1. BK21 Physics Division, Department of Energy Science, and Center for Nanotubes and Nanostructured Composites, Sungkyunkwan Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
2. Display Lab, Samsung Advanced Institute of Technology (SAIT), P.O. Box 111, Suwon 440-600, South Korea