Endless varieties
This ring is used to attach the jangdo to the clothes. Men would thread a special braid through the loop and fix it to their coat strings or belt, while women would fasten the dagger to the waistband under their skirt, often as part of a norigae, which is an ornament worn on the clothes.
The braided threads and knots, besides being pleasing to the eye, also have a symbolic meaning to them. Legend says that two soulmates are connected to each other by a red thread, the thread of fate. It is believed to be so strong that it will bring the two people together, no matter how far apart they are. The knots that are present in the norigae are very strong, extremely complicated, and will most likely end up more tangled when trying to take them apart by force. They can only be unraveled with patience, piece by piece, so the connection between the two proposed soulmates stays intact.
Being part of a norigae is just one of the ways a jangdo can be worn. On top of that, depending on how the knife is carried, it can be called by a different name. When a jangdo is worn on the clothes, as mentioned earlier, it is called a paedo. The dagger could also be carried around in a pocket, which would then be called a nangdo.