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Longitudinal intensity oscillations along coronal loops that are interpretedas signatures of magneto-acoustic waves are observed frequently in differentcoronal structures. The aim of this paper is to estimate the physicalparameters of the slow waves and the quantitative dependence of theseparameters on their frequencies in the solar corona loops that are situatedabove active regions with the Atmospheric Imaging Assembly (AIA) onboard SolarDynamic Observatory (SDO). The observed data on 2012-Feb-12, consisting of 300images with an interval of 24 seconds in the 171 $\rm{\AA}$ and 193 $\rm{\AA}$passbands is analyzed for evidence of propagating features as slow waves alongthe loop structures. Signatures of longitudinal intensity oscillations that aredamped rapidly as they travel along the loop structures were found, withperiods in the range of a few minutes to few tens of minutes. Also, theprojected (apparent) phase speeds, projected damping lengths, damping times anddamping qualities of filtered intensities centred on the dominant frequenciesare measured in the range of $\rm{C_s}\simeq 38-79~ \rm {km~s^{-1}}$,$\rm{L_d}\simeq 23-68 ~\rm{Mm }$, $\rm{\tau_d}\simeq 7- 21 ~\rm {min}$ and$\rm{\tau_d/P}\simeq 0.34- 0.77$, respectively. The theoretical andobservational results of this study indicate that the damping times and dampinglengths increase with increasing the oscillation periods, and are highlysensitive function of oscillation period, but the projected speeds and thedamping qualities are not very sensitive to the oscillation periods.Furthermore, the magnitude values of physical parameters are in good agreementwith the prediction of the theoretical dispersion relations of high-frequencyMHD waves ($>1.1~ \rm{mHz}$) in a coronal plasma with electron number densityin the range of $\rm{n_e}\simeq 10^{7} - 10^{12} ~\rm{cm^{-3}}$.

Phase speed and frequency-dependent damping of longitudinal intensity oscillations in coronal loop structures observed with AIA/SDO