Naoshi Hirai

上級研究員(研究院講師)

  • 777 Citations
  • 15 h-Index
1993 …2020

Research output per year

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Research Output

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Conference contribution

Aging mechanism of silicone rubber by heat and gamma-rays

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Citations (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 Nov 26, 2018 IEEE CEIDP Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2018. Institute of Electrical and Electronics Engineers Inc., Vol. 2018-October. p. 602-605 4 p. 8544872

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

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

Ogishima, T., Kozai, T., Hirai, N. & Ohki, Y., 2019 Feb 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).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Chemiluminescence as a clear diagnostic tool of polymer oxidation

Ohki, Y. & Hirai, N., 2012 Nov 26, ICPADM 2012 - 2012 IEEE 10th International Conference on the Properties and Applications of Dielectric Materials, Technical Papers. 6318953. (Proceedings of the IEEE International Conference on Properties and Applications of Dielectric Materials).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Chemiluminescence due to oxidation of ethylene propylene diene copolymers

Ohki, Y. & Hirai, N., 2014 Dec 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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Comparison of broadband impedance spectroscopy and time domain reflectometry for locating cable degradation

Hirai, N., Yamada, T. & Ohki, Y., 2012 Dec 1, Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012. p. 229-232 4 p. 6416417. (Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

18 Citations (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Citations (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Degradation in Dielectric Behavior of Soft Epoxy Resin by Concurrent Aging with Heat and Radiation

Ishii, H., Yamaguchi, H., Mori, K., Hirai, N. & Ohki, Y., 2019 Oct, 2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2019 - Proceedings. Institute of Electrical and Electronics Engineers Inc., p. 18-21 4 p. 9010557. (Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP; vol. 2019-October).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Degradation in Mechanical and Dielectric Properties of Silicone Rubber under Severe Aging Conditions

Hirai, N., Kaneko, T., Ito, S., Minakawa, T. & Ohki, Y., 2019 Oct, 2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2019 - Proceedings. Institute of Electrical and Electronics Engineers Inc., p. 126-129 4 p. 9009713. (Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP; vol. 2019-October).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Degradation of silicone rubber analyzed by instrumental analyses and dielectric spectroscopy

Ohki, Y., Hirai, N., Min, D., Yang, L. & Li, S., 2018 Jan 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; vol. Part F11).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Degradation of silicone rubber analyzed by instrumental analyses and dielectric spectroscopy

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Dielectric properties of biodegradable polylactic acid and starch ester

Hirai, N., Maeno, Y., Tamura, H., Kaneko, D., Tanaka, T., Ohki, Y., Tajitsu, Y., Kohtoh, M. & Okabe, S., 2004 Jan 1, Proceedings of the 2004 IEEE International Conference on Solid Dielectrics ICSD 2004. Institute of Electrical and Electronics Engineers Inc., p. 87-90 4 p. 1P-12. (Proceedings of the 2004 IEEE International Conference on Solid Dielectrics ICSD 2004; vol. 1).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

15 Citations (Scopus)

Dielectric properties of biodegradable polymers

Ohki, Y. & Hirai, N., 2006 Dec 1, 2006 Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP. p. 668-671 4 p. 4105521. (Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Citations (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 Dec 4, Proceedings of 2017 International Symposium on Electrical Insulating Materials, ISEIM 2017. Institute of Electrical Engineers of Japan, Vol. 2. p. 650-653 4 p.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

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 Nov 26, 2018 IEEE CEIDP Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2018. Institute of Electrical and Electronics Engineers Inc., Vol. 2018-October. p. 374-377 4 p. 8544768

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

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

Yang, Z., Hirai, N. & Ohki, Y., 2019 Apr, 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).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Citations (Scopus)

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

Hirai, N. & Ohki, Y., 2014 Jan 1, Proceedings of 2014 International Symposium on Electrical Insulating Materials, ISEIM 2014. Institute of Electrical Engineers of Japan, p. 144-147 4 p. 6870741. (Proceedings of the International Symposium on Electrical Insulating Materials).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

10 Citations (Scopus)

Highly sensitive location method of an abnormal temperature point in a cable by frequency domain reflectometry

Ohki, Y., Hirai, N., Yamada, T. & Kumagai, S., 2013 Dec 1, ICSD 2013 - Proceedings of the 2013 IEEE International Conference on Solid Dielectrics. p. 117-120 4 p. 6619799. (Proceedings of IEEE International Conference on Solid Dielectrics, ICSD).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Citations (Scopus)

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Improvement in sensitivity of broadband impedance spectroscopy for locating degradation in cable insulation by ascending the measurement frequency

Yamada, T., Hirai, N. & Ohki, Y., 2012 Dec 1, Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012. p. 677-680 4 p. 6416236. (Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

13 Citations (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Citations (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 Dec 4, Proceedings of 2017 International Symposium on Electrical Insulating Materials, ISEIM 2017. Institute of Electrical Engineers of Japan, Vol. 2. p. 716-719 4 p.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Measurement of hole mobility in dielectric liquids

Hirai, N., Arii, K., Kikuchi, H., Masoaka, T. & Nitanada, H., 1993 Dec 1, Proceedings of the 11th International Conference on Conduction and. Publ by IEEE, p. 101-105 5 p. (Proceedings of the 11th International Conference on Conduction and).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Need for condition monitoring and diagnosis of electric wires and cables used in nuclear power plants

Ohki, Y., Hirai, N. & Yamamoto, T., 2008 Jan 1, Proceedings of 2008 International Conference on Condition Monitoring and Diagnosis, CMD 2008. IEEE Computer Society, p. 1207-1211 5 p. 4580505. (Proceedings of 2008 International Conference on Condition Monitoring and Diagnosis, CMD 2008).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (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 Nov 28, CMD 2016 - International Conference on Condition Monitoring and Diagnosis. Institute of Electrical and Electronics Engineers Inc., p. 123-126 4 p. 7757791

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

Origins of Chemiluminescence in Polymeric Insulating Materials

Ohki, Y., Fujishima, D., Okamoto, M. & Hirai, N., 2019 Apr, 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).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Relation between the Glass Transition and Dielectric Properties in Bisphenol A and F Epoxy Resins

Mori, K., Hirai, N., Ohki, Y., Otake, Y., Umemoto, T. & Muto, H., 2019 Oct, 2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2019 - Proceedings. Institute of Electrical and Electronics Engineers Inc., p. 426-429 4 p. 9010555. (Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP; vol. 2019-October).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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 Jan 12, CEIDP 2017 - IEEE Conference on Electrical Insulation and Dielectric Phenomenon. Institute of Electrical and Electronics Engineers Inc., Vol. 2017-October. p. 157-160 4 p.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Space charge distributions in epoxy/MgO nanocomposites at various temperatures

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Citations (Scopus)

Successful detection of insulation degradation in cables by frequency domain reflectometry

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Successful detection of insulation degradation in cables by frequency domain reflectometry

Ohki, Y. & Hirai, N., 2018 Jan 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; vol. Part F11).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Terahertz absorption spectra of antioxidants in insulating polymers

Kozai, T., Kaneko, T., Hirai, N. & Ohki, Y., 2017 Oct 27, Proceedings of 2017 International Symposium on Electrical Insulating Materials, ISEIM 2017. Institute of Electrical Engineers of Japan, p. 61-64 4 p. (Proceedings of the International Symposium on Electrical Insulating Materials; vol. 1).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Terahertz absorption spectroscopy of poly(ether ether ketone)

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution