1. Dept. of Leisure Recreation and Travel Management, Toko Univ., Pu Tzu, Chiayi 61363, Taiwan.
2. Dept. of Land Management and Development, Chang Jung Christian Univ., Kway Jen, Tainan 71101, Taiwan (corresponding author).
3. Dept. of Civil Engineering, Clemson Univ., Clemson, SC 29634; and National Central Univ., Jhongli, Taoyuan 32001, Taiwan.
4. Dept. of Civil Engineering, National Cheng Kung Univ., Tainan 70101, Taiwan.