1. Department of Electrical Engineering, Hanbat National University, Daejeon 34158, Republic of Korea
2. High-Speed Railroad System Research Center, Korea Railroad Research Institute, Uiwang 16105, Republic of Korea
3. Department of Applied Materaials Science and Engineering, Hanbat National University, Daejeon 34158, Republic of Korea
4. Wellture Finetech Inc., Daejeon 34040, Republic of Korea