1. Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan, Republic of China,
2. Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan, Republic of China
3. Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan 701, Taiwan, Republic of China
4. Department of Mechanical and Automation Engineering, Kao Yuan University, Kaohsiung 821, Republic of China
5. Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204-4005, U.S.A.