Abstract:
A beamforming method is provided. The beamforming method includes determining different beams for pieces of user equipment based on channel information fed back from the pieces of user equipment, predicting beam qualities of the pieces of user equipment for the beams, determining whether the beam qualities satisfy Quality of Service (QoS) for the pieces of user equipment, generating a wide nulling beam by applying wide nulling to a second beam having a side lobe acting as interference against one first beam, when the beam quality of the first beam does not satisfy the QoS; predicting beam qualities for the beams including the wide nulling beam instead of the second beam, and simultaneously communicating with the user equipment through the beams including the wide nulling beam instead of the second beam, when the beam qualities for the beams including the wide nulling beam instead of the second beam satisfy the QoS.
Abstract:
Disclosed is a method for improving solar energy conversion efficiency of a metal oxide semiconductor photocatalyst, which includes rapidly performing hydrogenation and nitrogenation of a metal oxide semiconductor material through an H2/N2 mixed gas plasma treatment in a single process at room temperature, so as to enhance photocatalytic energy conversion efficiency. Specifically, disclosed is a treatment technique in which a plasma ball formed by controlling a mixing ratio of hydrogen gas to nitrogen gas in a range of 1:1 to 1:3 contacts with a surface of a metal oxide material, such that a great amount of oxygen vacancy and nitrogen elements are introduced in the surface of the metal oxide material to improve electron-hole pairs transfer ability thereof and decrease a size of the band-gap. A catalyst including the metal oxide material directly converts the solar energy into a compound by photocatalytic hydrogen generation and CO2 conversion.
Abstract:
Provided is a beamforming apparatus in a receiver in a mobile communication system. The beamforming apparatus includes a Local Oscillator (LO) signal generator for generating an LO signal; a phase shifter for generating a predetermined number of phase-shifted LO signals with respect to the generated LO signal; a switching network for mapping the phase-shifted LO signals to RF signals received via a plurality of receive paths; and a mixer for mixing the RF signals with the mapped LO signals to down-convert a frequency of the RF signals.
Abstract:
Provided is a method in which a Digital Pre-Distorter (DPD) performs digital pre-distortion on a received In-phase (I) signal, a received Quadrature-phase (Q) signal, a feedback I signal, and a feedback Q signal; a mixer mixes a signal output from the DPD with a frequency signal output from an oscillator; each of n phase shifters phase-shifts a signal output from the mixer according to a preset beamforming pattern; each of n Power Amplifiers (PAs) amplifies a signal output from an associated phase shifter according to a gain, the PAs connected to the associated phase shifter on a one-to-one basis; each of n envelope detectors detects an envelope signal from a signal output from an associated PA, the envelope detector connected to the associated PA on a one-to-one basis; and a control unit determines whether the n PAs operate normally, using the envelope signals output from the n envelope detectors.
Abstract:
The present invention discloses a method for improving solar energy conversion efficiency using metal oxide photocatalysts having an energy band of core-shell structure for ultraviolet (UV) ray and visible light absorption, comprising a first process of forming a nanoparticle thin film layer; a second process of preparing a core-shell metal oxide on metal oxide nanoparticles by a plasma reaction under a hydrogen and nitrogen gas atmosphere, and a third process of depositing a transition metal on surfaces of core-shell metal oxide nanoparticles to produce a photocatalyst for energy conversion. A great amount of oxygen vacancies is formed in a shell region by the core-shell metal oxide to achieve effects of improving transfer ability of electron-hole pairs excited by light, and extending a wavelength range of absorbable light to a visible light region by changing a band-gap structure.