1983–1986 Researcher, Genetic Eng. Center, KAIST, Korea
1991–1994 Post-doc, MIT, USA
1993–1994 Senior Scientist, Cubist Pharmaceuticals, USA
1994-2001 Associate Professor, Sung Kyun Kwan University, Korea
2001-present Professor, College of Pharmacy, Graduate Program in Bioinformatics , Genetic Engineering, Cancer Biology, Seoul National Univ.
1998-present Director, Center for Medicinal Protein Network and Systems Biology, Seoul National University
2008- Director, Information Center of Bio-pharmacological Network
2008- Director, Integrated Bioscience and Biotechnology Institute