1. Chief Research Engineer, Heavy Development Electricity & Electronics Cntr., Doosan Infracore, 489 (Hwasu-dong), Injung-Ro, Dong-Gu, Incheon, Korea 22502.
2. M.S. Student, Dept. of Civil & Environmental Engineering, Hanyang Univ., Seoul 04763, Korea.
3. Ph.D. Student, Dept. of Civil & Environmental Engineering, Hanyang Univ., Seoul 04763, Korea.
4. Professor, Dept. of Civil & Environmental Engineering, Hanyang Univ., Seoul 04763, Korea (corresponding author)