1. Postdoctoral Researcher, Water Environment and Remediation Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea.formerly, Ph.D. Student, Dept. of Civil, Urban & Geosystem Engineering, Seoul National Univ., San 56-1, Sillim-Dong, Gwanak-Gu, Seoul 151-742, Korea.
2. Ph.D. Student, Dept. of Civil, Urban & Geosystem Engineering, Seoul National Univ., San 56-1, Sillim-Dong, Gwanak-Gu, Seoul 151-742, Korea.
3. Associate Professor, Dept. of Civil, Urban & Geosystem Engineering, Seoul National Univ., San 56-1, Sillim-Dong, Gwanak-Gu, Seoul 151-742, Korea (corresponding author).