1. Researcher, Korea Institute of Construction Technology, 2311 Daewha-Dong, Ilsan-Gu, Goyang-Si, Gyeonggi-Do, 411-712, Korea.
2. Professor, School of Civil, Urban, and Geosystem Engineering, Seoul National Univ., San 56-1, Shinlim-Dong, Gwanak-Gu, Seoul, 151-742, Korea.
3. Researcher, Korea Highway Corp., Youngchun-Si, Kyungsang-Do, Korea; formerly, Graduate Student, Seoul National Univ.