1. Department of Surgery, Sun Medical Center, Daejeon, Korea.
2. Department of Surgery, Seoul National University Hospital, Seoul, Korea.
3. Department of Surgery, Samsung Medical Center, Seoul, Korea.
4. Department of Surgery, Asan Medical Center, Seoul, Korea.
5. Department of Surgery, Ewha Womans University Mokdong Hospital, Seoul, Korea.
6. Department of Surgery, Dong-A University College of Medicine, Busan, Korea.