This is a dictionary about how to pronounce Chinese characters in Korean. It was compiled by the Gyujanggak (the royal library) at the behest of King Jeongjo in 1800 (the 24th year of his reign). The dictionary contains both the Chinese pronunciation and the Korean pronunciation of each Chinese character, and classifies the characters according to their four tones. As the pronunciations are written in Korean letters, this dictionary constitutes an important material for the study of how Chinese characters were pronounced in Korean during the Joseon Dynasty.