1. Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine The Catholic University of Korea Seoul Korea
2. Department of Gastroenterology, Asan Medical Center University of Ulsan College of Medicine Seoul Korea
3. Division of Gastroenterology and Hepatology, Department of Internal Medicine Kyung Hee University College of Medicine Seoul Korea
4. Division of Gastroenterology, Department of Internal Medicine SHIWHA Medical Center Siheung Korea
5. Department of Internal Medicine, Bucheon St. Mary's Hospital College of Medicine The Catholic University of Korea Seoul Korea
6. Division of Gastroenterology, Department of Internal Medicine Hanyang University College of Medicine Seoul Korea