  The discovery of substructures in protoplanetary disks with ALMA has provided
us key insights on the formation of planets. However, observational constraints
on the formation of rocky planets have been still sparse, especially because of
the limited spatial resolution. The inner edge of so-called dead zone is one of
the preferential sites of rocky planet formation. We investigate the
capabilities of ALMA and ngVLA for observing a dust concentration expected at
the inner edge of the dead-zone around a Herbig star. Herbig Ae/Be stars are
useful laboratories for exploring the evolution of rocky grains in
protoplanetary disks because of their high luminosity which pushes the
dead-zone inner edge outward. We find that, thanks to its unprecedented angular
resolution and sensitivity, ngVLA can detect the dust concentration at the
dead-zone inner edge, with a reasonable integration time of 10 hrs at
$\lambda=3,7$ mm and 1 cm. The dust concentration is expected to be optically
thick at the ALMA wavelengths and cannot be spatially resolved due to its
limited resolution. On the other hand, the flux density from the inner disk
regions ($\sim$3--4 au) observed with current VLA is higher for disks with a
dust ring, and hence would be a useful indicator that help us choose potential
candidates of disks having a dust concentration at the inner most region. With
these observations we can characterize the process of dust concentration in the
innermost disk regions, where rocky planets can form.
