1. Department of Chemical Engineering, Pohang University of Science & Technology, San 31 Hyoja-dong Pohang, 790-784, Korea, Chemical Process & Catalysis Research Institute LG Chem, Ltd., Research Park, P.O. Box 61, Yu Seong, Science Town Daejeon, Korea, and P&I Consulting Co., Ltd., San 31 Hyoja-dong Pohang, 790-784, Korea