Hangul supremacy
Hangul supremacy is the belief, most widespread in Korea, that the Hangul alphabet developed by King Sejong the Great's Hall of Worthies in 1443 is the simplest, most logical, most beautiful and most scientific of the world's writing systems. In its extreme form, the belief holds that Hangul is in fact best suited for the expression of sounds in all languages.
Hunminjeongeum
Hunminjeongeum (lit. "The Correct/Proper Sounds for the Instruction of the People") is a document describing an entirely new and native script for the Korean language. The script was initially named after the publication, but later came to be known as hangul. It was created so that the common people illiterate in hanja could accurately and easily read and write the Korean language. It was announced in Volume 102 of the "Annals of King Sejong", and its formal supposed publication date, October 9, 1446, is now Hangul Day in South Korea. The Annals place its invention to the 25th year of Sejong's reign, corresponding to 1443–1444.