1. Associate Professor, Dept. of Civil Engineering, Kwandong Univ., Kangwon-do 215-800, Korea.
2. Associate Professor, School of Civil Engineering, Purdue Univ., West Lafayette, IN 47907-1284.
3. Assistant Professor, School of Civil and Environmental Engineering, Yonsei Univ., Seoul 120-749, Korea.
4. PhD Student, School of Civil Engineering, Purdue Univ., West Lafayette, IN 47907-1284.