Visiting Professor, Dept. of Math., Dokushima University, Japan, 2009,10-11.

Visiting Professor, Dept. of Math., Seoul National University, Korea, 2008,11-12.

Visiting Professor, Dept. of Math., Michigan State University, 2006,3-5.

Visiting Professor, Applied Mathematics Research Center, Delaware State University, 2006,6-2007,3.

Visiting Professor, Dept. of Math., University of Delaware, 2006,6.

Research Fellow Institute of Textiles & Clothing, The Hong Kong Polytechnic University, 1998,7-2000,7.

Research Associate, Institute of Textiles & Clothing, The Hong Kong Polytechnic University, Research Associate, 1997,10-1998,4.

Research Assistance, The Baptist University of Hong Kong, 1995,9-10.

Visiting Scholar, Dept. of Mathematics, the Chinese University of Hong Kong, 1995,12.