Text and Data Mining valid from 2018-02-12
Received: 20 November 2017
Accepted: 26 January 2018
First Online: 12 February 2018
Compliance with Ethical Standards
: Suk Kyun Hong, Kyung-Suk Suh, Hyo-Sin Kim, Kyung Chul Yoon, Sung-Woo Ahn, Hyeyoung Kim, Nam-Joon Yi, and Kwang-Woong Lee have no conflicts of interest.