Joseon Dynasty
The Joseon Dynasty under the reign of Sejong the Great was Korea's greatest period of scientific advancement. Under Sejong's new policy that allowed Cheonmin (low-status) people such as Jang Yeong-sil to work for the government. Jang is one of Korea's most famous inventors. When he was very young he built machines to help make worker's jobs easier such as aqueducts, canals among others. Jang eventually was allowed to live at the royal palace where he led a group of scientists to work on advancing Korea's science.
Some of his inventions were an automated (self-striking) water clock, the Jagyeokru which worked by activating motions of wooden figures to indicate time visually was invented in 1434 by Jang Yeong-sil, who later developed a more complicated water-clock with additional astronomical devices, as well as an improved model of the previous metal movable printing type created in the Goryeo Dynasty. The new model was of even higher quality and was twice as fast. Other inventions were the sight glass, and the udometer.
Also during the Joseon Dynasty Heo Jun, a court physician wrote a number of medical texts, but his most significant achievement is Dongeui Bogam, which is often noted as the defining text of Traditional Korean medicine. The work spread to China and Japan, where it is still regarded as one of the classics of Oriental medicine today.
The highpoint of Korean astronomy was during the Joseon period, where men such as Jang created celestial globes which could, whether day or night, allow the instrument to be updated on the positions of the sun, moon, and the stars among other devices Later celestial globes (Gyupyo, 규표) could measure time changes according to the seasonal variations.
The apex of astronomical and calendarial advances made under King Sejong was the Chiljeongsan, made up of compiled computations on the courses of the seven heavenly objects (five visible planets, the sun, and moon) developed in 1442. This work made it possible for scientists to calculate and accurately predict all the major heavenly phenomena, such as solar eclipses and other stellar movements. Honcheonsigye is an astronomical clock created by Song I-yeong in 1669. The clock has an armillary sphere with a diameter of 40 cm. The sphere is activated by a working clock mechanism, showing the position of the universe at any given time.
Kangnido, a Korean made map of the world was created in 1402, by Kim Sa-hyeong (김사형, 金士衡), Yi Mu (이무, 李茂) and Yi Hoe (이회, 李撓). The map was created in the second year of the reign of Taejong of Joseon. The map was made by combining Korean and Chinese maps.
Hangul, the first and only featural alphabet in current use for a national language, was promulgated by Sejong in 1444.
Read more about this topic: Science And Technology In Korea