After the war, he was dispatched as an emissary to the
Ming Dynasty. In Ming China, he acquired several books written on
Catholicism by an Italian priest,
Matteo Ricci, who was living in China at this time. He brought them back to Korea, which was the first time Western literature had been brought into Korea. He took great interest in the Western world. From the research he developed during his three missions to China, he was able to create a 20-volume encyclopedia, with the title
Jibong Yuseol. The
Jibong Yuseol contained not only information on Catholicism and China, but also on
Japan,
Vietnam, and
Thailand. It also contained basic information on the Western world, including the geography and weather of England, western food, and western weapons. He also wrote about the knowledge of
astronomy that he had acquired from an Italian priest staying in China at the time. He visited China several times, and even met
Thai (known then to Koreans as
Seomra people) emissaries in China. Taking a great interest in the Thais, he closely recorded the customs of the Thai people. He also had contact with emissaries from Vietnam and the Okinawan Islands. ==Government official==