  We present our analysis on the valence quark distribution functions of the
$K^{+}$ meson, $v^{K (u)} (x, Q^2)$ and $v^{K (\bar{s})} (x, Q^2)$, taking into
account the meson cloud effects in the framework of the chiral constituent
quark model. Assuming appropriate bare quark distribution functions at the
initial scale, evaluating the Goldstone boson dressing corrections with the
model, and performing the QCD evolution, one can obtain the realistic dressed
distributions at a certain scale. The phenomenologically satisfactory valence
quark distribution of the pion was obtained in the previous study and there are
available experimental data of the valence $u$ quark distribution ratio
$v^{K(u)} (x, Q^2) / v^{\pi (u)} (x, Q^2)$, which enable us to obtain the kaon
quark distribution functions. Besides presenting the resulting dressed
distributions, we also show how the meson cloud effects affect the bare
distributions in detail. A striking result is that the observed size of the
SU(3) flavor symmetry breaking is considerably smaller than those seen in the
preceding works based on other approaches.
