1. Professor, Department of Civil and Environmental Engineering, Kyungsung Univ., 608-736, KR, e-mail: ykchoi@ks.ac.kr
2. Senior Researcher, Research Division, Korea Expressway Corporation, 445-812 KR (Corresponding Author), e-mail: msnam@ex.co.kr
3. Professor, Department of Civil Engineering, Korea Maritime and Ocean Univ., 606-791 KR, e-mail: kth67399@kmou.ac.kr