In an image forming apparatus, when a first sheet discharger discharges a sheet bearing an image in a first direction from a proximal end to a distal end of the image forming apparatus, a post-processing device performs post-processing including at least one of stapling, punching, stamping, and sorting of the sheet discharged from the first sheet discharger. The metallic shell has a top shell and a bottom shell assembled to each other, and the metallic shell also defines a pair of blocking portions bent from a front end thereof, the blocking portions are perpendicular to a mating direction and adjacent to a front surface of the shielding member. On the other hand, a d-axis correction current setting unit sets a field weakening current in response to a voltage saturation output from a voltage saturation calculating unit. The second mode transfers heat to the exhaust gas. Circuits according to the present invention provide sufficient bandwidth with an error amplifier and drive capability to keep any secondary poles sufficiently far from the unity gain bandwidth while maintaining good power supply rejection. The method provides a response from a database to a natural language query.