origin : https://en.wikipedia.org/wiki/Jang_Yeong-sil
Jang Yeong-sil (c. 1390 – after 1442) was a Korean engineer and inventor during the Joseon dynasty (1392–1897). 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.
Early years
Jang Yeong-sil's birth is recorded only in the genealogy of the Jang family[1][2] and in the Annals of the Joseon Dynasty.[3] According to these records, his father, Jang Seong-hwi, was the 8th generation of the Jang family.[4][5] Jang Seong-hwi was the 3rd of 5 brothers and all of the brothers previously were ministers of Goryeo. There are many historical records[6] about his elder brother, Jang Seong-bal, who was born in 1344 and his grave located at Ui-seong in the province of Gyeongbuk. The Annals state that his mother was a gwangi (gisaeng), thereby their (Yeong-sil's and their mother) social status was a gwanno,[7] (a servant in civil service district courts).
National civil service
King Sejong the Great of Joseon instituted a policy of selecting officials based on their talent, not by their wealth or social class. Jang's fame gained him entry into the royal court at Hanseong (present-day Seoul), where selected commoners displayed their talents before the king and his advisers. Sejong saw that Jang met his expectations in crafts and engineering, and allowed Jang to work as a government official in the palace.[8] The talented scientists recruited under King Sejong's new program worked at the Hall of Worthies (집현전; 集賢殿; Jiphyeonjeon)
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