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