• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.1973-1974
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• 2006

The mean shift algorithm has achieved considerable success in object tracking due to its simplicity and robustness. It finds local maxima of a similarity measure between the color histograms of the target and candidate image. However, the mean shift tracking algorithm using only color histograms has a serious defect. It doesn't use the spatial information of the target. Thus, it is difficult to model the target more exactly. And it is likely to lose the target during the occlusions of other objects which have similar color distributions. To deal with these difficulties we use both color information and spatial information of the target. Our proposed algorithm is robust to occlusions and scale changes in front of dynamic, unstructured background. In addition, our proposed method is computationally efficient. Therefore, it can be executed in real-time.

• 대한전자공학회논문지
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• 제27권6호
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• pp.954-962
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• 1990

Experties of recognizing an object despite of every possible occlusions among objects is difficult to be provided directly to a system. In this paper, we propose a method for inferring inherent shape-characteirstics of an object from training views provided. The method learns rules incrementally by alternating the rule induction process from limited number of training views and the rule verification process from the following taining views. The learned rules are represented using logical expressions to enhance the readability. Thr proposed method is tested by simulating occlusions on 2-dimensional objects to examine the learning process and to show improvement of recognition rate. Thr result shows that it can be applied to a practical system for 3-dimensional object recognition.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.737-741
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• 2009

This paper addresses the factorization method to estimate the projective structure of a scene from feature (points) correspondences over images with occlusions. We propose both a column and a row space approaches to estimate the depth parameter using the subspace constraints. The projective depth parameters are estimated by maximizing projection onto the subspace based either on the Joint Projection matrix (JPM) or on the the Joint Structure matrix (JSM). We perform the maximization over significant observation and employ Tardif's Camera Basis Constraints (CBC) method for the matrix factorization, thus the missing data problem can be overcome. The depth estimation and the matrix factorization alternate until convergence is reached. Result of Experiments on both real and synthetic image sequences has confirmed the effectiveness of our proposed method.

• 스마트미디어저널
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• 제5권1호
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• pp.78-87
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• 2016

The major problems of recent object tracking methods are related to the inefficient detection of moving objects due to occlusions, noisy background and inconsistent body motion. This paper presents a robust method for the detection and tracking of a moving in infrared animal videos. The tracking system is based on adaptive optical flow generation, Gaussian mixture and Kalman filtering. The adaptive Gaussian model of optical flow (GMOF) is used to extract foreground and noises are removed based on the object motion. Kalman filter enables the prediction of the object position in the presence of partial occlusions, and changes the size of the animal detected automatically along the image sequence. The presented method is evaluated in various environments of unstable background because of winds, and illuminations changes. The results show that our approach is more robust to background noises and performs better than previous methods.

• Current Optics and Photonics
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• 제3권4호
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• pp.329-335
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• 2019

Wide FOV imaging systems are important for acquiring rich visual information. A conventional catadioptric imaging system deploys a camera in front of a curved mirror to acquire a wide FOV image. This is a cumbersome setup and causes unnecessary occlusions in the acquired image. In order to reduce both the burden of the camera deployment and the occlusions in the images, this study uses a secondary planar mirror in the catadioptric imaging system. A compact design of the catadioptric imaging system and a condition for the position of the secondary planar mirror to satisfy the central imaging are presented. The image acquisition model of the catadioptric imaging system with a secondary planar mirror is discussed based on the principles of geometric optics in this study. As a backward mapping, the acquired image is restored to a distortion-free image in the experiments.

• Journal of Chest Surgery
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• 제43권6호
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• pp.785-789
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• 2010

만성동맥폐색증 환자의 혈관내 시술 시 발생되는 기술적 실패의 가장 많은 이유 중의 하나는 폐색부위를 내막하 진행 후 진강내 재진입의 실패에 기인한다. 진강내 재진입 카테터는 유도철사의 진강내 재진입을 용이하게 하여, 대부분 수술로 전환될 만성폐색질환에서 성공적인 혈관내 시술을 가능하게 한다. 본원에서는 표재성 대퇴동맥의 만성동맥폐색증의 혈관내 시술 시 기존의 장비로 진강내 재진입이 실패한 3예에서 $Outback^{(R)}$ $LTD^{TM}$ catheter를 이용하여 성공적으로 치료하였기에 문헌 고찰과 함께 보고하는 바이다.

• Journal of Korean Neurosurgical Society
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• 제53권2호
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• pp.77-82
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• 2013

Objective : Sudden major cerebral artery occlusion often resists recanalization with currently available techniques or can results in massive symptomatic intracranial hemorrhage (sICH) after thrombolytic therapy. The purpose of this study was to examine mechanical recanalization with a retrievable self-expanding stent and balloon in acute intracranial artery occlusions. Methods : Twenty-eight consecutive patients with acute intracranial artery occlusions were treated with a Solitaire retrievable stent. Balloon angioplasty was added if successful recanalization was not achieved after stent retrieval. The angiographic outcome was assessed by Thrombolysis in Cerebral Infarction (TICI) and the clinical outcomes were assessed by the National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin Scale (mRS). Results : At baseline, mean age was 69.4 years and mean initial NIHSS score was 12.5. A recanalization to TICI 2 or 3 was achieved in 24 patients (85%) after stent retrieval. Successful recanalization was achieved after additional balloon angioplasty in 4 patients. At 90-day follow-up, 24 patients (85%) had a NIHSS improvement of ${\geq}4$ and 17 patients (60%) had a good outcome (mRS ${\leq}2$). Although there was sICH, there was one death associated with the procedure. Conclusion : Mechanical thromboembolectomy with a retrievable stent followed by additional balloon angioplasty is a safe and effective first-line therapy for acute intracranial artery occlusions especially in case of unsuccessful recanalization after stent thrombectomy.

• 방송공학회논문지
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• 제15권1호
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• pp.3-13
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• 2010

본 논문에서는 한 장의 기준 영상과 그에 상응하는 참 깊이 맵을 이용하여 가상의 다중 시점 영상 생성 시 발생하는 가려짐 영역 보간 방법을 제안한다. 이 방법은 영상 인페인팅 기술과 각각의 깊이 정도에 따른 층별 보간 기술을 이용한다. 우선, 기준 영상을 깊이 정보에 따라 여러 개의 층으로 분할한다. 각각의 층에 대해 가려짐 영역 내의 화소들은 영상 인페인팅 기술을 이용하여 보간한다. 마지막 단계 에서 개별적으로 보간된 층 영상들은 하나로 합성되어 가상 시점의 영상을 이룬다. 영상을 깊이 정보에 따라 분할함으로써, 각 깊이 정도에 대한 텍스처의 연관성을 보존하며 보간할 수 있으므로 기존의 방법에 비하여 보다 정확하고 세밀한 가려짐 영역 보간이 가능하다. 본 논문에서는 여러 가지 실험 결과를 통하여 제안한 방법의 효율성을 입증하였다.

• 한국인터넷방송통신학회논문지
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• 제10권6호
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• pp.23-29
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• 2010

오늘날은 사회 안전을 강화하기 위하여 공공장소에서 유기물을 자동으로 검출하는 지능적 비전 감시 시스템을 설계하는 것이 필요한 때이다. 그런데, 이미 인지된 유기물의 일부분 또는 전체는 주변사람들로 가려질 수가 있다. 필수 지표 중 하나인 PAT를 개선하기 위해서는 시스템이 이러한 가려짐 문제를 극복해야만 한다. 이 연구에서는 이러한 가려짐 문제를 고려하여 강인한 검출시스템을 구축하기 위해서 여러 단계로 구성된 새로운 설계 기법을 제안한다. 제안된 시스템의 유용성을 보이기 위하여 6개의 다양한 상황을 포함하는 이미지 스트림에 대해서 평가를 시행했고, 그 실험 결과는 침입과 유기 행위에 대해 각각 96%와 75%의 성능을 보인다. 마지막으로 다수의 사람에 의한 가림 현상에도 불구하고 제안된 시스템은 계속적으로 유기물을 인지하는 성능을 보이고 있다.

• Journal of information and communication convergence engineering
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• 제14권1호
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• pp.57-63
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• 2016

In generally, the resolution of reconstructed three-dimensional images can be seriously degraded by undesired occlusions in the integral imaging system, because the undesired information of the occlusion overlap the three-dimensional images to be reconstructed. To solve the problem of the undesired occlusion, we present an exemplar-based image restoration method in integral imaging system. In the proposed method, a minimum spanning tree-based stereo matching method is used to remove the region of undesired occlusions in each elemental image. After that, the removed occlusion region of each elemental images are re-established by using the exemplar-based image restoration method. For further improve the performance of the image restoration, the structure tensor is used to solve the filling error cause by discontinuous structures. Finally, the resolution enhanced three-dimensional images are reconstructed by using the restored elemental images. The preliminary experiments are presented to demonstrate the feasibility of the proposed method.