1 Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Republic of Korea.
2 Division of Pulmonary Medicine and Allergy, Department of Internal Medicine, Hanyang University College of Medicine, Hanyang Medical Center, Seoul, Republic of Korea.
3 Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University Medical School, Seoul, Republic of Korea.
4 Division of Pulmonary Medicine and Allergy, Department of Internal Medicine, Hanyang University College of Medicine, Hanyang Medical Center, Seoul, Republic of Korea. Electronic address: respiry@gmail.com.