Ming-Gang Wen*+, Kuo-Chin Fan* and Chin-Chuan Han
*Institute of Computer Science and Information Engineering
National Central University
Chungli, 320 Taiwan
E-mail: kcfan@csie.ncu.edu.tw
+Department of Information Management
Department of Computer Science and Information Engineering
National United University
Miaoli, 360 Taiwan
E-mail: mgwen@nuu.edu.tw