1. Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
2. Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan
3. Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
4. Department of Mechanical Engineering, National Cheng Kung University, Tainan 70101, Taiwan