1. a Division of Electronics and Information Engineering, Chonbuk National University, 664-14, Deokjin-dong, Deokjin-gu, Jeonju, Chonbuk 561-756, Republic of Korea
2. b Division of Electronics and Information Engineering, Chonbuk National University, 664-14, Deokjin-dong, Deokjin-gu, Jeonju, Chonbuk 561-756, Republic of Korea;, Email: ycjeong@jbnu.ac.kr
3. c Department of Electrical and Communication, Soonchunhyang University, Asan, Chungnam, Republic of Korea