1. School
of Integrative Engineering, Chung-Ang University, 221, Heukseok-Dong, Dongjak-Gu,
Seoul 156-756, Korea
2. School
of Chemical Engineering,
Department of Hydrogen and Fuel Cell Engineering, Chonbuk National University, JeonJu, Jeonbuk, Korea
3. Center
for Nanoparticle Research,
Institute for Basic Science (IBS), and School of Chemical Biological
Engineering, Seoul National University,
Seoul 151-742, Korea