1. (1) N. Hirai and Y. Ohki : “Applicability of Biodegradable Polymers to Electrical Insulation”, J. Instit. Engineers Electrical Discharges Japan, Vol. 47, No. 3, pp. 2-8 (2004) (in Japanese)
2. (2) N. Fuse, S. Fujita, N. Hirai, M. Kozako, T. Tanaka, Y. Ohki, M. Kohtoh, and S. Okabe : “Partial Discharge Degradation of Several Biodegradable Polymers”, The Papers of Joint Technical Meeting on Electrical Discharges, Dielectrics and Electrical Insulation and High Voltage Engineering, IEE Japan, DEI-05-26, pp. 19-25 (2005) (in Japanese)
3. (3) Y. Yamaguchi, N. Hirai, T. Tanaka, Y. Ohki, Y. Tajitsu, M. Kohtoh, and S. Okabe : “Effects of Ultraviolet Photon Irradiation on the Space Charge Accumulation Properties of Several Biodegradable Polymers”,Proc. of 2005 International Symposium on Electrical Insulating Materials (ISEIM 2005), Vol. 2, pp. 421-424 (2005)
4. (4) Y. Maeno, Y. Yamaguchi, N. Hirai, T. Tanaka, Y. Ohki, Y. Tajitsu, M. Khotoh, and S. Okabe : “Effect of Glass Transition on Electrical Conduction Characterristics of Poly-L-lactic-acid”, IEEJ Trans. FM, Vol. 125, No. 3, pp. 254-260 (2005-3) (in Japanese)
5. (6) K. Shinyama and S. Fujita : “Mechanical and Dielectric Breakdown Properties of Biodegradable Plastics”, IEEJ Trans. FM, Vol. 126, No. 1, pp. 31-36 (2006-1)