The town is spelled Busan
The battle there was not the one I was thinking of, but it sure was a terrible defeat for the Japanese navy, so I will accept it.
I was thinking of the battle of Myeongnyang in which the Koreans defeated the Japanese with only 13 ships while the Japanese had 133, plus about 200 supply ships. The Koreans didn't loose a single ship while 31 Japanese ships were sunk. The Japanese lost between 8000 and 12000 men, the Koreans 34.
Anyway, there were many naval battles during the Imjin War and almost every one was a decisive victory of an inferior Korean force over the Japanese. The battle of Busan is another example of a similarly terrible result for the Japanese.
Your turn Nick.