1. Research Engineer, Axelspace Corp., M & C Building 7F, 2-3-13 Kanda Ogawa-machi, Chiyoda-ku, Tokyo 101-0052, Japan; formerly, Graduate Research Assistant, Dept. of Geological Science and Engineering, Missouri Univ. of Science and Technology, Rolla, MO 65409.
2. Professor, Dept. of Civil, Architectural, and Environmental Engineering, Missouri Univ. of Science and Technology, Rolla, MO 65409 (corresponding author).