  We use the modified quark-meson coupling and the quantum hadrodynamics models
to study the properties of neutron star. Coupling constants of both models are
adjusted to reproduce the same saturation properties. The onset of kaon
condensation in neutron star matter is studied in detail over a wide range of
kaon optical potential values. Once the kaon condensation takes place, the
population of kaons increases very rapidly, and kaons become the dominant
component, possibly making the neutron star matter a kaonic matter if the kaon
optical potential is large.
