Chin-Chen Chang, Lin-Li Cheng and Tung-Shou Chen*
Institute of Computer Science and Information Engineering
National Chung Cheng University
Chiayi, Taiwan 621, R.O.C.
E-mail: {ccc, cll84}@cs.ccu.edu.tw
*Department of Information Management
National Taichung Institute of Technology
Taichung, Taiwan 404, R.O.C.
E-mail: ts.chen@taiwan.com