1. Department of Materials Science and Engineering, Seoul National University, 56-1 Shinlim-dong, Gwanak-gu, Seoul 151-742, Korea
2. Department of Advanced Metallic Materials, Korea Institute of Materials Science, 66 Sangnam-dong, Changwon, Kyeongnam 641-010, Korea
3. Mobile Communication Division, Samsung Electronics Co., Ltd., 416 Maetan-3dong, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-742, Korea