Circumstellar disks of young stellar objects (YSOs) at a later stage
are often called protoplanetary disks, as they are the natal place
of protoplanets. In this talk, we present continuum observations at λ
= 1.3 and 2.7 mm using the Combined Array for Research in Millimeter-wave
Astronomy toward six protoplanetary disks in the Taurus molecular
cloud: CI Tau, DL Tau, DO Tau, FT Tau, Haro 6-13, and HL Tau. We
constrain physical properties of the disks with Bayesian inference
using two disk models: the flared power-law disk model and flared
accretion disk model. Comparing the physical properties, we find
that the more extended disks are less flared and that the dust
opacity spectral index (β) is smaller in the less massive disks.
In addition, disks with a steeper mid-plane density gradient have
a smaller β, which suggests that grains grow and radially move. We
also discuss the possibilities of substructures on three extended
protoplanetary disks. Furthermore, the HL Tau disk images taken
by the Atacama Large Millimeter/submillimeter Array (ALMA) are shown
and discussed. If time is allowed, disk formation at earlier stages
of YSOs would be addressed as well.