1. Department of Sociology, Sungkyunkwan University, Jongno-gu, Seoul, Korea
2. NCHS, Hyattsville, MD, USA
3. Department of Epidemiology, School of Health Sciences and Practice Admissions, New York Medical College, Valhalla, NY, USA
4. Department of Sociology, Yonsei University, Seodaemun-gu, Seoul, Korea
5. University of Wisconsin Survey Center, University of Wisconsin, Madison, WI, USA
6. Mailman School of Public Health, Columbia University, New York, NY, USA