1. Ph.D. Student, Tishman Construction Management Program, Dept. of Civil and Environmental Engineering, Univ. of Michigan, Ann Arbor, MI 48109.
2. Associate Professor, Tishman Construction Management Program, Dept. of Civil and Environmental Engineering, Univ. of Michigan, Ann Arbor, MI 48109 (corresponding author).
3. Professor, Dept. of Civil Engineering, Hanyang Univ., Haengdang-Dong 17, Seongdong-gu, Seoul 133-791, Korea.