Many kinds of astronomical Instruments were made and used in early Joseon Dynasty, which are the Striking Clepsydra, Time-Determining Instrument by the Sun and Stars, Simplified Instrument, Gnomon, Armillary Sphere, Celestial Globe, Scaphe Sundial, Plummet Sundial, and so on. There are over fifteen kinds.

Especially Scaphe Sundial was made of bronze which shape is hemisphere. It was invented in AD 1434 during the King Sejong's Reign. It has been used as a public clock as well as time keeping system for astronomer during Joseon Dynasty (1392-1910). The sundial can be easily find the time and season of the day from the tip of gnomon's shadow on the circles of concave surface. Though the diameter of the hemisphere is about 35 cm, the reading accuracy for time is within five minutes, and for the season within five days.

The Sundial shows a lot of informations on the Sun's position as well as time and season. They are the Sun's azimuth and altitude, the direction of sunrise and sunset, and the duration of daytime on the day in the year. It is possible to estimate the seasonal change and the Sun's path on the sky in each season.

Astronomers and Confucian scholars during Joseon Dynasty understood the motion of heavenly bodies included the Sun and Moon, and cosmological idea from the sundial. The function of the sundial during the period has a clock and calendar as well as a instrument for astronomical purpose. Especially it shows clearly the relation between equatorial and horizontal coordinate system.