  We propose a new model for describing baryon semi-leptonic decays for
estimating $F$ and $D$ values with explicit breaking effects of both SU(3) and
SU(2) flavor symmetry, where all possible SU(3) and SU(2) breaking effects are
induced from an effective interaction. An overall fit including the weak
magnetism form factor yields $F=0.477\pm 0.001$ and $D=0.835\pm 0.001$ with
$\chi^2=4.43/5$ d.o.f. with $V_{ud}=0.975\pm 0.002$ and $V_{us}=0.221\pm
0.002$. The spin content of strange quarks $\Delta s$ is estimated from the
obtained values $F$ and $D$, and the nucleon spin problem is re-examined.
Furthermore, the unmeasured values of $(g_1/f_1)$ and $(g_1)$ for other hyperon
semi-leptonic decays are predicted from this new formula.
