2010 – Present: Professor, University of Kentucky.
2003-2010: Associate Professor, University of Kentucky.
1999-2003: Assistant professor, University of Kentucky.
1997-1998: Research Scientist, Science Application International, Inc.
1995 – 1997: Visiting assistant professor, research scientist Center for Computational Electromagnetics, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign.
1992 – 1995: graduate research assistant, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign.
1991 – 1992: visiting scholar, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign.
1986 – 1991: instructor and research associates, Department of Electrical Engineering, Beijing University of Aeronautics and Astronautics.