https://ftp.kaist.ac.kr/ubuntu/
https://mirror.morgan.kr/ubuntu/
https://ftp.kaist.ac.kr/ubuntu-ports/
https://ftp.lanet.kr/ubuntu/
https://mirror.siwoo.org/ubuntu/
http://ftp.daum.net/ubuntu/
https://mirror.kakao.com/ubuntu/
https://ftp.lanet.kr/ubuntu-ports/
https://mirror.yuki.net.uk/ubuntu-ports/
https://mirror.elice.io/ubuntu/
https://mirror.yuki.net.uk/ubuntu/
http://archive.ubuntu.com/ubuntu/