1. Sejong Advanced Institute of Nano Technologies, #98 Gunja-Dong, Gwangjin-Gu, Sejong University, Seoul, 143-747, Korea, Department of Chemistry, China Three Gorges University, Yichang, Hubei, 443002, People's Republic of China, Electric & Magnetic Devices Research Group, Korea Electrotechnology Research Institute, #28-1 Sungju-Dong, Changwon, Kyungnam 641-120, Korea, and Department of Materials Engineering, Chosun University, KwangJu 501-759, Korea