The interesting thing about the "Gwandongdo" map is that the island of Ulleungdo is labeled with both "Ulleungdo" (鬱陵島 - 울릉도) and "Usando" (干山島 - 간산도), which suggests that the two islands were right next to each other. [干山島 was a misspelling of 于山島.] That is confirmed by the Ulleungdo map, which was in the same book (Book 7) of the atlas and shows Usando as just a small neighboring island off Ulleungdo's east shore. The small island was labeled as "所謂 干山島" (소위 간산도), which means "the so-called Usando."
Notice that the Ulleungdo map has the same spelling error (干山島) for "Usando" (于山島) as the Gangwon Province map. Notice also that in addition to Usando, the Ulleungdo map shows five small islands off Ulleungdo's southern shore, which was a common feature of Korea's Ulleungdo maps.
In the geography section of the "Annals of King Sejong" (1454), Ulleungdo was mentioned in the section describing Uljin-hyeon (蔚珍縣) as follows:
于山武陵二島在縣正東海中二島相去不遠 風日淸明則可望見Korea uses the above passage to claim that Usan was "Dokdo" (Liancourt Rocks), and that the distance being talked about was the distance between Dokdo and Ulleungdo. ["Muleung" was an alternate spelling for Ulleungdo.] However, Japan claims that the distance was a referrence to the distance between Uljin-hyeon (on the mainland) and the two islands. The Gangwon Province map below, which shows the two islands grouped as just one island, supports the Japanese claim that the passage was talking about the distance from the Korean mainland to the two islands, not the distance between the two island.
The two islands of Usan (于山) and Muleung (武陵) are in the sea due east of this hyeon. The distance to the two islands is close enough that they can be seen on a clear day when the wind is blowing.
Both the "Gwandongdo" map and the Ulleungdo map came with attached notes, which are also shown below. The "Gwandongdo" map notes mentioned such things as the population of the region and the number of fields and paddies. The Ulleungdo map notes gave the size of the island and listed the flora and fauna found there.