A hollow-core structure including: an inner mold that has a hollow cylindrical shell shape; an outer mold that has a hollow cylindrical shell shape to correspond to the inner mold, and in which the inner mold is disposed to be separated; and a filling member that is filled in a separation space between the inner mold and the outer mold. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. Either a first pipeline or a cluster of threads is selected for a corresponding architecture for each independent set.