He is the founding director of the Institute for Basic Science Center for Theoretical Physics of the Universe.

[4] Moving to the United States, Choi started his career as a visiting postdoctoral research associate at Harvard in 1986.

Next he was postdoctoral research associate at Johns Hopkins University in 1987, Carnegie Mellon from 1988 to 1990, and UC San Diego from 1990 to 1992.

[5] Returning to Korea, the next two years were spent as a research professor at Chonbuk National University.

Leaving KAIST, he became the founding director of the Center for Theoretical Physics of the Universe (CTPU), established November 2013.