[1] Dept. of Civil Engineering, Kyoto University, Yoshida-honmachi, sakyou-ku, Kyoto 606-8501, Japan
[2] Dept. of Civil Engineering, Tottori University, Japan, Minami 4-101, Koyama, Tottori 680-8552, Japan
[3] District Public Works Station, Public Works Bureau, Osaka Municipal Government, 1-18 Imafuku-higashi 2-chome, Osaka 536-0002, Japan
[4] Coastal and Marine Design Department, Hitachi Zosen Corp., 7-89, Nanko Kita 1-Choume, Osaka 559-8559, Japan