1Department of Preventive and Occupational Medicine, School of Medicine, Pusan National University, Korea. kangdm@pusan.ac.kr
2Department of Occupational and Environmental Medicine, Pusan National University Yangsan Hospital, Korea.
3Pusan National University Medical Research Institute, Korea.
4Department of Internal Medicine, Pusan National University Yangsan Hospital, Korea. JFIF d d Ducky d qhttp://ns.adobe.com/xap/1.0/