1. Department of Internal Medicine, Kwandong University College of Medicine, Koyang, Korea.
2. Department of Surgery, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Surgery, Kwandong University College of Medicine, Koyang, Korea.
4. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
5. The Institute of Chest Diseases, Yonsei University College of Medicine, Seoul, Korea.