1. Dept. of Biomedical Engineering, Institute of Medical Engineering, Yonsei University, 220-710 Heungup, Maeji, Wonju, Gangwon, 220-710, South Korea
2. Alfred E. Mann Institute for Biomedical Engineering, University of Southern California Los Angeles, CA 90089-1112, USA
3. Dept. of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA 90089-9006, USA
4. Clinical Mechanics Group, Queen's University, Kingston, ON, K7L 3N6, Canada