1. Ministry of Employment and Labor of Korea, 2014 statistics of disabled, Report for Employment Development Institute of Korea, Report no. Statistic Survey 2014-04, December (2014) 25–29.
2. Ministry of Health and Welfare of Korea, 2011 report of an actual condition on disability, Report no. 11-1352000-000568-12, 127-130.
3. F. Sup, H. A. Varol, J. Mitchell, T. J. Withrow and M. Goldfarb, Self-contained powered knee and ankle prosthesis: Initial evaluation on a transfemoral amputee, IEEE 11th International Conference on Rehabilitation Robotics (2009) 638–644.
4. E. C. Martinez-Villalpando and H. Herr, Agonistantagonist active knee prosthesis: A preliminary study in level-ground walking, Journal of Rehabilitation Research & Development, 46 (3) (2009) 361–374.
5. C.-Y. Ko, S.-B. Kim, J. K. Kim, Y. Chang, H. Cho, S. Kim, J. Ryu and M. Mun, Biomechanical features of level walking by transtibial amputees wearing prosthetic feet with and without adaptive ankles, Journal of Mechanical Science and Technology, 30 (6) (2016) 2907–2914.