Text and Data Mining valid from 2019-02-01
First Online: 18 February 2019
Compliance with ethical standards
: JWJL, CJK, and KYH declare that they have no conflict of interest.
: The authors are solely responsible for the data and the content of the paper. In no way, the Honorary Editor-in-Chief, Editorial Board Members, or the printer/publishers are responsible for the results/findings and content of this article.