Jang Yeong-sil was a prominent Korean scientist and astronomer during the Joseon Dynasty (1392–1910). Although Jang was born as a peasant, King Sejong's (r. 1418–1450) new policy of breaking class barriers placed on the national civil service allowed Jang to work at the royal palace. Jang's inventions, such as the Cheugugi (the rain gauge) and the water gauge, highlight the technological advancements of the Joseon Dynasty.
Read more about Jang Yeong-sil: Early Years, National Civil Service, Expulsion