1. Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine , Seoul, South Korea
2. Department of Occupational and Environmental Medicine, Inha University Hospital, Inha University , Incheon, Republic of Korea
3. Department of Global Economics, Sungkyunkwan University , Seoul, Republic of Korea
4. Department of Occupational and Environmental Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea , Seoul, Republic of Korea