Individuals applying for a visa related to remunerative activities or long-term stay may apply for a certificate of visa issuance. (To see types of visas which qualify for the certificate, please visit g4f (http://www.g4f.go.kr).)
Procedure
A. Foreigners can obtain a visa by submitting the certificate received from a Korean national who intends to invite him or her. B. A Korean national can obtain the certificate by submitting an application form and required documents at the Korea Immigration Service. C. Foreigners can apply by completing a visa application form with a passport and recent passport-type color photograph, along with a visa fee.
*g4f(http://www.g4f.go.kr) stands for Government for Foreigners. This site provides comprehensive information for foreigners who want to visit or live in Korea, including guide on immigration to the Republic of Korea.