Naeuiwon, also known as Yakbang, was a place where medicine was made for the royal family. It was an institution responsible for the health of the king and the whole royal family. Doctors and women who studied Korean medicine worked here, and it is also the place where famous Korean dramas such as "Heojun" and "Dae Jang Geum” were filmed.

Doctors like Heojun, who worked at Naeuiwon, were all elites who passed the state examination. In the Joseon Dynasty, three examinations were set up to select medical officers. The first is the Noksi, an examination for students enrolled in Hyeminseo, Jeonuigam, and government offices as medical students to be in charge of medical care for the common people. The second is Uisi, which was a medical examination for selecting royal physicians and was held once every three years at Yejo. Yejo is a government office that has jurisdiction over schools and religious ceremonies. The last one is the Chuijae, a test for recruiting special talents. If the person passed even one of them and another exam in the medical office, he would be able to work as a medical officer at the Naeuiwon.

The highest-ranking medical officer among the royal physicians was called Eoui. Heojun was one of the doctors who worked at Naeuiwon and wrote many famous medical books. On the other hand, medical women didn't have to take any special exams. Even commoner-class women could work as medical women if they had knowledge of medicinal materials or could give out simple treatments.