1. Postdoctoral Research Associate, Dept. of Civil and Environmental Engineering, Rice Univ., Houston, TX 77005; Formerly, Graduate Student.
2. Assistant Professor, Dept. of Mechanical Engineering, Dongguk Univ., Seoul 100-715, Republic of Korea
3. Professor, Dept. of Civil and Environmental Engineering, and Dept. of Mechanical Engineering and Material Science, Rice Univ., Houston, TX 77005 (Corresponding author).