1. Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
2. Department of Family Medicine, Jeju National University School of Medicine, Jeju, Korea
3. Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
4. Department of Family Medicine, Korea University Guro Hospital, Seoul, Korea
5. Department of Family Medicine, Seoul National University Hospital, Seoul, Korea