https://www.uscis.gov/sites/default/files/files/form/i-485instr.pdf
All Form I-485 applicants, except refugees and asylees, must submit a photocopy of their birth certificate issued by
the appropriate civil authority from the country of birth.
https://travel.state.gov/content/travel/en/us-visas/Visa-Reciprocity-and-Civil-Documents-by-Country/SouthKorea.html
Issuing Authority: Both certificates are issued by competent government offices, ward offices, city halls, Myun offices, Eup offices, and Dong offices throughout the country.
(영사관이 여기 안적혀있음)