• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.3
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• pp.239-250
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• 2022

In this paper, we analyze the performance of an FM radio based passive radar in the presence of deception jamming such as false-target generation. To do this, we examine the effects of applying the deception jamming signal to the passive radar through the derivation of the construction of the amplitude-range-Doppler(ARD) plot. The analysis results show that applying the deception jamming signal with the low power similar to the target echo signal generates false targets at positions set by the jamming variables compared to the real target position in the ARD plot. Also, it is possible to induce the jamming effect so that only false targets are detected by selecting appropriate jamming power. Simulations are included to verify the theoretical results and to discuss on the effectiveness of the deception jamming on the FM radio based passive radar.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.1
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• pp.79-87
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• 2019

Radar detection range is decreased with an increase in the noise levels and detection thresholds in adaptive CFAR of a radar signal processor to the weather clutter reflection signal in the rain. When a high-velocity plot is generated in weather clutter, what are detected are not targets but false plots. Detection opportunity is reduced by radar time resource consumption from additional confirmations regarding the false plots. In this paper, the received signals are saved using a radar-received signal storage device. Based on the analysis of the received signals from weather clutter, the influence of the rainfall reflection has been mitigated by front-end attenuation of the signal processor. The improvement in the detection performance is verified through received signal and simulation results.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.3
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• pp.343-349
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• 2012

To detect targets for autonomous navigation of unmanned ground vehicle, mounted sensors are required to work all-weather condition. In this point of view, the FMCW radar is quietly appropriate. In this paper, we present development results of target signal simulator for multi-beam type FMCW radar. A target signal simulator make pseudo target signals which simulates multiple moving targets. And we describe how to make hit information for each target in multi-beam type radar. The developed methods are utilized for target tracking device. Moreover it can be applied to similar target signal simulator.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.1
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• pp.106-113
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• 2011

This paper describes Data Acquisition & Analysis System(DAS) for analysis of the multi-function radar. There are various information - beam probing data, clutter map data, plot data, target tracking data, RT tracking data, radar signal processing data, interface data - this device saves. The most important thing of data analysis is that a researcher gets a view of the whole data. The DAS intergrates with all of the data and provides overall information on the time matters occur. This is very useful advantage for approaching the matter easily. System algorithms of multi-function radar are improved by using this advantage. As a result of, range blank region have fallen about 72% and it is able to keep track in jammer environment.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.810-820
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• 2014

Recently many studies of Radar systems mounted on ground vehicles for autonomous driving, SLAM (Simultaneous localization and mapping) and collision avoidance are reported. In near field, several hits per an object are generated after signal processing of Radar data. Hence, clustering is an essential technique to estimate their shapes and positions precisely. This paper proposes a method of grouping hits in range-doppler domains into clusters which represent each object, according to the pre-defined rules. The rules are based on the perceptual cues to separate hits by object. The morphological connectedness between hits and the characteristics of SNR distribution of hits are adopted as the perceptual cues for clustering. In various simulations for the performance assessment, the proposed method yielded more effective performance than other techniques.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.194-196
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• 2022

When electromagnetic wave transmitted from the radar antenna hits the target, a specific type of electric field is formed according to the electrical characteristics and appearance of the target, which is called an RCS pattern. There are various commercial programs that calculate the RCS of the target and plot the RCS pattern. For the analysis of large targets such as warships or ships, a program with a high frequency analysis method, which has a faster calculation speed than the low frequency analysis method is suitable. XGTD, a high-frequency analysis program, can quickly plot a two-dimensional RCS pattern for 360 degrees of a target, but a three-dimensional RCS pattern cannot be obtained. In this paper, it is proposed that a method of plotting two-dimensional RCS patterns of a target from various angles using XGTD, generating a three-dimensional RCS pattern using this, and converting it into a three-dimensional antenna pattern file.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.568-573
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• 2023

Range resolution is the ability to distinguish different targets placed in same angular direction but at different distances from the radar. Normally, Range resolution requirement is defined as the width of transmitting pulse. The width of transmitting pulse does not mean the ability to distinguish two different targets. Range resolution performance to detect and track targets separately depends on the signal processing and tracking algorithm not only the width of transmitting pulse. This paper analyzes the processing steps in algorithms to affect the range resolution performance and verifies the results by roof-lab ground test using beacon signal. As a result, to track targets with the same angular position separately, it is desirable to have larger range difference than plot-track association test gate.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.157-157
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• 2019

This study derived the Flood-Inducing-Rainfall (FIR) and the Flood-Inducing-Runoff (FIRO) from the radar-gage composite data to be used as the basis of the flood warning initiation for the urban area of Seoul. For this, we derived the rainfall depth-duration relationship for the 261 flood events at 239 watersheds during the years 2010 and 2011 based on the 10-minute 1km-1km radar-gauge composite rainfall field. The relationship was further refined by the discrete ranges of the proportion of the flooded area in the watershed (FP) and the coefficient variation of the rainfall time series (CV). Then, the slope of the straight line that contains all data points in the depth-duration relationship plot was determined as the FIR for the specified range of the FP and the CV. Similar methodology was applied to derive the FIRO, which used the runoff depths that were estimated using the NRCS Curve Number method. We found that FIR and FIRO vary at the range of 37mm/hr-63mm/hr and the range of 10mm/hr-42mm/hr, respectively. The large variability was well explained by the FP and the CV: As the FP increases, FIR and FIRO increased too, suggesting that the greater rainfall causes larger flooded area; as the rainfall CV increases, FIR and FIRO decreased, which suggests that the temporally concentrated rainfall requires less total of rainfall to cause the flood in the area. We verified our result against the 21 flood events that occurred for the period of 2012 through 2015 for the same study area. When the 5 percent of the flooded area was tolerated, the ratio of hit-and-miss of the warning system based on the rainfall was 44.2 percent and 9.5 percent, respectively. The ratio of hit-and-miss of the warning system based on the runoff was 67 percent and 4.7 percent, respectively. Lastly, we showed the importance of considering the radar-gauge composite rainfall data as well as rainfall and runoff temporal variability in flood warning system by comparing our results to the ones based on the gauge-only or radar-only rainfall data and to the one that does not account for the temporal variability.

• Journal of the Korean Institute of Navigation
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• v.13 no.2
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• pp.1-21
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• 1989

The computer can be used to display a continuously updated list or plot of vessel position. The computer that accept input data from a number of different navigation systems, e.g., Loran , Satnav, Radar, Decca, Compass, Sextant with electrical output etc., can compute the position of a vessel relative to prerecorded objects. The celestial navigation system requires the computer to do not much calculation. Calculation are for trigonometeric, linear systems, finding roots of nonlinear equation and least square estimation etc, . In order to computerize the celestrial navigation system, these calculations must be programmed. The purpose of this thesis is to study the formulation, the design and the test of calculations of the coordinates of celestial bodies, the altitude correction and the solution of the navigational triangle processes.

• Composites Research
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• v.35 no.3
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• pp.201-215
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• 2022

This paper presents the development of thin and lightweight ultra-high temperature radar-absorbing ceramic composites composed of an aluminosilicate ceramic matrix-based geopolymer reinforced ceramic fiber and sendust magnetic nanoparticles in X-band frequency range (8.2~12.4 GHz). The dielectric properties with regard to complex permittivity of ceramic/sendust-aluminosilicate composites were proportional to the size of sendust magnetic nanoparticle with high magnetic characteristic properties as flake shape and its concentrations in the target frequency range. The characteristic microstructures, element composition, phase identification, and thermal stability were examined by SEM, EDS, VSM and TGA, respectively. The fabricated total thicknesses of the proposed single slab ultra-high temperature radar absorber correspond to 1.585 mm, respectively, exhibiting their excellent EM absorption performance. The behavior of ultra-high temperature EM wave absorption properties was verified to the developed free-space measurement system linked with high temperature furnace for X-band from 25℃ to 1,000℃.