- 1978-1980 Bachelor of Nuclear Engineering at State University of New York
- 1980-1982 Master of Nuclear Engineering at University of Michigan
- 1982-1986 Doctor of Nuclear Engineering at University of Michigan

- 1986-1987 Korea Advanced Energy Research Institute(Present: Korea Atomic Energy Research Institute, KAERI)
- 1987-2018 Professor at Hanyang University, Department of Nuclear Engineering
- 2000-2013 President of Innovative Technology Center for Radiation Safety (ITRS)
- 2002-2006 Vice-chairman of KEDO Nuclear Safety Advisory Committee
- 2005-2006 Chairman of American Nuclear Society Korea Branch
- 2006-2010 Chairman of Asia-Oceania Association for Radiation Protection (AOARP)
- 2008-2016 Executive Committee of International Radiation Protection Association (IRPA)
- 2010-2013 Committee of Nuclear Safety and Security Commission in Korea
- 2013-2014 Chairman of Korean Nuclear Society (KNS)
- 2014-2017 President of Korea Atomic Energy Research Institute (KAERI)
- 2016-2020 Vice-President Congress Affairs of International Radiation Protection Association (IRPA)
- 2019- Emeritus Professor at Hanyang University, Department of Nuclear Engineering