1. Professor, Dept. of Safety, Health and Environmental Engineering, National United Univ., Miao-Li 360, Taiwan, R.O.C. (corresponding author).
2. Associate Professor, Dept. of Environmental Engineering and Management, Chaoyang Univ. of Technology, Taichung 413, Taiwan, R.O.C.
3. Professor, Dept. of Safety, Health and Environmental Engineering, National United Univ., Miao-Li 360, Taiwan, R.O.C.
4. Master, Dept. of Safety, Health and Environmental Engineering, National United Univ., Miao-Li 360, Taiwan, R.O.C.