Abstract: A protection film for an electronic device includes an adhesive layer including a first surface to which an electronic device is attached, and a film layer which contacts a second surface of the adhesive layer and includes at least one member, where a thickness of the adhesive layer satisfies Inequality 1: z?(5.1x+57.4)·ln(y)?(14.7x+140.5), where z is the thickness of the adhesive layer in terms of micrometers, x is a modulus of a member of the film layer which directly contacts the adhesive layer in terms of gigapascals, and y is a total thickness of the film layer in terms of micrometers.

Abstract: An electric booster including: a motor; a booster body coupled to the motor; a bolt screw rotatably installed in the booster body, connected to the motor, and rotated by the motor; a buffer mounted in the booster body and made of a material different from the booster body; and a nut screw restricted from rotating by the buffer, and screwed to the bolt screw so as to be linearly moved in the longitudinal direction of the bolt screw.

Abstract: An electric booster including: a motor; a booster body coupled to the motor; a bolt screw rotatably installed in the booster body, connected to the motor, and rotated by the motor; a buffer mounted in the booster body and made of a material different from the booster body; and a nut screw restricted from rotating by the buffer, and screwed to the bolt screw so as to be linearly moved in the longitudinal direction of the bolt screw.