Theoretical physics, Quantum Field Theory & String Theory

1986-1988 Researcher at the National Fermi Accelerator Laboratory in the United States
1998-1990 Researcher at Boston University.
1990-1996 Assistant professor at Columbia University.
1992 Organisation Européenne pour la Recherche Nucléaire(CERN) Visiting Fellow
1993 The Institute for Advanced Study(IAS) Visiting Fellow
1996-1998 Associate professor at Columbia University.
1998-1999 Associate professor at Seoul National University.
1999~ Professor of Physics at the Korea Institute for Advanced Study, KIAS
2003~2004 Texas University (Austin) Visiting Fellow
2008 Harvard University Visiting Fellow
2013.9-2016.11 Korea Institute for Advanced Study, KIAS Vice president.

1991-1996 USA NSF Presidential Young Investigator (PYI)
1991-1994 A. Sloan Foundation Fellow
2006: The Ministry of Education and Human Resources Development and the Korea Academic Promotion Foundation.
2014: Korea's Best Science and Technology Award.