1. Department of Internal Medicine Seoul Metropolitan Government Boramae Medical Center Seoul National University College of Medicine Seoul Korea
2. Department of Preventive Medicine Seoul National University College of Medicine Seoul Korea
3. Department of Internal Medicine College of Medicine The Catholic University of Korea Seoul Korea
4. Department of Internal Medicine Kyung Hee University Hospital Kyung Hee University College of Medicine Seoul Korea
5. Institute for Digestive Research Soonchunhyang University Hospital Soonchunhyang University College of Medicine Seoul Korea
6. Department of Internal Medicine Dongguk University Ilsan Hospital Dongguk University College of Medicine Goyang Korea