• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.175-178
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• 2007

According to recently presented QoS architecture by 3GPP, a traffic conditioner may be deployed to provide conformance of the negotiated QoS. A real-time frame-layer rate control method which can be applied to the traffic conditioner is proposed. The proposed rate control method uses a non-iterative optimization method for low computational complexity, and performs bit allocation at the frame level to minimize the average distortion over an entire sequence as well as variations in distortion between frames. The proposed algorithm does not produce time delay from encoding, and is suitable for real-time low-complexity video encoder.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.6
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• pp.711-720
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• 2015

Recently many studies of Radar systems mounted on ground vehicles for autonomous driving, SLAM (Simultaneous localization and mapping) and collision avoidance have been reported. Since several pixels per an object may be generated in a close-range radar application, a width of an object can be estimated automatically by various signal processing techniques. In this paper, we tried to attempt to develop an algorithm to estimate obstacle width using Radar images. The proposed method consists of 5 steps - 1) background clutter reduction, 2) local peak pixel detection, 3) region growing, 4) contour extraction and 5)width calculation. For the performance validation of our method, we performed the test width estimation using a real data of two cars acquired by commercial radar system - I200 manufactured by Navtech. As a result, we verified that the proposed method can estimate the widths of targets.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.1-10
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• 2005

In this Paper, we propose a new block matching a1gorithm that extracts motion vectors from consecutive range data. The proposed method defines a matching metric that integrates intensity, hue, and range. Our algorithm begins matching with a small matching template. If the matching degree is not good enough, we slightly expand the size of a matching template and then repeat the matching process until our matching criterion is satisfied or the predetermined maximum size has been reached. As the iteration proceeds, we adaptively adjust weights of the matching metric by considering the importance of each feature. In the experiments, we show that our block matching approach can work as a promising solution by comparing the proposed method with previously known method in terms of performance.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.621-629
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• 2011

According to the development of technologies for generating the 3D spatial information, the needs for producing and updating the precise 3D objects with LoD 4 level are increased. On the other hand, the needs for real-time updating of 2D digital maps are expanded, based on the execution of various GIS projects. These 2D informations can be extracted from precisely constructed 3D spatial information, to do this the feasibility studies on extraction of the 2D information from the 3D spatial information is needed. In this study, 3D objects are modeled using multi-oblique images, and the objects are stereo-plotted using digital airborne images, as well. Then the two data sets are compared and analyzed. The results show that the accuracy assessments fulfill the 1/1,000 digital map accuracy standard of regulations for photogrametric surveying of National Geographic Information Institute, but the shapes and the areas of building objects are different between two data sets because of the portrayal standards. Consequently, researchers can conclude that it is possible to generate the building layer of large scale topographic map using multi-oblique images, but additional researches is needed to resolve the problems on differences of the portrayal standards.

• Journal of Space Technology and Applications
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• v.1 no.1
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• pp.33-40
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• 2021

Based on the requirements of a total weight of 42 kg or less, the NEXTSat-2 SAR (synthetic aperture radar) system was developed. As the NEXTSat-2 is a small-sized satellite, the SAR system was designed to account for about 40% of the dry mass of the payload relative to the total mass. Among the major components of the SAR system - which are an antenna, an RF transceiver, a baseband signal processor, and a power unit - a part with a particularly large dry mass is the antenna, the core of the SAR system. Whereas various selections are possible in consideration of gain and efficiency when designing the antenna, the micro-strip patch array antenna was adopted by reflecting the dry mass, power, and resolution required by the NEXTSat-2 project. In order to meet the mission requirement of the NEXTSat-2, the antenna was developed with a frequency of 9.65 GHz, a gain of 42.7 dBi, and a return loss of -15 dB. The performance of the antenna was verified by conducting a field test onboard the vehicle.

• The Transactions of the Korea Information Processing Society
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• v.5 no.4
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• pp.1057-1065
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• 1998

This paper describes a new fractal image coding algorithm to shorten time to take on fractal image encoding by using limited search area method and scaling method. First, the original image is contracted respectively by half and by quarter with the scaling method. And then, the corresponding domain block of the quarter-sized image which is most similar with one range block of the half-sized image is searched within the limited area in order to reduce the encoding time extremely. This searched block is used in encoding. Also, we propose an algorithm provided much shorter encoding time and better compression ratio with a little degradation of the decoded image quality than Jacquin's method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1582-1588
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• 2007

According to recently presented QoS architecture by 3GPP, a traffic conditioner may be deployed to provide conformance of the negotiated QoS. In this paper, a real-time frame-layer rate control method which can be applied to the traffic conditioner of 3GPP is proposed. The proposed rate control method uses an efficient frame skipping algorithm method for low computational complexity, and performs bit allocation at the frame level to minimize the average distortion over an entire sequence as well as variations in distortion between frames. The proposed algorithm does not produce time delay from encoding, and is suitable for real-time low-complexity video encoder.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.177-180
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• 2008

최근 유/무선 통신망과 접속 기술의 발달로 사용자들은 다양한 네트워크로의 접근이 가능하게 되었다. 하지만 이러한 여러 종류의 접속 기술은 접속 기술간 서비스 이동에 따른 이동성 보장이 서로 독립적이기 때문에 핸드오버 시 부가적인 지연이 발생하는 문제가 있다. 또한 다른 접속 서비스로의 비디오 전송 시 QoS 보장이 어려운 문제점이 있다. 따라서 본 논문에서 IEEE 802.21 Media Independent Handover 정보 서비스를 이용하여 네트워크 접속망에서 스케일러블 비디오 코딩 전송 방법을 제안한다. 이는 MIH Function에서 각 단말기에 대한 데이터 전송률과 QoS 정보를 MIH 정보 서버로부터 얻어 비디오 스케일링 레이어를 결정한다. 이렇게 결정된 스케일링 레이어를 이용하여 스케일러블 비디오 코딩을 수행한 후, 각각의 단말기에게 비디오를 전송하게 된다. 이러한 새로운 스케일러블 비디오 전송 모델은 서로 다른 여러 종류의 해상도, 화질, 프레임 전송률을 갖는 영상을 다양한 네트워크의 다양한 디바이스로 적응적인 비디오 전송이 가능하다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.589-591
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• 2000

비디오 데이터가 포함하고 있는 카메라와 이동물체의 동작정보를 추출하기 위한 대표적인 방법으로 동작벡터 추출알고리즘이 있다. 본 논문에서는 영상 내에 밝기 값 분포가 균일한 영역이 존재할 때 부정확한 정합 결과를 보이는 것은 기존 알고리즘의 문제점과 이를 개선할 수 있는 계층적 블록정합 알고리즘의 정합오류 전파가능성, 높은 시간복잡도 문제를 동시에 해결할 수 있는 블록정합 알고리즘을 제안한다. 제안하는 알고리즘은 Coarse-to-Fine 방식의 탐색방법과 Dynamic Control Strategy를 결합한 것으로서 정합한 블록의 상황에 따라 탐색 레이어를 동적으로 변경시키는 방법을 사용한다. 본 알고리즘은 크게 두단계로 나뉘어 지는데 탐색 레이어를 결정하는 Control 변경 결정 단계와 정합도 측정함수를 통해 블록에 대한 정합 정확도를 측정하는 단계로 구성이 된다.

• Journal of IKEEE
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• v.28 no.3
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• pp.465-468
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• 2024

In this paper, we propose a synthetic aperture radar based on FMCW using a nonlinear radar platform. we construct a nonlinear radar platform with different transmit and receive frequencies using FMCW signals. The platform moves along a 1.5 m path to acquire second harmonics signals, implementing a nonlinear SAR (synthetic aperture radar). Multiple nonlinear targets were placed in an indoor multipath environment with linear objects to detect weak second harmonics. After undergoing the SAR focusing precess, a 2D hamming window was applied to enhance the focusing performance.