1. Bengt Fellenius Consultants Inc., 1905 Alexander St., SE, Calgary, AB T2G 4J3, Canada (corresponding author).
2. Assistant Professor, Dept. of Civil Engineering, Dong-A Univ., 840 Hadan-dong, Saha-gu, Busan 604-714, Korea.
3. Professor, Dept of Civil Engineering, Dong-A Univ., 840 Hadan-dong, Saha-gu, Busan 604-714 Korea.