• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1285-1294
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• 2010

This study describes the design and verification of short range UWB(Ultra Wideband) imaging radar that is able to display high resolution radar image for front area of a UGV(Unmanned Ground Vehicle). This radar can help a UGV to navigate autonomously as it detects and avoids obstacles through foliage. We describe the relationship between bandwidth of transmitting signal and range resolution. A vivaldi antenna is designed and it's radiation pattern and reflection are measured. It is easy to make array antenna because of small size and thin shape. Aperture size of receiving array antenna is determined by azimuth resolution of radar image. The relation of interval of receiving antenna array, image resolution and aliasing of target on a radar image is analyzed. A vector network analyzer is used to obtain the reflected signal and corner reflectors as targets are positioned at grass field. Applicability of the proposed radar to UGV is proved by analysis of image resolution and penetrating capability for grass in the experiment.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.2
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• pp.118-124
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• 2022

Marine environment analysis and ship motion prediction during ship navigation are important technologies for safe and economical operation of autonomous ships. As a marine environment analysis technology, there is a method of analyzing waves by measuring the sea states through images acquired based on radar(radio detection and ranging) signal. However, in the process of deriving marine environment information from radar images, noises generated by external factors are included, limiting the interpretation of the marine environment. Therefore, image processing for noise removal is required. In this study, image inpainting by partial convolutional neural network model is proposed as a method to remove noises and reconstruct radar images.

• Journal of the Korean Institute of Navigation
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• v.13 no.1
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• pp.11-20
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• 1989

Radar image data were collected through the on-line data acquisition system of A/D converter and personal computer, and the image was restorated on CRT or plotter after digital image processing of the data. The digital image processing system which was developed for this study, consisted of some kinds of software as follows : rearrangement, transformation, and enhancement of the image data in real space or frequency space by Fourier transform, edge detection of the image, compact processing, state inferential processing, and so on. Since the image of PPI radar sweeps from the center to the circumference of a circle, the image within a given period has the shape of fan. Therefore the acquired data were transformed to have the same interval as that of data in outmost concentricity. The results of various image processing methods using transformed data were better than those of the methods using original data.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.1
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• pp.83-91
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• 2018

In this paper, usefulness of marine radar for water waves measurement in coastal waters is presented. We installed a marine radar to acquire radar images of water wave around light beacon at Jujeon in Ulsan. Also, a series of analysis procedures for obtaining the wave information from the acquired image is described with a schematic diagram. We compared analysis results of radar images with measurement values using wave height gauge at light beacon. In order to improve accuracy of analysis results, detailed water depth information is essential. In conclusion, in case of the use of radar for water waves measurement, it is shown that it is very necessary to increase the accuracy of measurement by consideration of the water depth in the dispersion relation of water waves.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.1
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• pp.51-57
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• 2020

The fighter pilot uses radar mounted on the fighter to obtain high-resolution SAR (Synthetic Aperture Radar) images for a specific area of distance, and then the pilot visually classifies targets within the image. However, the target configuration captured in the SAR image is relatively small in size, and distortion of that type occurs depending on the depression angle, making it difficult for pilot to classify the type of target. Also, being present with various types of clutters, there should be errors in target classification and pilots should be even worse if tasks such as navigation and situational awareness are carried out simultaneously. In this paper, the concept of operation and functional structure of radar system for fighter jets were presented to transfer the SAR image target classification task of fighter pilots to radar system, and the method of target classification with high accuracy was studied using the CNN ensemble model to archive higher classification accuracy than single CNN model.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.71-78
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• 2006

The image of an object obtained by the radar is not corresponding to its true shape, because the image of an object observed by the radar is receiving an influence such as multiple-reflections and expanded in bearing because of the beam width of a radar. In addition, a radio wave does not hit the entire surface of an object. Therefore, the image of the front side of a ship facing a radar antenna corresponds to its true shape. In this paper, a method to estimate a ship's shape by means of the integration of the front parts of images obtained from radars is proposed. In addition, a matter, which is observation error of each radar, in using multi-radars, and the process included in the proposed method for solving the matter, are described. As a result of the experiment, the accuracy of about 3 degrees in ship's heading and about 14 meters in length and about 9 meters in beam was obtained.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.40-41
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• 2023

This paper introduces the design of detection, recognition, and tracking algorithms for VTS radar image-based objects. The detection of objects in radar images utilizes artificial intelligence technology to determine the presence or absence of objects, and can classify the type of object using AI technology. Tracking involves the continuous tracking of detected objects over time, including technology to prevent confusion in the movement path. In particular, for land-based radar, there are unnecessary areas for detection depending on the terrain, so the function of detecting and recognizing vessels within the region of interest (ROI) set in the radar image is included. In addition, the extracted coordinate information is designed to enable various applications and interpretations by calculating speed, direction, etc.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.46-54
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• 2015

SAR is a Radar to obtain the video information using a radio wave. Platform emit the radio wave, depending backscattered waves returned from the target object the signal to the distance, to create a topographical map is recorded in two-dimensional image. In this paper, through a simulation to apply a variety of window in the SAR image processing for SAR image recovery is to study the application effect of the window, as a result, at the side of the signal of the SNR, Flattop window to improve the best performance it was confirmed to show.

• Journal of Korea Water Resources Association
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• v.41 no.11
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• pp.1153-1162
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• 2008

The use of radar rainfall for hydrological appraisal has been a challenge due to the limitations in raw data generation followed by the complex analysis needed to come up with precise data interpretation. In this study, RAIDOM (RAdar Image DigitalizatiOn Method) has been developed to convert synthetic radar CAPPI(Constant Altitude Plan Position Indicator) image data from Korea Meteorological Administration into digital format in order to come up with a more practical and useful radar image data. RAIDOM was used to examine a severe local rainstorm that occurred in July 2006 as well as two other separate events that caused heavy floods on both upper and mid parts of the HanRiver basin. A distributed model was developed based on the available radar rainfall data. The Flood Hydrograph simulation has been found consistent with actual values. The results show the potentials of RAIDOM and the distributed model as tools for flood prediction. Furthermore, these findings are expected to extend the usefulness of radar rainfall data in hydrological appraisal.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.421-426
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• 2005

Scattering center extraction schemes for radar cross section reduction of large complex targets, like warships, was developed, which are an 1-D radar image method(range profile), and a direct analysis based on an object precision method. The analysis result of partial dihedral model shows that the presented direct analysis method is more efficient than the 1-D radar image method for scattering center extraction of interested targets, in terms of radar cross section reduction design, not signal processing. In order to verify the accuracy of the direct analysis method, a scattering center analysis of an naval weapon system was carried out, and the result was coincident with that of another well-known RCS analysis program. Finally, an analysis result of RCS and its scattering center of an 120m class warship-like model presented that the direct analysis method can be an efficient and powerful tools for radar cross section reduction of large complex targets.