Apple is providing service discounts for Korean iPhone customers starting March 29, 2021 through March 28, 2022 for select out of warranty services and for new purchases of AppleCare+ for iPhone. Apple is also providing a credit for customers who purchased AppleCare+ for iPhone between September 11, 2019 and March 28, 2021. See below for details.
https://support.apple.com/ko-kr/apple-korea-iphone-service-discount