1. Department of Family Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Psychiatry, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Department of Family Medicine, Central Veterans Hospital, Seoul, Korea.
4. Department of Family Medicine, Konyang University Hospital, Daejeon, Korea.
5. Department of Family Medicine, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Korea.
6. Department of Family Medicine, Bundang CHA General Hospital, CHA University College of Medicine, Seongnam, Korea.
7. Department of Child Development and Family Studies, Institute of Human Ecology, Seoul National University, Seoul, Korea.