1. School of Civil and Environmental Engineering, Kookmin University, Jeongneung-Dong, Seongbuk-Gu, Seoul 136-702, Republic of Korea, Tel. ; Fax:
2. Department of Construction Environmental Research, Korea Institute of Construction Technology, 2311 Daehwa-Dong, Ilsan-Gu, Goyang-Si, Gyeonggi-Do 411-712, South Korea, Tel.