Author contributions
W Cho prepared the manuscript. W Cho and JH Lee prepared the overall organization of the article and collected data and literature. SB Park oversaw all aspects of the manuscript preparation. All authors critically reviewed the manuscript.
Financial & competing interests disclosure
This work was supported by the National Creative Research Initiative Grant (2014R1A3A2030423) through the National Research Foundation of Korea (NRF), funded by the Korean government (Ministry of Science and ICT). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.
No writing assistance was utilized in the production of this manuscript.