1. Department of Computer Science and Information Engineering, National University of Tainan, Tainan, Taiwan 70005, ROC
2. Department of Computer Science, National Tsing Hua University, Hsinchu, Taiwan 30013, ROC
3. Department of Biotechnology and Bioinformatics, Asia University, Taichung, Taiwan 41354, ROC
4. Department of Computer Science, University of Illinois, Chicago, IL 60607, USA