• 한국자동차공학회논문집
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• 제7권5호
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• pp.258-267
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• 1999

An intelligent safety vehicle(ISV) should have an ability to predict the possibility of an accident and help a driver avoid the accident in advance. The basic function of the ISV is to alert the driver by warning when the collision is to occur. For this purpose, the ISV has to function efficiently in sensing the environmental context. While image processing provides lane information, laser radar senses road obstacles including vehicles. By applying a simple clustering algorithm to radar signals, it is possible to obtain the vehicle information. Consequently, we can identify the existence of the vehicle of interest on my lane. The reliability of the sensing algorithm is evaluated by running on the highway with a test vehicle.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.18-23
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• 2000

The radar method is becoming one of the major nondestructive testing (NDT) techniques for concrete structures. Numerical modeling of electromagnetic wave is needed to analyze radar measurement results and to study the influence of measurement parameters on the radar measurements. Finite difference-time domain (FD-TD) method is used to simulate electromagnetic wave propagation through concrete specimens. Three concrete specimens with a 19.1 mm rebar embedded at 40 mm, 60 mm, and 80 mm depth are modeled in 3-dimension. As results, 2-D image processing scheme of modeling data has been developed and applied to the imaging of steel bars inside concrete.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권7호
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• pp.1858-1872
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• 2023

With the advance of radar technologies, the availability of synthetic aperture radar (SAR) images increases. To improve application of SAR images, a management system for SAR images is proposed in this paper. The system provides trainable land cover classification module and display of SAR images on the map. Users of the system can create their own classifier with their data, and obtain the classified results of newly captured SAR images by applying the classifier to the images. The classifier is based on convolutional neural network structure. Since there are differences among SAR images depending on capturing method and devices, a fixed classifier cannot cover all types of SAR land cover classification problems. Thus, it is adopted to create each user's classifier. In our experiments, it is shown that the module works well with two different SAR datasets. With this system, SAR data and land cover classification results are managed and easily displayed.

• 한국측량학회지
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• 제35권4호
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• pp.319-326
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• 2017

SAR (Synthetic aperture radar) images are less affected by the weather compared to optical images and can be obtained at any time of the day. Therefore, SAR images are being actively utilized for military applications and natural disasters. However, because SAR data are in grayscale, it is difficult to perform visual analysis and to decipher details. In this study, we propose a color mapping method using RF (random forest) regression for enhancing the visual decipherability of SAR images. COSMO-SkyMed 2 and WorldView-3 images were obtained for the same area and RF regression was used to establish color configurations for performing color mapping. The results were compared with image fusion, a traditional color mapping method. The UIQI (universal image quality index), the SSIM (structural similarity) index, and CC (correlation coefficients) were used to evaluate the image quality. The color-mapped image based on the RF regression had a significantly higher quality than the images derived from the other methods. From the experimental result, the use of color mapping based on the RF regression for SAR images was confirmed.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.254-257
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• 2007

This paper presents an examination of the spatial integration method for extracting the RCS of a trihedral corner reflector from SAR images for SAR external calibration. An exact external radiometric calibration technique is required for extracting an exact calibration constant. Therefore, we examine the accuracy of the spatial integration method, which is commonly used for the SAR external radiometric calibration. At first, an SAR image for a trihedral corner reflector is simulated with a high-resolution SAR impulse response with a known theoretical RCS of the reflector, and a background clutter image for the high resolution SAR system is also generated. Then, a SAR image in a high resolution is generated for a trihedral comer reflector located on a background clutter by superposition of the two SAR images. The radar cross section of a trihedral corner reflector in the SAR image is retrieved by integrating the radar signals of the pixels adjacent to the reflector for various size of the integration area. By comparison of the measured RCS by the integration method and the theoretical RCS of the reflector, the effect of the size of the integration area on the extraction of the calibration constant is examined.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.441-444
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• 2008

This paper describes the development of a circularly polarized microstrip antenna, as a part of the Circularly Polarized Synthetic Aperture Radar (CP-SAR) sensor which is currently under developed at the Microwave Remote Sensing Laboratory (MRSL) in Chiba University. CP-SAR is a new type of sensor developed for the purpose of remote sensing. With this sensor, lower-noise data/image will be obtained due to the absence of depolarization problems from propagation encounter in linearly polarized synthetic aperture radar. As well the data/images obtained will be investigated as the Axial Ratio Image (ARI), which is a new data that hopefully will reveal unique various backscattering characteristics. The sensor will be mounted on an Unmanned Aerial Vehicle (UAV) which will be aimed for fundamental research and applications. The microstrip antenna works in the frequency of 1.27 GHz (L-Band). The microstrip antenna utilized the proximity-coupled method of feeding. Initially, the optimization process of the single patch antenna design involving modifying the microstrip line feed to yield a high gain (above 5 dBi) and low return loss (below -10 dB). A minimum of 10 MHz bandwidth is targeted at below 3 dB of Axial Ratio for the circularly polarized antenna. A planar array from the single patch is formed next. Consideration for the array design is the beam radiation pattern in the azimuth and elevation plane which is specified based on the electrical and mechanical constraints of the UAV CP-SAR system. This research will contribute in the field of radar for remote sensing technology. The potential application is for landcover, disaster monitoring, snow cover, and oceanography mapping.

• 한국군사과학기술학회지
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• 제17권1호
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• pp.90-95
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• 2014

The system design and the system performance analysis of 3D imaging laser radar system for the mapping purpose is addressed in this article. For the mapping, a push-bloom scanning method is utilized. The pulsed fiber laser with high pulse energy and high pulse repetition rate is used for the light source of laser radar system. The high sensitive linear mode InGaAs avalanche photo-diode is used for the laser receiver module. The time-of-flight of laser pulse from the laser to the receiver is calculated by using high speed FPGA based signal processing board. To reduce the walk error of laser pulse regardless of the intensity differences between pulses, the time of flight is measured from peak to peak of laser pulses. To get 3D image with a single pixel detector, Risley scanner which stirs the laser beam in an ellipsoidal pattern is used. The system laser energy budget characteristics is modeled using LADAR equation, from which the system performances such as the pulse detection probability, false alarm and etc. are analyzed and predicted. The test results of the system performances are acquired and compared with the predicted system performance. According to test results, all the system requirements are satisfied. The 3D image which was acquired by using the laser radar system is also presented in this article.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 Asia Navigation Conference
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• pp.208-216
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• 2004

Since 2000, the authors have been developing remote radar network system to observe the vessel traffic in Tokyo Bay. In December 2002, the first operational remote radar station was set at the National Defense Academy in Yokosuka, and vessel traffic observation was started. However, it was impossible to perform accurate observation in the northern part of Tokyo Bay by this Yokosuka radar station only. In September 2003, the second remote radar station and AIS receiving station were installed at Higashi Ogishima in Kawasaki. This second radar enabled us to carry out accurate observation in that area. Both radars can be remotely controlled from the monitoring station in Tokyo University of Marine Science and Technology. On September 30 and October 1,2003, the vessel traffic observation was carried out using both radars. Combining radar images observed by both radars, the ships' tracks were taken and the dangerous ships were extracted by using SJ value and Bumper Model. The time changes of dangerous ship density in some areas in Tokyo Bay and utilization ratio of the traffic routes were also investigated. In addition, analyzing the AIS date received at Kawasaki station, the positions and speed vectors of the ships equipped with AIS were shown.

• 한국전자파학회논문지
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• 제26권4호
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• pp.404-413
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• 2015

대공 레이다에서 표적의 분류는 대 탄도탄 모드 수행의 가장 중요한 부분 중 하나이다. 대 탄도탄 모드에서는 항공기와 탄도탄을 분류하여 각 표적에 따른 대응 방법을 결정한다. 표적 분류의 속도와 정확도는 적의 공격에 대한 대응 능력과 직접적인 관련이 있으므로, 효율적이고 정확한 표적 분류 알고리즘이 필수적이다. 일반적으로, 레이다는 표적 분류를 위해 JEM(Jet Engine Modulation) 및 HRR(High Range Resolution), ISAR(Inverse Synthetic Array Radar) 영상 등을 사용하는데, 이러한 기법들은 표적 분류를 위한 별도의(광대역 등) 레이다 파형과 DB(Data Base) 및 분류 알고리즘을 요구한다. 본 논문은 별도의 파형 없이 실제 다기능 레이다에서 적용 가능한 표적 분류 기법을 제안한다. 특징 벡터로 추적 시 얻은 표적의 운동학적인 특징(kinematics features)을 이용하여 레이다 하드웨어 및 시간 관점에서 레이다 자원을 아끼고, 구현이 간단하여 빠르고 상대적으로 정확한 퍼지 논리(fuzzy logic)를 분류 알고리즘으로 사용하여 실제 환경에서의 적용성을 높였다. 항공기의 실측 데이터와 탄도탄의 모의 신호를 사용하여 제안한 분류 알고리즘의 성능과 적합성을 증명하였다.

• 한국컴퓨터정보학회논문지
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• 제29권3호
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• pp.117-125
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• 2024

본 논문은 다양한 매체를 활용하여 레이다 개발에 특화된 능동 전자 주사식 위상 배열(AESA, Active Electronically Scanned Array) 레이다 통합 분석 시스템을 구현하고 제안한다. 대부분 분석 시스템은 결함의 원인을 분석하고 개선하기 위해 활용되어 시험을 수월하게 한다. 그러나 기존에 텍스트 기반의 로그 분석 시스템은 로그 정보가 많으면 직관적이지 않고 원하는 정보를 한 번에 찾기 어려워 장비 결함 발생 시 결함의 원인을 분석하기에는 한계가 있다. 따라서 본 논문의 분석 시스템은 다양한 매체를 활용한다. 본 논문에서 정의하는 매체란 텍스트 기반의 데이터를 기록하고, 데이터를 이미지 및 영상으로 전시하며 데이터를 시각화하는 것을 말한다. 제안하는 분석 시스템은 레이다 장치 간에 송수신된 데이터, 레이다 표적 탐지 추적 알고리즘 데이터 등을 분류하여 저장하고 레이다 작동 결과 및 장비 결함 정보를 실시간 전시하고 시각화한다. 이 분석 시스템을 통해 사용자에게 원하는 정보를 빠르게 제공하고 완성도 높은 레이다 개발에 도움을 준다.