Goryeo nobility

At the time of Goryeo, Korean nobility was divided into 6 classes.

Gukgong (국공, 國公), Duke of a nation Gungong (군공, 郡公), Duke of a county Hyeonhu (현후, 縣侯), Marquis of a town Hyeonbaek (현백, 縣伯), Count of a town Gaegukja (개국자, 開國子), Viscount of a town Hyeonnam (현남, 縣男), Baron of a town

Also the title Taeja (Korean: 태자, Hanja: 太子) was given to sons of emperor. In most other east Asian countries this title meant crown prince. It was similar to Chinwang (Korean: 친왕, Hanja: 親王) of the Korean Empire.