1. Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
2. Department of Occupational and Environmental Medicine, College of Medicine, Kyung Hee University, Seoul, Korea
3. Departments of Preventive Medicine, School of Medicine, Kyung Hee University, Seoul, Korea
4. Total healthcare center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of medicine, Seoul, Korea