In many sects of Buddhism, new sculptures must be consecrated and blessed. Although the ritual varies, it often includes filling the hollow space of the statue with mantra rolls, incense, grain offerings, or as Byron mentioned, silk dyed to represent the cardinal directions. Many believe this invites the deity to inhabit it’s likeness.
Here is a video of the practice performed in the Tibetan tradition:
More information on the history of Korean Buddhist sculpture can be found here.
The consecration ritual continues to be performed both in temples and in the home.