Embodiments of the present invention provide a method and an apparatus for acquiring a weight coefficient of a digital filter so as to enhance a processing effect of images or videos and reduce the complexity of operations. The hollow fiber membrane module comprises sheet-form hollow fiber membranes and an anchoring member which anchors the sheet-form hollow fiber membranes in a roughly parallel manner while maintaining in an open state at least one end portion of the sheet-form hollow fiber membranes. An oxidation prevention film is formed of such as gold on an upper surface or a part of the upper surface and side surface. The outer core is over-molded around the pre-formed insert to form a spherical core. The present invention is also directed to methods of treating a subject in need of analgesia with the pharmaceutical compositions of the invention.