1. Department of Critical Care Medicine, Korea University College of Medicine, Korea University Ansan Hospital, Ansan 15355, Republic of Korea
2. Division of Infectious Disease, Department of Internal Medicine, Korea University College of Medicine, Korea University Ansan Hospital, Ansan 15355, Republic of Korea
3. Division of Pulmonology, Department of Internal Medicine, Korea University College of Medicine, Korea University Ansan Hospital, Ansan 15355, Republic of Korea
4. Department of Thoracic and Cardiovascular Surgery, Korea University College of Medicine, Korea University Ansan Hospital, Ansan 15355, Republic of Korea