Funding for this research was provided by:
National Research Foundation of Korea (2018R1D1A1B07049079)
Text and Data Mining valid from 2019-10-22
Received: 18 July 2019
Accepted: 10 October 2019
First Online: 22 October 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of The Catholic University of Korea (No. SC18ZES10009). Anonymous and de-identified information was used for analysis and, therefore, informed consent was not obtained.
: Not applicable.
: The authors declare that they have no competing interests.