1. Department of Thoracic and Cardiovascular Surgery, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea
2. Department of Thoracic and Cardiovascular Surgery, Kyung Hee University Hospital, Kyung Hee University School of Medicine, Seoul, Korea
3. Department of Preventive Medicine, Kyung Hee University School of Medicine, Seoul, Korea