  We present the analysis results of the simultaneous multifrequency
observations of the blazar 4C +28.07. The observations were conducted by the
Interferometric Monitoring of Gamma-ray Bright Active Galactic Nuclei (iMOGABA)
program, which is a key science program of the Korean Very Long Baseline
Interferometry (VLBI) Network (KVN). Observations of the iMOGABA program for 4C
+28.07 were conducted from 16 January 2013 (MJD 56308) to 13 March 2020 (MJD
58921). We also used {\gamma}-ray data from the Fermi Large Array Telescope
(Fermi-LAT) Light Curve Repository. We divided the iMOGABA data and the
Fermi-LAT data into five periods from 0 to 4, according to the prosody of the
22 GHz data and the presence or absence of the data. In order to investigate
the characteristics of each period, the light curves were plotted and compared.
However, a peak was observed earlier than the period of a strong {\gamma}-ray
flare at 43-86 GHz in period 3 (MJD 57400-58100). Therefore, we assumed that
the minimum total CLEANed flux density for each frequency was quiescent flux
(Sq), with the variable flux (Svar) obtained by subtracting Sq from the values
of the total CLEANed flux density. We then compared the variability of the
spectral indices ({\alpha}) between adjacent frequencies. Most notably,
{\alpha}22-43 showed optically thick spectra in the absence of a strong
{\gamma}-ray flare, and when the flare appeared, {\alpha}22-43 became optically
thinner. In order to find out the characteristics of the magnetic field in the
variable region, the magnetic field strength in the synchrotron self-absorption
(BSSA) and the equipartition magnetic field strength (Beq) were obtained. We
found that BSSA is largely consistent with Beq within the uncertainty, implying
that the SSA region in the source is not significantly deviated from the
equipartition condition in the {\gamma}-ray quiescent periods.
