Royal Noble Consort was the title of royal concubines of Korean kings (including the Three Kingdoms, Unified Silla, Goryeo and Joseon Dynasty periods). During the Joseon Dynasty (not including the Korean Empire at the end of Joseon), they were part of the naegung (내궁) and ranked beneath the queen, but above low-ranked concubines and court ladies (rank 5a and below). This meant that Royal Noble Consorts from rank 1 to 4 were considered part of the Royal Family.
Thus, the Queen Consort (jungjeon 중전) was followed by 4 categories of high-ranked royal consorts, with 2 levels each. Level a (jeong, 정) ranked above level b (jong, 종):
1a. Bin 빈 (嬪): Royal Noble Consort rank 1
1b. Gwiin 귀인 (貴人)
2a. Soeui 소의 (昭儀): Royal Noble Consort rank 2
2b. Sukeui 숙의 (淑儀)
3a. Soyong 소용 (昭容): Royal Noble Consort rank 3
3b. Sukyong 숙용 (淑容)
4a. Sowon 소원 (昭媛): Royal Noble Consort rank 4
4b. Sukwon 숙원 (淑媛)
For the rank of Bin, the King or Queen consort would attach a prefix in association with the character/personality of the Royal Consort, such as Huibin (Hui = Radiant), Sukbin (Suk = Clarity/Purity), Euibin (Eui = Appropriate/Fitting), and so forth. However, they are all of the same rank "Bin" so they are all of equal rank.
5a. sanggung (상궁 or 尙宮) and sangeui (상의 or 尙儀) Court Ladies who served directly under the royal family members, and the head manager of their assigned department. Depending on their role and department, there would be internal ranking within the sanggung. For example, a sanggung who served the Queen has higher authority and ranking than a sanggung who serves a prince, princess, and/or concubine. A sanggung could also become a "Royal Concubine" if the King showed favor. They would be called "favored sanggung" and would be considered the highest rank of the 5a. However, since they are still in the rank of 5, the "favored sanggung" would not be considered a member of the royal family, part of the naegung, and considered a Royal Noble Consort. Instead, they would just be known as a concubine of the rank of sanggung. However, the favored sanggung would have a sanggung of her own to serve her.
5b to 9b. Rankings of the lower class palace ladies and girls. Palace ladies are usually admitted into the palace from a young age. Therefore, the palace becomes their primary residence. They are not allowed to leave the palace except on special occasions with the permission of the higher ranking.