1. Division of Gastroenterology, Department of Medicine, Soonchunhyang University College of Medicine, Cheonan, Korea
2. Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea
3. Department of Pathology, CHA Bundang Medical Center, CHA University, Seongnam, Korea
4. Digestive Disease Center, Department of Internal Medicine, Inha University School of Medicine, Incheon, Korea