1. Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-747, Republic of Korea
2. School of Chemical and Biological Engineering, Seoul National University, Seoul 151-747, Republic of Korea
3. Fuel Cell Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea
4. Graduate School of EEWS, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
5. Department of Energy Science and Technology,
Graduate School of Energy Science and Technology (GEST), Chungnam National University, Daejeon 305-764, Republic of Korea
6. Department of Science, Republic of Korea Naval Academy, Jinhae-gu, Changwon 645-797, South Korea