1. Department of Electronic Engineering, Engineering Research Institute (ERI), Gyeongsang National University, Jinju, South Korea
2. Spatial Wireless Transmission Research Section, Electronics and Telecommunications Research Institute (ETRI), Daejeon, South Korea
3. Department of Electrical, Electronic and Computer Engineering, University of Ulsan, Ulsan, South Korea
4. Department of Electrical and Computer Engineering, Institute of New Media and Communications (INMC), Seoul National University, Seoul, South Korea