We applied the coda-derived source spectrum method of Mayeda et al. (2003) to earthquakes in and around the Korean peninsula. After empirical calibrations, we derived source spectra of the earthquakes. From the coda-derived spectra, we estimated valuable source parameters such as the seismic moment, corner frequency, and radiated energy for small events with Mw<3.5. We derived simple linear relationships between the coda spectral amplitudes and local magnitudes reported from the Korea Meteorological Administration and Korea Institute of Geoscience and Mineral Resources. These relationships can be used to estimate stable local magnitudes for future earthquakes using a small number of stations. To investigate whether the earthquakes occurring in this region obey self-similarity, we examined the scaling relationships between dynamic and static source parameters, such as the corner frequency, radiated energy, and scaled energy versus seismic moment. The scaling relationship between the corner frequency and seismic moment showed clear nonself-similarity with a scaling parameter of 0.54; this value is more or less consistent with previous results for different regions. Scaling relations of radiated energy and scaled energy versus the seismic moment also show size-dependent behavior that cannot be explained by self-similarity; this result implies that the rupture dynamics of small and large earthquakes are different in this region. Our observation provides further evidence supporting the nonself-similarity of earthquakes.