1. Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Daemyung-Dong, Nam-Gu, Daegu, Korea
2. Department of Physical Medicine and Rehabilitation, College of Medicine, Catholic University, Daegu, Korea
3. Research Institute of Medical Engineering, Yeungnam University, Daegu, Korea
4. Department of Anesthesia, University of Kansas School of Medicine, Wichita, KS, USA