1. Department of Energy and Power Conversion Engineering, University of Science and Technology (UST), Daejeon, Republic of Korea
2. Pohang Accelerator Laboratory (PAL), Pohang, South Korea
3. Electrophysics Research Center, Korea Electrotechnology Research Institute (KERI), Changwon, South Korea
4. Electrophysics Research Center, Korea Electrotechnology Research Institute (KERI), Changwon, Republic of Korea