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.
Hangul Day
In 1931, the celebration of the day was switched to October 29 of the Gregorian Calendar, the calendar which is in contemporary use. Three years later, the date was moved to October 28, to coordinate the date with that of the Julian Calendar, which had been in use during the 15th century, when King Sejong had made his proclamation.