1. Department of Cardiovascular and Thoracic Surgery, Korea University Medical Center, Ansan Hospital, Ansan, Gyeonggi-do, South Korea
2. Department of Health Care Administration and Policy, School of Community Health Science, University of Nevada, Las Vegas, Las Vegas, NV, USA
3. Department of Health Administration and Management, Soonchunhyang University, Asan, Chungcheongnam-do, South Korea
4. Department of Internal Medicine, University of Nevada Las Vegas School of Medicine, Las Vegas, NV, USA
5. Department of Medicine, Southern Nevada Veterans Affairs Health System, North Las Vegas, NV, USA