1. Tamkang University, Graduate Institute of Management Science, 151 Ying-Chuan Road, Tamsui, Taipei Hsien, 25137 Taiwan, R.O.C. Tel.: ; Fax: ; E-mail: 118888@mail.tku.edu.tw
2. Tamkang University, Graduate Institute of Management Sciences and School of Entrepreneurial Development, Taiwan, R.O.C. E-mail: pclii@mail.tku.edu.tw