Abstract: A prefabricated structure for a composite window apparatus using different frame materials. The sides of the corners of adjacent first window frames and adjacent first sash frame which made of synthetic resin are punched, the punched parts of the first window frames, the punched parts of the first sash frames and the parts of the angle pieces are bent inwardly. When the punched parts of the angle piece are bent into the corner piece, the window frame compression flanges of the first window frames are pressurized by the angle piece and the corner piece, and the sash frame compression flanges of the first sash frames are pressurized by the angle piece and the corner piece, so that the corners of the first window frames and the corners the first sash frames are connected to respective angle pieces and corner pieces.

Abstract: There is provided a window/door system having an easily changeable structure characterized in that: a striker holder connected to a striker to be laid in an installation space on a side jamb of a window or door frame, a finishing cap connected to the striker holder, to support the striker in the striker holder, the striker and the striker holder are laid in the installation space between frame rails, not to protrude into a passage space of the window or door frame.

Abstract: There is provided a window/door system having an easily changeable structure characterized in that: a striker holder connected to a striker to be laid in an installation space on a side jamb of a window/door frame, a finishing cap connected to the striker holder, to support the striker in the striker holder, the striker and the striker holder are laid in the installation space between frame rails, not to protrude into a passage space of the window/door frame. Therefore, since the striker does not protrude into the passage space of the window/door frame, the nice appearance of the window/door system is maintained. Also, when a user passes the passage space of the door frame, since the striker does not contact any part of the user, any accident is prevented.

Abstract: There is provided a prefabricated window/door structure with interconnecting 45 degree joints where a horizontal bar has its both ends cut at an angle of 45 degrees and includes: a first connection space formed in the direction of the length of the horizontal bar so that the inner space of the horizontal bar is open to the outside, and a screw fastening part with a screw fastening groove protruding in the first connection space; a vertical bar has its both ends cut at an angle of 45 degrees to form a joint of 45 degrees when each of the ends of the vertical bar faces each of the ends of the horizontal bar and includes: a second connection space formed in the direction of the length of the vertical bar so that the inner space of the vertical bar is open to the outside, and a screw hole formed on a side wall in the second connection space, to be aligned with the screw fastening groove; and a support block includes: a first support part to be inserted into the first connection space of the horizontal bar and a s