1. Division of Gastroenterology and Hepatology, Indiana University School of Medicine, Indianapolis, IN, USA
2. Division of Gastroenterology, Chung-Ang University College of Medicine, Seoul, Korea
3. Division of Gastroenterology, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
4. Department of Anesthesiology and Pain Medicine, Chung-Ang University College of Medicine, Seoul, Korea