  We examine the effects of the different viscosity prescriptions and the
magnitude of the viscosity parameter, $\alpha$, on the structure of the slim
disk, and discuss the observational implications on accretion-flow into a
stellar-mass black hole. For the range of $\alpha = 10^{-2} \sim 10^{0}$ we
calculate the disk spectra and from spectral fitting we derive $\Tin$, maximum
temperature of the disk, $\Rin$, the size of the region emitting blackbody
radiation with $\Tin$, and $p\equiv -{\rm dln} T_{\rm eff}/{\rm dln}~r$, the
slope of the effective temperature distribution. It was founded that the
estimated $\Tin$ slightly increases as $\alpha$ increases. This is because the
larger the magnitude of viscosity is, the larger becomes the accretion velocity
and, hence, the more enhanced becomes advective energy transport, which means
less efficient radiative cooling and thus higher temperatures. Furthermore we
check different viscosity prescriptions with the form of the viscous stress
tensor of $t_{r \varphi} = -\alpha \beta^{\mu}p_{\rm total}$, where $\beta$ is
the ratio of gas pressure to total pressure, and $\mu$ is a parameter ($0 \le
\mu \le 1$). For $\mu=0$ we have previously found that as luminosity approaches
the Eddington, $L_{\rm E$, $\Rin$ decreases below 3$\rg$ (with $r_{\rm g}$
being Schwarzschild radius) and the effective temperature becomes flatter,
$T_{\rm eff} \propto r^{-1/2}$. Such a slim-disk nature does not appear when
$\mu$ is large, $\mu \sim 0.5$, even at $L_{\rm E}$. Hence, the temperature of
the innermost region of the disk sensitively depends on the $\mu$ value. We can
rule out the case with large $\mu~(\sim 0.5)$, since it will not be able to
produce a drop in $\Rin$ with an increase in luminosity as was observed in an
ultraluminous X-ray source, IC~342, source 1.
