1. Department of Internal Medicine, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, Daegu, Korea
2. Department of Internal Medicine, Keimyung University Dongsan Medical Center, Daegu, Korea
3. Department of Internal Medicine, Daegu Catholic University Medical Center, Daegu, Korea
4. Department of Internal Medicine, School of Medicine, Kyungpook National University, Kyungpook National University Chilgok Hospital, Daegu, Korea