See first photo in https://www.yna.co.kr/view/AKR20230307131700056 (article in Korean)

The machine in the second photo looks like a cannon but actually sprays insecticide. The goal is to remove insects that the birds feed on, giving them less reason to approach the area in the first place.

Due to the proximity of most Korean airports to residential areas and important military targets, an automated cannon that makes explosive sounds at random would be a big no-no. People would think the airport was being bombarded, or more likely, the President had declared martial law again :(