After completing his Ph. D., Physical Chemistry, Pohang University of Science and Technology (Adviser: Kwang S. Kim), he worked at Pohang University of Science and Technology and Columbia University (Adviser: Philip Kim). In 2010 he pioneered the development of touch-screen with transparent electrodes made from graphene, opening new horizons for manufacturing these transparent films on a large scale (Roll-to-roll production of 30-inch graphene films for transparent electrodes, Nature Nanotechnology 5, 574578 (2010)). In 2010, he was awarded the Joong-Ang Daily-Yumin Award of Science and the SKKU Young Fellowship.