1. 1) H. Kanisawa and T. Ochi: Nippon Steel Tech. Rep., 81 (2000), 22.
2. 2) Q. Wang, G. Li and H. Dong: J. Iron Steel Res. Int., 3 (1996), 37.
3. 3) H. Takada and Y. Koyasu: Nippon Steel Tech. Rep., 64 (1995), 7.
4. 4) T. Furuhara, J. Yamaguchi, N. Sugita, G. Miyamoto and T. Maki: ISIJ Int., 43 (2003), 1630.
5. 5) T. Ochi, T. Takahashi and H. Takada: Iron Steelmaker, 16 (1989), 21.