Abstract: Disclosed are a heat exchanger capable of cooling a coolant and a sewage treatment plant comprising same. An aspect of the present embodiment provides a sewage treatment plant which cools a coolant for dissipating heat of each component inside a data center, the sewage treatment plant comprising at least one removal means, for receiving sewage and removing organic material and pollutants in the sewage, and a cooling pipe, through which a coolant which has dissipated the heat of each component inside the data center flows, disposed inside the removal means so as to induce heat exchange between the treated water, from which organic material and pollutants of the sewage have been removed, and the coolant flowing through the cooling pipe, thereby lowering the temperature of the latter.

Abstract: Disclosed are a wastewater filtering method and apparatus comprising filter media of different sizes. According to one aspect of the present embodiment, provided a wastewater filtering method and apparatus capable of stable and efficient operation by minimizing the head loss as well as simultaneously removing organic matter and solids in a large flow of wastewater.

Abstract: There is provided a variable vane apparatus including: a housing portion; a plurality of vane gear portions configured to rotate and provided on the housing portion to be spaced apart from one another; a plurality of variable vane portions connected to the plurality of vane gear portions; a drive gear portion configured to transfer power to the plurality of vane gear portions; and a connection gear portion arranged between the plurality of vane gear portions and configured to transfer power amongst the plurality of vane gear portions.

Abstract: There is provided a variable vane apparatus including: a housing portion; a plurality of vane gear portions configured to rotate and provided on the housing portion to be spaced apart from one another; a plurality of variable vane portions connected to the plurality of vane gear portions; a drive gear portion configured to transfer power to the plurality of vane gear portions; and a connection gear portion arranged between the plurality of vane gear portions and configured to transfer power amongst the plurality of vane gear portions.

Abstract: A brushless direct current motor, includes a rotor which comprises a permanent magnet, a stator which comprises coils associated with a plurality of phases which form an electrical field for generating a torque by interaction with a magnetic field which is generated by the permanent magnet, and a load prevention part which is disposed inside the stator to electrically connect and disconnect the coils of the plurality of phases according to a temperature variation.

Abstract: A brushless direct current motor, includes a rotor which comprises a permanent magnet, a stator which comprises coils associated with a plurality of phases which form an electrical field for generating a torque by interaction with a magnetic field which is generated by the permanent magnet, and a load prevention part which is disposed inside the stator to electrically connect and disconnect the coils of the plurality of phases according to a temperature variation.

Abstract: An apparatus and a method for controlling radiation power of a mobile terminal in a call waiting state, having two antennas for supporting dual mode communication. The method for controlling radiation power of a mobile terminal includes receiving a call from a second communication network while communicating with a first communication network; holding a call of the first communication network in a call waiting state in response to input of an acceptance key for receiving the call from the second communication network; and communicating with the second communication network by reducing a call transmission power to the first communication network. Interference between the antennas may be reduced by reducing a call transmission power in a call waiting state.

Abstract: A portable radio terminal where the total length of a terminal body and an antenna is less than ½ wavelength. The terminal equipment includes a conductor connected to a printed circuit board in the terminal body so that an electrical equivalent length is ½ wavelength. The portable radio terminal equipment maintains a good radiation efficiency, while reducing the total size of a body and an antenna of the terminal equipment.

Abstract: A rotary compressor having a plurality of compression chambers and adapted to vary a compression capacity according to a direction of rotation of roller pistons within the compression chambers. A rotating shaft provided with a plurality of eccentric parts drives the roller pistons to compress refrigerant in the compression chambers by eccentric rotations of the eccentric parts. A reversible motor selectively rotates the rotating shaft in opposite directions, and a clutch engages the roller pistons such that the roller pistons perform a compressing action or an idle action according to a rotating direction of the rotating shaft, thus varying the compression capacity of the compressor according to a rotating direction of the rotating shaft. Thus, the compression capacity may be varied without using an inverter circuit.

Abstract: A retractable/extendable antenna unit having a conductive tube for a mobile communication terminal with improved communication performance by means of an elongated rod antenna of a whip antenna in its extended position. The antenna unit has an antenna housing extending from a main body of the terminal, provided with an helical antenna; a whip antenna disposed retractably or extendably with respect to the antenna housing, having in its one end an insulator having a length shorter than that of the helical antenna and in its other end a rod antenna; and a conductive tube disposed in a longitudinal direction of the main body, for receiving the rod antenna. The insulator is positioned within the helical antenna when the whip antenna is fully retracted into the antenna housing. The antenna unit improves antenna performance and decreases SAR.

Abstract: Disclosed is a multi-band voltage controlled oscillator circuit comprising a resonant circuit including at least one varactor, at least one capacitor and at least one inductor operated in response to a control voltage, the resonant circuit having a resonance frequency determined according to capacitances of the varactor and capacitor and an inductance of the inductor. The multi-band voltage controlled oscillator circuit further comprises at least one band selection circuit for adjusting the resonance frequency in response to a band selection signal, the band selection circuit including at least one capacitor connected in parallel to the resonant circuit, and a switching element for turning on/off the capacitor in response to the band selection signal.

Abstract: A rotary compressor having a plurality of compression chambers and adapted to vary a compression capacity according to a direction of rotation of roller pistons within the compression chambers. A rotating shaft provided with a plurality of eccentric parts drives the roller pistons to compress refrigerant in the compression chambers by eccentric rotations of the eccentric parts. A reversible motor selectively rotates the rotating shaft in opposite directions, and a clutch engages the roller pistons such that the roller pistons perform a compressing action or an idle action according to a rotating direction of the rotating shaft, thus varying the compression capacity of the compressor according to a rotating direction of the rotating shaft. Thus, the compression capacity may be varied without using an inverter circuit.

Abstract: Disclosed is a multi-band voltage controlled oscillator circuit comprising a resonant circuit including at least one varactor, at least one capacitor and at least one inductor operated in response to a control voltage, the resonant circuit having a resonance frequency determined according to capacitances of the varactor and capacitor and an inductance of the inductor. The multi-band voltage controlled oscillator circuit further comprises at least one band selection circuit for adjusting the resonance frequency in response to a band selection signal, the band selection circuit including at least one capacitor connected in parallel to the resonant circuit, and a switching element for turning on/off the capacitor in response to the band selection signal.

Abstract: A retractable/extendable antenna unit having a conductive tube for a mobile communication terminal with improved communication performance by means of an elongated rod antenna of a whip antenna in its extended position. The antenna unit has an antenna housing extending from a main body of the terminal, provided with an helical antenna; a whip antenna disposed retractably or extendably with respect to the antenna housing, having in its one end an insulator having a length shorter than that of the helical antenna and in its other end a rod antenna; and a conductive tube disposed in a longitudinal direction of the main body, for receiving the rod antenna. The insulator is positioned within the helical antenna when the whip antenna is fully retracted into the antenna housing. The antenna unit improves antenna performance and decreases SAR.