[Inst. Electr. Eng. Japan 2001 International Symposium on Electrical Insulating Materials (ISEIM 2001) 2001 Asia Conference on Electrical Insulation Diagnosis (ACEID 2001). 33rd Symposium on Electrical and Electronic Insulating Materials and Applications in Systems - Himeji, Japan (19-22 Nov. 2001)] Proceedings of 2001 International Symposium on Electrical Insulating Materials (ISEIM 2001). 2001 Asian Conference on Electrical Insulating Diagnosis (ACEID 2001). 33rd Symposium on Electrical and Electronic Insulating Materials and Applications in System - Study on the ultra-high-frequency sensors for PD detection in power transformer