[1] In 2006, based on multiple historical sources including the Journal of the Royal Secretariat, Yi Cheong published a 4-volume compilation about the history of his ancestor, Heungseon Daewongun.
[4] In 1942, as a member of noble family, Yi Cheong enrolled in Gakushuin; as of 1944, he returned to Keijō (now Seoul of Korea) and resided in his ancestral home, Unhyeongung.
[8] Under their procession, nevertheless, the scale of current Unhyeongung is much smaller than it used to be, because parts of the land were sold in decades, for various reasons including debt settlement and road expansion.
[10][11] In 1954, Yi Cheong went to Kyunggi High School and later, in 1960, he acquired the decree from the Department of Civil Engineering of Marquette University, United States.
[13] In 1993, due to inability to maintain Unhyeongung, Yi Cheong and his mother decided to sell the palace to the municipal government of Seoul, and he moved to Bugahyeon-dong in Seodaemun District[14] and later to Pyeongchang-dong.