  The single-flavor excluded-volume model based on the effective size of
baryons reproduces the hard-soft density evolution of the equation of state
(EoS) required by the recent studies of GW170817. This phenomenological model
basically realizes the concept of quarkyonic matter which is introduced from
large-$N_{c}$ gauge theory for dense matter. Enhanced nucleon interactions and
dynamically generated quark degrees of freedom can reproduce the hard-soft
evolution of the EoS. In this paper, we extend the excluded-volume model to a
three-flavor system by considering electromagnetic charge and possible weak
equilibrium in order to obtain a proper description for the hard-soft behavior
of the EoS inferred from the gravitational waves observations.
