1. Department of Electrical and Computer Engineering, Seoul National University, Seoul, South Korea
2. Applied Superconductivity Center, Electric Power Research Institute, Seoul National University, Seoul, South Korea
3. National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
4. Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, South Korea
5. Department of Electrical Engineering, Kangwon National University, Gangwon, South Korea
6. Department of Electrical Engineering, Korea National University of Transportation, Chungju, South Korea