International students must apply for a residence permit at the Immigration Office of the Korean Government within 90 days from the date of arrival in Korea. When students are registered as an alien, an Alien Registration Card is issued, which is needed in a variety of circumstances. Students are legally obliged to have it on their person. Alien registration should be done at the Immigration Office with jurisdiction for the area in which the applicant lives. Those who stay in Korea more than 90 days without being registered will be considered as illegal aliens and punished by law.
Any inquiries regarding alien registration, entry and exit inspection, visa, immigration laws and regulations, and detention should be directed to one on the Ministry of Justice Immigration Offices.
(http://www.hikorea.go.kr / ☎ 1345)