Abstract: The pre-cast concrete structure of the present invention comprises a lower unit structure 110 having the lowest stage unit structure 111, the middle stage unit structure 112, and the highest stage unit structure 113 which are vertically orderly piled on another and wedged from each other; a middle unit structure 130 having the lowest stage unit structure 131, the middle stage unit structure 132, and the highest stage unit structure 133 which are vertically orderly piled on another and wedged from each other; and a upper unit structure 150 having the lowest stage unit structure 151, the middle stage unit structure 152, and the highest stage unit structure 153 which are vertically orderly piled on another and wedged from each other.

Abstract: The apparatus 100 of the present invention comprises a supporting body 110 for firmly supporting the pipe 10 from its inside, a guiding body 130 for guiding the movement of the supporting body 110 in longitudinal and radial directions of the pipe 10, an operating body 150 for operating the supporting body 110, the operating body 150 movably connected to the guiding body 110, a connecting member 170 for connecting the supporting body 110 and the operating body 150, and a contact preventing body 190 for preventing the direct contact between the operating body 150 and the connecting member 170 so as to guarantee the well operation of the operating body 150.

Abstract: The apparatus 100 for connecting bars according to the present invention comprises a pair of bodies 100 for receiving the bars 1, the pair of bodies having cylindrical shape which faces from each other; a plurality of stoppers 120 for firmly holding the bars 1, the plurality of stoppers 120 provided in the pair of bodies in two steps or several steps; a spring 130 for elastically longitudinally supporting the pair of bodies 110, the spring 130 provided in the bottom surface of the plurality of stoppers 120; and an elastic ring 140 for elastically supporting the plurality of stoppers 120 in the radial direction of the pair of bodies, the elastic ring 140 provided on the inner peripheral surface of the plurality of stoppers 120.