1. Department of Biomedical Engineering, School of Medicine, Kyunghee University, Seoul 130-702, Korea.
2. Healthcare Industry Research Institute, Kyunghee University, Seoul 130-702, Korea.
3. Department of Neurosurgery, Kyunghee University Medical Center, Kyunghee University, Seoul 130-702, Korea.
4. Program of Medical Engineering, Kyunghee University, Seoul 130-702, Korea.