• The Journal of the Acoustical Society of Korea
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• v.20 no.8
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• pp.44-57
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• 2001

This paper analyses the performance of FFTSA (Fast Fourier Transform Synthetic Aperture) in the effects of temporal coherence and oscillatory towed course, which is one of the techniques for passive synthetic aperture SONAR process using linearly distributed towed array. Also this paper proposes the FFTSA technique using towed array having conformal shape to alleviate the performance degradation for estimating the incident angle under inconsistent under water environments. And this paper analyses the performance of the proposed FFTSA technique making use of conformal structure throughout exhaustive computer simulations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.190-190
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• 2004

목표물이 시선의 중심에서 벗어났을 때 모터를 구동시켜 목표물을 시선의 중심에 고정시킴과 동시에 외란으로 인한 카메라의 시선이 흔들리는 것을 막아주는 것을 시선 안정화 시스템이라 한다. 이러한 시스템은 능동 서스펜션 역할출 하는 서보제어기 설계기술이 요구된다. 이론 위하여 본 연구에서는 3축의 회전운동이 가능하고 회전운동에 따른 카메라의 시선의 회전축이 일체화가 되도록 하는 짐벌(gimbals) 구조를 설계한다.(중략)

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1880-1881
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• 2011

본 논문에서는 2차원 평면상을 주행하는 이동 로봇의 목표물에 대한 상대 위치 및 방향각을 측정하는 방법에 대하여 제안한다. 측정을 위해 사용되는 센서는 스테레오 카메라로, 이동 로봇은 3DOF의 특징을 갖고 있으므로 두 개의 점을 이용하여 상대 위치 및 방향각을 측정하는 방법을 제안한다. 상대 위치를 측정하는 과정에서 외란에 의한 위치 오차가 발생하게 되며, 이에 대한 대책으로 칼만 필터를 적용하여 더욱 강건한 상대 위치 추정을 한다. 마지막으로 MATLAB을 이용한 시뮬레이션을 통하여 외란이 존재하는 환경 하에서 제안된 시스템의 성능을 확인한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.668-670
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• 2010

It is necessary to estimate the range and Doppler shifted spectrum for the extraction of useful information from the return echoes in the frequency modulated continuous wave radar systems used for the remote sending purpose such as detection of moving targets. However, the spectrum estimation using the FFT method causes the very large sidolobes of clutter masking the essential signal information if the acquisition time of an echo signal is pretty short. Therefore, in this paper, the efficient data windowing method is investigated to suppress the strong sidelobe levels of the clutter and results are analyzed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.4
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• pp.333-339
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• 2017

Transmission signal in wireless environment receives a signal in which a source signal, interference, and noise are mixed. The goal of this study is to estimate the desired signal from the received signal. In this paper, we have studied a method correctly estimating a target in spatial by modified beamformer method. The modified bemaformer uses an adaptive array antenna and perturbation matrix to obtain the optimal weight, and estimate the desired signal by radiating the beam in spatial. We estimate a desired signal of the target by improving resolution with the modified beamformer method which does not have complicated calculation amount. Through simulation, we compare and analyze the modified beamformer method and the MUSIC method with good resolution. In result of simulation, we showed that modified beamformer method has better resolution of 10degree than classical beamformer method and showed similar performance as the MUSIC method. The resolution of this paper was estimated to be about 5 degrees.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2511-2517
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• 2009

Recently, a FMCW radar is used for the various purposes in the short range detection and tracking of targets. The main advantages of a FMCWradar are the comparative simplicity of implementation and the low peak power transmission characterizing the very low probability of signal interception. Since it uses the frequency modulated continuous wave for transmission and demodulation, the received beat frequency represents the range and Doppler information of targets. Detection and extraction of useful information from targets are performed in this beat frequency domain. Therefore, the resolution and accuracy in the estimation of a beat spectrum are very important. However, using the conventional FFT estimation method, the high resolution spectrum estimation with a low sidelobe level is not possible if the acquisition time is very short in receiving target echoes. This kind of problems deteriorates the detection performance of adjacent targets having the large magnitude differences in return echoes and also degrades the reliability of the extracted information. Therefore, in this paper, the model parameter estimation methods such as autoregressive and eigenvector spectrum estimation are applied to mitigate these problems. Also, simulation results are compared and analyzed for further improvement.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.2
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• pp.160-168
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• 2001

Change detection using difference picture has been used to detect the location of moving targets and to track them. This method needs the assumption of static camera, and the global motion compensation is required in case of a moving camera. This paper suggests a method for finding a minimum bounding rectangles(MBR) of moving targets in the image sequences using moving region detection, especially with a moving camera. If the global motion parameter is inaccurately estimated, the estimated locations of targets will be accurate either To alleviate this problem, we introduce the concept of the confidence measure and achieve more accurate estimation of global motion. Experimental results show that the proposed method successfully removes background region and extracts MBRs of the targets. Even with a moving camera, the new global motion estimation algorithm performs more precise]y and it reduces the background compensation errors of change detection.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.845-848
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• 2000

운동(motion) 벡터는 보고 있는 카메라와 관측되는 대상물 사이의 상대적인 움직임에 의해서 발생되는 3차원 물체의 속도가 2차원 영상에 투사되어 맺히는 영상에서의 2차원 속도 벡터를 가리킨다 영상에서 물체의 움직임은 3차원 공간상의 운동을 알 수 있는 중요한 정보로써 물체를 추적하는데 응용되고 있다. 본 논문에서는 여러 장의 연속적인 2차원 밝기 영상으로부터 카메라의 움직임을 추정하는 문제를 다룬다. 기존의 특징 기반 추적 기법에서는 저 단계의 영상 처리 과정에서 모델과 배경의 특징점이 서로 분리되지 않거나, 모델의 특징(feature)이 소실되었을 경우, 추적이 용이하지 못하고, 카메라와 3차원 물체의 병진과 회전 운동에 의해 발생된 움직임의 경우 3차원 표적 특징이 많이 사라져서 오차가 많이 누적되기도 한다. 본 논문에서는 이러한 문제를 해결하기 위하여 목표물 및 배경 특징들을 사용하여 카메라의 운동 정보를 찾아내는 기법을 제안한다. 제안하는 3차원 카메라의 운동 정보 추정 기법은 크게 두 장의 연속된 영상으로부터 3차원 모델과 배경의 많은 특징들에 대한 광류(optical flow) 검색 과정과, 이로부터 취득한 움직임 벡터와 카메라의 비선형 운동 방정식과 Lagrange multiplier를 통한 카메라의 운동 정보 추정 과정으로 구성된다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.3
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• pp.291-297
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• 2016

In this paper, we are comparative analysis of exit algorithm and proposal algorithm for desired target direction of arrival estimation in correlation signal system. Proposed algorithm in this paper is to decrease target direction of arrival an estimation error probability using bayesian, maximum posterior, and MUSIC algorithm in order to decrease direction of arrival error probability as optimize and use linear constrained minimum variance to update weight value. Through simulation, we were comparative analysis proposed algorithm and exit MUSIC algorithm. In case SNR is 10dB and antenna element arrays are 9 and 12, We show the superior performance of the proposed method relative to the class method to decrease of signal estimation error probability about 11% and 13%, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.8
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• pp.1752-1758
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• 2010

A FM-CW radar is used for the various purposes as a remote sensing device since it has the advantages of the relatively simple implementation and the low probability of signal interception. A FM-CW radar uses the same frequency modulated continuous wave for both transmission and demodulation. Therefore, the received beat frequency represents the range and Doppler information of targets. However, using the conventional FFT method, the degree of accuracy and resolution in the spectrum estimation can be seriously degraded in the detection and tracking of fast moving targets because of the short dwell time. Therefore, in this paper, the model parameter estimation methods called as an autoregressive method is applied to overcome these problems and showed that the improved accuracy and resolution can be obtained for the target range and velocity estimation.