1. Mitsubishi Electric Corporation, 8-1-1 Tsukaguchi Honmachi, Amagasaki-shi, Hyogo 661-8661, Japan
2. Department of Mechanical Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe-shi, Kyoto 610-0321, Japan
3. Department of Mechanical Engineering, National Institute of Technology, Maizuru College, 234 Shiroya, Maizuru-shi, Kyoto 625-8511, Japan