- Microbial toxicology, Biochemical toxicology and
Immunotoxicology
- Study on the effects of microbial toxins, environmental
contaminants, etc. on the
human health and their mode of action

1974~1979 Research Scientist, University of Wisconsin,
Madison, WI, U.S.A.
1979~1999 Professor, Department of Biological Science
and Engineering, Korea
Advanced Institute of Science and Technology
(KAIST)
1984~1985 Visiting Professor, Department of Pharmacology
and Toxicology, Medical College of Virginia, Richmond, VA,
U.S.A.
1985~1985 Visiting Scientist, National Cancer Institute,
Washington D.C., U.S.A.
1989~1990 Visiting Professor, Department of Pharmacology
and Toxicology,
Medical College of Virginia, Richmond, VA,
U.S.A.
1999~2000 President, National Institute of Toxicological
Research
2000~2002 Commissioner, Korea Food and Drug
Administration(KFDA)
2002~ President, Korea Research Institute of
Bioscience and Biotechnology