• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.187-197
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• 2005

In this paper, we propose an extended TB-tree, called ETB-tree, which can improve the performance of an existing TB-tree proposed for indexing the trajectories of moving objects in Location-Based Service(LBS). The proposed ETB-tree directly accesses the preceding node by maintaining a direct table, called D-Table which contains the page number in disk and memory pointers pointing the leaf node with the first and last lines segment of moving objects. It can improve the insertion performance by quick searching the preceding node of a moving object and retrieval performance owing to accessing directly the corresponding trajectories In disk for the trajectory-based query. In addition, the ETB-tree provides consistency of a tree by reflecting a newly inserted line segment to the tree both in memory and disk. The experimental results show that the proposed indexing technique gains better performance than other traditional ones with respect to the insertion and retrieval of a trajectory query.

• Advances in aircraft and spacecraft science
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• v.7 no.3
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• pp.271-290
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• 2020

The paper describes the analysis of deployment strategies and trajectories design suitable for executing the inspection of an operative spacecraft in orbit through re-usable CubeSats. Similar missions have been though indeed, and one mission recently flew from the International Space Station. However, it is important to underline that the inspection of an operative spacecraft in orbit features some peculiar characteristics which have not been demonstrated by any mission flown to date. The most critical aspects of the CubeSat inspection mission stem from safety issues and technology availability in the following areas: trajectory design and motion control of the inspector relative to the target, communications architecture, deployment and retrieval of the inspector, and observation needs. The objectives of the present study are 1) the identification of requirements applicable to the deployment of a nanosatellite from the mother-craft, which is also the subject of the inspection, and 2) the identification of solutions for the trajectories to be flown along the mission phases. The mission for the in-situ observation of Space Rider is proposed as reference case, but the conclusions are applicable to other targets such as the ISS, and they might also be useful for missions targeted at debris inspection.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.142-148
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• 2014

A descriptor which is suitable for motion analysis by using the motion features of moving objects from the real time image sequence is proposed. To segment moving objects from the background, the background learning is performed. We extract motion trajectories of individual objects by using the sequence of the 1st order moment of moving objects. The center points of each object are managed by linked list. The descriptor includes the 1st order coordinates of moving object belong to neighbor of the pre-defined position in grid pattern, The start frame number which a moving object appeared in the scene and the end frame number which it disappeared. A video retrieval by the proposed descriptor combining global and local feature is more effective than conventional methods which adopt a single feature among global and local features.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.307-312
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• 2006

멀티미디어의 비중이 커짐에 따라 컴퓨터 과학 각 분야에서 독자적인 기술들을 이용하여 실제 응용 및 시스템을 구축하고 있다. 하지만 멀티미디어 동영상 내에서 객체의 행위 단독적인 움직임을 수치로만 표현하여 자료를 처리함에 따라 의미를 해석하는 것이 부자연스럽고 정확한 숫자에 부합하는 행동의 검출이 어렵다. 본 논문에서는 멀티미디어 동영상의 기본적인 행위를 추출하고 이를 추상화, 정형화하여 보다 상위단계로 접근을 유도하여 멀티미디어 데이터에 대한 접근을 용이하게 하기위한 방법에 대하여 논의하였다.

• The KIPS Transactions:PartB
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• v.15B no.5
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• pp.391-396
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• 2008

Motion of object in a video clip often plays an important role in characterizing the content of the clip. A number of methods have been developed to analyze and retrieve video contents using motion information. However, most of these methods focused more on the analysis of direction or trajectory of motion but less on the analysis of the movement of an object itself. In this paper, we propose the shape sequence descriptor to describe and compare the movement based on the shape deformation caused by object motion along the time. A movement information is first represented a sequence of 2D shape of object extracted from input image sequence, and then 2D shape information is converted 1D shape feature using the shape descriptor. The shape sequence descriptor is obtained from the shape descriptor sequence by frequency transform along the time. Our experiment results show that the proposed method can be very simple and effective to describe the object movement and can be applicable to semantic applications such as content-based video retrieval and human movement recognition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.898-902
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• 2012

A descriptor which is suitable for motion analysis by using the motion features of moving objects from the real time image sequence is proposed. To segment moving objects from the background, the background learning is performed. We extract motion trajectories of individual objects by using the sequence of the $1^{st}$ order moment of moving objects. The center points of each object are managed by linked list. The descriptor includes the $1^{st}$ order coordinates of moving object belong to neighbor of the per-defined position in grid pattern, the start frame number which a moving object appeared in the scene and the end frame number which it disappeared. A video retrieval by the proposed descriptor combining global and local feature is more effective than conventional methods which adopt a single feature among global and local features.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.590-593
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• 2004

Extraction of ocean surface current velocity offers important physical oceanographic parameters especially on understanding ocean environment. Although Remote Sensing techniques were highly developed, the investigation of ocean surface current using Synthetic Aperture Radar (SAR) is not an easy task. This paper presents the results of ocean surface current observation using Doppler Centroid of ERS-1 SAR data obtained off the coast of Korea peninsula. We employed the concept, in which Doppler frequency shift and the ocean surface current are closely related, to evaluate ocean surface current. Moving targets cause Doppler frequency shift of the back scattered radar waves of SAR, thus the line-of-sight velocity component of the scatters can be evaluated. The Doppler frequency shift can be measured by estimating the difference between Doppler Centroid of raw SAR data and reference Doppler Centroid. Theoretically, the Doppler Centroid is zero; however, squinted antenna which is affected by several physical factors causes Doppler Centroid to be nonzero. The reference Doppler Centroid can be obtained from measurements of sensor trajectory, attitude and Earth model. The estimated Doppler Centroid was compensated by considering the accurate attitude estimation of ERS-1 SAR. We could verify the correspondence between the estimated ocean surface current and observed in-situ data in the error bound.

• Journal of Korea Spatial Information System Society
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• v.9 no.3
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• pp.51-65
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• 2007

In order to analyze moving object trajectories on road networks, its representation needs to be defined correctly. The most previous methods representing moving object trajectories on road networks defined moving object trajectories as a set of passed location and its time. It is required much time in processing analysis such as retrieval for moving object trajectories. In this paper, we focus on POI(Points of Interest) on road networks and propose methods simplifying moving object trajectories based on it. Our method simplifies moving object trajectories by reducing the number of POIs that moving object trajectories passed and maintains its form after moving object trajectories were simplified.

• The KIPS Transactions:PartB
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• v.11B no.1
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• pp.1-6
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• 2004

Motion Information in a video clip often plays an important role in characterizing the content of the clip. A number of methods have been developed to analyze and retrieve video contents using motion information. However, most of these methods focused more on the analysis of direction or trajectory of motion but less on the analysis of the movement of an object. In this paper, we introduce the shape variation descriptor for describing shape variation caused by object movement along time, and propose a method to describe and retrieve the shape variation of the object using shape variation map. The experimental results shows that the proposed method performed much better than the previous method by l1％ and is very effective for describing the shape variation which is applicable to semantic retrieval applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.812-820
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• 2012

In this paper, multiple pedestrians tracking system using Histogram of Oriented Gradient and occlusion detection is proposed. The proposed system is applicable to Intelligent Surveillance System. First, we detect pedestrian in a image sequence using pedestrian's feature. To get pedestrian's feature, we make block-histogram using gradient's direction histogram based on HOG(Histogram of Oriented Gradient), after that a pedestrian region is classified by using Linear-SVM(Support Vector Machine) training. Next, moving objects are tracked by using position information of the classified pedestrians. And we create motion trajectory descriptor which is used for content based event retrieval. The experimental results show that the proposed method is more fast, accurate and effective than conventional methods.