1. Department of Surgery, Seoul National University College of Medicine, Seoul, Korea
2. Department of Surgery, Korea University College of Medicine, Seoul, Korea
3. Department of Surgery, Uijeongbu Eulji Medical Center, Uijeongbu, Korea
4. Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Korea
5. Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea