1. Department of Systems Innovation; School of Engineering; The University of Tokyo, Hongo, Bunkyo-ku; Tokyo 113-8656 Japan
2. Faculty of Pharmaceutical Sciences; Hoshi University, Ebara, Shinagawa-ku; Tokyo 142-8501 Japan
3. Fuel Cell System Development Center; Toyota Motor Corporation, Mishuku, Susono; Shizuoka 410-1193 Japan