Module coordination(分數), which is crucially relevant to plan shape of a fortress and the location of its gates and chis(雉, protruding posts), have not been thoroughly studied, despite its importance in fortress system. While plan shape of Goryeo fortress features orderly placement of gates and chis, under medium-sized Joseon fortress doesn’t follow it strictly. As a result, fortresses with various plan shapes greatly outnumber those of Goryeo. Especially, Gimhaeeupseong Fortress, which is a large-scale town wall, shows such a complicated plan shape, making it difficult to figure out its modular coordination. Presumably, the reason for Joseon fortress’ complicated plan shapes, which doesn’t follow the orderly modular coordination, is thought to be in its various geographical conditions. Also, it seems that the building of fortress with such various and complicated plan shapes was to deter enemies from intruding by confusing them. And various plan shapes of fortress are also figured out to be pertinent to street system of towns and positions of public offices.