1. Department of Anesthesiology and Pain Medicine, Yonsei University Health System, Seoul, Korea.
2. Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Anesthesiology and Pain Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
4. Department of Pediatric Neurosurgery, Yonsei University Health System, Seoul, Korea.