King Sejong the Great(1397 - 1450) A master of Confucian learning, King Sejong's contributions to Korean life ranged from academic studies to practical advice for the peasantry. During his reign, Sejong achieved remarkable advances in many fields, including medicine, astronomy, music, and printing. He invented Hunminjungum; 'the right sounds for the people,' later known as Hangul; the Korean alphabet. He is revered as the greatest king in Korean history.