1. Department of Chemical and Biomolecular Engineering & Center for Ultramicrochemical Process Systems (CUPS), Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea, and Fuel Research Team, Daeduck Central Research Center, LG-Caltex Oil Corporation, 104-4 Munji-dong, Yuseong-gu Daejon 305-380, Republic of Korea