1. Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, 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. Department of Neurology, College of Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
5. Department of Radiology, College of Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
6. Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea