  We examine the behavior of the vortex defects, which are represented by the
sine-Gordon potential, on the world-sheet when a solitonic d-5 brane is
existing in the d-dimensional target space. The d-5 brane solution is obtained
as an extension of 5-brane in 10d supergravity. It is shown that the vortices
of any charge should be dissociated to the free gas when they approach to the
brane. The meanings of this fact are addressed through the analysis of the
renormalization group equations on the world sheet.
