1. Department of System Design Engineering, Keio University, 3-14-1 Hiyoshi Kouhoku-ku Yokohama 223-8522, Japan,
2. Department of System Design Engineering, Keio University, 3-14-1 Hiyoshi Kouhoku-ku Yokohama 223-8522, Japan
3. Fujikura kasei Co. Ltd., 5-13-1 Sakurada Washimiya-machi Kitakatsushika, Saitama 340-0200, Japan