Funding for this research was provided by:
National Research Foundation of Korea (NRF-2019K2A9A2A08000108, NRF-2019R1A2C1003259, NRF-2020R1A2C1003378, NRF-2018R1A6A1A03023718)
Received: 2 February 2020
Accepted: 9 May 2020
First Online: 16 May 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Institutional Review Board of Yonsei University (7001988-201903-HR-544-01E), which waived the requirement to obtain informed consent because of the de-identified nature of the data.
: Not applicable.
: The authors declare that they have no competing interests.