1. Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea
2. Department of Internal Medicine, Jeonbuk National University Medical School, Jeonju, Republic of Korea
3. Department of Internal Medicine and Digestive Disease Research Institute, Wonkwang University School of Medicine, Iksan, Republic of Korea
4. Department of Internal Medicine, College of Medicine, Chosun University, Gwangju, Republic of Korea.