1. Graduate School of Science and Engineering Kindai University, 3–4–1 Kowakae, Higashi‐osaka Osaka 577–8502 Japan
2. Engineering Department Shikoku Railway Company, 8–33 Hamano‐cho Takamatsu Kagawa 760–8580 Japan
3. Department of Mechanical Engineering National Institute of Technology, Niihama College, 7–1 Yagumo‐cho Niihama Ehime 792–8580 Japan
4. Graduate School of Technology, Industrial and Social Sciences Tokushima University, 2–1 Minamijosanjima‐cho Tokushima 770–8506 Japan