1. Research Professor, Dept. of Civil Engineering, Kyungpook National Univ., Daegu 41566, South Korea; formerly, Assistant Specialist, Dept. of Civil and Environmental Engineering, Univ. of California, Irvine, CA 92697.
2. Professor and Chair, Dept. of Civil and Environmental Engineering, Univ. of California, Irvine, CA 92697 (corresponding author).