Associate Dean for Graduate Study 2014-2015: Seoul National University College of Medicine; Director 2013-present: Seoul National University College of Medicine, Wide River Institute of Immunology; Associate Dean for Planning 2012-2013: Seoul National University College of Medicine; Professor 2004-present: Department of Microbiology and Immunology, Seoul National University College of Medicine; Research Fellow 2001-2004: NIAID, NIH Bethesda, United States; Assistant professor and Associate professor 1998-2010: Department of Microbiology and Immunology, Seoul National University College of Medicine; Doctor for public health 1995-1998: Biomedical Research Center, Korea Institute of Science and Technology; Research assistant 1990-1995: Department of Microbiology and Immunology, Seoul National University College of Medicine.