1. Institute for Digestive Research, Digestive Disease Center Soonchunhyang University College of Medicine, Seoul, Korea
2. Digestive Disease Center and Research Institute, Department of Internal Medicine, Soonchunhyang University College of Medicine, Bucheon, Gyeonggi-do, Korea
3. Division of Gastroenterology, Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Chungcheongnam-do, Korea