[1] Dept. of Mat. Science and Processing, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
[2] NKK Corporation, Grad. Sch. of Osaka University, Hiroshima 721-8510, Japan
[3] Hitachi, Ltd., Grad. Sch. of Osaka University, Kanagawa 244-0817, Japan