A fuel control system that regulates a purge flow from a fueling system to an engine includes a sensor that monitors an engine speed and a first module that determines a PWM frequency of a purge valve based on the engine speed. In one embodiment, a power amplifier circuit assembly includes a power amplifier and an impedance matching network. The back panel is divided so as to expose electrode terminals, and a groove part V-shaped in cross section is formed at the divided portion. The supplier may accept all of the terms of the purchase order or submit changes in the purchase order response. 5 to 6 wt % of a polymerization initiator.