1. Department of Chemical and Biomolecular Engineering, KAIST, 373-1 Guseong-dong, Yusong-gu, Daejeon, Republic of Korea; Fuel Cell Program Team, SAIT (Samsung Advanced Institute of Technology), San14-1, Nongseo-Ri, Kihueng-Eup, Yongin-Shi, Kyunggi-Do, Republic of Korea; and Korea Institute of Industrial Technology 472, Kajwa 4-dong, Seo-Ku, Incheon, 404-254, Republic of Korea