A direct coupling connector assembly comprising a male connector mountable to a first module provided with a first printed circuit board, and a female connector mountable to a second module provided with a second PCB, wherein: the male connector comprises a male connector body comprising a male flange and a male protrusion protruding from the male flange, a plurality of male contacts which penetrate the male connector body and are connectable to the first PCB, a coupling bolt configured to be connected to the male connector so as to be rotatable in place, and a male O-ring recessed into the male flange; and the female connector comprises a female connector body comprising a female flange and a female protrusion protruding from the female flange, a plurality of female contacts each comprising a pin which penetrate through the female connector body and are connectable to the second PCB and a receptor connected to an end of the pin, an inner seal provided in the female protrusion and configured to be in contact with at least a portion of the male connector, a coupling nut provided in the female connector body, a female O-ring recessed into an outer wall of the female protrusion, and a support protruding from a center of the female flange and supporting the coupling nut, wherein the female protrusion comprises: an inner female protrusion separate from the support and surrounding an outer side of the support, and protruding from the female flange; and an outer female protrusion separate from the inner female protrusion and surrounding the inner female protrusion, the male protrusion comprising: an inner male protrusion separate from the coupling bolt, protruding from the male flange and configured to be inserted into an inner side of the inner female protrusion; an outer male protrusion insertable between the inner female protrusion and the outer female protrusion; and a coupling O-ring surrounding the coupling bolt, the coupling bolt comprising a coupling groove indented in a direction perpendicular to a lengthwise direction of the coupling bolt and supporting the coupling O-ring. the male connector comprises a male connector body comprising a male flange and a male protrusion protruding from the male flange, a plurality of male contacts which penetrate the male connector body and are connectable to the first PCB, a coupling bolt configured to be connected to the male connector so as to be rotatable in place, and a male O-ring recessed into the male flange; and the female connector comprises a female connector body comprising a female flange and a female protrusion protruding from the female flange, a plurality of female contacts each comprising a pin which penetrate through the female connector body and are connectable to the second PCB and a receptor connected to an end of the pin, an inner seal provided in the female protrusion and configured to be in contact with at least a portion of the male connector, a coupling nut provided in the female connector body, a female O-ring recessed into an outer wall of the female protrusion, and a support protruding from a center of the female flange and supporting the coupling nut, wherein the female protrusion comprises: an inner female protrusion separate from the support and surrounding an outer side of the support, and protruding from the female flange; and an outer female protrusion separate from the inner female protrusion and surrounding the inner female protrusion, the male protrusion comprising: an inner male protrusion separate from the coupling bolt, protruding from the male flange and configured to be inserted into an inner side of the inner female protrusion; an outer male protrusion insertable between the inner female protrusion and the outer female protrusion; and a coupling O-ring surrounding the coupling bolt, the coupling bolt comprising a coupling groove indented in a direction perpendicular to a lengthwise direction of the coupling bolt and supporting the coupling O-ring. an inner male protrusion separate from the coupling bolt, protruding from the male flange and configured to be inserted into an inner side of the inner female protrusion; an outer male protrusion insertable between the inner female protrusion and the outer female protrusion; and a coupling O-ring surrounding the coupling bolt, the coupling bolt comprising a coupling groove indented in a direction perpendicular to a lengthwise direction of the coupling bolt and supporting the coupling O-ring.