1. Department of Internal Medicine and Institute of Gastroenterology, Graduate School of Medical Science, Brain Korea 21 Project, Seoul, Korea
2. Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
3. Department of Medicine, Yonsei University College of Medicine, Seoul, Korea
4. Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea