Electronic brake system and method for operating the same

An electronic brake system comprising:

• a hydraulic-pressure supply device configured to generate a hydraulic pressure by operating a hydraulic piston using an electric signal that is output in response to a displacement of a brake pedal, as well as to include not only a first pressure chamber formed at one side of the hydraulic piston movably disposed in a cylinder block, but also a second pressure chamber formed at the other side of the hydraulic piston;
• and
• a hydraulic control unit configured to include not only a first hydraulic circuit to control a hydraulic pressure applied to two wheel cylinders, but also a second hydraulic circuit to control a hydraulic pressure applied to two other wheel cylinders,
• wherein the hydraulic control unit includes:
• a first hydraulic passage configured to communicate with the first pressure chamber;
• a second hydraulic passage branched from the first hydraulic passage;
• a third hydraulic passage connected to the second hydraulic circuit while being branched from the first hydraulic passage;
• a fourth hydraulic passage configured to communicate with the second pressure chamber;
• fifth and sixth hydraulic passages that are branched from an intermediate part of the fourth hydraulic passage and are then linked again to the fourth hydraulic passage;
• a seventh hydraulic passage configured to connect a second hydraulic passage to a third hydraulic passage;
• and
• an eighth hydraulic passage configured to connect both the second hydraulic passage and the fourth hydraulic passage to the first hydraulic circuit.