  Sagittarius A* (Sgr A*), the Galactic Center supermassive black hole (SMBH),
is one of the best targets to resolve the innermost region of SMBH with very
long baseline interferometry (VLBI). In this study, we have carried out
observations toward Sgr A* at 1.349 cm (22.223 GHz) and 6.950 mm (43.135 GHz)
with the East Asian VLBI Network, as a part of the multi-wavelength campaign of
the Event Horizon Telescope (EHT) in 2017 April. To mitigate scattering
effects, the physically motivated scattering kernel model from Psaltis et al.
(2018) and the scattering parameters from Johnson et al. (2018) have been
applied. As a result, a single, symmetric Gaussian model well describes the
intrinsic structure of Sgr A* at both wavelengths. From closure amplitudes, the
major-axis sizes are ~704$\pm$102 $\mu$as (axial ratio
$\sim$1.19$^{+0.24}_{-0.19}$) and $\sim$300$\pm$25 $\mu$as (axial ratio
$\sim$1.28$\pm$0.2) at 1.349 cm and 6.95 mm respectively. Together with a
quasi-simultaneous observation at 3.5 mm (86 GHz) by Issaoun et al. (2019), we
show that the intrinsic size scales with observing wavelength as a power-law,
with an index $\sim$1.2$\pm$0.2. Our results also provide estimates of the size
and compact flux density at 1.3 mm, which can be incorporated into the analysis
of the EHT observations. In terms of the origin of radio emission, we have
compared the intrinsic structures with the accretion flow scenario, especially
the radiatively inefficient accretion flow based on the Keplerian shell model.
With this, we show that a nonthermal electron population is necessary to
reproduce the source sizes.
