1. School of Materials Science and Engineering and Intellectual Textile System Research Center (ITRC), College of Engineering, Seoul National University, Shillim9dong 56-1, Kwanakgu, Seoul, Korea 151-744, KIST R&D Academy, Hawolgokdong 39-1, Sungbukku, Seoul, Korea 130-650, Polymer Processing Technology Team, LG Chemical Ltd./Tech Center, Moonjidong 104-1, Yousungku, Daejon, Korea 305-738, and School of Advanced Materials Engineering, Kookmin University, Chongnungdong, Sungbukku, Seoul, Korea 133-791