1. Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan,
2. Department of Physical Therapy, Osaka Electro-Communication University, 1130-70 Kiyotaki, Shijo-nawate 575-0063, Japan
3. Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan