1. 1) F. Tanaka and H. Ohira : Trans. Soc. Instrum. Control Eng., 25 (1989), 1031.
2. 2) T. Yamamoto, K. Hiramoto, C. Uematsu and J. Ueda : Tetsu-to-Hagané, 79 (1993), 779.
3. 3) Y. Fukutaka, N. Nagahisa, T. Iwamura, I. Hishikari, T. Ide and T. Suzuki : Kawasaki Steel Giho, 24 (1992), 63.
4. 4) C. Manabe, M. Akamatsu, T. Yanai, N. suzuki, K. Terai and S. Fujimoto : CAMP-ISIJ, 6 (1993), 326.
5. 5) Y. Yamada, D. Yuasa, M. Uesugi, T. Yamada, T. Manabe, N. Inue and K. Yamauchi : Proc. of 35th SICE Annu. Conf, (1996), 321.