Here is some important information with regard to overseas visitor.

Korea government announced “From June 8, people entering the Republic of Korea will be exempt from 7 days quarantine regardless of whether they have been vaccinated against COVID-19."

※ Please note that submission of COVID-19 negative confirmation and Q-code are still maintained.

Q-code webpage:   English     Korean 

1) The COVID-19 PCR negative confirmation certificate required for entry into the Republic of Korea is 'a test certificate issued within 48 hours of the departure date (not the departure time)'.

2) Inspection of overseas entrants is maintained twice before and after entry.
    - (Before entry) PCR or RAT, (After entry) PCR test within 3 days

* For all travelers entering the Republic of Korea, a supervised negative COVID-19 Rapid Antigen Test (RAT) result will be additionally accepted from May 23, 2022.

Related document from the government (mohw.go.kr)