Inspector's Map of Ulleungdo Shows Jasando (子山嶋)?

The following is one of the old maps of Ulleungdo drawn by one of the Joseon Dynasty inspectors to the island. I do not know the date of the map, but the map was shown on a KBS special on Ulleungdo Inspector Lee Gyu-won. You can see the special HERE if you are registered with the KBS Web site. It is quite interesting. You can see the map below at 17 minutes 38 seconds (17:38) into the video.

Anyway, on the map below you will notice that the sizes of the rocks surrounding Ulleungdo are exaggerated. If you look off Ulleungdo's east shore, there seems to be an island labeled as Jasando (子山嶋), which would be a misspelling of Usando (于山島). I do not know if that island is supposed to be Jukdo or Gwaneumdo, but it does seem to be labeled as "Jasando" (子山嶋). Korea claims that Usando was the old name for "Dokdo" (Liancourt Rocks), but Korea's old maps of Ulleungdo show that Usando was Ulleungdo's neighboring island of Jukdo. I wonder why none of Korea's Dokdo books or Web sites include the map below?

By the way, in the video, the KBS reporter interviewed a man at the Daepungheon (待風軒), which is a building at Gusan Harbor in Uljin County, North Gyeongsang Province, that was the very same building that Lee Gyu-won and other Ulleungdo inspectors stayed while waiting for fair winds to take them to Ulleungdo. During the interview, the men at the building, which is now a community center, showed the reporter a few of the old documents from those inspections. The man said that they used to have a lot more documents, but they were all intentionally burned a few decades ago. Can anyone imagine a reason for burning such historic documents? Did the Rhee or Park administrations have something to hide?