Gat

A gat is a type of Korean traditional hat worn by men along with hanbok (Korean traditional clothing) during the Joseon period. It is made from horsehair with a bamboo frame and is partly transparent.

Most gat are cylindrical in shape with a wide brim on a bamboo frame. Before the late 19th century, only noble class men could wear gat, which represented their social status and protected their topknots (Korean: 상투; RR: sangtu).

Gwanghwamun, September 1, 1894
Artisans who make gat are called gatiljang (갓일장) in Korean, from gatil (갓일 “hatmaking, millinery”) + jang (Korean: 장; Hanja: 匠 “artisan, craftsman, master of a craft”). As it is a very complex process and requires different materials, gatiljang today is considered as Intangible Cultural Property No.4. More details can be found from Youtube video “Culture Heritage I The making of the Korean Gat”.

+ref  Wikipedia