Cheopji was an ornament placed on the top of knotted hair, which was arranged into a jjeokjin meori style, and used to be worn when women dressed in ceremonial dresses (dangui).
It’s the counterpart of baetssi daenggi, another hair ornament designed for the top of the head which was used to be worn by unmarried women, however, unlike the baetssi daenggi, cheopji was made of metals (often gold or silver) in the shape of dragon, peacock, phoenix, duck, bird, frog, or flowers.
Long tails were attached on both sides and knotted together with the hair.
Royal court ladies used it everyday, but commoners wore it only with ceremonial dress. It also functioned as a fastening for jokduri or hwagwan.
As it’s with other accessories the social status of the wearer was indicated by the decoration, shape, and materials used.
This kind of hairpin was always worn by women of the royal family to show their status. A gilt ornamental dragon hairpin was worn by the queen.
The phoenix yet again by the wife of the crown prince and the royal concubines,frogs by wives of the hightest ranking officials, silver frogs worn by court ladies and black frogs by upper-class women at the funerals of their parents or husbands.
However, the cheopji designs also include flower or animal shapes such as various kinds of birds.
Source: wikipedia.com, http://blog.naver.com/springceo1,