1. a Department of Radio Wave Engineering, Hanbat National University, San 16–1, Dukmyung-Dong, Yuseong-Gu, Daejeon 305–719, Korea
2. b Department of Radio Wave Engineering, Hanbat National University, San 16–1, Dukmyung-Dong, Yuseong-Gu, Daejeon 305–719, Korea
3. c Department of Radio Wave Engineering, Hanbat National University, San 16–1, Dukmyung-Dong, Yuseong-Gu, Daejeon 305–719, Korea;, Email: ingpark@hanbat.ac.kr
4. d Department of Electronic Engineering, Sogang University, 1 Shinsu-dong, Mapo-gu, Seoul 121–742, Korea