1. Materials Research Department, Kure Research Laboratory, Babcock Hitachi K.K. 3-36, Takara-machi, Kure-shi, Hiroshima-ken, 737-8508, Japan
2. Structural Design Department, Kure Division, Babcock Hitachi K.K. 6-9, Takara-machi, Kure-shi, Hiroshima-ken, 737-8508, Japan
3. Tokyo Metropolitan University, 1-1, Minamiosawa, Hachioji-shi, Tokyo, 192-0093, Japan
4. Tokyo Denki University, 2-2, Kandanishiki-cho, Chiyoda-ku, Tokyo, 101-8457, Japan