  We consider the situation where a spin-induced wavy perturbation is present
on disks of neutron-star low-mass X-ray binaries. By non-linearly coupling with
the perturbation, some modes of disk oscillations resonantly interact with the
disks. We examine the resonant conditions under the assumption that the disks
are vertically isothermal. The results show that when the spin frequency has
some particular values, resonant coupling occurs at some radii. The modes and
frequencies of these resonant oscillations are summarized. Some of these
resonant oscillations seem to explain the frequencies of the observed kHz QPOs
in objects of which the spin frequency is known.
