Queen Sasuk of the Gyeongwon Yi clan (Korean: 사숙왕후 이씨; Hanja: 思肅王后 李氏; c.1065 – c.1107) was a Korean Goryeo queen consort as the second wife of her first cousin, King Seonjong of Goryeo,[3] and the mother of his successor, King Heonjong.
But after his first wife's death, she formally became Duchess Consort Gukwon (국원공비; 國原公妃) and lived in the Duke's manor (공부; 公府) until his ascension.
As a queen mother, she moved to Yeongnyeong Mansion (영녕부; 永寧府) in Junghwa Hall (중화전; 中和殿) from her reigned day on 1 June in order to purpose the strengthening of the royal power.
[3] While under such circumstances, the queen mother's cousin, Yi Cha-ŭi (이자의), must have lost his life after trying to revolt against Gyerim by making Wang Yun ascend the throne.
"From this point, it can be seen that Yi played a certain role as the spouse of Duke Gukwon and in Goryeosa, (임조칭제, 臨朝稱制; Imjochingje) referred to the political power of the Queen Mother which she used for her regency on behalf of the young-weak King.
""사숙태후는 고려의 문벌귀족 정치가 성하던 시절 대표 문벌가문의 딸로서 섭정을 하며 최고의 권력을 누렸던 여성이라 할 수 있다.