1. a College of Pharmacy and Research Institute of Pharmaceutical Sciences , Seoul National University , San 56-1, Shinlim-Dong, Kwanak-Gu, Seoul, 151-742, Korea
2. b AgroPharma Research Institute , Dongbu Hannong Chemical Company , 103-2, Moonji-Dong, Daeduck Science Town, Taejeon, 305-708, Korea
3. c Korea Research Institute of Chemical Technology , P.O. Box 107, Yusong, Taejeon, 305-600, Korea