1. Assistant Professor, Dept. of Architectural Engineering, Dong-Eui Univ., 176 Eomgwangno, Busanjin-gu, Busan 614-714, Korea (corresponding author).
2. Assistant Professor, Dept. of Civil, Architectural and Environmental Engineering, Illinois Institute of Technology, 3201 S. Dearborn St., Alumni Memorial Hall Room 216, Chicago, IL 60616.
3. Professor, Dept. of Civil, Architectural and Environmental Engineering, Univ. of Texas at Austin, 1 University Station C1752, Austin, TX 78712.