 He then returned to Korea to start work as an assistant professor in the Department of Chemistry, POSTECH.He later became an assistant professor, full professor, and chair of POSTECH's Department of Life Sciences before being the head of the School of Interdisciplinary Biosciences and Bioengineering (I-BIO) and Hong Deok Distinguished Professor.Outside of his work at POSTECH, he founded and directed the Biological Research Information Center (BRIC) () from 1996 to 2005.