Professor Jae Choon Cha studies geometric topology and related algebraic topology, algebra, and analysis. In particular, he is interested in topology of manifolds and knots, focusing on the study of 4-manifolds and low dimensional topology, disk embedding problem, difference and similarity between smooth and topological categories in dimension 4, concordance of knots and links, and quantitative topology. His recent research and papers can be found on the website http://gt.postech.ac.kr/~jccha/