Abstract: Disclosed is a wireless power receiver that controls a level of a communication signal. A wireless power receiver according to an embodiment includes a resonator for receiving wireless power, a rectifier for converting an alternating current power received from the resonator to a direct current power and outputting a rectifier output voltage, a switch for receiving a communication signal and controlling a rectifier output voltage through switching, and a regulator for adjusting a voltage change of a rectifier output voltage by modulating a communication signal.

Abstract: A braking force control valve for an air brake system. The air brake system includes an air compressor for generating compressed air, an air tank for storing the compressed air supplied from the air compressor, an air bellows connected to the air tank, a load sensing valve connected to the air bellows to equilibrate braking force applied to front and rear wheels of the vehicle, a brake valve for operating the load sensing valve, a brake chamber for supplying braking force by receiving the compressed air from the air tank when the brake valve is operated. The braking force control valve comprises a valve body provided with a first port connected to the air tank, a second port connected to the air bellows, a third port connected to the load sensing valve, and a valve mechanism for selectively connecting the third port to either the first port or the second port according to a height variation between a body and an axle shaft of the vehicle.