Origin of Hangul
Ledyard holds that the Koreans adopted five core consonant letters from ’Phags-pa, namely ㄱ "g" , ㄷ "d" , ㅂ "b" , ㅈ "j" , and ㄹ "l" . These were the consonants basic to Chinese phonology, rather than the graphically simplest letters (ㄱ "g" , ㄴ "n" , ㅁ "m" , and ㅅ "s" ) taken as the starting point by the "Haerye." A sixth letter, the null initial ㅇ, was invented by Sejong. The rest of the consonants were developed through featural derivation from these six, essentially as described in the "Haerye"; a resemblance to speech organs was an additional motivating factor in selecting the shapes of both the basic letters and their derivatives.
Movable type
A potential solution to the linguistic and cultural bottleneck that held back movable type in Korea for 200 years appeared in the early 15th century—a generation before Gutenberg would begin working on his own movable-type invention in Europe—when Sejong the Great devised a simplified alphabet of 24 characters (hangul) for use by the common people, which could have made the typecasting and compositing process more feasible. But Korea's cultural elite, "appalled at the idea of losing hanja, the badge of their elitism", stifled the adoption of the new alphabet.