1Department of Occupational & Environmental Medicine, Seoul St. Mary's Hospital, Korea.
2Department of Preventive Medicine, Center for Occupational & Environmental Medicine, The Catholic University of Korea, Korea. jwkoo@catholic.ac.kr
3Health Promotion Center, Yeouido St. Mary's Hospital, Korea. JFIF d d Ducky d qhttp://ns.adobe.com/xap/1.0/