平井 直志

主任研究員(研究院准教授)

  • 658 引用
  • 13 h指数
1993 …2019
Pureに変更を加えた場合、すぐここに表示されます。

研究成果 1993 2019

  • 658 引用
  • 13 h指数
  • 63 Conference contribution
  • 33 Article
  • 1 Chapter
  • 1 Comment/debate
2019
Flame retardants
Nuclear power plants
Polyethylenes
Aging of materials
Permittivity
1 引用 (Scopus)
Propylene
Accidents
Rubber
Ethylene
Cables
1 引用 (Scopus)

Broadband Far-infrared Spectroscopic Identification and Quantification of Antioxidants in Polymeric Insulation

Ogishima, T., Kozai, T., Hirai, N. & Ohki, Y., 2019 2 13, ICHVE 2018 - 2018 IEEE International Conference on High Voltage Engineering and Application. Institute of Electrical and Electronics Engineers Inc., 8641948. (ICHVE 2018 - 2018 IEEE International Conference on High Voltage Engineering and Application).

研究成果: Conference contribution

Antioxidants
Insulation
Infrared radiation
Low density polyethylenes
Infrared absorption
公開
Infrared absorption
Low density polyethylenes
Antioxidants
Absorption spectra
Absorption spectroscopy
1 引用 (Scopus)

Degradation mechanisms of silicone rubber under different aging conditions

Kaneko, T., Ito, S., Minakawa, T., Hirai, N. & Ohki, Y., 2019 10 1, : : Polymer Degradation and Stability. 168, 108936.

研究成果: Article

silicone rubber
Silicone Elastomers
Silicones
Rubber
Aging of materials
1 引用 (Scopus)

Degradation of silicone rubber analyzed by instrumental analyses and dielectric spectroscopy

Ohki, Y., Hirai, N., Min, D., Yang, L. & Li, S., 2019 1 1, Minerals, Metals and Materials Series. Springer International Publishing, p. 1323-1332 10 p. (Minerals, Metals and Materials Series).

研究成果: Conference contribution

Silicone Elastomers
Dielectric spectroscopy
Silicones
Rubber
Degradation

Evaluation of Aging Status of Flame-retardant Cross-linked Polyethylene by Measuring Indenter Modulus

Yang, Z., Hirai, N. & Ohki, Y., 2019 4 1, ICEMPE 2019 - 2nd International Conference on Electrical Materials and Power Equipment, Proceedings. Institute of Electrical and Electronics Engineers Inc., p. 57-60 4 p. 8727348. (ICEMPE 2019 - 2nd International Conference on Electrical Materials and Power Equipment, Proceedings).

研究成果: Conference contribution

Flame Retardants
Polyethylene
Flame retardants
Polyethylenes
Aging of materials
1 引用 (Scopus)
Low density polyethylenes
Polyethylene
Phenol
Antioxidants
Phenols
Nuclear power plants
Insulation
Accidents
Cables
Steam
Coaxial cables
Fast Fourier transforms
Cables
Low density polyethylenes
Heating

Origins of Chemiluminescence in Polymeric Insulating Materials

Ohki, Y., Fujishima, D., Okamoto, M. & Hirai, N., 2019 4 1, ICEMPE 2019 - 2nd International Conference on Electrical Materials and Power Equipment, Proceedings. Institute of Electrical and Electronics Engineers Inc., p. 12-16 5 p. 8727389. (ICEMPE 2019 - 2nd International Conference on Electrical Materials and Power Equipment, Proceedings).

研究成果: Conference contribution

Chemiluminescence
Insulating materials
Polymers
Siloxanes
Epoxy Resins

Successful detection of insulation degradation in cables by frequency domain reflectometry

Ohki, Y. & Hirai, N., 2019 1 1, Minerals, Metals and Materials Series. Springer International Publishing, p. 1293-1301 9 p. (Minerals, Metals and Materials Series).

研究成果: Conference contribution

Insulation
Cables
Degradation
Organic polymers
Electromagnetic waves
公開
fillers
nanocomposites
epoxy resins
absorption spectra
polymers
2018
1 引用 (Scopus)

Aging State Analysis of Safety-related Cables for Nuclear Power Plants Exposed to Simulated Accident Conditions

Minakawa, T., Ikeda, M., Hirai, N. & Ohki, Y., 2018 11 26, 2018 IEEE CEIDP Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2018. Institute of Electrical and Electronics Engineers Inc., 巻 2018-October. p. 602-605 4 p. 8544872

研究成果: Conference contribution

Siloxanes
Nuclear power plants
Accidents
Cables
Aging of materials

Degradation behavior and mechanisms of several polymeric insulating materials exposed to heat and radiation

Yang, L., Ohki, Y., Hirai, N. & Li, S., 2018 2 2, 2017 3rd International Conference on Condition Assessment Techniques in Electrical Systems, CATCON 2017 - Proceedings. Institute of Electrical and Electronics Engineers Inc., 巻 2018-January. p. 98-103 6 p.

研究成果: Conference contribution

Insulating materials
Flame retardants
Radiation
Degradation
Dielectric properties

Degradation of silicone rubber analyzed by instrumental analyses and dielectric spectroscopy

Ohki, Y., Hirai, N., Min, D., Yang, L. & Li, S., 2018 1 1, Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. Springer International Publishing, p. 107-116 10 p. (Minerals, Metals and Materials Series; 巻数 Part F11).

研究成果: Conference contribution

Silicone Elastomers
Dielectric spectroscopy
Silicones
Rubber
Degradation
2 引用 (Scopus)
Cables
Electric cables
Degradation
Fast Fourier transforms
Polymers

Effects of Heat and Radiation Aging and Burning on the Surface Physical Properties of Polymer-Insulated Cables

Ito, S., Hirai, N., Minakawa, T., Kuroda, C. & Ohki, Y., 2018 11 26, 2018 IEEE CEIDP Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2018. Institute of Electrical and Electronics Engineers Inc., 巻 2018-October. p. 374-377 4 p. 8544768

研究成果: Conference contribution

Polymers
Cables
Physical properties
Aging of materials
Radiation
1 引用 (Scopus)

Effects of Heat and Radiation on the Terahertz Absorption in Silicone Rubber

Kaneko, T., Hirai, N. & Ohki, Y., 2018 9 19, 2018 IEEE 2nd International Conference on Dielectrics, ICD 2018. Institute of Electrical and Electronics Engineers Inc., p. 223DUMMY 8470044

研究成果: Conference contribution

Silicone Elastomers
Silicones
Rubber
Radiation
Absorption spectra
6 引用 (Scopus)
Terahertz spectroscopy
Insulating materials
antioxidants
Antioxidants
Absorption spectroscopy
2 引用 (Scopus)
Cables
Low density polyethylenes
Polymers
Coaxial cables
Electric network analyzers

Location Attempt of Multiple Heated Spots in a Polymer-insulated Coaxial Cable by Frequency Domain Reflectometry

Hirai, N. & Ohki, Y., 2018 11 14, 2018 Condition Monitoring and Diagnosis, CMD 2018 - Proceedings. Abu-Siada, A. (版). Institute of Electrical and Electronics Engineers Inc., 8535734

研究成果: Conference contribution

Coaxial cables
Low density polyethylenes
Polymers
Fast Fourier transforms
Cables
2 引用 (Scopus)

Similarity in degradation behavior by heat and irradiation between ethylene-propylene-diene rubber and silicone rubber

Ohki, Y., Kotani, H., Fujishima, D. & Hirai, N., 2018 1 12, CEIDP 2017 - IEEE Conference on Electrical Insulation and Dielectric Phenomenon. Institute of Electrical and Electronics Engineers Inc., 巻 2017-October. p. 157-160 4 p.

研究成果: Conference contribution

Silicone Elastomers
Silicones
Propylene
Rubber
Ethylene
1 引用 (Scopus)

Successful detection of insulation degradation in cables by frequency domain reflectometry

Ohki, Y. & Hirai, N., 2018 1 1, Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. Springer International Publishing, p. 77-85 9 p. (Minerals, Metals and Materials Series; 巻数 Part F11).

研究成果: Conference contribution

Insulation
Cables
Degradation
Organic polymers
Electromagnetic waves

Terahertz time-domain spectroscopic analyses on crystallinity of several organic polymers

Ohki, Y., Azeyanagi, C., Kaneko, T. & Hirai, N., 2018 6 29, ICPADM 2018 - 12th International Conference on the Properties and Applications of Dielectric Materials. Institute of Electrical and Electronics Engineers Inc., 巻 2018-May. p. 86-89 4 p.

研究成果: Conference contribution

Terahertz spectroscopy
Organic polymers
Absorption spectroscopy
crystallinity
Polyether ether ketones
2017
7 引用 (Scopus)
Polyether ether ketones
ketones
Gamma rays
Dielectric properties
dielectric properties
3 引用 (Scopus)

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

Hirai, N. & Ohki, Y., 2017 12 4, Proceedings of 2017 International Symposium on Electrical Insulating Materials, ISEIM 2017. Institute of Electrical Engineers of Japan, 巻 2. p. 753-756 4 p.

研究成果: Conference contribution

Flame Retardants
Silicone Elastomers
Elongation
Rubber
Polymers
1 引用 (Scopus)

Effects of addition of MgO fillers with various sizes and co-addition of nano-sized SiO2 fillers on the dielectric properties of epoxy resin

Yanashima, R., Hirai, N. & Ohki, Y., 2017 12 4, Proceedings of 2017 International Symposium on Electrical Insulating Materials, ISEIM 2017. Institute of Electrical Engineers of Japan, 巻 2. p. 650-653 4 p.

研究成果: Conference contribution

Epoxy Resins
Epoxy resins
Dielectric properties
Fillers
Polymers
13 引用 (Scopus)

Experimental investigation of the degradation mechanism of silicone rubber exposed to heat and gamma rays

Hanada, S., Miyamoto, M., Hirai, N., Yang, L. & Ohki, Y., 2017 6, : : High Voltage. 2, 2, p. 92-101 10 p.

研究成果: Article

公開
Gamma rays
Silicones
Rubber
Degradation
Mechanical properties

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 5 31, 2017 IEEE International Workshop on Integrated Power Packaging, IWIPP 2017. Institute of Electrical and Electronics Engineers Inc., 7936745

研究成果: Conference contribution

Magnesium Oxide
Epoxy Resins
Magnesia
Epoxy resins
Dielectric properties
1 引用 (Scopus)

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

Minakawa, T., Ikeda, M., Hirai, N. & Ohki, Y., 2017 12 4, Proceedings of 2017 International Symposium on Electrical Insulating Materials, ISEIM 2017. Institute of Electrical Engineers of Japan, 巻 2. p. 716-719 4 p.

研究成果: Conference contribution

Nuclear power plants
Insulation
Accidents
Cables
Containment vessels

Terahertz absorption spectra of antioxidants in insulating polymers

Kozai, T., Kaneko, T., Hirai, N. & Ohki, Y., 2017 10 27, Proceedings of 2017 International Symposium on Electrical Insulating Materials, ISEIM 2017. Institute of Electrical Engineers of Japan, 巻 1. p. 61-64 4 p.

研究成果: Conference contribution

Antioxidants
Absorption spectra
Polymers
Polyethylene
Polyethylenes
3 引用 (Scopus)

Terahertz absorption spectroscopy of poly(ether ether ketone)

Kaneko, T., Hirai, N. & Ohki, Y., 2017 12 4, Proceedings of 2017 International Symposium on Electrical Insulating Materials, ISEIM 2017. Institute of Electrical Engineers of Japan, 巻 2. p. 539-542 4 p.

研究成果: Conference contribution

Terahertz spectroscopy
Polyether ether ketones
Absorption spectroscopy
Infrared absorption
Absorption spectra
2016
4 引用 (Scopus)

Aging mechanism of silicone rubber by heat and gamma-rays

Ohki, Y., Hanada, S., Miyamoto, M., Hirai, N. & Yang, L., 2016 12 15, 2016 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2016. Institute of Electrical and Electronics Engineers Inc., 巻 2016-December. p. 869-872 4 p. 7785487

研究成果: Conference contribution

Silicone Elastomers
Gamma rays
Silicones
Rubber
Aging of materials
3 引用 (Scopus)

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

Ikeno, R., Hirai, N. & Ohki, Y., 2016 12 15, 2016 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2016. Institute of Electrical and Electronics Engineers Inc., 巻 2016-December. p. 853-856 4 p. 7785443

研究成果: Conference contribution

Flame Retardants
Silicone Elastomers
Chemiluminescence
Flame retardants
Silicones

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

Ohki, Y. & Hirai, N., 2016 12 27, ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application. Institute of Electrical and Electronics Engineers Inc., 7800602

研究成果: Conference contribution

Coaxial cables
Cables
Low density polyethylenes
Degradation
Silicones
8 引用 (Scopus)
flame retardants
Scanning probe microscopy
dienes
Flame retardants
propylene
10 引用 (Scopus)
Spectroscopic analysis
Propylene
Ethylene
Permittivity
Copolymers
18 引用 (Scopus)
Cable cores
Insulation
Cables
Polyvinyl chlorides
Coaxial cables
Organic polymers
Photoluminescence
Fluorescence
Photons
Polyolefins
7 引用 (Scopus)

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

Ohki, Y. & Hirai, N., 2016 11 28, CMD 2016 - International Conference on Condition Monitoring and Diagnosis. Institute of Electrical and Electronics Engineers Inc., p. 36-39 4 p. 7757782

研究成果: Conference contribution

Electric fault location
Nuclear power plants
Cables
Flame retardants
Radiation
2 引用 (Scopus)
Propylene
Ethylene
Copolymers
Irradiation
Oxidation
2 引用 (Scopus)

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

Hanada, S., Odaka, D., Yang, L., Hirai, N. & Ohki, Y., 2016 11 28, CMD 2016 - International Conference on Condition Monitoring and Diagnosis. Institute of Electrical and Electronics Engineers Inc., p. 123-126 4 p. 7757791

研究成果: Conference contribution

Scanning probe microscopy
Silicones
Rubber
Thermal aging
Radiation
5 引用 (Scopus)

Space charge distributions in epoxy/MgO nanocomposites at various temperatures

Xie, Q., Cheng, Y. H., Hirai, N. & Ohki, Y., 2016 12 27, ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application. Institute of Electrical and Electronics Engineers Inc., 7800636

研究成果: Conference contribution

Charge distribution
Magnesia
Electric space charge
Nanocomposites
Epoxy resins

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

Ohki, Y., Kozai, T., Komatsu, M. & Hirai, N., 2016 8 18, Proceedings of the 2016 IEEE International Conference on Dielectrics, ICD 2016. Institute of Electrical and Electronics Engineers Inc., 巻 2. p. 646-649 4 p. 7547698

研究成果: Conference contribution

Flame Retardants
Terahertz spectroscopy
Propylene
Infrared spectroscopy
Ethylene
2015
5 引用 (Scopus)

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

Ohki, Y. & Hirai, N., 2015 12 9, Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP. Institute of Electrical and Electronics Engineers Inc., 巻 2015-December. p. 274-277 4 p. 7352023

研究成果: Conference contribution

Electric fault location
Cables
Cable cores
Flame Retardants
Silicone Elastomers
2014
3 引用 (Scopus)

Chemiluminescence due to oxidation of ethylene propylene diene copolymers

Ohki, Y. & Hirai, N., 2014 12 22, 2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2014. Institute of Electrical and Electronics Engineers Inc., p. 425-428 4 p. 6995786

研究成果: Conference contribution

Chemiluminescence
Propylene
Ethylene
Copolymers
Low density polyethylenes
8 引用 (Scopus)

Highly sensitive detection of distorted points in a cable by frequency domain reflectometry

Hirai, N. & Ohki, Y., 2014, Proceedings of the International Symposium on Electrical Insulating Materials. Institute of Electrical Engineers of Japan, p. 144-147 4 p. 6870741

研究成果: Conference contribution

Cables
Electric cables
Flame Retardants
Telecommunication cables
Coaxial cables