A magnetic element includes a drum core provided with a flange portion having a flange surface at each end portion of a winding shaft, a coil wound on the winding shaft, a terminal to connect each end portion of the coil, and a shield core provided with an engagement portion having such a shape that partially fits in along an outer circumference of the flange portion. Gas extraction at a well site occurs through a gas extractor at a set pressure, detected temperature, detected density, and controlled volume rate. A battery monitoring IC having a plurality of auxiliarythermistor AD inputs measures respective voltages of the battery cells. An event of the one or more events indicates a means of interaction of the user with the web based software application. The pair of bottom boards are respectively pivotally connected to the two opposite surfaces of the vertical board and respectively pivotally connected to the surfaces of the pair of side boards facing the vertical board. Each of the first heating element and the second heating element is formed into a spiral shape so as not to contact the other from a central portion of the base to an outer circumferential portion thereof in substantially the same plane parallel to a heating surface of the base.