1. Associate Professor, Dept. of Safety, Health and Environmental Engineering, National United Univ., Miao-Li 360, Taiwan, R.O.C. (corresponding author).
2. Professor, Dept. of Safety, Health and Environmental Engineering, National United Univ., Miao-Li 360, Taiwan, R.O.C.
3. Research Assistant of Dept. of Safety, Health and Environmental Engineering, National United Univ., Miao-Li 360, Taiwan, R.O.C.