1. Member, ASCE
2. Sr. Engr., Envir. Technol. Team, Inst. of Technol., Samsung Corp., 428-5 Gongseri, Yongin 449-900, Korea.
3. PhD Candidate, School of Earth and Envir. Sci., Seoul Nat. Univ., Seoul 151-742, Korea.
4. School of Earth and Envir. Sci., Seoul Nat. Univ., Seoul 151-742, Korea.
5. Assoc. Prof. of Ground-Water Hydro., School of Earth and Envir. Sci., Seoul Nat. Univ., Seoul 151-742, Korea (corresponding author). E-mail: kklee@snu.ac.kr