1992.2 - 2000.12 - Senior Research Scientist, Biomedical Research Team R&D Center, CJ Corp. 1995.10 - 1996.10 - Exchange Research Scientist - Department of Communicable Diseases and Immunity - Walter Reed Army Institute of Research, Department of Army, Washington, D.C., U.S.A. 2000.12 - Present - Executive Director, R&D Center, GeneMatrix Inc. - Guest Scientist, Cancer Research Institute, Seoul National University - R&D Committee, Korean Society for Cancer Prevention - Advisory Committee, National Pharmacogenomics Research - Network, Korean Ministry of Health and Welfare - R&D Planning and Evaluation Committee, Korean Ministry of Commerce, Industry and Energy Present - Editorial board, Future Microbiology - Editorial board, World Journal of Gastroenterology - Consulting editor, Gut and Liver