Funding for this research was provided by:
Ministry of Science, Korea through the R&D program (NRF-2017R1C1B2010379)
Text and Data Mining valid from 2018-09-10
Received: 14 June 2018
Accepted: 23 August 2018
First Online: 10 September 2018
Compliance with ethical guidelines
: S.H. Choi, H.I. Yoon, S. Yi, J.W. Park, J. Cho, D.A. Shin, Y. Ha, D.-S. Kim, S.H. Kim, S.-K. Lee, J.H. Chang and C.-O. Suh declare that they have no competing interests.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.