The author is currently a professor in the Department of Systems Biology at Yonsei University. He received his Ph.D in molecular cell biology from Seoul National University and continued his research on DNA repair mechanisms as a model of gene-environment interaction at North Carolina State University, U.S. In 1998, he began his research in epigenetics to address questions about the structure and function of chromatins, with a focus on how highly compacted heterochromatin structures are formed. From 2002, he was a principal investigator at the National Cancer Center Research Institute, where he studied the link between epigenetic regulation and cancer development. Since moving to Yonsei University, he has researched the link between epigenetics and the differentiation process of embryonic stem cells.