1. Professor, Dept. of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea (corresponding author).
2. Postdoctoral Researcher, Center for Transportation Research, The University of Texas at Austin, 1616 Guadalupe Street, Austin, TX 78701; fomerly, Postdoctoral Researcher, Dept. of Civil and Environmental Engineering, Texas Tech Univ., 10th and Akron, Lubbock, TX 79409.
3. Professor, School of Civil Engineering, Purdue Univ., 550 Stadium Mall Dr., West Lafayette, IN 47907.