1. Department of Precision Engineering, Gifu University, 1-1 Yanagido, Gifu-shi, 501-11, Japan
2. Department of Education, Gifu University, Nagara-Jonouchi, Gifu-shi, 502, Japan
3. Department of Mechanical Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464, Japan