| 摘要 |
<p>A collapsible sash for ventilation of a building according to an embodiment of the present invention may comprise: an apparent frame forming outward appearance; a first frame and a second frame mounted on the apparent frame to be able to rotate from the apparent frame; and a third frame mounted on at least one of the first frame and the second frame and separated from the apparent frame if either the first frame or the second frame rotates.</p> |
