1. Department of Computer Science and Information Management, Providence Univ., Taichung 43301, TW.
2. Department of Business Administration, National Formosa Univ., Huwei, Yunlin 63201, TW (Corresponding author), e-mail address: cdliou@nfu.edu.tw
3. Department of Applied Mathematics, National Chung-Hsing Univ., Taichung 40227, TW.