1. Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea
2. Department of Materials Science and Engineering, Chungnam National University, Daejeon 34134, Republic of Korea
3. Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
4. Korea Institute of Fusion Energy (KFE), Gunsan 54004, Republic of Korea
5. Department of Electrical Engineering, Hanyang University, Seoul 04763, Republic of Korea