Captain Hall kept diaries and published a book based on them ("A Voyage of Discovery to the Western Coast of Corea and the Great Loo-Choo Island in the Japan Sea") upon return home in 1818. He reported the Koreans to be inhospitable, constantly encouraging the White visitors to leave. Captain Hall speculated that the locals' paranoia may have been due to a fear of the government. I learned all this from a post at Gusts of Popular Feeling.
Interestingly, at the back of Captain Hall's book there is included what must be the first Korean-English 'dictionary':
The one that confuses me the most is the supposed translation of "No", though. Captain Hall has it as "Poodong", which is not right at all. Where could that come from?