If you change housing then you are required to report this to the Immigration office. The change must be noted on your alien registration card. It is, however, an easy process. You need to fill out a form and take it to either the Immigration Office, or your local Municipal (dong) office.
Notification of a change of address needs to happen within two weeks of moving.
Note: For people living near KAIST and Chungnam University, you can get your address updated from "Yusueong Gu-Cheong" office.