1. Department of Orthopedic Surgery, Stanford University College of Medicine (Visiting professor), Stanford, CA, USA.
2. Department of Orthopaedic Surgery, Konyang University School of Medicine, Deajeon, Korea.
3. Department of Orthopaedics, Graduate School of Medicine, Yonsei University, Seoul, Korea.
4. Department of Orthopaedic Surgery, Ajou University School of Medicine, Suwon, Korea.