This study aims to develop a restoration model of an armillary sphere of Tongcheon-ui (Pan-celestial Armillary Sphere) by referring to the records of Damheonseo (Hong Dae-Yong Anthology) and the artifact of an armillary sphere in the Korean Christian Museum of Soongsil University. Between 1760 and 1762, Hong, Dae-Yong (1731-1783) built Tongcheon-ui, with Na, Kyung-Jeok (1690-1762) designing the basic structure and Ann, Cheo-In (1710-1787) completing the assembly. The model in this study is a spherical body with a diameter of 510 mm. Tongcheon-ui operates the armillary sphere by transmitting the rotational power from the lantern clock. The armillary sphere is constructed in the fashion of a two-layer sphere: the outer one is Yukhab-ui that is fixed; and the inner one, Samsin-ui, is rotated around the polar axis. In the equatorial ring possessed by Samsin-ui, an ecliptic ring and a lunar-path ring are successively fixed and are tilted by 23.5° and 28.5° over the equatorial ring, respectively. A solar miniature attached to a 365-toothed inner gear on the ecliptic ring reproduces the annual motion of the Sun. A lunar miniature installed on a 114-toothed inner gear of the lunar-path ring can also replay the moon's orbital motion and phase change. By the set of ‘a ratchet gear, a shaft and a spur gear’ installed in the solstice-colure double- ring, the inner gears in the ecliptic ring and lunar-path ring can be rotated in the opposite direction to the rotation of Samsin-ui and then the solar and lunar miniatures can simulate their revolution over the period of a year and a month, respectively. In order to indicate the change of the moon phases, 27 pins were arranged in a uniform circle around the lunar-path ring, and the 29-toothed wheel is fixed under the solar miniature. At the center of the armillary sphere, an earth plate representing a world map is fixed horizontally. Tongcheon-ui is the armillary sphere clock developed by Confucian scholars in the late Joseon Dynasty, and the technical level at which astronomical clocks could be produced at the time is of a high standard.

ABSTRACT
1. 서론
2. 문헌과 유물
    2.1. 홍대용『담헌서』의 〈통천의〉
    2.2. 국립중앙과학관의 천하도
    2.3. 숭실대학교 혼천의 유물
3. 통천의의 혼천의 모델
    3.1. 태양·달 모형의 운행 모델
    3.2. 구조와 제원
4. 토의
    4.1. 자동운행 혼천의
    4.2. 통천의의 역사적 의미
5. 결론
REFERENCES

• 민병희(한국천문연구원/과학기술연합대학원대학교) | BYEONG-HEE MIHN (Korea Astronomy and Space Science Institute/Korea University of Science and Technology)
• 윤용현(국립중앙과학관) | YONG-HYUN YUN (National Science Museum)
• 김상혁(한국천문연구원) | SANG HYUK KIM (Korea Astronomy and Space Science Institute)
• 기호철(문화유산연구소 길) | HO CHUL KI (Ghil Institute of Cultural Heritage)