Below is a Korean map of the Korean provinces of Gangwon-do (江原道), Cheongcheong-do (忠淸道), and Gyeonggi-do (京畿道) from a Korean atlas from the 1760s called the "Seon Yeok Do" (鮮域圖). A photo of the atlas cover is shown on the left, and the introduction to the map is shown below. The map is stored HERE in the United States Library of Congress.
The interesting thing about the map is that it gives a long history of Usando (于山島) and Ulleungdo (鬱陵島), and shows Usando as a larger island east of Ulleungdo, which would explain why Usando is listed before Ulleungdo in the description of the two islands.
I may add more to this post later, but I first wanted to get the maps and description posted for possible discussion. If anyone has any opinions on the map, please feel free to express them in the comments section.