1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Soonchunhyang University College of Medicine, Seoul, Korea
2. Digestive Disease Center and Research Institute, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
3. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Soonchunhyang University College of Medicine, Cheonan, Korea
4. Clinical Research Center, Asan Medical Center, Seoul, Korea