Gukjo

Gukjo (literally meaning National ancestor) was a temple name given to one of the ancestors of King Taejo of Goryeo. The identity of this ancestor varied depending on the source, with the official history of Goryeo, the Goryeosa, stating that it was his great-great-grandfather, Kang Po-yuk.

Po-yuk
According to P'yŏnnyŏn t'ongnok and Koryŏsa chŏryo, the identity of Gukjo was Kang Po-yuk.

Kang Po-yuk was the son of Gang Chung. He had two brothers named as Ijegŏn and Po-sŭng. Kang Po-yuk married his niece Kang Tŏk-chu, the daughter of his brother Ijegŏn, and their daughter Kang Chin-ŭi was born. Chin-ŭi would be the mother of Chakchegŏn, the grandfather of King Taejo.

Other people
Later period Goryeo individuals questioned the identification of Po-yuk as Gukjo. Yi Che-hyŏn questioned the fact that Po-yuk, who was traditionally portrayed as not being a direct male ancestor of the House of Wang, was given a temple name rather than his son-in-law, Taejo's paternal great-grandfather. Yi believed that Gukjo could not have been Po-yuk as he was not a direct male ancestor of the House of Wang. He pointed out that in the Wangdae Chongjok-ki (Genealogical Record of the Wang Dynasty), a now-lost work, that the temple name Gukjo was given to the great-grandfather of Taejo, the husband of Chin-ŭi. While traditionally her husband was Suzong of Tang, this was already in dispute by the late Goryeo period.

During the late Goreyo period, Yi Saek would claim that that Gukjo was instead Ho-gyŏng instead of Po-yuk.