1. Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Anesthesiology, Bundang Jaeseng Hospital, Seongnam, Korea.
3. Department of Anesthesiology and Pain Medicine, Kyungpook National University College of Medicine, Daegu, Korea.
4. Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea.