1 Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea.
2 Department of Research and Development, Korean Institute of Tuberculosis, Osong, South Korea.
3 Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea. Electronic address: yimjj@snu.ac.kr.