1. Department of Pediatrics, Yonsei University Wonju College of Medicine, Wonju, Korea.
2. Department of Pediatrics, Ajou University School of Medicine, Suwon, Korea.
3. Department of Psychiatry, Yonsei University Wonju College of Medicine, Wonju, Korea.
4. Department of Psychiatry, Wonju Severance Christian Hospital, Wonju, Korea.
5. Department of Biostatistics, Yonsei University Wonju College of Medicine, Wonju, Korea.