1. Research Assistant, Dept. of Hydraulic and Ocean Engineering, National Cheng Kung Univ., Tainan 701, Taiwan.
2. Associate Professor, Dept. of Hydraulic and Ocean Engineering, National Cheng Kung Univ., Tainan 701, Taiwan.
3. Professor, Faculty of Engineering and Applied Science, Univ. of Regina, 3737 Wascana Pkwy., Regina, SK, Canada S4S 0A2 (corresponding author).