1. Advanced Material Group, Electronic Chemical Materials R&D Center, Cheil Industries Inc., 332-2 Gogcheon-dong, Uiwang-si, Gyunggi-do 437-711, Korea, and Samsung Advanced Institute of Technology, Mt. 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712, Korea