1. 1) K. Ohe, Y. Morimoto, S. Kajiura, T. Ujino, S. Simada, K. Anraku, A. Mizuta and N. Kim: 6th Int. Rolling Conf., Stahleisen, Düsseldorf, (1994), 78.
2. 2) Y. Hori, Y. Mizutani, T. Ogawa and K. Nishioka: 6th Int. Rolling Conf., Stahleisen, Düsseldorf, (1994), 93.
3. 3) Y. Tozawa, T. Ishikawa and N. Iwata: Numerical Methods for Industrial Forming Processes (NUMIFORM 82), Pineridge Press, Swansea, (1982), 787.
4. 4) T. Ishikawa, N. Yukawa and Y. Tozawa: Proc. 4th Int. Steel Rolling Conf., Vol. 2, IRSID/ATS, Deauville, (1987), E7-1.
5. 5) H. Matsumoto: ISIJ Int., 31 (1991), 550.