1. Department of Electrical, Electronic, and Control Engineering, Hankyong National University, 327 Jungang-ro, Anseong-si, Gyeonggi-do, 456-749 Korea
2. Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
3. Department of Computational Science and Engineering, Yonsei University, Seoul 03722, Korea
4. BIT Micro Fab Research Center, Yonsei University, Seoul 03722, Korea