1. Department
of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
2. Department
of Electrical Engineering, Universitas Kristen Krida Wacana, Jakarta Barat 11470, Indonesia
3. Creative
Future Research Laboratory, Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, South Korea
4. KU-KIST
Graduate School of Converging Science and Technology, Korea University, Seoul 02841, South Korea