Potential conflict of interest
Disclosure forms provided by the authors are available with the full text of this article at http://dx.doi.org/10.3109/10428194.2015.1117610 (www.informahealthcare.com/lal). This research was supported by a grant from the National Research Foundation of Korea (NRF) (NRF-2013R1A1A2013210) funded by Ministry of Education, Science and Technology (MEST), and a grant for the Global Core Research Center (GCRC) (No. 2012-0001190) funded by Ministry of Science, ICT & Future Planning (MSIP), Republic of Korea.