1. Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Rehabilitation Medicine, Incheon Workers' Compensation Hospital, Incheon, Korea.
3. Department of Intelligent Systems Engineering, Indiana University, Bloomington, IN, USA.
4. Department of Rehabilitation Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Incheon, Korea.
5. Institute of Public Health and Medical Service, Seoul National University Hospital, Seoul, Korea.