1. Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), Seoul
136-791, Korea
2. Division
of WCU Multiscale Mechanical
Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Korea
3. Center for Nanoparticle Research,
Institute for Basic Science (IBS), and School of Chemical Biological
Engineering, Seoul National University,
Seoul 151-742, Korea