History of South Korea
On August 15, 1948, the Republic of Korea was formally established, with Rhee Syngman as the first president. With the establishment of Rhee's government, de jure sovereignty also passed into the new government. On September 9, 1948, a communist regime, the Democratic People's Republic of Korea (North Korea), was proclaimed under Kim Il-sung. However, on December 12, 1948, by its resolution 195 in the Third General Assembly, the United Nations recognized the Republic of Korea as the sole legal government of Korea.
Public holidays in South Korea
These days celebrate events considered joyous to Korea. In the beginning, Independence Declaration Day (March 1) was first stipulated in 1946. After the establishment of the Government of the Republic of Korea in 1948, four major National Celebration Days (Independence Declaration Day, Constitution Day, Liberation Day, National Foundation Day) were provided by "The Law Concerning the National Celebration Days" (국경일에관한법률) in 1949. 
In 2005, Hangul Day became the 5th National Celebration day.