 From 1442 to 1446, he cooperated with other members of that body to compose the "Hunmin Jeongeum", in which the hangul alphabet was first presented to the world.The level of his involvement in the creation of the Korean alphabet Hangul (and that of other Hall of Worthies scholars) is disputed, although he and other scholars were sent on trips to consult with a Ming Chinese phoneticist several times, presumably because one of the first uses the new alphabet was put to was to transcribe the sounds of hanja, or Sino-Korean characters.In 1447, Seong achieved the highest score on the higher literary examination.