  We have constructed an $SU(3)_L \times U(1)_N$ gauge model utilizing an
$U(1)_{L^\prime}$ symmetry, where $L^\prime$ = $L_e-L_\mu-L_\tau$, which
accommodates tiny neutrino masses generated by $L^\prime$-conserving one-loop
and $L^\prime$-breaking two-loop radiative mechanisms. The generic smallness of
two-loop radiative effects compared with one-loop radiative effects describes
the observed hierarchy of $\Delta m_{atm}^2$ $\gg$ $\Delta m_\odot^2$. A key
ingredient for radiative mechanisms is a charged scalar ($h^+$) that couples to
charged lepton-neutrino pairs and $h^+$ together with the standard Higgs scalar
($\phi$) can be unified into a Higgs triplet as ($\phi^0$, $\phi^-$,
$h^+$)$^T$. This assignment in turn requires lepton triplets ($\psi_L^i$) with
heavy charged leptons ($\kappa_L^{+i}$) as the third member:
$\psi_L^i=(\nu^i_L,\ell^i_L,\kappa^{+i}_L)^T$, where $i$ ($=1,2,3$) denotes
three families. It is found that our model is relevant to yield quasi-vacuum
oscillations for solar neutrinos.
