There might be a month of waiting time to get a Korea Visa. Therefore it is recommended that you register well in advance and apply for your visa. The full list of countries whose nationals do not need a visa can be found on Ministry Of Foreign Affairs website (http://www.hikorea.go.kr/pt/en/info/popup/icis/VisaWaiver_pop.htm).
Invitation letters will be sent upon request only. Please send requests to firstname.lastname@example.org with the title "VISA invitation letter" and include your name, affiliation, mailing address, and email address. Letters will be sent electronically unless a paper copy is requested.