Text and Data Mining valid from 2018-12-01
Received: 26 July 2018
Accepted: 5 December 2018
First Online: 20 December 2018
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Yonsei University Wonju College of Medicine. We obtained written informed consent from each participant and his legal guardian. Participation was voluntary, and Participants could withdraw at any time from the study.
: Not applicable.
: The authors declare that they have no competing interests.
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