[1] Division of Gastroenterology, Department of Internal Medicine, Inha University, School of Medicine, Incheon
[2] Yonsei University, College of Medicine, Seoul
[3] Soon Chun Hyang University, School of Medicine, Cheonan Hospital, Cheonan
[4] Ajou University, School of Medicine, Suwon
[5] Occupational and Environmental Medicine, Inha University, School of Medicine, Incheon