Korea is becoming a popular place to further education and have the experience of a lifetime or to study some Korean. There are over 45,000 foreigners studying in Korea every year. The majority are on D-4 visas and studying Korean in university or at a language school. Others are participating in university exchange programs, on scholarships or obtaining a masters degree or PHD.
People who wish to attend a university and study need the D-2 visa (D-4 if you wish to study Korean). Here is a guide on how to get the D-4 visa. The D-2 visa procedure is quite similar to that of the D-4 visa.
In Korea the beginning of the school year starts in March. This is usually a good thing as it gives western students time to prepare for the big move to Korea after they finish their course. For people who wish to attend a language school or university language course the programs usually run at intervals of 3 months. The first course usually starts in Feb / March and the next in June / July and so on. You can join at anytime.
For more information about studying in Korea check out this Study in Korea site run by the government.