1. Department of Chemical Engineering, Pohang University of Science and Technology, and ISYSTECH Company Ltd., San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784, South Korea, and School of Chemical Engineering and Automation and Systems Research Institute and Institute of Chemical Processes, Seoul National University, Shillim-dong, Kwanak-gu, Seoul 151-742, South Korea