1. Department of Anesthesiology and Pain Medicine; Severance Hospital; Yonsei University College of Medicine; Seoul Korea
2. Anesthesia and Pain Research Institute; Yonsei University College of Medicine; Seoul Korea
3. Department of Anesthesiology and Pain Medicine; Gangnam Severance Hospital; Yonsei University College of Medicine; Seoul Korea
4. Department of Research Affairs; Biostatistics Collaboration Unit; Yonsei University College of Medicine; Seoul Korea