1. BK21 Physics Division, Center for Nanotubes and Nanostructured Composites, Sungkyunkwan University, Suwon 440-746, Korea
2. Sungkyunkwan Advanced Institute of Nanotechnology, Center for Nanotubes and Nanostructured Composites, Sungkyunkwan University, Suwon 440-746, Korea
3. Display Laboratory, Samsung Advanced Institute of Technology, Yongin, Gyeonggi, 446-712, Korea
4. Department of Energy Science, Center for Nanotubes and Nanostructured Composites, Sungkyunkwan University, Suwon 440-746, Korea
5. BK21 Physics Division, Department of Energy Science, Center for Nanotubes and Nanostructured Composites, Sungkyunkwan Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, Korea