Aegukka (lit. ”Patriotism Song”) is the national anthem of Korea.
Originally adopted by the Korean exile government (1919–1945) in Shanghai, China as their national anthem Aegukkga was sung to the tune of Auld Lang Syne.
The words were written by Pak Se Yong and the music was composed by Kim Won Gyun. After World War II, South Korea kept the original words, but changed the tune from Auld Lang Syne.
Source: Wikipedia
North Korea adopted the newly written version (top of this post) in 1947.