At least one of lower and upper magnetic cores is composed of magnetic films each of which contains two or more elements of Co, Ni, and Fe, which are formed by electroplating in a plating bath with pH 2 or less, and which have a saturation magnetic flux density of 23,000 gauss or more. In that method, when the running state of the internal combustion engine becomes idle running during the filter regeneration process, the oxygen concentration in the exhaust gas flowing into the filter is reduced. A telecommunications relay service or gateway switch routing number, a network routing number for a third point, and an initial address message may be communicated. In order that the screws can be used in situ for very different lengths, the threaded section and the head are designed as separate parts.