1. 1) M. Nishikawa and K. Hiraoka: Sanyo Tech. Rep., 14(2007), 42 (in Japanese).
2. 2) T. Urita, K. Namiki and T. Iikubo: Electr. Furn. Steel, 59(1988), 33 (in Japanese).
3. 3) T. Gladman: Proc. R. Soc. Lond. A, 294(1966), 298.
4. 4) T.Murakami, H.Hatano and H.Yaguchi: Kobe Steel Eng. Rep., 56(2006), No.3, 59 (in Japanese).
5. 5) K. Hashimoto: J. Jpn. Soc. Technol. Plast., 46(2005), 304 (in Japanese).