A flap valve mechanism in an open-close device for fuel tank includes an open-close member, a shaft support mechanism, a spring and a gasket. The positive bit line voltages combined with the word line voltage create a channel voltage that is sufficient to program a required Vt level into each cell in parallel during a predetermined amount of time. The fixing base is adapted to be fixed to a fixing object. A portion of each of the plurality of focused object beams is reflected off of a surface of the object as a modulated object beam. To realize this, the angular velocity sensor has a mixed gas of inert gas and oxygen gas in the package so that the mixed gas in the package has a pressure higher than the atmospheric pressure. The dried coal is then fed to a cooler where the temperature of the product is reduced to approximately 200 degrees Fahrenheit and water is added to further passivate the coal.