1. Chemical Process and Engineering Center, Applied and Engineering Chemistry Division, Korea Research Institute of Chemical Technology, P.O. Box 107, Yusong, Taejon 305‐606, South Korea
2. Energy and Environment Research Team, Research and Development Center, Korea Heavy Industries and Construction Co., Changwon P.O. Box 77, Kyongnam 641‐792, South Korea
3. Department of Chemical Engineering, Hannam University 133 Ojung‐Dong, Daedeog‐Ku, Taejon 300‐791