• 한국군사과학기술학회지
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• 제17권6호
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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.

• International Journal of Aeronautical and Space Sciences
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• 제18권1호
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• pp.129-137
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• 2017

When the micro-Doppler (MD) image of a ballistic missile is derived, the translational motion compensation (TMC) method is usually applied to the inverse synthetic aperture radar (ISAR) image, but yields poor results because of the micro-motion of the ballistic missile. This paper proposes an efficient TMC method to obtain a focused MD image of a ballistic missile engaged in complicated micro-motion. During range alignment, range profiles (RPs) are coarsely aligned by using the 1D entropy cost function of RPs as a mark, then the coarsely-aligned RPs are fine-aligned by using the minimum 2D entropy of the MD image. During phase adjustment, the gradient of the phase error is appropriately weighted and added to the previous phase error to further fine-tune the aligned RPs. In simulations using the point scatterer model and the measured data from the real missile model, the proposed method provided better image focus than the existing method.

• 대한의용생체공학회:의공학회지
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• 제10권1호
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• pp.33-42
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• 1989

도플러 효과는 혈관의 혈류속도를 측정하는데 이용된다. 대부분의 도플러 시스템은 측정위치에 대한 정보를 제공하는 펄스 도플러 시스템이다. 본 논문에서는 2차 샘플링 방식과 직렬 신호 처리를 이용한 새로운 2차원 펄스 도플러 시스템을 제안한다. 제안된 시스템은 직각 위상 검파 방식에서 동상과 $90^{\circ}$ 지연된 위상신호의 불평형성을 해결하고, 또한 직렬 신호 처리를 사용하므로서 2차원 도플러 시스템에서의 채널 간의 평형성 문제를 해결했다.

• Journal of the Optical Society of Korea
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• 제14권3호
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• pp.199-203
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• 2010

A mobile direct detection Doppler LIDAR based on molecular backscattering for measurement of wind in the stratosphere has been developed in Hefei, China. First, the principle of wind measurement with direct detection Doppler LIDAR is presented. Then the configuration of the LIDAR system is described. Finally, the primary experimental results are provided and analyzed. The results indicate that the detection range of the designed Doppler LIDAR reached 50 km altitude, and there is good consistency between the molecular Doppler wind LIDAR(DWL) and the wind profile radar(WPR) in the low troposphere.

• 디지털콘텐츠학회 논문지
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• 제11권2호
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• pp.117-122
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• 2010

본 연구는 레이저 도플러의 진동모드에 대한 분석연구이다. 도플러에서 생성되는 진동모드를 측정하여 각 성분을 분석하여 2차원 연구로부터 3차원을 예측 할 수 있는 성질들을 연구하고자 한다. 진동모드는 범위 탐지기(거리 측정 센서)에 의존하고 있다. 즉, 측정거리에 의해 결정되고 있으므로, 생성되는 변수들로부터 2차원에서부터 3차원에서의 진동모드가 어떻게 생성되는지, 어떤 특성의 패턴으로 나타나는지를 연구함과 더불어, 진동모드와 거리와의 관계도 아울러 연구한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.167-170
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• 2001

A low power pulse Doppler radar should integrate a large number of data to provide a required maximum detectable distance. Doppler filter needs a window that has good out-of-bard rejection level to maintain high dynamic range. From these facts, we can apply decimation and presumming to increase the speed of Doppler processing. This Paper investigates the efficiencies of several decimation methods and the loss of presumming. And I propose a method to increase processing speed but to maintain the maximum detectable distance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.392-397
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• 1987

This paper concerns a method for micro-wave imaging. The image reconstruction of a perfect conducting cylinder by phase and amplitude measurement using the X-Band multifrequency is presented troll the simulated data. The high degree of range resolution is achieved using large signal band-width and cross-range resolution is obtained by doppler processing. The comparison of image reconstruction between range doppler processing and circular convolution algorithm is also shown.

• 한국군사과학기술학회지
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• 제13권6호
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• pp.1139-1146
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• 2010

Simulated target generators are used to evaluate the various radar performance. Using the radar parameters such as target range(time delay), doppler frequency, target RCS, simulated target generator can be developed. Especially moving targets are simulated by control time delay and update target signal intensive for target range. Base on this concepts, in this paper, simulated target generators are designed and developed for X-band Radar performance test. Developed equipment is evaluated its performance and then tested with X-band Radar. This paper presents these design, development, and test results of developed target generator.

• 한국해양공학회지
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• 제18권4호
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• pp.33-39
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• 2004

This paper presents a hybrid underwater navigation system for unmanned underwater vehicles, using an additional range sonar, where the navigation system is based on inertial and Doppler velocity sensors. Conventional underwater navigation systems are generally based on an inertial measurement unit (IMU) and a Doppler velocity log (DVL), accompanying a magnetic compass and a depth sensor. Although the conventional navigation systems update the bias errors of inertial sensors and the scale effects of DVL, the estimated position slowly drifts as time passes. This paper proposes a measurement model that uses the range sonar to improve the performance of the IMU-DVL navigation system, for extended operation of underwater vehicles. The proposed navigation model includes the bias errors of IMU, the scale effects of VL, and the bias error of the range sonar. An extended Kalman filter was adopted to propagate the error covariance, to update the measurement errors, and to correct the state equation, when the external measurements are available. To illustrate the effectiveness of the hybrid navigation system, simulations were conducted with the 6-d.o.f. equations of motion of an AUV in lawn-mowing survey mode.

• 한국음향학회지
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• 제38권2호
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• pp.154-159
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• 2019

수중 이동 음원의 방사 소음을 측정하는 경우 음원과 수신기 사이의 거리 정보가 중요한 평가 요소이며, 수신기 위치, 음원의 수심 및 속도 등과 같이 측정 규격이 정해져 있다. 이동하는 수중 음원의 거리를 찾는 방법으로써 상호 상관도를 사용하는 방법이 있지만 이 방법은 송신기와 수신기 사이의 시간 동기화 과정을 필요로 한다. 본 논문에서는 이론적으로 계산된 다중 경로 신호 사이의 도달 주파수 차와 수신 신호에서 추정된 다중 경로 신호의 도달 주파수 차를 비교하여 거리를 추정하는 방법을 제안한다. 기존의 방법과는 다르게 제안한 방법은 시간 동기화 과정이 필요하지 않다. 성능 검증을 위해 모의실험을 수행하였으며, 거리 오차가 기존의 방법에 비해 약 95 % 감소하였다.