1. Department of Surgery, Ajou University School of Medicine, Suwon, Korea.
2. Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4. Department of Surgery, Ewha Womans University Mokdong Hospital, Ewha Womans University School of Medicine, Seoul, Korea.