Keijo Seto received a B.E. and M.E. from kusashi Institute of Technology, Tokyo, Japan in 1987 and 1989, respectively. Upon graduation, he joined Fuji Xerox Co., Ltd., Kanagawa, Japan. Mr. Seto is a member of the Institute of Electrical Engineers of Japan.;2. Musashi Institute of Technology, Department of Electrical and Electronic Engineering

Tairo Ito received a B.E. degree from Musashi Institute of Technology in 1960 and Ph.D. degree from Nagoya University in 1977. Heiscurrently Professor of Electrical and Electronic Engineering at Musashi Institute of Technology. His research interests include deterioration of insulating material and gaseous reaction due to discharge. Dr. Ito is a member of the Institute of Electrical Engineers of Japan and received a Paper Award from the I.E.E., Japan in 1986.;3. Musashi Institute of Technology, Department of Electrical and Electronic Engineering

Takao Sakai received a B.E., M.E. and Ph.D. degree from Tohoku University, Sendni, Japan i n 1956, 1958, 1966, respectively. He iscurrently Professor of Electrical and Electronic Engineering at Musashi Institute of Engineering. His research interests include characteristics of conduction, deterioration and surface discharge on polymeric materials. Dr. Sakai is a member of the Institute of Electrical Engineers of Japan;4. Applied Physics Society;5. and I.E.E.E. He received the Paper Award from the I.E.E., Japan in 1972, 1974, 1981, and 1986.;6. Musashi Institute of Technology, Department of Electrical and Electronic Engineering

Yoshiyasu Ehara received a B.E. from Gunma University, Kiryu, Japan in 1979. Tn 1980, he joined Sankei Giken Kogyo CO., Ltd., Mie, Japan. Since 1984, he has been with the Department of Electrical and Electronic Engineering at Musashi Institute of Technology.