Korean Post is located in English at http://www.koreapost.go.kr/eng/index.jsp
What zone is your country in? Australia is Zone 3
The most important page is the one that where you type in how heavy your letter/parcel is, what country you wish it to be delivered to and it then lists all the services and prices for you.
http://www.koreapost.go.kr/eng/postal/interfeecheck_eng.jsp