  We reanalyze the photoevaporation problem of subgalactic objects irradiated
by UVB radiation in a reionized universe. For the purpose, we perform
three-dimensional radiation smoothed-particle-hydrodynamics calculations, where
the radiative transfer is solved by a direct method and also the
non-equilibrium chemistry of primordial gas including H$_2$ molecules is
incorporated. Attention is concentrated on radiative transfer effects against
UVB for the formation of subgalactic objects with $T_{\rm vir}\la 10^4$K. We
consider the reionization model with $z_{\rm reion} \approx 7$ and also the
earlier reionization model ($z_{\rm reion} \approx 17$) inferred by the WMAP.
We find that the star formation is suppressed appreciably by UVB, but baryons
at high-density peaks are self-shielded even during the reionization, forming
some amount of stars eventually. In that sense, the photoevaporation for
subgalactic systems is not so perfect as argued by one-dimensional spherical
calculations. The final stellar fraction depends on the collapse epoch and the
mass of system, but almost regardless of the reionization epoch. For instance,
a few tenths of formed stars are born after the cosmic reionization in $z_{\rm
reion} \approx 7$ model, while more than 90% stars are born after the
reionization in the WMAP reionization model. Thus, effects of UVB feedback on
the substructure problem with CDM scenario should be evaluated with careful
treatment of the radiative transfer. The star clusters formed at high-density
peaks coalesce with each other in a dissipationless fashion in a dark matter
potential, resultantly forming a spheroidal system. As a result, these low-mass
galaxies have large mass-to-light ratios such as observed in dwarf spheroidals
in the Local Group.
