https://www.epo.org/en/service-support/faq/searching-patents/asian-patent-information/korea/filing-grant/how-soon-after

How soon after filing an application in Korea do I need to file a request for examination?

For both patent and utility model applications, you should submit this request within three years of the date of filing or (for PCT applications) the international filing date.

With regard to filings until 28 February 2017, the time period for submitting the examination request was five years from filing day for patent applications and three years from filing day for utility model applications.

It is also possible to request accelerated examination on certain specific grounds.

If you require a more detailed answer, please send us your question using the contact form.