Jungin
The chungin (중인, 中人) were the middle people in Joseon Korea. In fact, the name "chungin" literally means "middle people". This small middle class consisted of government employees(government workers, administrative clerks, and palace servants), physicians, teachers, students, and other literati as well professional businessmen, chefs, technicians, court astronomers, artists, and soldiers. Chungin were known as the technical experts of the Korea and the machinery and backbone of the Confucian bureaucracy, for they were the subordinates and assistants of the yangban(upper class). A chungin was a person with intermediate social status, and scholarly habits, as they were the lowest-ranking Koreans who could read and write. Chungin were basically the educated professionals of the Joseon Dynasty. They held professions in law, government, medicine, military arts, culinary culture, commerce, science, art, and language.
In everyday life, the chungin were below the aristocratic yangban but superior to the sangmin. Their roles were minor technical and administrative officials who supported the structure of the government. They were the common professionals we see today: doctors, clerks, lawyers, agents, storekeepers, teachers, and designers who lived a comfortable life but could not afford too many luxuries. The highest-ranking chungin, local functionaries, were the oppressive link between the yangban and sangmin. They lived in the countryside, unlike most chungin, who lived in world class neighborhoods in Seoul. Often, these people were de facto rulers of local regions of the kingdom. The chungin were a very small social level and was therefore not a discreet class till the 1500s.
Although they lived beside poorer city people, the chungin had many privileges the common people did not have. They were not bear the burden of taxation and in times of war, the military draft would not apply to them. However, to become a chungin, one had to pass the chapkwa examination, which tested several technical subjects.
A typical Korean chungin is the equivalent of a lower middle class American. A local functionary would be the equivalent of an American in the upper middle class.