1. Kanto Gakuin University Yokohama,Dept. of Electrical and Electronic Engineering,Kanagawa,Japan,236-8501
2. Sekii PE Laboratory Chiba,Chiba,Japan,275-0005
3. Research Division of Product Reliability Osaka Research Institute of Industrial Science and Technology Izumi,Osaka,Japan,594-1157
4. Tokyo City University Setagaya,Dept. of Mechanical System Engineering,Tokyo,Japan,158-8557