I read on website of the Embassy of the Republic of Korea in the USA (mirror):
(sorry for the low resolution, that's the original resolution...)
How am I supposed to undergo diagnostics COVID-19 test within three days after entering South Korea given that I'm supposed to quarantine for 14 days? Does someone come to my place? Or do I have to go to a diagnostics facility, and if so, is there any restrictions on which means of transportation I can take to go there?