1. Associate Professor, Dept. of Creative Technology Engineering, National Institute of Technology, Anan College, 265 Aoki Minobayashi Anan, Tokushima 774-0017, Japan.
2. Professor, Dept. of Civil and Environmental Engineering, Colorado State Univ., 1372 Campus Delivery, Fort Collins, CO 80526 (corresponding author).
3. Professor, Faculty of Science and Technology, Gunma Univ., 1-5-1 Tenjin Kiryu, Gunma 376-8515, Japan.