1. Department of Electrical, Electronics and Comm. Eng. Edu., Chungnam National University, Daejeon, Korea
2. Department of Electrical Engineering, Chungnam National University, Daejeon, Korea
3. Electrical Engineering, Chungnam National University, Daejeon, Korea
4. Chonnam National University College of Fisheries and Ocean Sciences, Yeosu, Korea
5. Department of Mechanical Engineering Edu., Chungnam National University, Daejeon, Korea
6. Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA