerical Analyses of Molecular Vibrations in Amorphous and Crystalline Polylactide at Terahertz Frequencies

IEEE 2010 International Conference on Solid Dielectrics, Potsdam, Germany2010/07/07

Detail

International conferencePoster presentation

Detection of Electrochemical Migration Growth along the Thickness Direction in a Paper/phenol-resin Composite

2010 International Conference on Solid Dielectrics, Potsdam, Germany, July 4-9, 20102010/07/06

Detail

International conferencePoster presentation

Space Charge Behavior in Multi-layered Dielectrics with LDPE and LDPE/MgO Nanocomposites

2010 International Conference on Solid Dielectrics, Potsdam, Germany, July 4-9, 20102010/07/05

Detail

International conferencePoster presentation

Evaluation of Broadband Impedance Spectroscopy on its Monitoring Ability of Cable Aging

International Symposium on the Aging Management & Maintenance of Nuclear Power Plants (ISaG2010, 2010.5.27-28, Tokyo, Japan)2010/05/27

Detail

International conferenceOral presentation(general)

Characteristics tests on monitoring / diagnosis of cable degradation (Broadband Impedance Spectroscopy: BIS)

International Symposium on the Aging Management & Maintenance of Nuclear Power Plants (ISaG2010, 2010.5.27-28, Tokyo, Japan)2010/05/27

Detail

International conferencePoster presentation

Vibrations in Amorphous and Crystalline Polylactide

2010/03

Detail

National conferenceOral presentation(general)

at Terahertz Frequencies

2010/03

Detail

National conferenceOral presentation(general)

Detection of Nanomaterials Using Color-sensitive Waveguide Mode

The Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy (PITTCON 2010)2010/02/04

Detail

International conferenceOral presentation(general)

Broadband Dielectric Spectroscopy as a Tool for Polymer Analysis

2nd International Workshop on Terahertz Technology2009/12

Detail

International conferenceOral presentation(general)

Analysis of Terahertz Spectra of Amorphous Polylactide Using Density Functional Theory

2nd International Workshop on Terahertz Technology2009/12

Detail

International conferenceOral presentation(general)

Numerical Modeling of the Thermal Evolution in a Phase Change Material Thin Film under the Irradiation of a Pulsed Laser

Comsol Conference 20092009/12

Detail

International conferenceOral presentation(general)

Identification of Impurity Contained in LaAlO3 by Photoluminescence

2009 Materials Research Society Fall Meeting2009/11

Detail

International conferenceOral presentation(general)

Shape Estimation of Au Nanostructures Using Optical Near-Fields Induced in Waveguide-Mode Sensors

FACSS (Federation of Analytical Chemistry and Spectroscopy Societies) Conference 20092009/10/22

Detail

International conferenceOral presentation(general)

Possibility of Non-destructive Detection of Electrochemical Migration in Epoxy Resin by the Pulsed Electroacoustic Method

IEEE 2009 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2009/10/18

Detail

International conferenceOral presentation(general)

Tree Initiation and Growth in LDPE/MgO Nanocomposites and Roles of Nano Fillers

IEEE 2009 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2009/10

Detail

International conferenceOral presentation(general)

Complex Permittivity Spectra of Several Insulating Polymers at Electrical and THz Frequencies

IEEE 2009 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2009/10

Detail

International conferenceOral presentation(general)

Evaluation of Dielectric Properties in Polypropylene/clay Nanocomposites

IEEE 2009 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2009/10

Detail

International conferenceOral presentation(general)

Effect of Crystallinity on the Partial Discharge Resistance of Poly-L-Lactide

IEEE 2009 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2009/10

Detail

International conferenceOral presentation(general)

Improvement in High-temperature Dielectric Properties of Epoxy Resin by Abundant Addition of Micro-silica

IEEE 2009 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2009/10

Detail

International conferenceOral presentation(general)

Terahertz Spectroscopy for Dielectric Material Analysis

6th International Discussion Meeting on Relaxations in Complex Systems2009/09

Detail

International conferenceOral presentation(general)

Nano-clay and Micro-silica Mixed Composites for Insulating Materials for Environmentally-conscious Switchgear

Proc. International Conference on Properties and Applications on Dielectric Materials (ICPADM), Harbin, China2009/07

Detail

International conferenceOral presentation(general)

Role of Nano-Filler on Partial Discharge Resistance and Dielectric Breakdown Strength of Micro-Al2O3/Epoxy Composites

Proc. International Conference on Properties and Applications on Dielectric Materials (ICPADM), Harbin, China2009/07

Detail

International conferenceOral presentation(general)

Tree Initiation Time Evaluation of Epoxy/Silica Composites by Partial Discharge Detection

Proc. International Conference on Properties and Applications on Dielectric Materials (ICPADM), Harbin, China2009/07

Detail

International conferenceOral presentation(general)

Suppression of Packet-like Space Charge Formation in LDPE by the Addition of Magnesia Nanofillers

Proc. International Conference on Properties and Applications on Dielectric Materials (ICPADM), Harbin, China2009/07

Detail

International conferenceOral presentation(general)

A Plasmonic Photocatalyst of Silver Nanoparticles Embedded in TiO2

8th Pacific Rim Conference on Ceramic and Glass Technology2009/06

Detail

International conferenceOral presentation(general)

A Thermally Stable High Sensitivity Sensor for Molecular Adsoption Detection

9th Workshop on (Bio)sensors and Bioanalytical Microtechniques in Environmental and Clinical Analysis2009/06

Detail

International conferenceOral presentation(general)

Effects of Nano- and Micro-Al2O3 Fillers on Surface and Partial Discharge Resistance of Epoxy Resins

2009/01/29

Detail

National conferenceOral presentation(general)

Tree Initiation Time Evaluation in Opaque Epoxy-Based Composites by Partial Discharge Detection Method using On-line Monitoring System

2009/01

Detail

National conferenceOral presentation(general)

Terahertz Time-Domain Spectroscopy of LaAlO3 Single Crystal

The Annual Meeting of the Spectroscopical Society of Japan2008/11

Detail

International conferenceOral presentation(general)

Solution conductivity as a key factor for thin silica coating on colloidal Ag

21st International Microprocesses and Nanotechnology Conference2008/10/29

Detail

International conferencePoster presentation

Enhanced Performance of Tree Initiation V-t Characteristics of Epoxy/Clay Nanocomoposite in Comparison with Neat Epoxy Resin

2008 Annual Report of Conference on Electrical Insulation and Dielectric Phenomena2008/10

Detail

International conferenceOral presentation(general)

Effects of Crystallinity on Thermally Stimulated Current and Complex Permittivity of Poly(L-lactide)

2008 Annual Report of Conference on Electrical Insulation and Dielectric Phenomena2008/10

Detail

International conferenceOral presentation(general)

Comparison of Dielectric Properties of Low-density Polyethylene/MgO Composites with Different Size Fillers

2008 Annual Report of Conference on Electrical Insulation and Dielectric Phenomena2008/10

Detail

International conferenceOral presentation(general)

Effects of mica nanofillers on the complex permittivity of polyamide nanocomposites

2008 Annual Report of Conference on Electrical Insulation and Dielectric Phenomena2008/10

Detail

International conferenceOral presentation(general)

Terahertz Spectroscopy as a New Analyzing Tool for Dielectric Properties of Various Insulating Materials

2008 Annual Report of Conference on Electrical Insulation and Dielectric Phenomena2008/10

Detail

International conferenceOral presentation(general)

Detection of Ion Migration in Composites for Printed Circuit Boards by the Pulsed Electroacoustic Method

Proceedings of the 2008 International Symposium on Electrical Insulating Materials2008/09/07

Detail

International conferenceOral presentation(general)

Effects of Coupling Agent and Filler Dispersion on V-t Characteristics of Epoxy/Silica Nanocomposite

Proceedings of the 2008 International Symposium on Electrical Insulating Materials2008/09/07

Detail

International conferenceOral presentation(general)

Synthesis and optical properties of Au nanorods oriented parallel to each other

2nd International Congress on Advanced Electromagnetic Materials in Microwaves and Optics2008/09

Detail

International conferenceOral presentation(general)

Nanocomposite Insulating Materials for Environmental-conscious Heavy Electric Apparatuses

Proceedings of the 2008 International Symposium on Electrical Insulating Materials2008/09

Detail

International conferenceOral presentation(general)

Nano- and Micro-filler Combination Enabling Practical Use of Nanocomposite Insulating Materials

Proceedings of the 2008 International Symposium on Electrical Insulating Materials2008/09

Detail

International conferenceOral presentation(general)

Effects of Blending Various Biodegradable Polymer Plasticizers on the Conduction Current and AC Breakdown Strength in Starch Ester

Proceedings of the 2008 International Symposium on Electrical Insulating Materials2008/09

Detail

International conferenceOral presentation(general)

Terahertz Dielectric Relaxation Spectroscopy in Polyamide Nanocomposite

Proceedings of the 2008 International Symposium on Electrical Insulating Materials2008/09

Detail

International conferenceOral presentation(general)

Plasmonic activity of gold nanoparticles in silica elongated by irradiation with swift heavy ions

Gordon Research Conferences, Bioanalytical Sensors2008/07

Detail

International conferenceOral presentation(general)

Interface between Filler and Resin in Epoxy Nanocomposites Cured with Acid Anhydride

The International Conference on Electrical Engineering 20082008/07

Detail

International conferenceOral presentation(general)

Applicability of Biodegradable Polymers to Electrical Insulation

The International Conference on Electrical Engineering 20082008/07

Detail

International conferenceOral presentation(general)

A Waveguide-Mode Biosensor Utilizing a Thermally Grown SiO2 Waveguide

Gordon Research Conferences, Bioanalytical Sensors2008/07

Detail

International conferenceOral presentation(general)

Cable Aging - Its Mechanism and Monitoring Methods - b. Development of Monitoring Methods (b1. Broadband Impedance Spectroscopy (BIS))

International Symposium on the Aging Management and Maintenance of Nuclear Power Plants 20082008/07

Detail

International conferenceOral presentation(general)

Improving epoxy-based insulating materials with nano-fillers toward practical application

Conference of the IEEE International Symposium on Electrical Insulation, 2008 (ISEI 2008)2008/06

Detail

International conferenceOral presentation(general)

Mechanism of Elongation of Gold Nanoparticles in Silica by Irradiation With Swift Heavy Ions

Seventh International Symposium Swift Heavy Ions in Matter (SHIM) 20082008/06

Detail

International conferenceOral presentation(general)

Need for Condition Monitoring and Diagnosis of Electric Wires and Cables Used in Nuclear Power Plants

2nd International Conference on Condition Monitoring and Diagnosis 2008/04

Detail

International conferenceOral presentation(general)

Role of the Voltage Zero-crossing in the Growth of Water Trees

2008 International Conference on Condition Monitoring and Diagnosis, Beijing, China, April 21-24, 20082008/04

Detail

International conferenceOral presentation(general)

Reduction of Polarization Dependent Loss of a Planar Optical Waveguide using Ion Implantation

MRS Spring Meeting2008/03

Detail

International conferenceOral presentation(general)

Photoluminescence Analysis of Lanthanum Aluminate Single Crystals

UVSOR Users Meeting2007/11

Detail

International conferenceOral presentation(general)

High sensitivity Bio-sensor using optical waveguides comprising high aspect ratio cylindrical nanoholes

MRS Fall Meeting2007/11

Detail

International conferenceOral presentation(general)

Search for Adequate Biodegradable Polymer as an Eco-friendly Electrical Insulating Material

International Symposium on EcoTopia Science 20072007/11

Detail

International conferenceOral presentation(general)

Defects in yttria-stabilized zirconia induced by irradiation of ultraviolet photons

29th International Symposium on Dry Process (DPS 2007)2007/11

Detail

International conferenceOral presentation(general)

Thermally Stimulated Current in Polybutylene Succinate

2007 J-K Joint Symposium on ED & HVE2007/11

Detail

International conferenceOral presentation(general)

Effects of Curing and Filler Dispersion Methods on Dielectric Properties of Epoxy Nanocomposites

Conference on Electrical Insulation and Dielectric Phenomena2007/10

Detail

International conferenceOral presentation(general)

Electrical Conduction Properties of Several Biodegradable Polymers

Conference on Electrical Insulation and Dielectric Phenomena2007/10

Detail

International conferenceOral presentation(general)

Treeing Phenomena in Epoxy /Alumina Nanocomposite

Proc. CIGRE SC A1/D1 Joint Colloquium2007/10

Detail

International conferenceOral presentation(general)

Aiming at a More Rigorous Understanding in Electrical Insulating Materials Research

Conference on Electrical Insulation and Dielectric Phenomena2007/10

Detail

International conferenceOral presentation(general)

Frequency Accelerated Partial Discharge Resistance of Epoxy/Clay NanocompositePrepared by Newly Developed Organic Modification and Solubilization Methods

9th International Conference on Solid Dielectrics2007/07

Detail

International conferenceOral presentation(general)

Effects of Humidity and Temperature on Space Charge Distribution Profiles in Printed Circuit Board Insulations

9th International Conference on Solid Dielectrics2007/07

Detail

International conferenceOral presentation(general)

Compariso of Partial Discharge Resistance among Several Biodegradable Polymers

9th International Conference on Solid Dielectrics2007/07

Detail

International conferenceOral presentation(general)

Dielectric Properties of Polybutylene Succinate and Polybutylene Succinate Adipate

9th International Conference on Solid Dielectrics2007/07

Detail

International conferenceOral presentation(general)

Search for Adequate Biodegradable Polymer as an Eco-friendly Electrical Insulating Material

Proceedings of International Symposium on Ecotopia Science 20072007

Detail

International conferenceOral presentation(general)

Effect of Endothermic Reaction Associated with Glass Transition on the Breakdown Strength of Biodegradable Polymer Films

2006 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2006/10

Detail

International conferenceOral presentation(general)

Effect of Crystallinity on Electrical Conduction Characteristics of Poly-L-lactic Acid

2006 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2006/10

Detail

International conferenceOral presentation(general)

Dielectric Properties of Biodegradable Polymers

2006 Annual Report of Conference on Electrical Insulation and Dielectric Phenomena2006/10

Detail

International conferenceOral presentation(general)

Biomolecular sensors utilizing waveguide modes excited by evanescent fields due to metal reflection films

9th International conference on near-field optics, nanophotonics and related techniques2006/09

Detail

International conferenceOral presentation(general)

Nanoscale pore fabricaton for high sensitivity waveguide-mode biosensors

32nd International Conference on Micro- and Nano- Engineering (MNE) 20062006/09

Detail

International conferenceOral presentation(general)

Superiority in Partial Discharge Resistance of Several Polymer Nanocomposites

CIGRE Paper D1-3032006/08

Detail

International conferenceOral presentation(general)

Treeing phenomena in epoxy/alumina nanocomposite

2006/08

Detail

National conferenceOral presentation(general)

Comparison of Treeing Breakdown Channel between Base Epoxy and Epoxy/Alumina Nanocomposite

2006/08

Detail

National conferenceOral presentation(general)

Photoluminescence in Low-Density Polyethylene/MgO Nanocomposites Induced by Ultraviolet Photons at 10 K

2006 Annu. Conf. Fundamentals and Materials2006/08

Detail

International conferenceOral presentation(general)

Formation of Mica Layers on the Surface of Polyamide-6 Nanocomposite due to Oxygen Plasma Exposure

2006 Annu. Conf. Fundamentals and Materials2006/08

Detail

International conferenceOral presentation(general)

Space Charge Distribution in Low-density Polyethylene/MgO Nanocomposites under Low Electric Field

2006 Annu. Conf. Fundamentals and Materials2006/08

Detail

International conferenceOral presentation(general)

Three-dimensional Space Charge Distribution in Glass Fiber/Epoxy Composite

Proc. 8th International Conference on Properties and Application of Dielectric Materials2006/06

Detail

International conferenceOral presentation(general)

Comparison of Dielectric Properties among Various Poly(lactide) Films

Proc. 8th International Conference on Properties and Application of Dielectric Materials2006/06

Detail

International conferenceOral presentation(general)

Dielectric Properties of Low-Density Polyethylene/MgO Nanocomposites

Proc. 8th International Conference on Properties and Application of Dielectric Materials2006/06

Detail

International conferenceOral presentation(general)

Micro-photoluminescence study on defects induced by ion microbeam in silica glass

SiO20062006/06

Detail

International conferenceOral presentation(general)

PD Resistance Evaluation of LDPE/MgO Nanocomposite by a Rod-to-Plane Electrode System

Proc. 8th International Conference on Properties and Application of Dielectric Materials2006/06

Detail

International conferenceOral presentation(general)

Characterization of polymer nanocomposites by photoluminescence

UVSOR Lunch Seminar2006/06

Detail

National conferenceOral presentation(general)

Nature, Growth Mechanism, and Diagnosis Methods of Water Trees and Their Relations with Charge Behavior

International Conference of Condition Monitoring and Diagnosis 20062006/04

Detail

International conferenceOral presentation(general)

Core/Shell Nanocrystalline Clusters in a Glass Matrix: A High Pressure Synchrotoron X-ray Diffraction Study

2006 APS (American Physical Society) March Meeting2006/03

Detail

International conferenceOral presentation(general)

Comparison of Dielectric Properties among Various Polylactide Films

The Papers of Technical Meeting on Dielectrics and Electrical Insulation , IEE Japan2005/12

Detail

International conferenceOral presentation(general)

In Situ Space Charge Measurement of PCB Insulations During the Aging Test

2005 Annual Report Conference on Electrical Insulation and Dielectric Phenomena,2005/10

Detail

International conferenceOral presentation(general)

Effects of Mica Fillers on Dielectric Properties of Polyamide Nanocomposites

2005 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2005/10

Detail

International conferenceOral presentation(general)

Thermally stimulated polarization and depolarization currents in polyethylene terephthalate succinate

2005 Annual Report Conference on Electrical Insulation and Dielectric Phenomena2005/10

Detail

International conferenceOral presentation(general)

Modification of structural and optical properties of silica glass induced by ion microbeam

International Conference on Surface Modification of Materials by Ion Beams (SMMIB '05)2005/09

Detail

International conferenceOral presentation(general)

Modification of structural and optical properties of silica glass induced by ion microbeam

International Conference on Surface Modification of Materials by Ion Beams (SMMIB’05)2005/09

Detail

International conferenceOral presentation(general)

Measurement of Conduction Current and Space Charge in Low-Density Polyethylene/MgO Nanocomposite

The Papers of Technical Meeting on Dielectrics and Electrical Insulation, IEE Japan2005/09

Detail

International conferenceOral presentation(general)

Discussion of a Multi-core Model of Polymer Nanocomposites for their Dielectric and Insulating Characteristics

The Papers of Technical Meeting on Dielectrics and Electrical Insulation, IEE Japan2005/09

Detail

International conferenceOral presentation(general)

On the Mechanisms of Superior Dielectric Properties in Polymer Nanocomposites

The Papers of Technical Meeting on Dielectrics and Electrical Insulation, IEE Japan2005/09

Detail

International conferenceOral presentation(general)

Preparation and Preliminary Characteristic Evaluation of Epoxy/Boehmite Alumina Nanocomposites

The Papers of Technical Meeting on Dielectrics and Electrical Insulation, IEE Japan2005/09

Detail

International conferenceOral presentation(general)

Two and Three-dimensional photonic crystals of titanium dioxide and optical properties

Nanoengineering: Fabrication, Properties, Optics, and Devices II (San Diego)2005/08

Detail

International conferenceOral presentation(general)

Various Characteristics of Epoxy/Alumina Nanocomposite Processed in Laboratory Scale

International Conference on Electrical Engineering, China2005/07

Detail

International conferenceOral presentation(general)

Characterization of Partial Discharge Degradation of Polyamide-6 Nanocomposites by a Photoluminescence Analysis

UVSOR Activity Report 20042005/07

Detail

National conferenceOral presentation(general)

Various Characteristics of Epoxy/Alumina Nanocomposite Processed in Laboratory Scale

International Conference on Electrical Engineering, China2005/07

Detail

International conferenceOral presentation(general)

Influence of Water Absorption on Charge Formation in Printed Circuit Board Insulations

Proceedings of 2005 International Symposium on Electrical Insulating Materials2005/06

Detail

International conferenceOral presentation(general)

Temperature Effects on Luminescence Properties of Cr3+ Ions in Heterophased Oxide Glass Based Nanostructured Media

17th University Conference on Glass Science, and 1st NSF International Materials Institute Workshop on New Functionality in Glasses2005/06

Detail

International conferenceOral presentation(general)

Effects of Glass Transition on the Dielectric Breakdown and Electrical Conduction in Several Biodegradable Polymers

Proceedings of 2005 International Symposium on Electrical Insulating Materials2005/06

Detail

International conferenceOral presentation(general)

Influence of Metallic Defects on the Partial Discharges at the Interface between Epoxy Resin and Silicone Rubber

Proceedings of 2005 International Symposium on Electrical Insulating Materials2005/06

Detail

International conferenceOral presentation(general)

Preparation and Preliminary Characteristic Evaluation of Epoxy/Alumina Nanocomposites

Proceedings of the 2005 International Symposium on Electrical Insulating Materials2005/06

Detail

International conferenceOral presentation(general)

Irradiation Effects on Silica Glass by Ion Microbeam for Fabrication of Optical Elements

Proceedings of 2005 International Symposium on Electrical Insulating Materials2005/06

Detail

International conferenceOral presentation(general)

Effects of Water Temperature on Degradation of Several Biodegradable Polymers Immersed in Water

Proceedings of the 2005 International Symposium on Electrical Insulating Materials2005/06

Detail

International conferenceOral presentation(general)

Dipolar Polarization and Depolarization Currents in Biodegradable Polymers

Proceedings of 2005 International Symposium Electrical Insulating Materials2005/06

Detail

International conferenceOral presentation(general)

Effects of Ultraviolet Photon Irradiation on the Space Charge Accumulation Properties of Several Biodegradable Polymers

Proceedings of 2005 International Symposium on Electrical Insulating Materials2005/06

Detail

International conferenceOral presentation(general)

High Pressure Synchrotron X-Ray Diffraction Studies of a Nanocomposite: Stability of the Nanocrystalline Phase

SMEC 20052005/04

Detail

International conferenceOral presentation(general)

Nature, Growth Mechanism, and Diagnosis Methods of Water trees and Their Relations with Charge Behavior

2005 Annual Meeting Record I.E.E. Japan2005/03

Detail

International conferenceOral presentation(general)

Enhanced crystallization of strontium bismuth tantalate thin films by irradiation of elongated pulses of a KrF excimer laser

2004 Japan-Korea Joint Workshop on Advanced Semiconductor Processes and Equipments2004/11

Detail

International conferenceOral presentation(general)

Two inherent photoluminescence bands in hafnia and zirconia

Proceedings of 4th International Symposium on Dry Process,2004/11

Detail

International conferenceOral presentation(general)

Fabrication of Two-dimensional Photonic Structure of Titanium Dioxide with Sub-micrometer Resolution by Deep x-ray Lithography

Material Research Society Symposium Proceedings2004/11

Detail

International conferenceOral presentation(general)

Difference in Surface Degradation due to Partial Discharges between Polyamide, Nanocomposite and Microcomposite

2004 Conference on Electrical Insulation and Dielectric Phenomena2004/10

Detail

International conferenceOral presentation(general)

Possible Mechanism of Superior Partial-Discharge Resistance of Polyamide Nanocomposites

2004 Conference on Electrical Insulation and Dielectric Phenomena2004/10

Detail

International conferenceOral presentation(general)

Effect of Glass Transition on Conduction Current in Biodegradable Poly-L-lactic Acid

2004 Conference on Electrical Insulation and Dielectric Phenomena2004/10

Detail

International conferenceOral presentation(general)

Spatial distribution of irradiation effects on silica glass induced by ion microbeam

14th International Conference on Ion Beam Modification of Materials2004/09

Detail

International conferenceOral presentation(general)

Spatial distribution of irradiation effects on silica glass induced by ion microbeam

14th International Conference on Ion Beam Modification of Materials2004/09

Detail

International conferenceOral presentation(general)

Proton Microbeam Irradiation Effects on Silica Glass

1st International Workshop on Proton Beam Writing2004/07

Detail

International conferenceOral presentation(general)

Dielectric Properties of Biodegradable Polylactic Acid and Starch Ester

8th International Conference on Solid Dielectrics2004/07

Detail

International conferenceOral presentation(general)

Effect of the Applied Voltage Frequency on the Water Tree Shape in Polyethylene

8th International Conference on Solid Dielectrics2004/07

Detail

International conferenceOral presentation(general)

Three-Dimensional photonic structures with nano-order resolution of titanium dioxide

Materials Research Society Spring Meeting (San Francisco)2004/04

Detail

International conferenceOral presentation(general)

Three-Dimensional Lithography for Rutile TiO2 Single Crystals using Swift Heavy Ions

Material Research Society Symposium Fall Meeting2003/12

Detail

International conferenceOral presentation(general)

Estimation of the energy band profile of hafnium silicates by x-ray photoelectron spectroscopy

Proceedings of International Symposium on Dry Process2003/11

Detail

International conferenceOral presentation(general)

Comparison of Surface Roughness Change due to Partial Discharges between Polyamide-6 and Nanocomposites

2003 Japan-Korea Joint Symposium on Electrical Discharge and High Voltage Engineering2003/11

Detail

International conferenceOral presentation(general)

Surface change of polyamide nanocomposite caused by partial discharges

2003 Conference on Electrical Insulation and Dielectric Phenomena2003/10

Detail

International conferenceOral presentation(general)

Roles of cumyl alcohol and crosslinked structure in homo-charge trapping in crosslinked polyethylene

2003 Conference on Electrical Insulation and Dielectric Phenomena2003/10

Detail

International conferenceOral presentation(general)

Breakdown strength at the interface between epoxy resin and silicone rubber

2003 Conference on Electrical Insulation and Dielectric Phenomena2003/10

Detail

International conferenceOral presentation(general)

Effects of Ion Microbeam Irradiation on Silica Glass

IUMRS-ICAM, International Union of Materials Research Societies2003/10

Detail

International conferenceOral presentation(general)

Ferroelectricity of monodisperse and single-crystalline lead zirconate titanate nanoparticles 9 nm in diameter

2003 Korea-Japan Joint Workshop on Advanced Semiconductor Processes and Equipments (ASPE2003)2003/08

Detail

International conferenceOral presentation(general)

Role of the Number of Consecutive Voltage Zero-crossings on the Water Tree Growth in Polyethylene

2003 International Conference on Properties and Applications of Dielectric Materials2003/06

Detail

International conferenceOral presentation(general)

Effect of Crosslinking on Space Charge Formation in Crosslinked Polyethylene

2003 International Conference on Properties and Applications of Dielectric Materials2003/06

Detail

International conferenceOral presentation(general)

Absorption changes induced by UV-photon irradiation in Ge-doped SiO2 thin films fabricated by plasma CVD method from tetraethoxysilane

International Conference on Properties and Applications of Dielectric Materials2003/06

Detail

International conferenceOral presentation(general)

Effect of post-nitriding on electrical properties of high-permittivity hafnium and zirconium silicate films

2003 International Conference on Properties and Applications of Dielectric Materials2003/06

Detail

International conferenceOral presentation(general)

Effect of an air layer on the insulation performance at the interface between epoxy resin and silicone rubber

2003 International Conference on Properties and Applications of Dielectric Materials2003/06

Detail

International conferenceOral presentation(general)

3D-Nano Fabrication for TiO2 by Energetic Beams

Nanotech 2003 + Future (Open Session)2003/03

Detail

International conferenceOral presentation(general)

Gas-phase production of monodisperse ferroelectric nanoparticles (&lt;10 nm in diameter)

Nanotech 20032003/02

Detail

International conferenceOral presentation(general)

Preparation and characterization of monodisperse lead zirconate titanate nanoparticles

The 24th International Symposium on Dry Process2002/10

Detail

International conferenceOral presentation(general)

Chemical group in crosslinking byproducts responsible for charge trapping in polyethylene

2002 Conference on Electrical Insulation and Dielectric Phenomena2002/10

Detail

International conferenceOral presentation(general)

Origins of photoluminescence bands induced by ultraviolet photons in polyethylene,

2002 Conference on Electrical Insulation and Dielectric Phenomena2002/10

Detail

International conferenceOral presentation(general)

Characterization of refractive index changes of silica glass induced by ion microbeam

The 8th International Conference on Nuclear Microprobe Technology and Applications2002/09

Detail

International conferenceOral presentation(general)

Characterization of ion-implanted silica glass by micro-photoluminescence and raman spectroscopy

The 8th International Conference on Nuclear Microprobe Technology and Applications2002/09

Detail

International conferenceOral presentation(general)

High Pressure X-Ray Diffraction Studies of Novel Nanostructured Transparent Vitroceramic Medium

SiO2 and Advanced Dielectrics2002/09

Detail

International conferenceOral presentation(general)

Monodisperse lead zirconate titanate nanoparticles prepared by pulsed laser ablation and subsequent on-line thermal treatment

The 4th Japan-Korea Conference on Ferroelectrics2002/08

Detail

International conferenceOral presentation(general)

Monodisperse lead zirconate titanate nanoparticles prepared by pulsed laser ablation and subsequent on-line thermal treatment

The 4th Japan-Korea Conference on Ferroelectrics2002/08

Detail

International conferenceOral presentation(general)

Characterization of hafnium and zirconium silicate films fabricated by plasma-enhanced chemical vapor deposition

International Workshop on Gate Insulator 20012001/11

Detail

International conferenceOral presentation(general)

Characterization of hafnium silicate films fabricated by plasma-enhanced chemical vapor deposition

23rd International Symposium on Dry Process2001/11

Detail

International conferenceOral presentation(general)

Chemical structures and dielectric properties of hafnium and zirconium silicate films fabricated by plasma enhanced chemical vapor deposition

2001 Material Research Society Fall Meeting2001/11

Detail

International conferenceOral presentation(general)

Effect of blending on the dielectric breakdown of polyethylene

2001 International Symposium on Electrical Insulating Materials2001/11

Detail

International conferenceOral presentation(general)

Effect of photon irradiation on SBT films

2001 International Symposium on Electrical Insulating Materials2001/11

Detail

International conferenceOral presentation(general)

Effects of Liquid Chemicals on Space Charge Evolution in Low-density Polyethylene

2001 International Symposium on Electrical Insulating Materials2001/11

Detail

International conferenceOral presentation(general)

Electrical properties in silicon oxynitride and silicon nitride prepared by plasma-enhanced chemical vapor deposition

2001 International Symposium on Electrical Insulating Materials2001/11

Detail

International conferenceOral presentation(general)

Fabrication of hafnium silicate films by plasma-enhanced chemical vapor deposition

2001 International Symposium on Electrical Insulating Materials2001/11

Detail

International conferenceOral presentation(general)

On the Mechanism of Recovery Voltage in a Dielectric Solid - Proposal of a Simple Equation-

2001 International Symposium on Electrical Insulating Materials2001/11

Detail

International conferenceOral presentation(general)

Photoluminescence properties of hydrogenated amorphous silicon nitride films

2001 International Symposium on Electrical Insulating Materials2001/11

Detail

International conferenceOral presentation(general)

Ultraviolet-photon-induced paramagnetic centers in Ge and Sn co-doped silica glass

2001 International Symposium on Electrical Insulating Materials2001/11

Detail

International conferenceOral presentation(general)

Effects of Byproducts of Dicumyl Peroxide on Space Charge Formation in Low-density Polyethylene

2001 Conference on Electrical Insulation and Dielectric Phenomena2001/10

Detail

International conferenceOral presentation(general)

Evaluation of Degradation in Polyimide by Recovery Voltage Measurement

2001 Conference on Electrical Insulation and Dielectric Phenomena2001/10

Detail

International conferenceOral presentation(general)

Characterization of Ion-implanted Silica Glass by Vacuum Ultraviolet Absorption Spectroscopy

11th International Conference on Radiation Effects in Insulators2001/09

Detail

International conferenceOral presentation(general)

Evaluation of Silica Glasses Implanted by High-Energy Ions Using a UV-excited Microspectroscopy

11th International Conference on Radiation Effects in Insulators2001/09

Detail

International conferenceOral presentation(general)

Radiation Effects and Surface Deformation of Silica by Ion Microbeam

11th International Conference on Radiation Effects in Insulators2001/09

Detail

International conferenceOral presentation(general)

Effects of Byproducts of Dicumyl Peroxide on Space Charge Formation in Polyethylene

7th International Conference on Solid Dielectrics2001/06

Detail

International conferenceOral presentation(general)

Photoluminescence in Polymeric Insulating Materials (Low Density Polyethylene and Polypropylene) Induced by Ultraviolet Photons

7th International Conference on Solid Dielectrics2001/06

Detail

International conferenceOral presentation(general)

Application of Low Frequency Raman Scattering Spectroscopy to Size Determination of Nanoscale Structures in Solid Matrices

1st International Workshop on Nanoscale Spectroscopy and Its Applications to Semiconductor Research2000/12

Detail

International conferenceOral presentation(general)

Non-linear Glasses by Metal Cluster Formations: Nucleation and Optical Properties of Quantum Dots in Amorphous Matrix

Toyota Technological Institute, Photonics Forum2000/12

Detail

International conferenceOral presentation(general)

Low Temperature Crystallization of SrBi2 Ta2 O9 and YMnO3 Ferroelectric Films by Ultraviolet Laser Irradiation

22nd Symposium on Dry Process2000/11

Detail

International conferenceOral presentation(general)

Nucleation and Optical Properties of Quantum Dots in Amorphous Matrix

The 32nd Symposium of Electric and Electronic Insulating Materials2000/11

Detail

International conferenceOral presentation(general)

Low Temperature Crystallization of SrBi2 Ta2 O9 and YMnO3 Ferroelectric Films by Ultraviolet Laser Irradiation

22nd Symposium on Dry Process2000/11

Detail

International conferenceOral presentation(general)

Effects of Byproducts of Crosslinking Agent on Space Charge Formation in Polyethylene -comparison between acetophenone and alpha-methylstyrene-

2000 Conference on Electrical Insulation and Dielectric Phenomena2000/10

Detail

International conferenceOral presentation(general)

Growth and optical properties of semiconductor nanocrystals in a glass matrix

The Japan Society of Applied Physics Congress2000/09

Detail

International conferenceOral presentation(general)

ATR infrared spectroscopy applied to in situ analysis of atheromatous plaques in aorta

The Japan Society of Applied Physics Congress2000/09

Detail

International conferenceOral presentation(general)

Comparison of degradation between all-aromatic and thermoplastic polyimide films

2000/09

Detail

National conferenceOral presentation(general)

Electroluminescence in silicon oxynitride

The 6th International Conference on Properties and Applications of Dielectric Materials2000/06

Detail

International conferenceOral presentation(general)

Photoluminescence in Polypropylene Induced by Ultraviolet Laser Irradiation

The 6th International Conference on Properties and Applications in Dielectric Materials2000/06

Detail

International conferenceOral presentation(general)

Recovery voltage measurements for the evaluation of degradation of polyimide films

2000/03

Detail

National conferenceOral presentation(general)

Metal Nanoparticales in Dielectric Matrix: Optical Properties

The 11th Meeting on Glasses for Photonics2000/01

Detail

International conferenceOral presentation(general)

Low Temperature Crystallization of SrBi2 Ta2 O9 Ferroelectric Films by Uotraviolet Laser Irradiation

1999 Dry Process Symposium1999/11

Detail

International conferenceOral presentation(general)

Conductivity and Permittivity of Water Tree in Polyethylene

1999 Conference on Electrical Insulation and Dielectric Phenomena1999/10

Detail

International conferenceOral presentation(general)

Effect of Acetophenone on the Space Charge Evolution in LDPE and LLDPE

1999 Conference on Electrical Insulation and Dielectric Phenomena1999/10

Detail

International conferenceOral presentation(general)

Space Charge Distribution Measurement in XLPE Cable for Detection of the Water Tree Location

1999 Conference on Electrical Insulation and Dielectric Phenomena1999/10

Detail

International conferenceOral presentation(general)

Effect of Acetophenone on the Space Charge Evolution in LDPE and LLDPE

1999 Conference on Electrical Insulation and Dielectric Phenomena1999/10

Detail

International conferenceOral presentation(general)

Low temperature crystallization of SrBi2Ta2O9 film by excimer laser irradiation

Materials Research Society 1998 Fall Meeting1998/12

Detail

International conferenceOral presentation(general)

Direct Deposition of Blanket Tungsten Layer on SiO2 by Pre-exposure of Helium Plasma

Proceedings of Symposium on Dry Process, IEEJ1998/11

Detail

International conferenceOral presentation(general)

Time-resolved Space Charge Observation in Water-treed XLPE

IEEE Conference on Electrical Insulation and Dielectric Phenomena1998/10

Detail

International conferenceOral presentation(general)

Effect of Acetophenone on Space Charge Formation in LDPE and LLDPE

1998 IEEE International Symposium on Electrical Insulating Materials, in conjunction with 1998 Asian International Conference on Dielectrics and Electrical Insulation and the 30th Symposium on Electrical Insulating Materials1998/09

Detail

International conferenceOral presentation(general)

Effect of Ozone Annealing on the Charge Trapping Property of Ta2 O5-Si3 N4-p-Si Capacitor Grown by Low Pressure Chemical Vapor Deposition

IEEE International Symposium on Electrical Insulating Materials, in conjunction with 1998 Asian International Conference on Dielectrics and Electrical Insulation and the 30th Symposium on Electrical Insulating Materials1998/09

Detail

International conferenceOral presentation(general)

Effects of Ion Implantation and Thermal Annealing on the Photoluminescence in Amorphous Silicon Nitride Films

1998 IEEE International Symposium on Electrical Insulating Materials, in conjunction with 1998 Asian International Conference on Dielectrics and Electrical Insulation and the 30th Symposium on Electrical Insulating Materials1998/09

Detail

International conferenceOral presentation(general)

Photoluminescence and Electron-Spin-Resonance Studies of Defects in Amorphous SiO2 Films

1998 IEEE International Symposium on Electrical Insulating Materials, in conjunction with 1998 Asian International Conference on Dielectrics and Electrical Insulation and the 30th Symposium on Electrical Insulating Materials1998/09

Detail

International conferenceOral presentation(general)

Structural Changes in Ge-Doped SiO2 Planar Waveguides Induced by Ultraviolet Photons

1998 IEEE International Symposium on Electrical Insulating Materials, in conjunction with 1998 Asian International Conference on Dielectrics and Electrical Insulation and the 30th Symposium on Electrical Insulating Materials1998/09

Detail

International conferenceOral presentation(general)

Effect of Plasma Treatment on the Charge Distribution in Some Polymers

1998/07

Detail

National conferenceOral presentation(general)

Dielectric Breakdown in F-Doped SiO2 Films Formed by Plasma-Enhanced Chemical Vapor Deposition

1998 IEEE International Conference on Conduction and Breakdown in Solid Dielectrics1998/06

Detail

International conferenceOral presentation(general)

Dielectric Properties of New-Type Polyethylene Polymerized Using a Single-Site Catalyst

1998 IEEE International Conference on Conduction and Breakdown in Solid Dielectrics1998/06

Detail

International conferenceOral presentation(general)

Electrical Properties of Thermoplastic Polyimide

1998 IEEE International Conference on Conduction and Breakdown in Solid Dielectrics1998/06

Detail

International conferenceOral presentation(general)

Role of voltage zero-crossing in propagation of water trees

Conference on Electrical Insulation and Dielectric Phenomena1997/10

Detail

International conferenceOral presentation(general)

Role of voltage zero-crossing in propagation of water trees

Conference on Electrical Insulation and Dielectric Phenomena1997/10

Detail

International conferenceOral presentation(general)

Generation mechanism of germanium electron center in Ge-doped silica glass

International Workshop on "Structure and Functional Optical Properties of Silica and Silica-related Glasses" Shizuoka, Japan1997/07

Detail

International conferenceOral presentation(general)

Correlation between paramagnetic centers and absorption bands induced by KrF excimer laser photons in Ge-doped SiO2 glass

The 14th University Conference on Glass Science, Bethlehem, Pennsylvania, U.S.A.1997/06

Detail

International conferenceOral presentation(general)

Effect of Gamma-Ray Irradiation on the Thermally Stimulated Current in Polyethersulfone

5th International Conference on Properties and Applications of Dielectric Materials1997/05

Detail

International conferenceOral presentation(general)

Effect of post-oxidation on the oxygen deficiency of buried oxides

Materials Research Society,1996 Fall Meeting1996/12

Detail

International conferenceOral presentation(general)

Dielectric Breakdown Properties of Low-density Polyethylene under Power-frequency Voltages with High-Frequency Components

1996 Asian International Conference on Dielectrics and Electrical Insulation1996/10

Detail

International conferenceOral presentation(general)

Effect of Fluorine-doping on the Dielectric Strength of Thin SiO2 Films Formed by Plasma-enhanced Chemical Vapor Deposition

Conference on Electrical Insulation and Dielectric Phenomena/IEEE Dielectrics and Electrical Insulation Society1996/10

Detail

International conferenceOral presentation(general)

Energy Distribution of Traps in Polyethersulfone Film Estimated through Surface Potential Measurements

1996 Asian International Conference on Dielectrics and Electrical Insulation1996/10

Detail

International conferenceOral presentation(general)

Experimental Observation and Numerical Calculation of Space Charge Formation in Gamma-irradiated Polyethylene

1996 Asian International Conference on Dielectrics and Electrical Insulation1996/10

Detail

International conferenceOral presentation(general)

Space Charge Behavior under AC Voltage Application in Water-treed Polyethylene Observed by the Pulsed Electroacoustic Method

Conference on Electrical Insulation and Dielectric Phenomena/IEEE Dielectrics and Electrical Insulation Society1996/10

Detail

International conferenceOral presentation(general)

Treeing and Water Treeing Resistance of Ethylene-Styrene Copolymers

1996 Asian International Conference on Dielectrics and Electrical Insulation1996/10

Detail

International conferenceOral presentation(general)

Water tree characteristics in low-density polyethylene under power-frequency voltages with high-frequency components

Conference on Electrical Insulation and Dielectric Phenomena/IEEE Dielectrics and Electrical Insulation Society1996/10

Detail

International conferenceOral presentation(general)

Photoluminescence and electron-spin-resonance studies of defects in amorphous SiO2 films

Proceedings of the third International Symposium on Physics and Chemistry of SiO2 and the Si-SiO2 interface1996/05

Detail

International conferenceOral presentation(general)

Photoluminescence and electron-spin-resonance studies of defects in amorphous SiO2 films

Proceedings of the third International Symposium on Physics and Chemistry of SiO2 and the Si-SiO2 interface1996/05

Detail

International conferenceOral presentation(general)

Microscopic Structural Randomness of F-doped SiO2 films Prepared by Plasma Enhanced Chemical Vapor Deposition and Its Effect on Dielectric Strength

13th Plasma Processing Symposium1996/01

Detail

International conferenceOral presentation(general)

Structural Stabilization Induced by Post-irradiation of Plasma in TEOS-SiO2 Films Deposited at Low Temperature

13th Plasma Processing Symposium1996/01

Detail

International conferenceOral presentation(general)

Anomalous Discharging Current in Polymethylpentene

1995 Conference on Electrical Insulation and Dielectric Phenomena/IEEE1995/10

Detail

International conferenceOral presentation(general)

Origins of Thermally Stimulated Current Peaks in Polyethersulfone Investigated through the Measurement of Space Charge Distribution

1995 Conference on Electrical Insulation and Dielectric Phenomena/IEEE1995/10

Detail

International conferenceOral presentation(general)

Effect of gamma-ray Irradiation on Thermally Stimulated Current in Polyethersulfone

1995 International Symposium on Electrical Insulating Materials/IEEJ/IEEE1995/09

Detail

International conferenceOral presentation(general)

Electrical Conduction and Breakdown in Polyolefin with Carbonyl Groups

1995 International Symposium on Electrical Insulating Materials/IEEJ/IEEE1995/09

Detail

International conferenceOral presentation(general)

Low-Temperature TSC Peak of Polyethersulfone

1995 International Symposium on Electrical Insulating Materials/IEEJ/IEEE1995/09

Detail

International conferenceOral presentation(general)

Luminescence Properties of Defects in P+ or B+ implanted Thermally Grown Silicon Dioxide

1995 International Symposium on Electrical Insulating Materials/IEEJ/IEEE1995/09

Detail

International conferenceOral presentation(general)

Photoluminescence from Er-doped SiO2 Films Synthesized by Plasma-enhanced Chemical Vapor Deposition of Tetraethoxysilane

11th International Conference on Gas Discharges and Their Applications/IEEJ1995/09

Detail

International conferenceOral presentation(general)

Dielectric Breakdown of SiO2 Formed by Plasma-enhanced Chemical Vapor Deposition of Tetraethoxysilane

Proceedings of 5th International Conference on Conduction and Breakdown in Solid Dielectrics/IEEE1995/07

Detail

International conferenceOral presentation(general)

Observation and Numerical Calculations of Space Charge Behavior in Gamma-irradiated Low Density Polyethylene

Proceedings of 5th International Conference on Conduction and Breakdown in Solid Dielectrics/IEEE1995/07

Detail

International conferenceOral presentation(general)

Spontaneous Current of Polyethersulfone Investigated through the Measurement of Space Charge Distribution by the Pulsed Electroacoustic Method and Thermally Stimulated Current

Proceedings of 5th International Conference on Conduction and Breakdown in Solid Dielectrics/IEEE1995/07

Detail

International conferenceOral presentation(general)

Laser-power Dependence of KrF Excimer Laser Induced Absorption in Ge-doped SiO2 Glass.

VII International Conference on the Physics of Non-crystalline Solids.1995/06

Detail

International conferenceOral presentation(general)

Aging Properties of High-Voltage XLPE Cables

Proceedings of Prediction of Remnant Life and Insulation Diagnosis Technology on Power Apparatus and System/韓国電気学会1995/05

Detail

International conferenceOral presentation(general)

Insulation characteristics of XLPE cables and their accessories for high frequency voltage with PWM inverter

Proceedings of the IEEE Power Engineering Society Transmission and Distribution Conference1994

Detail

International conference

Dominant donduction carriers in poyethersulfone

Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)1994

Detail

International conference

Measurement of residual space charge distribution in gamma-irradiated polyethylene

IEEE International Conference on Properties and Applications of Dielectric Materials1994

Detail

International conference

Electrical breakdown characteristics of liquid-crystal polymer

IEEE International Conference on Properties and Applications of Dielectric Materials1994

Detail

International conference

Ionic dc transport in polyetheretherketone

IEEE International Conference on Properties and Applications of Dielectric Materials1994

Detail

International conference

Breakdown characgteristics of thin SiO2 films deposited from TEOS using plasma CVD method

Conference on Electrical Insulation and Dielectric Phenomena1993

Detail

International conference

Conduction process in polymethylpentene

Proceedings of the Symposium on Electrical Insulation Mateials1993

Detail

International conference

Electrical breakdown characteristics of liquid-crystal polymer

Proceedings of the Symposium on Electrical Insulating Materials1993

Detail

International conference

Measurement of space charge distribution in gamma-irradiated polyethylene

Proceedings of the Symposium on Electrical Insulating Materials1993

Detail

International conference

Conduction characteristics in ethylene carbon monoxide copolymer

Proceedings of the Symposium on Electrical Insulating Materials1993

Detail

International conference

Patent

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グレーティング並びにグレーティング形成方法及び装置(日本, ヨ-ロッパ, アメリカ)

大木 義路

H11-224272、2001-051133、3456927

Reference Number:31

透過光特性調整方法及び透過光特性調整装置並びに長周期グレーティング(日本)

大木 義路, 藤巻 真, 宮崎 奈穂子, 内藤 要

2000- 88540、2001-272553

Reference Number:45

耐熱処理装置及び耐熱処理方法並びにグレーティング(日本)

大木 義路, 徳廣 真一郎, 藤巻 真, 野村 健一

2000-264328、2002-071974

Reference Number:53

酸化物強誘電体素子の作製方法(日本)

大木 義路, 薛 光洙, 平松 大直, 伊藤 貴俊

2000-340845、2002-151503

Reference Number:98

光導波路形成方法及び光導波路(日本)

大木 義路, 加藤 宙光, 藤巻 真, 野間 崇

2001-270151、2003-075659

Reference Number:144

結晶TiO2の微細加工方法及び微細加工された結晶TiO2(日本, PCT)

島 邦博, 石井 聡, 大木 義路, 中西 哲也, 野村 健一

2002- 87052、2003-279766、4025886

Reference Number:368

光ファイバデポラライザの製造方法(日本)

藤巻 真, 山口 英祐, 奥出 聡, 劉 昇, 河辺 柱太, 大木 義路

2004- 41002、2005-234078

Reference Number:526

荷電粒子加速器のメンテナンス方法(日本)

藤巻 真, 大木 義路

2005-205570、2007- 26816、4674898

Reference Number:807

電気絶縁材料及びそれを用いた絶縁電線、通信用ケーブル、電気部品(日本)

大木 義路, 平井 直志

2008- 79669、2009-238411

Reference Number:1168

プリント配線板とその製造方法(日本)

大木 義路, 夏井 正嗣, 浅川 洋貴

2011- 43975、2011-205083、5807225

Reference Number:1172

プリント配線板(日本)

大木 義路, 浅川 洋貴, 難波 裕, 田中 祀捷

2011- 48956、2012-186345、5982710

Reference Number:1205

絶縁信頼性を高めた固体絶縁スイッチギヤ(日本)

大木 義路, 田中 祀捷, 田上 直紀

2008-262024、2010- 93956

Reference Number:1326

絶縁電線又はケーブルの温度変化箇所の位置標定方法(日本)

大木 義路, 平井 直志, 山田 貴之

2012-146311、2014- 10027、5763594

Reference Number:1446

絶縁電線又はケーブルの歪み量変化箇所の位置標定方法(日本)

大木 義路, 平井 直志

2013-208460、2015- 72217

Reference Number:1670

高分子の異物検査方法、および電力ケーブルの製造方法(日本)

小松 麻里奈, 井筒 智之, 大木 義路, 小髙 大祐

2015-041786、2016-161462、6238245

Reference Number:288-JP

金属ベースプリント配線板(日本)

廣瀬 雄一, 和田 玄太, 田中 祀捷, 大木 義路

2014-528222、6239510

Research Grants & Projects

Grant-in-aids for Scientific Research Adoption Situation

Research Classification:

Dielectric Properties and Insulation Diagnosis of Polymers by Ultra-wideband Dielectric and Absorption Spectroscopy

2012/-0-2014/-0

Allocation Class:¥4030000

Research Classification:

Evaluation of Oxidation for Biodegradable Polymers by the Measurement of Chemiluminescence

2011/-0-2014/-0

Allocation Class:¥5590000

Research Classification:

Development of High Performance Insulating Materials Using Polymer Nanocomposites with Inorganic Fillers

2011/-0-2014/-0

Allocation Class:¥19630000

Research Classification:

Mechanism of Refractive Index Increase Induced in Polymers by Ion Irradiation and Its Application to the Development of Optical Devices

Allocation Class:¥3340000

Research Classification:

Dominant factors influencing dielectric properties in several biodegradable polymers

Allocation Class:¥18330000

Research Classification:

Dielectric and Electrical Insulation Performance of Polymer Nanocomposites Viewed from Mesoscopic Properties of Organic and Inorganic Nano-scale Interfaces

Allocation Class:¥14520000

Research Classification:

Structures and Generation Mechanisms of Defects in High-k Dielectric Films for Silicon ULSIs

Allocation Class:¥14900000

Research Classification:

Development of Functional Dielectrics for Future All-Solid Substations

Allocation Class:¥13000000

Research Classification:

Mechanism of refractive index increase in silica glass for the development of fiber-optic photodevices

Allocation Class:¥10800000

Research Classification:

Defect detection and structure analysis in silica thin films by use of photoluminescence

Allocation Class:¥9600000

Research Classification:

Point Defects in Ge-doped SiO_2 Glass-Their Structures and Roles in Nonlinear Optical Effects

Allocation Class:¥7400000

Research Classification:

Excitation states and defect formation in high purity silica glass under gamma-ray or excimer-laser irradiation

Allocation Class:¥6600000

Research Classification:

Study on the Cause of Light Scattering, Especially Due to Refractive Index Fluctuation in High-purity Silica Glass.

Allocation Class:¥6100000

Research Classification:

Defects in pure-silica glass: study on non-radical defects and development of optical fibers for adverse environments.

Allocation Class:¥6500000

Research Classification:

Mechanism of Radiation Induced Loss in Optical Fibers and Development of Radiation-Resistant Fibers

Allocation Class:¥4800000

Research Classification:

Control of Superstructure and Functionalization of DNA by THz Wave Illumination

2017/-0-2020/-0

Allocation Class:¥6240000

Research Fund Acceptance Situation

Embodiment:Joint research programs

Development of Nanocomposite Insulating Matertials for Eco-friencly Power Apparatus2005-

Embodiment:Joint research programs

Structure and Function Mechanism of Point Defects in High-k Dielectric Films for Next Generation2004-

Embodiment:Joint research programs

Degradation of Polymeric Dielectric Materials1999-1999

Embodiment:Joint research programs

Fabrication of Functional Silica-based Glasses by micro-ion-beam.2000-2000

Embodiment:Joint research programs

Low-temperature Crystallization of Ferroelectric Thin Films1999-1999

On-campus Research System

Special Research Project

絶縁材料中の空間電荷分布の精密計測とそれによる直流ケーブル用材料の開発

1995

Research Results Outline:(1)ポリエーテルスルホン(PES)は,ガラス転移点である225℃までの間に,2つの熱刺激電流ピークを持ち,このうち低温側のβピークは,ポーリング温度(1)ポリエーテルスルホン(PES)は,ガラス転移点である225℃までの間に,2つの熱刺激電流ピークを持ち,このうち低温側のβピークは,ポーリング温度とともにピーク温度が最高150℃まで上昇し,高温側のαピークは約210℃付近にピークを持つ。このう...(1)ポリエーテルスルホン(PES)は,ガラス転移点である225℃までの間に,2つの熱刺激電流ピークを持ち,このうち低温側のβピークは,ポーリング温度とともにピーク温度が最高150℃まで上昇し,高温側のαピークは約210℃付近にピークを持つ。このうち,αピークについては元々試料内部に不均一な分布を持って存在していたK+イオンなどのイオンが原因であることが既にわかっている。本報告では,パルス静電応力法による空間電荷分布の測定とサーマルサンプリング法による熱刺激電流の測定を組み合わせることにより,βピークの原因となっているキャリアの推測を行った。この結果,βピークの出現に対応する形で陰極前面に見られていた多量の正電荷が減少していくことがわった。さらに,直流伝導電流は熱処理および電圧印加後の時間の経過につれて減少していく。これらの事実は,βピークや伝達に不純物イオンが関与していることをうかがわせる。また,電流値は,イオンのホッピング電流の理論式に合い,算出される電荷密度やホッピング距離は妥当な値となる。αピークの原因がイオンであることと合わせて,PESにおける主たるキャリアはイオンであると考えられる。(2)誘電体に印加していた電圧を除去したときに流れる放電電流は通常,印加電界と逆方向に流れる。筆者らがポリメチルペンテン(PMP)の放電電流を測定したところ,高温領域(100~120℃)において,通常観測される方向とは逆の,すなわち,それまで印加されていた電界と同方向に流れる異常放電電流が生じることが見いだされた。また異常放電電流が生じる条件で,電界を印加後,パルス静電応力法によって空間電荷分布を測定した結果,電極近傍にヘテロ電荷の蓄積がみられた。そこで空間電荷自身が形成する内部電界により電荷が移動すると仮定し,観測された空間電荷分布をもとにシミュレーションをおこなったところ,正電荷と負電荷の移動度をそれぞれ,μp=2.5×10-10cm2/Vs, μn=7×10-11cm2/Vsと仮定した時に,実験結果の放電電流と近い電流波形および放電電流観測後の実測電荷分布に近い電荷分布が得られた。このポリメチルペンテンにおける異常放電電流には不純物イオンが関与していると推測される。

フォトルミネセンス法によるSiO2薄膜中の欠陥の検出ならびに構造解析

1997Collaborator:浜 義昌

Research Results Outline:本年度の研究において、強力な紫外―真空紫外光であるエキシマレーザ光やシンクロトロン放射光を用いることにより、a-SiO2薄膜からでも充分な強度を有した本年度の研究において、強力な紫外―真空紫外光であるエキシマレーザ光やシンクロトロン放射光を用いることにより、a-SiO2薄膜からでも充分な強度を有したフォトルミネセンスが得られることが証明され、今まで、有力な評価手段のなかったa-SiO2薄膜の点欠...本年度の研究において、強力な紫外―真空紫外光であるエキシマレーザ光やシンクロトロン放射光を用いることにより、a-SiO2薄膜からでも充分な強度を有したフォトルミネセンスが得られることが証明され、今まで、有力な評価手段のなかったa-SiO2薄膜の点欠陥に対する検出手法としてのフォトルミネセンス法が確立できた。さらに、この手法を用いて、シリコン熱酸化膜やSIMOX埋め込み酸化膜を対象として、その膜の製法に起因して膜が本質的に含有する欠陥とイオン注入や高温熱処理等のデバイス製造プロセスにより生じる欠陥の検出と欠陥構造の同定を行うことができた。 イオン注入されたシリコン熱酸化膜にKrFエキシマレーザ光を照射することにより三つの発光帯(4.3 eV、2.7 eV、1.9 eV)を観測した。また、4.3 eV発光の励起帯が約5.0 eVと7.3 eVにあることをシンクロトロン放射光を用いた発光励起測定から観測した。さらに、シングルバンチ運転下のシンクロトロン放射光(光パルス幅約0.55 ns)を用いた時間相関単一光子計数法等の測定により4.3 eV発光の寿命は5.0 eV光励起では約2.6 nsであり、7.3 eV光励起では約1.9 nsであること、2.7 eV発光の寿命は約6 msであることを明らかにし、これらの発光がイオン注入によりシリコン熱酸化膜に誘起された酸素空孔に起因していること、および、イオン注入により熱酸化膜に誘起された欠陥の消滅に対して、高温での熱酸化中に酸化膜に溶け込んでいた酸素が重要な役割を果たしていることを明らかにした。 つぎに、シリコン基板への酸素イオン注入後、高温の熱処理により形成されたSIMOX埋め込み酸化膜を試料として、埋め込み酸化膜上のSi層をKOH溶液でエッチング除去したのち、KrFエキシマレーザ光励起下で発光を観察すると、4.3 eV発光の強度はSIMOX埋め込み酸化膜の残存膜厚に対してほぼ直線的に比例することから、酸素空孔は酸化膜中にほぼ均等に分布しているとしていると推察できる。また、イオン注入のされていないシリコン熱酸化膜ではこれらの発光が観測されないことから、SIMOX埋め込み酸化膜はシリコン熱酸化膜より遥かに酸素欠乏性の程度が高いことを明らかにした。研究成果の発表:K. S. Seol et al.Concentration of neutral oxygen vacancies in buried oxide formed by implantation of oxygenJ. Appl. Phys., Vol. 83, No. 4, 1998, 2357-2359M. Fujimaki et al.Structures and generation mechanisms of paramagnetic centers and absorption bands responsible for Ge-doped SiO2 optical fiber gratings Phys. Rev. B, Vol. 57, No. 7, 1998, 3920-3926H. Nishikawa et al.Photoluminescence of oxygen-deficient-type defects in a-SiO2J. Non-Cryst. Solids, Vol. 222, 1997, 221-225K. S. Seol et al.Thermal annealing behavior of defects induced by ion implantation in thermally grown SiO2 filmsMicroelectronic Eng., Vol. 36, 1997, 193-195K. S. Seol et al.Effect of post-oxidation on the oxygen deficiency of buried oxideMat. Res. Soc. Symp. Proc., Vol. 446, 1997, 219-223M. Fujimaki et al.Generation mechanism of germanium electron center in Ge-doped silica glass.International Workshop on “Structure and Functional Optical Properties of Silica and Silica-related Glasses”., 1997, 1-4

無機絶縁体薄膜の構造欠陥とその電気特性・光学特性への影響

1999

Research Results Outline: 近年LISデバイスの微細化・高機能化・低電力化に伴いトランジスタのゲート酸化膜に使われてきたSiO2が物理的限界まできている。またキャパシタにおける 近年LISデバイスの微細化・高機能化・低電力化に伴いトランジスタのゲート酸化膜に使われてきたSiO2が物理的限界まできている。またキャパシタにおける静電容量の確保といったさまざまな問題がこの分野において浮上してきている。そのため、SiO2より高誘... 近年LISデバイスの微細化・高機能化・低電力化に伴いトランジスタのゲート酸化膜に使われてきたSiO2が物理的限界まできている。またキャパシタにおける静電容量の確保といったさまざまな問題がこの分野において浮上してきている。そのため、SiO2より高誘電率であるSi3N4, Ta2O5の利用が考えられている。そこで半導体デバイス各種用途に用いられる無機絶縁体薄膜の欠陥構造とその電気特性・光学特性への影響について過去に我々がSiO2に対して用いた研究手法と同様の手法を用いて研究を行ってきた。すなわち、Si3N4については、フォトルミネッセンス法によりバンド端の局在準位から電子・正孔の再結合による2.6eVにピークを持つ発光が観測された。この発光現象から局在準位の状態を考えることが可能である。また、成膜法による発光スペクトルの差やイオン照射や熱アニールを施したときの発光量の変化から水素離脱によりバンド内部に準位を形成する欠陥が生成されること明らかになった。バンド端の局在準位を介してPoole-Frenkel伝導により漏れ電流が流れていると考えられるデータも得られていることから、Si3N4における局在準位がその電気特性・光学特性へあたえる影響が明らかになった。Ta2O5においては漏れ電流が最大の問題点であるが、オゾン処理を施すことにより減少させることができた。この機構を探るために電荷トラッピング特性を高周波容量測定法により調べた。その結果、オゾン処理により電子捕獲準位の減少を確認し、さらに正孔捕獲準位の生成が明らかにされた。Ta2O5は基本的に電子性伝導であることからこの電子捕獲準位の減少が漏れ電流低減の理由と考えられる。これらの成果は、裏面に記載した各論文が掲載されているほか、現在、2篇の関連論文を執筆中である。

各種生分解性高分子の誘電特性支配因子の解明

2007

Research Results Outline: 環境負荷の低い材料として、生分解性高分子が注目を集めている。多くの生分解性高分子のうちでポリ乳酸(PLA)は、電気特性もある程度調べられており、コン 環境負荷の低い材料として、生分解性高分子が注目を集めている。多くの生分解性高分子のうちでポリ乳酸(PLA)は、電気特性もある程度調べられており、コンピューターや光ディスク基板等に使われ始めた。PLAの電気特性に大きな影響を与える因子は、結晶化度と... 環境負荷の低い材料として、生分解性高分子が注目を集めている。多くの生分解性高分子のうちでポリ乳酸(PLA)は、電気特性もある程度調べられており、コンピューターや光ディスク基板等に使われ始めた。PLAの電気特性に大きな影響を与える因子は、結晶化度と温度である。例えば、PLAの導電率や誘電率は、ガラス転移温度(=68℃)を超えると急増する。これは、ゴム状態においてはミクロブラウン運動が起こり、カルボニル基など双極子の配向分極や、おそらくはイオン性と思われる電荷の移動が容易になることを反映している。本研究では、上記PLAに加えて、ポリカプロラクトンブチレンサクシネート(PCL-BS)、ポリエチレンテレフタレートサクシネート(PETS)、ポリブチレンサクシネート(PBS)、さらに比較のために低密度ポリエチレン(LDPE)と架橋ポリエチレン(XLPE)を試料として電気特性のいくつかを調べた。結果を概観すると、室温で可撓性を有するPCL-BS、PBSは、電流が流れ易く他の絶縁性能も悪い。逆に、電流が流れにくく絶縁性能の良いPLLAやPETSは可撓性に乏しい。すなわち、可撓性が必要で、かつ、厳しいスペックの要求される絶縁材料として、直ちに使用可能な生分解性高分子はない。但し、機械的強度は必要であるが、可撓性は要求されない場合には、PLAは有望な材料である。このことが、PLAが実際に民生用電気機器の筐体等に使われ始めた理由であろう。高温での物性に劣るといった問題点があるものの、添加剤や他の高分子とのブレンド等による改質も可能なPLAについては、今後ますます多様な利用が進んでゆくと思われる。また他の生分解性高分子については、PLAとのブレンド材として使用可能なものがあると思われる。

PL法によるSiC-MOS-FET高耐電圧化のためのゲート酸化膜の膜質評価

2013

Research Results Outline:MOSデバイスの製造において、イオン注入がしばしば行われる。しかしながら、イオン注入による欠陥生成や、結晶性低下などの影響はあまり明らかにされていないMOSデバイスの製造において、イオン注入がしばしば行われる。しかしながら、イオン注入による欠陥生成や、結晶性低下などの影響はあまり明らかにされていない。また、MOSデバイスの性能向上のための微細化に伴い、注目されているのが、SiO2より比誘電率(k...MOSデバイスの製造において、イオン注入がしばしば行われる。しかしながら、イオン注入による欠陥生成や、結晶性低下などの影響はあまり明らかにされていない。また、MOSデバイスの性能向上のための微細化に伴い、注目されているのが、SiO2より比誘電率(k)を高めたhigh-k膜を用いることである。さらに、Siに代わるMOS-FETパワー半導体材料として、バンドギャップの大きなSiCが実用化されつつあり、Si-MOS-FETでは1kV以下であった耐圧は将来的には5kV程度まで上昇すると言われている。この実現のひとつの大きな障害は、絶縁膜の絶縁破壊であるが、その原因は電荷のトンネル放出であるので、ゲート絶縁膜を厚くすることができるhigh-k膜が、やはり注目されている。high-k膜材料の中でもYAlO3およびLaAlO3が次世代材料として注目されている。以上の理由から、本研究では、YAlO3単結晶(100)、LaAlO3単結晶(100)を試料とし、加速電圧150keVでP+、B+を1×1015cm-2照射し、その前後で、X線回折(XRD)測定、分子科学研究所のSR光源を用いた10Kでのフォトルミネセンス(PL)測定、光吸収測定などを行った。その結果、イオン照射後、とくにYAlO3において、バンドギャップ(7.7eV)近傍の吸収が大きく増加すること、両試料においてXRDピーク強度が著しく減少することから、イオン照射により結晶性が低下することが示唆される。また、LaAlO3ではイオン照射前後でXRDピーク位置は変わらないのに対し、YAlO3ではピークの位置がシフトする。これは、YAlO3では格子間隔が変化していることを示す。Laより原子量が小さいYではB、Pによる置換が生じやすいことを示唆している。さらに、両試料には酸素空孔と不純物(Cr、Erなど)が点欠陥として存在するが、イオン照射後、両試料において、酸素空孔に起因するPLの強度には変化がなく、Cr3+のR線発光に起因するPLやEr3+の発光に起因するPLの強度は、減少すると言う事実を得た。たとえば、Cr3+のR線の発光は、遷移金属不純物であるCr3+とO2-とが八面体型配位子場を形成し、シュタルク効果が働くことにより出現する発光であり、当然配位子場に敏感であり、結晶性が高い場合にのみ現れる。一方、酸素空孔によるPLは、YSZ、ZnO、SiO2など多くの物質で、単結晶、アモルファスを問わず見られ、例えば、スート再溶融法により成膜した完全にアモルファスであるSiO2においても発光が確認されている。以上より、イオン照射後に、結晶においてのみ見られるPLだけが消滅している事が分かる。これらをまとめると、試料のごく表面のみしか結晶性を評価することができないXRD測定に加えて、イオン通過範囲全域にわたって高感度な検出が可能なPL測定を補完する形で用いることにより、イオン照射により、YAlO3およびLaAlO3の結晶性が低下すること、YAlO3に比べてLaAlO3の方がイオン照射に対する耐性が強いことなどを明らかにすることに成功した。

テラヘルツ波照射によるデオキシリボ核酸の高次構造制御と機能性付与

2014Collaborator:福永 香, 水野 麻弥, 小嶋 寛明

Research Results Outline:テラヘルツ域を含む遠赤外光の全域においてDNAの吸収スペクトルを取得し,その解析を行うことを目的としている。本年度は,最初に安定的なスペクトル取得方法テラヘルツ域を含む遠赤外光の全域においてDNAの吸収スペクトルを取得し,その解析を行うことを目的としている。本年度は,最初に安定的なスペクトル取得方法について検討した。その後,ヌクレオチドがチミン,アデニン,シトシン,グアニンの各塩基を持つ一本鎖D...テラヘルツ域を含む遠赤外光の全域においてDNAの吸収スペクトルを取得し,その解析を行うことを目的としている。本年度は,最初に安定的なスペクトル取得方法について検討した。その後,ヌクレオチドがチミン,アデニン,シトシン,グアニンの各塩基を持つ一本鎖DNAの遠赤外吸収スペクトルを得た。その結果,塩基の種類によらず100~300cm^-1と520~570cm^-1付近に広い吸収が現れ,チミンを塩基としたDNAにのみ強度がチミンの総数に比例する吸収が422cm^-1と490cm^-1付近に現れることが分かった。

テラヘルツ波照射によるデオキシリボ核酸の高次構造制御と機能性付与

2015

Research Results Outline:テラヘルツ域を含む遠赤外光の全域においてDNAの吸収スペクトルを取得し,その解析を行うことを目的としている。本年度は,ヌクレオチドがチミン,アデニン,テラヘルツ域を含む遠赤外光の全域においてDNAの吸収スペクトルを取得し,その解析を行うことを目的としている。本年度は,ヌクレオチドがチミン,アデニン,グアニン,シトシンの各塩基を持つ一本鎖DNAとともに,ヌクレオチドの構成要素の一つであるデオキシリ...テラヘルツ域を含む遠赤外光の全域においてDNAの吸収スペクトルを取得し,その解析を行うことを目的としている。本年度は,ヌクレオチドがチミン,アデニン,グアニン,シトシンの各塩基を持つ一本鎖DNAとともに,ヌクレオチドの構成要素の一つであるデオキシリボースの遠赤外吸収スペクトルを得た。その結果,塩基の種類によらず100~300cm^-1と520~570cm^-1付近に広い吸収が現れ,チミンを塩基としたDNAにのみ強度がチミンの総数に比例する吸収が422cm^-1と490cm^-1付近に現れる。一方で,デオキシリボースは100~600cm^-1の波数域において特徴的な吸収を持たないことが分かった。

テラヘルツ分光による高分子ナノコンポジットの優れた絶縁特性発現機構の解明

2017Collaborator:森本貴明

Research Results Outline:エポキシ樹脂にMgO,SiO2,TiO2などの種々のナノあるいはマイクロサイズのフィラーを添加した高分子ナノコンポジットに対して,示差走査熱量,誘電率エポキシ樹脂にMgO,SiO2,TiO2などの種々のナノあるいはマイクロサイズのフィラーを添加した高分子ナノコンポジットに対して,示差走査熱量,誘電率,電流およびテラヘルツ(THz)分光の測定を行ったところ,THz域の吸収が著しく増大する高分子とフ...エポキシ樹脂にMgO,SiO2,TiO2などの種々のナノあるいはマイクロサイズのフィラーを添加した高分子ナノコンポジットに対して,示差走査熱量,誘電率,電流およびテラヘルツ(THz)分光の測定を行ったところ,THz域の吸収が著しく増大する高分子とフィラーの組合せがあることが分かった。また,エポキシ樹脂に添加するMgOナノフィラーの粒径が小さくなるにつれて,導電率およびガラス転移温度がともに低下する。これは,粒径が小さくなる,または添加量が増加することで樹脂とMgOの界面面積が増加し,MgOの表面にイオンが捕獲されやすくなることにより,電荷の移動が抑制されることを示唆する。

テラヘルツ分光による高分子ナノコンポジットの優れた絶縁特性発現機構の解明

2018

Research Results Outline:高分子をナノコンポジットとすることで絶縁特性が向上する現象を明らかにするために,種々のフィラーをエポキシ樹脂に添加したコンポジット材料のTHz吸収スペ高分子をナノコンポジットとすることで絶縁特性が向上する現象を明らかにするために,種々のフィラーをエポキシ樹脂に添加したコンポジット材料のTHz吸収スペクトルを取得し,エポキシ樹脂とフィラー界面に働く相互作用の評価を試みた。エポキシ樹脂にナノサイズの...高分子をナノコンポジットとすることで絶縁特性が向上する現象を明らかにするために,種々のフィラーをエポキシ樹脂に添加したコンポジット材料のTHz吸収スペクトルを取得し,エポキシ樹脂とフィラー界面に働く相互作用の評価を試みた。エポキシ樹脂にナノサイズのルチル型TiO2または,ナノサイズのSiO2とマイクロサイズのMgOを共添加すると,THz領域の吸収量が増加し,フィラー自身から求めた吸収量よりも2倍以上大きくなる。この結果は,コンポジット材料のTHz領域における吸収増加の要因として,フィラー自身の吸収とは別にエポキシ樹脂とフィラー界面における相互作用の影響が,1つの可能性であることを示唆している。

Lecture Course

Course TitleSchoolYearTerm
Introduction to Nuclear Science and TechnologySchool of Advanced Science and Engineering2020fall semester
Introduction to Nuclear Science and TechnologySchool of Advanced Science and Engineering2020fall semester
Introduction to Nuclear Science and TechnologySchool of Advanced Science and Engineering2020fall semester
Introduction to Nuclear Power GenerationSchool of Creative Science and Engineering2020spring semester
Introduction to Nuclear Power GenerationSchool of Advanced Science and Engineering2020spring semester
Introduction to Nuclear Power GenerationSchool of Advanced Science and Engineering2020spring semester
Frontiers of Electrical Engineering and BioscienceSchool of Advanced Science and Engineering2020spring semester
Frontiers of Electrical Engineering and Bioscience [S Grade]School of Advanced Science and Engineering2020spring semester
Laboratory A on Electrical Engineering and BioscienceSchool of Advanced Science and Engineering2020fall semester
Laboratory A on Electrical Engineering and Bioscience [S Grade]School of Advanced Science and Engineering2020fall semester
Laboratory C on Electrical Engineering and BioscienceSchool of Advanced Science and Engineering2020fall semester
Laboratory C on Electrical Engineering and Bioscience [S Grade]School of Advanced Science and Engineering2020fall semester
Project Laboratory ASchool of Advanced Science and Engineering2020spring semester
Project Laboratory A [S Grade]School of Advanced Science and Engineering2020spring semester
Project Laboratory BSchool of Advanced Science and Engineering2020fall semester
Project Laboratory B [S Grade]School of Advanced Science and Engineering2020fall semester
Graduation Thesis ASchool of Advanced Science and Engineering2020spring semester
Graduation Thesis A [S Grade]School of Advanced Science and Engineering2020spring semester
Graduation Thesis BSchool of Advanced Science and Engineering2020fall semester
Graduation Thesis B [Spring]School of Advanced Science and Engineering2020spring semester
Graduation Thesis B [S Grade]School of Advanced Science and Engineering2020fall semester
Graduation Thesis B [Spring] [S Grade]School of Advanced Science and Engineering2020spring semester
Electromagnetism B (1)School of Advanced Science and Engineering2020fall semester
Electromagnetism B : Exercises (1)School of Advanced Science and Engineering2020fall semester
Dielectric MaterialsSchool of Advanced Science and Engineering2020spring semester
Electromagnetism A (1)School of Advanced Science and Engineering2020spring semester
Electromagnetism A [S Grade]School of Advanced Science and Engineering2020spring semester
Electromagnetism A : Exercises (1)School of Advanced Science and Engineering2020spring semester
Electromagnetism A : Exercises [S Grade]School of Advanced Science and Engineering2020spring semester
Graduation Thesis ASchool of Advanced Science and Engineering2020fall semester
Graduation Thesis BSchool of Advanced Science and Engineering2020spring semester
Advanced Electrical EngineeringSchool of Advanced Science and Engineering2020spring semester
Advanced Electrical EngineeringSchool of Advanced Science and Engineering2020spring semester
Master's Thesis (Department of Electrical Engineering and Bioscience)Graduate School of Advanced Science and Engineering2020full year
Master's Thesis (Department of Cooperative Major in Nuclear Energy)Graduate School of Advanced Science and Engineering2020full year
Research on Dielectric Materials ResearchGraduate School of Advanced Science and Engineering2020full year
Research on Dielectric Materials ResearchGraduate School of Advanced Science and Engineering2020full year
Electronic Properties of DielectricsGraduate School of Advanced Science and Engineering2020fall semester
Electronic Properties of DielectricsGraduate School of Advanced Science and Engineering2020fall semester
Advanced Seminar AGraduate School of Advanced Science and Engineering2020spring semester
Advanced Seminar AGraduate School of Advanced Science and Engineering2020spring semester
Advanced Seminar BGraduate School of Advanced Science and Engineering2020fall semester
Advanced Seminar BGraduate School of Advanced Science and Engineering2020fall semester
Seminar on Dielectric Materials AGraduate School of Advanced Science and Engineering2020spring semester
Seminar on Dielectric Materials AGraduate School of Advanced Science and Engineering2020spring semester
Seminar on Dielectric Materials BGraduate School of Advanced Science and Engineering2020fall semester
Seminar on Dielectric Materials BGraduate School of Advanced Science and Engineering2020fall semester
Seminar on Dielectric Materials CGraduate School of Advanced Science and Engineering2020spring semester
Seminar on Dielectric Materials CGraduate School of Advanced Science and Engineering2020spring semester
Seminar on Dielectric Materials DGraduate School of Advanced Science and Engineering2020fall semester
Seminar on Dielectric Materials DGraduate School of Advanced Science and Engineering2020fall semester
Research on Accelerator Application Science and Engineering BGraduate School of Advanced Science and Engineering2020full year
Nuclear Materials and Fuels, Adv.Graduate School of Advanced Science and Engineering2020spring semester
Seminar on Accelerator Application Science and Engineering BIGraduate School of Advanced Science and Engineering2020spring semester
Seminar on Accelerator Application Science and Engineering BIIGraduate School of Advanced Science and Engineering2020fall semester
Accelerator ExperimentsGraduate School of Advanced Science and Engineering2020an intensive course(spring and fall)
Master's Thesis (Department of Electrical Engineering and Bioscience)Graduate School of Advanced Science and Engineering2020full year
Research on Dielectric Materials ResearchGraduate School of Advanced Science and Engineering2020full year
Energy Next Systems and DevicesGraduate School of Fundamental Science and Engineering2020spring semester
Energy Next Systems and DevicesGraduate School of Creative Science and Engineering2020spring semester
Energy Next Systems and DevicesGraduate School of Advanced Science and Engineering2020spring semester
Energy Next Systems and DevicesGraduate School of Advanced Science and Engineering2020spring semester