In Korean tradition, dreaming of a prison is read as inauspicious. It is most often tied to 전반, 직장.
Prison is a stifling situation and lost freedom; yet being freed from it was often read as misfortune spent and great luck to come.
Tradition reads the symbol as an omen; psychology reads the same dream as a mirror of your present state. Describe your dream and both readings appear together. Interpret your dream