• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.1
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• pp.65-74
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• 2002

A three dimension(3D) link analysis is peformed considering multipath effects caused by a reflected signal and the difference angle between the antenna bore-sight and Line-Of-Sight(LOS). In addition, a direction of a receive antenna is determined for a receiver to get maximum signal strength in a telemetry situation. For a fixed receive antenna, the angle is determined to maximize the average Carrier to Noise Ratio(CNR) over the interested part of a trajectory. For a tracking antenna, the angle at every position is selected to give maximum CNR or to direct the boresight to the flying projectile.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.8
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• pp.15-26
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• 2011

In this paper, we present a new beamforming scheme for a downlink of multiuser multiple-input multipleoutput (MIMO) communication systems. Recently, a block-diagonalization (BD) algorithm has been proposed for the multiuser MIMO downlink where both a base station and each user have multiple antennas. However, the BD algorithm is not efficient when the number of supported streams per user is smaller than that of receive antennas. Since the BD method utilizes the space based on the channel matrix without considering the receive combining, the degree of freedom for beamforming cannot be fully exploited at the transmitter. In this paper, we optimize the receive beamforming vector under a zero forcing (ZF) constraint, where all inter-user interference is driven to zero. We propose an efficient algorithm to find the optimum receive vector by an iterative procedure. The proposed algorithm requires two phase values feedforward information for the receive combining vector. Also, we present another algorithm which needs only one phase value by using a decomposition of the complex general unitary matrix. Simulation results show that the proposed beamforming scheme outperforms the conventional BD algorithm in terms of error probability and obtains the diversity enhancement by utilizing the degree of freedom at the base station.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.159-165
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• 2008

In this paper the signal analysis of eddy current test using transmit-receive(T/R) pancake coil of ECT array probe using electromagnetic finite element method(FEM) is performed. For characteristics analysis, the notch defect is used. The depth of defect is 40[%] of steam generator tube thickness, and inside defect and outside defect are used as simulation examples. The signal analysis is performed according to the variation of receive coil position. The receive coil is positioned $0[^{\circ}]$, $30[^{\circ}]$, $60[^{\circ}]$, $90[^{\circ}]$ of circumferential position of transmit coil. To obtain e electromagnetic characteristics of robes, the governing equation is derived from Maxwell's equations, and the problem is solved using the 3-dimensional finite element method. The signal magnitude of inside defect is bigger than that of outside defect, and the signal difference can be seen according to the variation of position of receive coil. The experimental signal and numerical signal of ASME standard tube show similar results. The results in this paper can be helpful when the ECT signals from ECT array probe are evaluated and analyzed.

• Journal of the Korea Society of Computer and Information
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• v.21 no.4
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• pp.25-30
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• 2016

We consider energy efficient transmit and receive strategy for a delay sensitive data. More specifically, we investigate an energy optimum scheduling characteristics for the 2 user interference channel where each user interferes to each other. First, we determine the optimum transmission rate region each individual user may have for optimum transmission. Next, we consider the optimum transmission region of two users together. Shortest path algorithm can be used for further reduction of search space. Eventually, we can reduce computational complexity. We then examine the performance of the optimum transmission strategy for various system environments.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.185-186
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• 2008

We propose an efficient spectrum sensing scheme for cognitive radio systems with multiple antennas. By utilizing the property of multiple receive antennas, spectrum sensing without idle period is possible. Simulation results show that the detection probability is enhanced with the number of receive antennas, which explains the effect of the spatial diversity.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.4
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• pp.182-194
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• 2009

The optical fiber subscriber receive communication system is multimedia home network core technology because it is providing the high-level data quality and service. Therefore, it is required to analyze and research this communication system. This paper presents the theoretical background of the optical fiber subscriber receive system for the purpose of understanding the optical communication system principle, and then explain the flow of signal process of each block divided for ASIC implementation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.2047-2051
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• 2009

In this paper, we propose the localization method on WSN(Wireless Sensor Network) using fuzzy model and Kalman filter. The proposed method is as follows: First, we estimate the distance of RSSI(Receive Signal Strength Index) by using fuzzy model in order to minimize the distance error. Second, we use a triangulation measurement for estimating the localization. And then, we minimize the localization error using a Kalman filter. Finally, we show the effectiveness and feasibility of the proposed method through some experiments.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.9 no.2
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• pp.56-67
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• 2010

Optical fiber subscriber receive communication system is a core technology of multimedia home networks because it provides the high-level quality of data and services. This paper executes an analysis and research on this communication systems and presents the theoretical background for the purpose of understanding the optical communication system principal and explaining signal process flows to divide each block for the implementing ASIC design.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.1-11
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• 2012

This paper describes the transmit/receive(T/R) module for the space based X-band active phased array radar. T/R module is the integrated module which is assembled by the transmitting and receiving RF semiconductor devices to enable the electronically beam steering of the phased array antenna and the key component of the SAR payload. T/R module can selectively receive the polarization signals by the switch according to the established technology but now the technological trend of the T/R module is to receive the horizontal and vertical polarization signal simultaneously. Therefore the research and development of the dual polarization receiving channel T/R module is actively in progress. In this study, as the prior research for the next generation SAR payload, the technological trend of the active phased array radar T/R module and the result of the preliminary design of the dual receiving channel T/R module were described.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.435-444
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• 2015

This paper specifies on a virtual array design of a 77 GHz vehicle radar for detecting a moving target at a time division transmit and a near range. The virtual array designed reduces a hardware complexity, weight and price. However, a synthesized beam of the virtual array has a high side lobe by a phase distortion of receive signals when the moving target is detected at the time division transmit. For this, a subarray receive signal with a same phase is used and the side lobe of the synthesized beam is suppressed above at least 10 dB. Also the virtual array has a beam distortion by a spherical wave when the vehicle radar operates at near range. So a boresight receive signal of each target range is compensated at each receive signal. Therefore the synthesized beam with compensation recovers a normal main lobe and improves the side lobe about 10~15 dB.