This promulgator of Confucianism established the Hall of Worthies, a group of scholars whose most famous work during his reign was entitled The Proper Sounds For the Instruction of the People.
This ruler lends his name to an Aegis-enabled KDX Phase III class of destroyers. A poetry collection compiled by this man includes an entry detailing how trees with deep roots don't sway in the wind, and is entitled The Songs of the Dragons Flying to Heaven.  During this man's reign, one of his children and an originally low-class scientist collaborated to invent the rain gauge. This ruler established a series of four forts and six military outposts to counteract the Jurchen. Under the guidance of his father, this man launched an expedition against a polity controlled by So Sadashige that had become a base for pirates; that assault on Tsushima was the (*) Oei invasion. This man's second son was targeted in a coup attempt by the Six Martyred Ministers, who were originally appointed by this man. This promulgator of Confucianism established the Hall of Worthies, a group of scholars whose most famous work during his reign was entitled The Proper Sounds For the Instruction of the People. For 10 points, name this Joseon ruler of Korea who created the Hangul alphabet.
This ruler lends his name to an Aegis-enabled KDX Phase III class of destroyers.
King {Sejong} the Great