1. Department of Electrical and Computer Engineering University of Kentucky, Lexington, KY, USA
2. School of Computer Science and Engineering, Seoul National University, 151-742, Korea
3. College of Electrical Engineering, Zhejiang University, Yuquan Campus, Hangzhou 310027, P.R. China
4. Department of Electrical and Computer Engineering, State University of New York at Binghamton, USA
5. Department of Computer Science and Engineering, University of Nebraska-Lincoln, USA
6. School of Microelectronic, Shanghai Jiaotong University, Shanghai 200240, P.R. China