Abstract: The present invention relates to a lens optical system including a first lens, a second lens, a third lens, a fourth lens, and a fifth lens that are sequentially arranged from an object side to an image side, in which the first lens has positive refractive power and the second lens has negative refractive power.

Abstract: A four-lens optical system is provided which is capable of minimizing a total length of an optical system while having a high numerical aperture (NA), and, more particularly, to an optical system including a first lens, a second lens, a third lens, and a fourth lens that are sequentially arranged from an object side to an image side of the four-lens optical system, in which the first lens and the second lens continuously disposed in front of the optical system are each configured to have positive refractive power and in which the first lens is a lens is made of a plastic material, and the fourth lens is a lens made of a glass material.

Abstract: Provided is a coupling structure for easy installation and separation of a faucet. The coupling structure includes a connection body which is connected to a water supply pipe at one side and has a coupler at an opposite side. A connection pipe formed in the faucet is fitted to the coupler such that the faucet is coupled to the connection body to allow the faucet to be supplied with water and to discharge the water. A grab ring is formed in the coupler, and an actuation ring is installed in the connection pipe so as to be moved forward and backward. When the actuation ring is moved forward, the actuation ring expands the grab ring to allow the connection pipe to be separated from the coupler. Easy installation of the faucet enhances convenience in construction. Easy separation of the faucet, when necessary, enhances convenience in maintenance.

Abstract: Provided is a coupling structure for easy installation and separation of a faucet. The coupling structure includes a connection body which is connected to a water supply pipe at one side and has a coupler at an opposite side. A connection pipe formed in the faucet is fitted to the coupler such that the faucet is coupled to the connection body to allow the faucet to be supplied with water and to discharge the water. A grab ring is formed in the coupler, and an actuation ring is installed in the connection pipe so as to be moved forward and backward. When the actuation ring is moved forward, the actuation ring expands the grab ring to allow the connection pipe to be separated from the coupler. Easy installation of the faucet enhances convenience in construction. Easy separation of the faucet, when necessary, enhances convenience in maintenance.

Abstract: A power supply circuit including a voltage regulator and a headphone driving circuit employing the same are disclosed. In accordance with the present invention, the power supply circuit may provide stable power supply to the amplifier since the power supply circuit generates the constant voltage +Vreg and the constant voltage ?Vreg from +VDD robust to stronger than a power noise, and the balanced signal path for isolating the noise of the input signal to be amplified is not required, thereby simplifying the constitution of the circuit.

Abstract: A power supply circuit including a voltage regulator and a headphone driving circuit employing the same are disclosed.