1. Department of Mechanical Systems Engineering, National Defense Academy of Japan, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 239-8686, Japan
2. Osaka Research Institute of Industrial Science and Technology, 2-7-1 Ayumino, Izumi, Osaka 594-1157, Japan
3. Hyogo Prefectural Institute of Technology, 3-1-12 Yukihira, Suma, Kobe, Hyogo 654-0037, Japan