1. Department of Social and Preventive Medicine, Sungkyunkwan University School of Medicine, Suwon, Korea
2. Occupational Safety and Health Research Institute, Korea Occupational Safety and Health Agency, Incheon, Korea
3. Department of Internal Medicine, College of Medicine, Dongguk University, Gyeongju, Korea
4. Department of Diagnostic Radiology, College of Medicine, Gyeongsang National University, Jinju, Korea
5. Department of Pathology, College of Medicine, Dongguk University, Gyeongju, Korea