He received a Ph.D. degree in Computer Science from Stanford University and a B.S. degree in physics from Seoul National University. His main research interests are in the study of the evolution, management, retrieval and mining of information on the World-Wide Web. He publishes research papers in major international journals and conference proceedings. He serves on program committees of top international conferences, including SIGMOD, VLDB and WWW. He is a recipient of the 10-Year Best-Paper Award at VLDB 2010, NSF CAREER Award, IBM Faculty Award, Okawa Research Award and Northrop Grunmann Excellence in Teaching Award.