1. Department of Biomechatronic Engineering College of Biotechnology and Bioengineering Sungkyunkwan University Suwon 16419 South Korea
2. Department of Neurosurgery, Spine and Spinal Cord Institute Severance Hospital Yonsei University College of Medicine Seoul 03722 South Korea
3. Department of Neurosurgery CHA University School of Medicine CHA Bundang Medical Center Seongnam‐si 13497 South Korea
4. Biomedical Institute for Convergence at SKKU (BICS) Sungkyunkwan University Suwon 16419 Republic of Korea