1. School of Applied Chemical Engineering and Engineering Research Institute, Gyeongsang National University Chinju 660‐701, South Korea, Fax: (internat.) + 82‐55‐753‐6311
2. Division of Science Education, Kangwon National University, Chuncheon 200‐701, South Korea
3. School of Materials Science and Engineering, Seoul National University Seoul 151‐744, South Korea
4. LG Electronic Institute of Technology 16 Woomyeon‐Dong, Seocho‐Gu, Seoul 137‐724, South Korea