1. Department of Internal Medicine, Chungbuk National University Hospital, Chungbuk National University College of Medicine, Cheongju, Korea.
2. Graduate School of Health Science Business Convergence, Chungbuk National University, Cheongju, Korea.
3. Department of Health Information and Management, Chungbuk National University College of Medicine, Cheongju, Korea.
4. College of Business, Chungbuk National University, Cheongju, Korea.
5. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Daejeon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Daejeon, Korea.