1Institute of Occupational Medicine, Koje Hospital, Korea. kohhj@chollian.net
2Department of Preventive Medicine and Institute of Occupational Medicine, Wonju College of Medicine, Yonsei University, Korea.
3Department of Preventive Medicine, Seoul National University College of Medicine, Korea.
4Department of Health Research, Korea Institute for Health and Social Affairs, Korea.
5Department of Occupational Medicine, College of Medicine, Inje University, Korea. JFIF d d Ducky d qhttp://ns.adobe.com/xap/1.0/