1. Plasma Technology Research Center, National Fusion Research Institute, Gunsan, Jeonbuk 54004, South Korea
2. Kwongwon Tech. Co., Ltd., Seongnam, Geonggi 13497, South Korea
3. Jeonbuk National University, Jeonju, Jeonbuk 54896, South Korea
4. SK Hynix, Inc., Icheon, Geonggi 17336, South Korea
5. Advanced Instrumentation Institute, Korea Research Institute of Standard and Science, Daejeon 34114, South Korea