1. Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji City, Tokyo 192-0983, Japan
2. Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, Saitama 338-8570, Japan
3. Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196, Japan