1. a Department of Electrical Engineering , National Chung Hsing University , Taichung, 402, Taiwan, R.O.C. Phone: Fax: E-mail:
2. b Department of Electrical Engineering , National Chung Hsing University , Taichung, 402, Taiwan, R.O.C.
3. c Department of Biomedical Engineering , Jen‐Ai Hospital , Taichung County, 412, Taiwan, R.O.C.