1. Nanjing University of Posts and Telecommunications, School of Computer Science, Nanjing, Jiangsu 210003, China
2. Incheon National University, Department of Embedded Systems Engineering, 119 Academy-ro, Yeonsu-gu, Incheon 406-772, Republic of Korea
3. Hanyang University, Department of Electronics and Computer Engineering, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea