1. Division of Gastroenterology, Department of Internal Medicine, Kangbuk Samsung Hospital; Sungkyunkwan University School of Medicine; Seoul Korea
2. Department of Internal Medicine, Hanyang University Guri Hospital; Hanyang University College of Medicine; Guri Korea
3. Biostatistical Consulting and Research Lab, Medical Research Coordinating Center; Hanyang University; Seoul Korea
4. Division of Gastroenterology, Department of Internal Medicine, Hanyang University Hospital; Hanyang University College of Medicine; Seoul Korea