1. School of Electrical Engineering, Chungbuk National University, Cheongju 28644, South Korea
2. School of Information and Communication Engineering, Chungbuk National University, Cheongju 28644, South Korea
3. Department of Applied Mathematics, Bharathiar University, Coimbatore 641046, India
4. Department of Mathematics, Sungkyunkwan University, Suwon 440746, South Korea