Flag of the Republic of Korea 

The flag of the Republic of Korea (taegukki) was raised officially for the first time in history in 1882 as a symbol of the national sovereignty. It happened at the time when a group of progressive statesmen of Korea went to visit Japan. 
On March 6, 1883 the King Kojong issued a decree about the image of the flag. At the center of white background there is a red and blue round symbol of yin and yang energies which in confronting each other give harmony and balance. Trigrams, corresponding to different classical elements. 

Three solid lines on top represent heaven, three interrupted lines in the right bottom corner mean earth. Two solid lines with an interrupted one in between at the left bottom corner symbolize fire, and the trigram cornerwise is the symbol of water.