- Professor, Department of Industrial and Enterprise Systems Engineering, University of Illinois at Urbana-Champaign, August 2012 to present.
- Professor, Department of Mathematics, University of Illinois at Urbana-Champaign, August 2006 to present.
- Associate Professor, Department of Mathematics , University of Illinois at Urbana-Champaign, August 2001 to August 2006.
- Assistant Professor, Department of Mathematics , University of Illinois at Urbana-Champaign, January 1996 to August 2001.
- Visiting Assistant Professor, Department of Mathematics, Northwestern University, September 1994 to December 1995 (with NSF Postdoctoral Fellowship).
- Visitor, Department of Mathematics, University of Maryland at College Park, September 1993 to August 1994 (with NSF Postdoctoral Fellowship).
- Postdoctoral Research Assistant Professor, Center for Applied Mathematical Sciences, University of Southern California, August 1991 to August 1993.