1. Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
2. Department of Surgery, Myongji Hospital, Hanyang University Medical Center, Goyang, Korea.
3. Department of Surgery, Inha University Hospital, Inha University School of Medicine, Incheon, Korea.
4. Department of Surgery, Dongguk University Medical Center, Goyang, Korea.