Funding for this research was provided by:
National Research Foundation of Korea (2018R1D1A1B07049996)
Text and Data Mining valid from 2019-11-21
Received: 4 July 2019
Accepted: 13 November 2019
First Online: 21 November 2019
Ethics approval and consent to participate
: All authors reveal that there is no ethical problem in the production of this paper.
: The authors declare that they have no competing interests.
: All authors want to publish this paper in this journal.