1. Division of Gastroenterology, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine The Catholic University of Korea Seoul South Korea
2. Division of Gastroenterology, Department of Internal Medicine Inha University Hospital, Inha University School of Medicine Incheon South Korea
3. Divison of Gastroenterology, Department of Internal Medicine Gachon University, Gil Medical Center Incheon South Korea
4. Division of Gastroenterology, Department of Internal Medicine, Bucheon St. Mary's Hospital, College of Medicine The Catholic University of Korea Seoul South Korea