1. Department of Surgery, Daejeon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Daejeon, Korea.
2. Department of Surgery, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Incheon, Korea.
3. Department of Surgery, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea.
4. Department of Surgery, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Surgery, Chonnam National University Medical School, Gwangju, Korea.
6. Department of Surgery, Ajou University School of Medicine, Suwon, Korea.
7. Department of Surgery, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.