He is a full professor in the Department of Physics of Korea University where he serves as the associate director at the IBS Center for Molecular Spectroscopy and Dynamics.

The second position was in the Michael S. Feld Group in the George R. Harrison Spectroscopy Laboratory of MIT for a period of three and a half years in which he focused on biomedical optics.

During this time, he invented tomographic phase microscopy which enables quantitative 3-D imaging of the refractive index of living cells and tissues[6] of which a patent was later filed.

The lab is within the IBS Center for Molecular Spectroscopy and Dynamics which falls under both the Institute for Basic Science and the Department of Physics in Korea University.

[16] The research direction of his laboratory is to resolve tissue turbidity for super-depth optical imaging, light manipulation and phototherapy.