1. Department of Engineering Science; The University of Electro-Communications, Chofu; Tokyo 182-8585 Japan
2. Innovation Research Center for Fuel Cells; The University of Electro-Communications, Chofu; Tokyo 182-8585 Japan
3. Department of Complexity Science and Engineering; Graduate School of Frontier Sciences; The University of Tokyo, Kashiwa; Chiba 277-8561 Japan