He is currently serving as a standing commissioner of the Truth & Reconciliation Commission, Republic of Korea. He received his Ph.D. from Seoul National University. His research has focused on the historical sociology of Korean politics, working class formation and the Korean War. He has also acted as an organizer of progressive academic movements since the 1980s and has participated in several civil movements in South Korea. In 2004, The Hankyoreh newspaper nominated him as one of the "100 people who will lead Korean society." He has written several academic books, including Social Movements in 1960s Korea (1991); A Study of Korea's Working Class (1995); Shadow of Modernity (2000); War and Society (2000); The Engine of the American Market and War (2004); and Reflections on Korean Society Since 1987 (2006).