From 1991 to 1995, Dr. Lee worked on the analysis of geopressured-geothermal aquifer and long-time behaviour of closed gas reservoirs as a research assistant at Center for Petroleum and Geosystems Engineering, University of Texas at Austin, U.S.A. Obtaining a Ph.D. at the University of Texas at Austin in 1995, he worked as a research specialist at Kumho & Co. and a lecturer at Seoul National University. Since 1998, he has worked on various aspects reservoir engineering as a professor of Environmental and Energy Systems Engineering at Kyonggi University. Since 2011, he has been a professor at Hanyang University, Seoul, Korea.