1. Department of Surgery, Kyungpook National University Medical Centre, Kyungpook National University School of Medicine, Daegu, Korea
2. Department of Surgery, Yonsei University College of Medicine, Seoul, Korea
3. Department of Surgery, Korea University Anam Hospital, Seoul, Korea
4. Department of Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
5. Department of Surgery, Kyung Hee University, Seoul, Korea
6. Department of Surgery, Inje University Paik-Hospital, Pusan, Korea
7. Department of Surgery, Eulji University Hospital, Daejeon, Korea