1. Department of Civil Engineering, Kunsan National University, San 68, Miryong-dong, Kunsan, Jeollabuk-do, 573-701, Republic of Korea.
2. Department of Civil Engineering, Chonbuk National University, 664-14 Deokjin-dong 1Ga, Deokjin-ku, Jeonju, Jeollabuk-do, 561-756, Republic of Korea.