Since the movement of the injected resin expands in concentric circles, the injection pressure will not produce defects or separation. Made of transparent material, users can easily observe the injection volume clearly with eyes. Because it allows users to clean structural maintenance while maintaining the original state without disassembly or access, it costs less maintenance costs and saves working time. Since the injection is carried out through a low pressure similar to a rubber band, the damage to the sealing area is less. Moreover, in order to provide higher work accuracy, construction management has also become easier.