  Various instabilities have been proposed as a promising mechanism to
accumulate dust. Moreover, some of them are expected to lead to the
multiple-ring structure formation and the planetesimal formation in
protoplanetary disks. In a turbulent gaseous disk, the growth of the
instabilities and the dust accumulation are quenched by turbulent diffusion of
dust grains. The diffusion process has been often modeled by a diffusion term
in the continuity equation for the dust density. The dust diffusion model,
however, does not guarantee the angular momentum conservation in a disk. In
this study, we first formulate equations that describe the dust diffusion and
also conserve the total angular momentum of a disk. Second, we perform the
linear perturbation analysis on the secular gravitational instability (GI)
using the equations. The results show that the secular GI is a monotonically
growing mode, contrary to the result of previous analyses that found it
overstable. We find that the overstability is caused by the non-conservation of
the angular momentum. Third, we find a new axisymmetric instability due to the
combination of the dust-gas friction and the turbulent gas viscosity, which we
refer to as two-component viscous gravitational instability (TVGI). The most
unstable wavelength of TVGI is comparable to or smaller than the gas scale
height. TVGI accumulates dust grains efficiently, which indicates that TVGI is
a promising mechanism for the formation of multiple-ring-like structures and
planetesimals. Finally, we examine the validity of the ring formation via the
secular GI and TVGI in the HL Tau disk and find both instabilities can create
multiple rings whose width is about 10 au at orbital radii larger than 50 au.
