1. Central Research Institute of Electric Power Industry, 2-11-1 Iwadokita, Komae-shi, Tokyo 201-8511, Japan
2. The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
3. Okayama University, 1-1-1 Tsushima-Naka,
Kita-ku, Okayama 700-8530, Japan