1. 1Department of Civil and Railroad Engineering, Daewon University College, 599 Shinwol, Jecheon, 390-702, Republic of Korea
2. 2Department of Civil Engineering, Gyeongnam National University of Science and Technology, 150 Chilam, Jinju, 660-758, Republic of Korea
3. 3Division of Construction and Environmental Engineering, Kongju National University, 275 Budai, Cheonan, 330-717, Republic of Korea