1996-1997, Visiting Researcher, Michigan State University, E. Lansing, MI, U.S.A.
1999-2002, Post-doctoral fellow, Laboratory of Immunology, Korea Research Institute of Bioscience and Biotechnology, Taejon, Korea.
2002-2004, Visiting Research Scientist, University of Alabama at Birmingham, AL, USA
2004-2006, Research Scientist, Humoral Immunology Section, International Vaccine Institute, Seoul, Korea
2006-2010, Assistant Professor, School of Dentistry, Seoul National University, Seoul, Korea
2006-2012, Adjunct Chief, Clinical Immunology Section, International Vaccine Institute, Seoul, Korea
2006-2008, Consultant, Korea Center for Disease Control & Prevention, Seoul, Korea
2007-2008, Managing Editor of the Korean Journal of Microbiology
2007-2007, Temporary Advisor, World Health Organization
2007-2008, Secretary of Scientific Programs, The Korean Association of Immunologists
2007-2009, Committee members of the Dental Research Institute, Seoul National University
2008-2008, Secretary of International Cooperation, The Korean Society for Microbiology and Biotechnology
2009-2011, Managing editor of The Journal of Microbiology
2010-2015, Associate Professor, School of Dentistry, Seoul National University, Seoul, Korea
2012-2013, Visiting Associate Professor, University of British Columbia, Canada
2014-2014, Vice-chairman of Council for Education Accreditation, Korean Society of Toxicology/Korean Environmental Mutagen Society
2014-2015, Committee member of the Dental Research Institute, Seoul National University
2014-2016, Expert of Central Pharmacists Standard Commission
2014-2015, Vice-Chair of Educational Committee for VII International Congress of Asian Society of Toxicology
2015-Current, Professor, School of Dentistry, Seoul National University, Seoul, Korea
2017-2017, Chair of Department of Dentistry, School of Dentistry, Seoul National University, Seoul, Korea
2017-2018, Associate Dean for Research Affairs, School of Dentistry, Seoul National University, Seoul, Korea
2018-2020, Director, SNU R&DB Foundation Yeongeon Campus, Seoul National University, Seoul, Korea
2018-2022, Committee member of Institutional Biosafety Committee, Seoul National University, Seoul, Korea
2020-2020, Associate Director, BK21 Plus Dental Life Science, Seoul National University, Seoul, Korea
2020-2021, Committee member of Patent Deliberation Committee, Seoul National University, Seoul, Korea
2020-Current, Vice-principal professor of SNU Bio-CEO Programs, Seoul National University, Seoul, Korea
2021-2024, Committee member of The Presidential Advisory Council on Science and Technology, Seoul, Korea
2021-Current, Review Board of National Research Foundation of Korea, Daejeon, Korea