<Honcheonui> is an astronomical observatory used to measure the movement and position of celestial bodies and is depicted on the 10,000 won bill. It is assumed that Honcheonui was made and used from the late Three Kingdoms period, but it is the first time that Jang Yeong-sil and others made it in 1433 under the order of King Sejong of the Joseon Dynasty. The present Honcheonui is a Honcheon clock made by Song Yi-yeong during the reign of King Hyeonjong of the Joseon Dynasty (1669). The celestial robe is in the shape of the Earth as the center and the planets such as the sun and the moon revolving around the Earth. Since the Earth is at the center and the Earth's axis of rotation passes through it, the Earth's axis of rotation is connected to a clockwork device to make it rotate once a day, thus representing the seasons and time. made it possible to notice the change.