1. Division of Pulmonology, Department of Internal Medicine, Institute of Chest Disease, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Epidemiology and Biostatistics, School of Public Health, Seoul National University, Seoul, Korea.
4. The Center for Genome Science, Korea National Institute of Health, KCDC, Osong, Korea.
5. Department of Pulmonary and Critical Care Medicine, Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.