1. Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Gwangju, Korea
2. Department of Anesthesiology and Pain Medicine, Chosun University Hospital, Gwangju, Korea
3. Department of Anesthesiology and Pain Medicine, Medical School, Chonnam National University, Gwangju, Korea
4. Department of Premedics, School of Medicine, Chosun University, Gwangju, Korea