The study analyzed how beach changes occurred after building submerged breakwaters in South Korea. The researchers looked at wave currents, wave heights, beach shapes, and shoreline movements to see how sand moved in the area. They found that building a harbor in 2006 caused sand to shift from one beach to another, leading to erosion. Even after building breakwaters, erosion continued in some places due to new sand patterns. The breakwaters also created rip currents that moved sand offshore. One beach lost sand while another gained it, and erosion continued near the breakwaters. The study shows that careful monitoring is needed during breakwater construction to prevent unexpected erosion.