1. School of Materials Science and Engineering, Pusan National University, Jangjeon 2-dong, Geumjeoung-gu, Busan, 609-735, Republic of Korea, Dongnam Technology Service Division, Korea Institute of Industrial Technology, Jisa-dong, Gangseo-gu, Busan, 618-230, Republic of Korea, Department of Chemical Engineering, Pohang University of Science and Technology, San 31 Hyojadong, Namgu, Pohang, 790-784, Republic of Korea, and Department of Advanced Materials Engineering, Dong-Eui University, Busan 341-714, Korea