And as I know, there is not historical material to prove that.
(Sorry. I'm not convinced since I'm not mager in history.)
I found a paper about it, and I'll introduce it.
Korean History : A Study of Description to Corea and Korea
- 한국사상과 문화, 36권, 단일호, 시작쪽수 269p, 전체쪽수 16p - by 이민식
At present, many Koreans have interested in the description of Corea and Korea. I studied the description through History. It was description of Corea that many foreigners had been eary written according to the rule of the description of Latin. Many Portugeseses initially began to write from AD 1517 ``Coreia``. French geographer J. B. B. D′Anville wrote in his map ``Coree``. The description of Corea was written in USA from AD 1818. In 1832, Edmund Robers write ``Corea``(高麗) on his paper. Afterward it was Corea that the USA Congress used on the description of Korea at the proposal for Korea in 1845.