• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.292-302
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• 2022

The radar tomographic imaging is based on the Radar Cross-Section "RCS" of the materials of a shape under examination and investigation. The RCS varies as the conductivity and permittivity of a target, where the target has a different material profile than other background objects in a scene. In this research paper, we use Hierarchical Performance Modeling "HPM" and a framework developed earlier to determine/spot bottleneck(s) for pattern recognition of materials using a combination of the Single Layer Perceptron (SLP) technique and tomographic images in radar systems. HPM provides mathematical equations which create Objective Functions "OFs" to find an average performance metric such as throughput or response time. Herein, response time is used as the performance metric and during the estimation of it, bottlenecks are found with the help of OFs. The obtained results indicate that processing images consumes around 90% of the execution time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.2
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• pp.120-128
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• 2017

The refraction phenomenon of radio waves should be considered to improve the detection accuracy of target altitudes for long-range surveillance radars, however, it is difficult to estimate accurate refractivity of atmosphere for every location. In this paper, we propose the atmosphere evaluation metric(AEM) to estimate atmospheric conditions at target locations using target altitudes obtained from primary surveillance radar(PSR) and secondary surveillance radar(SSR). To verify the suitability of the proposed metric, we observed atmospheric conditions and calculated estimation errors of target altitudes using measured data.

• Journal of applied mathematics & informatics
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• v.33 no.1_2
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• pp.157-172
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• 2015

We introduce a non-Euclidean metric for transportation systems with a defined minimum transportation cost (initial fare) and investigate the continuous single-facility Weber location problem based on this metric. The proposed algorithm uses the results for solving the Weber problem with Euclidean metric by Weiszfeld procedure as the initial point for a special local search procedure. The results of local search are then checked for optimality by calculating directional derivative of modified objective functions in finite number of directions. If the local search result is not optimal then algorithm solves constrained Weber problems with Euclidean metric to obtain the final result. An illustrative example is presented.

• Journal of electromagnetic engineering and science
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• v.19 no.1
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• pp.13-19
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• 2019

This paper proposes a systematic method for estimating detection performances of a frequency-modulated continuous wave radar using electromagnetic simulations. The proposed systematic method includes a radar system simulator that can obtain range-Doppler images using the electromagnetic (EM) simulations in conjunction with a test setup employed for performance evaluation of multiple targets at different velocities in a traffic environment. This method is then applied for optimizing the half-power beamwidths of the antenna array using an evaluation metric defined to improve the detection strengths for the multiple targets. The optimized antenna has vertical and horizontal half-power beam widths of $10^{\circ}$ and $60^{\circ}$, respectively. The results confirm that that the proposed systematic method is suitable to improve the radar detection performance with the enhanced radar-Doppler images.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.6
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• pp.735-744
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• 2019

One of the key factors for recognition performance in the automatic target recognition for synthetic aperture radar imagery(SAR-ATR) system is reliability of the SAR target database. To achieve optimal performance, the database should be constructed using the images obtained under the same operating condition as the SAR sensor. However, it is impractical to have the extensive set of real-world SAR images, and thus those from the electro magnetic prediction tool with 3-D CAD models are suggested as an alternative where their reliability can be always questionable. In this paper, a method for similarity assessment between target SAR images is presented inspired by the fact that a target SAR image is mainly characterized by the features of scattering centers. The method is demonstrated using a variety of examples and quantitatively measures the similarity related to reliability. Its assessment performance is further compared with that of the existing metric, structural similarity(SSIM).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.11
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• pp.894-901
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• 2017

In the existence of motion, azimuth phase error due to accuracy limitation of GPS/IMU and system delay is unavoidable and it is essential to apply autofocus to estimate and compensate the azimuth phase error. In this paper, autofocus algorithm using MWLS(Modified WLS) is proposed. It shows the robust performance compared with original WLS using new target selection/sorting metric and iterative azimuth phase estimation technique. SAR raw data obtained in a captive flight test is used to validate the performance of the proposed algorithm.

• Proceedings of the KSRS Conference
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• v.1
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• pp.376-379
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• 2006

A numerous oil slicks of natural origin were revealed in the southwest (SW) part of Caspian Sea by the synthetic aperture radar (SAR) images acquired by Envisat satellite in 2003-2004. On the basis of computer processing, visual analysis of SAR images and comparisons with bathymetry, geophysical and seismic data in geographic information system (GIS), a link between these slicks and unloading of liquid hydrocarbons in the SW Caspian is established. Oil slicks are basically concentrated above domes of local geological formations of the sedimentary cover. In total more than 90 seeps and mud volcanoes having a repeating regime and representing an active type were identified; they are distributed across the SW Azerbaijan and West Iranian sectors. Periodical occurrence of slicks can reflect alternation of mud volcanism pulses forced by intensive seismicity with the quiet periods. Seepage rate of oil in the SW part of the Caspian Sea according to SAR images is estimated to be up to 16,000 metric tons per year. The importance of unloading of oils on hydrochemistry and ecological conditions of the Caspian Sea is demonstrated. Conclusion is done that the Envisat SAR to be an excellent tool for studying oil seeps through observation oil slicks floating on the sea surface.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.527-532
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• 2020

Seoul terminal maneuvering area (TMA) that includes Incheon International Airport (ICN) and Gimpo International Airport is a very congested airspace with around 1,000 daily flights and the airspace blocked at the boundary between Incheon flight information region (FIR) and Pyongyang FIR. Consequently, with frequency radar vectorings, separation assurance in this airspace is complicated thus resulting in higher controller workload. In this paper, the conflict and collision risks in Seoul TMA are analyzed using recorded ADS-B data for past three years. Using the recorded trajectories, original flight plan procesures and routes are reconstructed and the risks are quantified using detect and avoid well clear (DWC) metric that is developed for large unmanned aircraft system. The region west of ICN was found to be the highest risk area regardless of the runway directions. In addition, merge and crossing points between procedures displayed relatively high risks.