1. Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2. Department of Mechanical Engineering, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
3. Department of Social Design Engineering, National Institute of Technology, Kochi College, 200-1 Monobe, Nankoku, Kochi 783-8508, Japan