1. Department of Electrical Engineering, School of Electrical and Computer Engineering, College of Engineering, Chang Gung University, Taoyuan 333, Taiwan
2. Portable Energy System Group, Green Technology Research Center, College of Engineering, Chang Gung University, Taoyuan 333, Taiwan
3. Department of Biomedical Engineering, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, China
4. Department of Anesthesiology, Taipei Veterans General Hospital and National Yang-Ming University, No. 201, Section 2, Shi-Pai Road, Taipei 112, Taiwan
5. Section of Anesthesiology, Ton-Yen General Hospital, Hsinchu 302, Taiwan