An air-knife is described in the form of a segmented air distribution bar equipped with control valves along the length of the bar to enable a user to incrementally adjust the air distribution across the width of an inking roller of a printing press. In one embodiment, in response to a request for searching target data in a storage system, first representative data for the target data being searched are generated by applying a predetermined algorithm to at least a portion of the target data. The first coupling factor is the coupling factor to a waveguide having the same width as that in a first position in an inherent mode in the case where the tapered waveguide is cut in the first position. The rough structures are disposed on a portion of the black matrix and distributed corresponding to the peripheral area. A method of cut grooving and chamfering the pipe section is also disclosed.