1. Dept. of Industrial Engineering and Engineering Management, National Tsing Hua Univ., Hsinchu, TW.
2. Dept. of Statistics and Informatics Science, Providence Univ., Taichung, TW (Corresponding author), e-mail: myliao@pu.edu.tw
3. Dept. of Industrial Engineering and Systems Management, Feng Chia Univ., Taichung, TW.