1. Ph.D. Student, Dept. of Civil and Environmental Engineering, Hanyang Univ., Seoul 133-791, Republic of Korea; and Lecturer, Dept. of Agricultural Engineering, Univ. of Engineering and Technology, Peshawar 25120, Pakistan.
2. Associate Professor, Dept. of Civil and Environmental Engineering, Hanyang Univ., Ansan 426-791, Republic of Korea (corresponding author). E-mail: twkim72@hanyang.ac.kr