1. Professor, Dept. of Civil and Environmental Engineering, Pusan National Univ., Construction Engineering Bldg. Room 509, Busan 46241, Korea.
2. Researcher, Dept. of Civil and Environmental Engineering, Pusan National Univ., Construction Engineering Bldg. Room 625, Busan 46241, Korea.
3. Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Pusan National Univ., Construction Engineering Bldg. Room 625, Busan 46241, Korea (corresponding author).