1. National Fusion Research Institute, Daejeon
34133, South Korea
2. Department of Physics, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
3. Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
4. Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027,
USA
5. School of Electrical and Computer Engineering, Kyungpook National University, Daegu 41566, South Korea
6. Department of Electrical and Computer Engineering, University of California at Davis, Davis, California 95616,
USA