I think you misunderstood me; of course the idea of shooting (with pre-gunpowder weapons) from a fortress is common, because its part of the idea behind fortifications; but that was not what i meant, i rather wondered how widespread the use of cannons and firearms and other gun-powder weapons were in Korea, and to what extent they were employed in defence of fortifications.
Japan was the first nation to use guns in Asia but cannons were frequently used and developed in Korea. As Yang Zongbao explained, the prototype originated in China called Huoche and Koreans innovated this and made variations of the machine.
Cloud God. Be nice.
I will be careful on the words.