1. Department of Anesthesiology and Pain Medicine, School of Medicine & Institute for Medical Science, Keimyung University, Daegu, Korea.
2. Department of Preventive Medicine, School of Medicine & Institute for Medical Science, Keimyung University, Daegu, Korea.
3. Department of Thoracic and Cardiovascular Surgery, School of Medicine & Institute for Medical Science, Keimyung University, Daegu, Korea.