1. Senior Research Engineer, GS Engineering and Construction Research Institute, Seoul 100-722, Korea.
2. Manager, Korea Water Resources Corporation (KWATER), Daejeon 306-711, Korea.
3. Professor, Dept. of Civil and Environmental Engineering, KAIST, Daejeon 305-701, Korea (corresponding author).
4. Senior Researcher, Korea Water Resources Corporation (KWATER), Daejeon 306-711, Korea.