  We considered the quark-meson coupling model for a nucleon. The model
describes a nucleon as an MIT bag, in which quarks are coupled to the scalar
and the vector mesons. A set of coupled equations for the quark and the meson
fields are obtained and are solved in a self-consistent manner. We show that
the mass of a dressed MIT bag interacting with $\sigma$- and $\omega$-meson
fields differs considerably from the mass of the free MIT bag. The effects of
the density-dependent bag constant are investigated. The results of our
calculations imply that the self-energy of the bag in the quark-meson coupling
model is significant and needs to be considered in doing the calculations for
nuclear matter or finite nuclei.
