Imun is a set of two doors, one taller than the other. Imun can be seen at the outer boundaries of a palace and also at the boundaries of the inner areas of a palace.
Imun at the outer boundaries of a palace connects the inside and outside of the palace. Examples of imun are Gyeongchumun Gate at the western side of the palace and Wolgeunmun and Seoninmun gates at the eastern side of the palace. The doors of imun were made of wooden boards and used as a gate. Multiple wooden boards were used for a door of a palace for greater security. If we look at royal residential areas such as Yeongyeongdang, Sujeongjeon, and Mansesongeun, we can see imun in different forms at major buildings such as the main hall of the palace and royal bedchambers of the King and the Queen. Imun at these areas were either sets of two wooden doors or a wooden door and drape door. A wooden door was made by inserting a board into a door frame. Depending on the size of a door, a number of wood boards may be inserted separately into several sections. A drape door is like a modern curtain and is made of silk. It was actually two drapes, which were opened by tying the two drapes to each side. Erected in royal residential areas, the taller door of imun was used by members of the royal family and the lower door was used by court ladies. The lower door was used much more frequently that the taller door.