1. Center for Advanced Functional Polymers and Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, 373-1, Kusong, Yusong, Taejon 305-701, Korea, Department of Material Science and Technology, Kwangju Institute of Science and Technology, 1, Oryong-dong, Buk-gu, Kwangju 500-712, Korea, and Polymer Materials Laboratory, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea