1. Department of Information Engineering and Computer Science; Feng Chia University; Taichung Taiwan, R.O.C
2. Department of Electronic Engineering; National United University; Miaoli City Taiwan, R.O.C
3. Department of Computer Science and Information Engineering; National Ilan University; Yilan City Taiwan, R.O.C
4. Department of Electrical and Computer Engineering; Purdue University; West Lafayette IN USA