• 방송공학회논문지
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• 제3권1호
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• pp.50-60
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• 1998

본 논문에서는 콤팩트한 동영상 표현과 객체기반의 generic한 동영상압축을 위한 파라미터릭 움직임 모델의 파라미터 추정과 세그맨테이션 기법에 관해서 기술한다. 동영상의 optical flow와 같은 국소적 움직임 정보와 파라미터 움직임 모델의 특징을 이용해서 영상의 콤팩트한 구조적 표현을 추출하기 위해, 본 논문에서는 2 스템의 과정 즉, 초기영역을 추출하는 과정과, 파라미터릭 움직임 파라미터의 추정과 세그맨테이션을 동시에 수행하는 과정으로 구성된 새로운 알고리즘을 제안한다. 혼합 모델이 ML 추정에 의거한 확률적 클러스터링에 의해 움직임 물체의 움직임과 형상을 반영한 초기영역을 추출하고, 파라미터릭 움직임 모델을 사용해서 각각의 초기 영역마다 움직임 파라미터를 추정하고 세그맨테이션을 수행한다. 또한, CIF 표준 동영상을 사용한 모의 실험을 통해 본 제안 알고리즘의 유효성을 평가한다.

• 한국컴퓨터산업학회논문지
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• 제6권5호
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• pp.801-812
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• 2005

H.264/AVC는 부호화 효율을 크게 향상시킨 비디오 부호화에 대한 표준이다. ITU-T와 MPEG는 가변블록의 움직임, 다중참조화면, l/4 화소 움직임 추정/보상기법과 비트율-왜곡 최적화 기법 등 다양하고 복잡한 부호화 기법들을 적용했다. H.264 참조 모델은 비트율-왜곡 최적화 기법에 기반을 둔 복잡한 부호화 모드 결정 기법을 채택했는데, 이는 부호화기의 높은 복잡성을 요구한다. 본 논문에서는 매크로 블록 부호화 모드의 순서에 대한 비트율-왜곡의 비용 값의 분포에 기초한 효율적인 부호화 모드 결정 기법을 제안하였다. 실험결과는 제안한 방법이 부호화 시간에 있어 34%를 감소시켰으며, 비트율-왜곡의 계산 량을 82% 줄였음을 보여준다.

• 대한전자공학회논문지
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• 제26권1호
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• pp.78-87
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• 1989

본 논문에서는 백색 Gauss 잡음이 섞인 연속영상으로 부터 물체의 이동정보를 검출하기 위하여 최소자승추정의 시공간경사법을 제안하였다. 제안된 방법은 하나의 이동물체를 실시간으로 추적하도록 고속의 16-bit 마이크로 프로세서를 사용한 자동목표 추적장치에 적용되었다. 실험결과 제안된 방법은 기존의 최소자승추정의 시공간경사법에 비해서 매우 우수한 성능을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권7호
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• pp.3239-3267
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• 2018

Image and video dehazing is a popular topic in the field of computer vision and digital image processing. A fast, optimized dehazing algorithm was recently proposed that enhances contrast and reduces flickering artifacts in a dehazed video sequence by minimizing a cost function that makes transmission values spatially and temporally coherent. However, its fixed-size block partitioning leads to block effects. The temporal cost function also suffers from the temporal non-coherence of newly appearing objects in a scene. Further, the weak edges in a hazy image are not addressed. Hence, a video dehazing algorithm based on well designed spectral clustering is proposed. To avoid block artifacts, the spectral clustering is customized to segment static scenes to ensure the same target has the same transmission value. Assuming that edge images dehazed with optimized transmission values have richer detail than before restoration, an edge intensity function is added to the spatial consistency cost model. Atmospheric light is estimated using a modified quadtree search. Different temporal transmission models are established for newly appearing objects, static backgrounds, and moving objects. The experimental results demonstrate that the new method provides higher dehazing quality and lower time complexity than the previous technique.

• 한국ITS학회 논문지
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• 제9권6호
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• pp.129-135
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• 2010

본 논문은 애드 혹 네트워크에서 다중 경로 설정을 위한 탐색 기법을 제안한다. 데이터 경로 설정은 요구기반 방식으로 동작하며, 소스와 목적지 노드 간의 다중 경로는 초기 경로 설정 과정에서 함께 구해진다. 이러한 다중 경로는 데이터 경로의 백업이나 부하 분산에 사용될 수 있다. 제안 방식에서는 소스와 목적지 노드 간 다중 경로를 찾기 위해, 사전 질의 방법을 사용한다. 이 방안은 중간 노드에서 응답 메시지를 처리할 때, 주변 노드와의 정보 교환을 통해 최적의 다음노드를 선택하는 방안이다. 시뮬레이션 결과를 통해, 제안된 다중 경로 체계가 경로간의 만나는 횟수를 감소시켜 다중경로의 더 좋은 분리도를 주고, 노드들이 이동하는 환경에서 더 높은 경로 생존 확률을 달성함을 알 수 있었다.

• 한국해양공학회지
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• 제34권4호
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• pp.272-276
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• 2020

This paper presents an optimization process for a catamaran hull form. The entire optimization process was managed using the CAD-CFD integration platform CAESES. The resistance of the demi-hull was simulated in calm water using the CFD solver STAR-CCM+, and an inviscid fluid model was used to reduce the computing time. The Free-Form Deformation (FFD) method was used to make local changes in the bulbous bow. For the optimization of the bulbous bow, the Non-dominated Sorting Genetic Algorithm (NSGA)-II was applied, and the optimization variables were the length, breadth, and angle between the bulbous bow and the base line. The Lackenby method was used for global variation of the bow of the hull. Nine hull forms were generated by moving the center of buoyancy while keeping the displacement constant. The optimum bow part was selected by comparing the resistance of the forms. After obtaining the optimum demi-hull, the distance between two demi-hulls was optimized. The results show that the proposed optimization sequence can be used to reduce the resistance of a catamaran in calm water.

• International Journal of Aeronautical and Space Sciences
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• 제12권4호
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• pp.305-317
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• 2011

This paper presents an overview on flutter boundary prediction in tests which is principally based on a system stability measure, named Jury's stability criterion, defined in the discrete-time domain, accompanied with the use of autoregressive moving-average (AR-MA) representation of a sampled sequence of wing responses excited by continuous air turbulences. Stability parameters applicable to two-, three- and multi-mode systems, that is, the flutter margin for discrete-time systems derived from Jury's criterion are also described. Actual applications of these measures to flutter tests performed in subsonic, transonic and supersonic wind tunnels, not only stationary flutter tests but also a nonstationary one in which the dynamic pressure increased in a fixed rate, are presented. An extension of the concept of nonstationary process approach to an analysis of flutter prediction of a morphing wing for which the instability takes place during the process of structural morphing will also be mentioned. Another extension of analytical approach to a multi-mode aeroelastic system is presented, too. Comparisons between the prediction based on the digital techniques mentioned above and the traditional damping method are given. A future possible application of the system stability approach to flight test will be finally discussed.

• 한국CDE학회논문집
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• 제2권2호
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• pp.93-102
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• 1997

Most design changes are due to interferences and fit-up as parts are assembled if such a large product as an automobile or an aircraft is developed by many concurrent engineers. In this part (1) of the thesis, the assembly-centric modeling methodology with CAD systems is proposed in order to reduce the design changes. Unlike part-centric modeling method, a part is modeled with its own coordinate system which is used in downstream process as machining and measuring. The part coordinates initially have the same orientation as its assembly which is predefined in BOM (Bill of Material). Then, the corrdinates origin of the part is moved to its location to be assembled from that of its assembly coordinate system. To implement this methodology, the position data of the part w.r.t. its assembly are stored in a database to build the same hierarchical assembling structure as BOM structure. This modeling approach has the advantage of reflecting asembling sequence, because the process of positioning parts is similar to that of real assembling. And with the method, a designer can easily adjust all of the part positions of an assembly to resolve interferences if he modifies just the coordinates origin of the assembly, which results in moving included parts and assemblies together.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2004년도 추계학술대회 및 정기총회
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• pp.13-16
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• 2004

This paper deals with a one-searcher multi-target search problem where targets with different detection priorities move in Markov processes in each discrete time over a given space search area, and the total number of search time intervals is fixed. A limited search resource is available in each search time interval and an exponential detection function is assumed. The searcher can obtain a target detection award, if detected, which represents the detection priority of target and is non-increasing with time. The objective is to establish the optimal search plan which allocates the search resource effort over the search areas in each time interval in order to maximize the total detection award. In the analysis, the given problem is decomposed into intervalwise individual search problems each being treated as a single stationary target problem for each time interval. An associated iterative procedure is derived to solve a sequence of stationary target problems. The computational results show that the proposed algorithm guarantees optimality.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제9권3호
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• pp.166-171
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• 2009

In recent years, video detection systems have been implemented in various infrastructures such as airport, public transportation, power generation system, water dam and so on. Recognizing moving objects in video sequence is an important problem in computer vision, with applications in several fields, such as video surveillance and target tracking. Segmentation and tracking of multiple vehicles in crowded situations is made difficult by inter-object occlusion. In the system described in this paper, the mean shift algorithm is firstly used to filter and segment a color vehicle image in order to get candidate regions. These candidate regions are then analyzed and classified in order to decide whether a candidate region contains a license plate or not. And then some characters in the license plate is recognized by using the fuzzy ARTMAP neural network, which is a relatively new architecture of the neural network family and has the capability to learn incrementally unlike the conventional BP network. We finally design a license plate recognition system using the mean shift algorithm and fuzzy ARTMAP neural network and show its performance via some computer simulations.