1. Ph.D. Student, Dept. of Civil and Environmental Engineering, Hong Kong Univ. of Science and Technology, Clear Water Bay, Kowloon, Hong Kong; and Korea Advanced Institute of Science and Technology, Daejeon 305-701, Daehak-ro 291, Republic of Korea.
2. Professor, Dept. of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Daehak-ro 291, Republic of Korea (corresponding author).
3. Professor, Dept. of Civil and Environmental Engineering, Hong Kong Univ. of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.