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. Graduate Institute of Medical Mechatronics, Chang Gung University, Taoyuan 333, Taiwan
4. Department of Mechanical Engineering, Chang Gung University, Taoyuan 333, Taiwan