Funding for this research was provided by:
Korea Health Industry Development Institute (Grant HC15C1335)
Article History
Received: 8 January 2019
Accepted: 27 August 2019
First Online: 18 September 2019
Ethics approval and consent to participate
: This study was approved by the institutional ethics review committee of Ulsan University Hospital (approval number 2009-09-061-011). The parents or legal guardians of all participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.