Text and Data Mining valid from 2018-02-13
Received: 23 July 2017
Accepted: 7 February 2018
First Online: 13 February 2018
Compliance with ethical standards
: Drs. Cheal Wung Huh, Joon Sung Kim, Hyun Ho Choi, Ja In Lee, Jeong-Seon Ji, Byung-Wook Kim, and Hwang Choi have no conflicts of interest or financial ties to disclose.