According to THIS KOREAN LANGUAGE POST, the writer says that after Professor Ledyard's hour-long presentation on Kim Jeong-ho's 1861 "Daedong Yeojido" map, he approached the professor and asked why he had not mentioned anything about Dokdo (獨島) and Gando (間島) in his presentation. He says that Professor Ledyard responded by saying, "Kim Jeong-ho had absolutely no concept of Dokdo and Gando." The writer says he was shocked to hear that America's top expert on the "Daedong Yeojido" did not know that Kim Jeong-ho had drawn "Dokdo" on his 1834 "Jeonggu-do" map of Ulleungdo even though the professor had talked about the "Jeonggu-do" map in his presentation. He says he then showed Professor Ledyard a copy of Kim Jeong-ho's 1834 Ulleungdo map to prove that Kim had known of Dokdo, but that after looking at the map, the professor told him, "Dokdo is not written there." He says that Professor Ledyard then walked away.
The Korean attendee obviously thought that the island labeled as "Usan" (于山) on Kim Jeong-ho's 1834 map of Ulleungdo was proof that Kim had known of "Dokdo" (Liancourt Rocks) and was "shocked" to hear that Professor Ledyard disagreed. I guess the attendee would also be shocked to know that the head of Korea's Dokdo Museum also said that the island labeled as "Usan" on Kim's 1834 map was Ulleungdo's neighboring island of Jukdo, not Dokdo. Here is what the head of Korea's Dokdo Museum said about the island labeled as "Usan" on Kim's 1834 map in a March 19, 2007 article:
Dokdo Museum Director Lee Seung-jin said, “After confirming the three old maps, it is obvious to anyone that they showed Jukdo, not Dokdo; and even in our country’s academic circles, it is judged to be Jukdo.
By the way, the "Daedong Yeojido" map at the University of Wisconsin - Milwaukee has a unique index map that provides more evidence that Kim Jeong-ho did not consider Liancourt Rocks (Dokdo) to be a part of Korea.