1Department of Preventive Medicine, Yonsei University College of Medicine, The Institute for Occupational Health College of Medicine, 50, Yonsei-ro, Seodaemun-gu, Seoul, 120-749 South Korea
2Graduate School of Public Health, Yonsei University College of Medicine, Soul, South Korea
3Incheon Worker’s Health Center, Incheon, South Korea
4Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, South Korea JFIF d d Ducky d qhttp://ns.adobe.com/xap/1.0/