• 한국멀티미디어학회논문지
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• 제22권2호
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• pp.311-321
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• 2019

Virtual reality applications in Head-Mounted Displays require high frame rates and low latency rendering techniques. Ray tracing offers many benefits, such as high-quality image generation, but has not been utilized due to lower performance than rasterization. But that can obtain good result combined with gaze-tracking technology and human visual system's operation principle. In this paper, we propose a method to optimize the foveated sampling map and to maintain the visual quality through the fast voronoi nearest interpolation. The proposed method further reduces the computational cost that has been improved by the previous foveated sampling. It also smoothes the voronoi boundary using adaptive sibson interpolation, which was not possible in real-time. As a result, the proposed method can render real-time high-quality images with low visual difference.

• International Journal of Internet, Broadcasting and Communication
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• 제15권2호
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• pp.22-30
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• 2023

The portable mobile devices with high performance and high speed 5G network activate and explode the demands for ubiquitous information services that remove the limitations of time for the communication and places to request for the information. NN (Nearest Neighbor) search is one of the most important types of queries to be processed efficiently in the information services. Various indexes have been proposed to support efficient NN search in the wireless broadcast system. The indexes adopting Hilbert curve, grid partition or Voronoi diagram enable the clients to search for NN quickly in the wireless broadcast channel. It is necessary that an efficient means to evaluate the performances of various indexes. In this paper, we propose an open framework that can adopt a variety of indexing schemes and evaluate and compare the performances of them. The proposed framework is organized with open and flexible structure that can adopt hybrid indexing schemes extensible to Voronoi diagram as well as simple indexing schemes. With the implemented framework, we demonstrate the efficiency and scalability and flexibility of the proposed framework by evaluating various indexing schemes for NN query.

• Structural Engineering and Mechanics
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• 제91권3호
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• pp.239-250
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• 2024

With the aim to provide better predication about fracture behavior, a numerical simulating strategy based on the rigid spring model is proposed for reinforced concrete (RC) structures in this study. According to the proposed strategy, concrete is partitioned into a series of irregular rigid blocks based on the Voronoi diagram, which are connected by interface springs. Steel bars are simulated by bar elements, and the bond slip element is defined at bar element nodes to describe the interaction between reinforcement and concrete. A concrete damage evolution model based on the separation criterion is adopted to describe the weakening process of interface spring between adjacent blocks, while a nonlinear bond slip model is introduced to simulate the synergy behaviour of reinforced steel bars and concrete. In the damage evolution model of concrete, the influence of compressive stress perpendicular to the interface on the shear strength is considered. To check the effectiveness and applicability of the proposed modelling, experimental and numerical studies about a simply-supported RC beam and the two-notched concrete plates in Nooru-Mohamed's experiment are conducted, and the grid sensitivity are investigated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1892-1893
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• 2011

본 논문에서는 Centroidal Voronoi Tessellation을 이용하여 군집로봇의 협조탐색을 위한 공간분할기법을 제안한다. 탐색공간은 Centroidal Voronoi Tessellation을 이용하여 분할한다. 전역 경로 계획 및 군집 로봇 간의 충돌 회피는 포텐셜 필드를 이용한다. 탐색공간에 밀도 함수를 사용하여 공간분할의 유동성을 부여한다. 마지막으로, 군집로봇의 협조탐색의 가능성을 시뮬레이션을 통하여 확인한다.

• Communications for Statistical Applications and Methods
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• 제4권1호
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• pp.129-138
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• 1997

In this paper, the problem for choosing design points in the two dimensional case is condidered. In the one dimensional case, given the design density function, we can choose design points using the quantile function. However, in the two dimensional case, there is no clear definition of the percentile. Therefore, the idea of choosing design points in the univariate case can not be applied directly to the two dimensional case. We convert this problem into an optimization problem using the Voronoi diagram.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2016년도 제53차 동계학술대회논문집 24권1호
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• pp.283-284
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• 2016

사물인터넷이란 인간의 일상생활에 사용 중인 가전제품, 의료기기, 기타 센서 부착 기기들이 인터넷에 연결되어 스스로 통신하고 제어하는 환경이다. 본 논문에서는 사물인터넷을 구성하는 각 사물들 간의 효율적인 통신을 위해 센터노드를 설정하고 각 사물들이 센터 노드를 중계기로 활용하여 다른 사물들과 효과적인 통신할 때 보로노이 다이어그램을 적용하는 방법을 제안한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.174-179
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• 2003

Through the simultaneous localization and map building (SLAM) technique, a robot can create maps about its unknown environment while it continuously localizes its position. Grid maps and feature maps have been widely used for SLAM together with application of probability methods and POMDP (partially observed Markov decision process). But this approach based on grid maps suffers from enormous computational burden. Topological maps, however, have drawn more attention these days because they are compact, provide natural interfaces, and are easily applicable to path planning in comparison with grid maps. Some topological SLAM techniques like GVG (generalized Voronoi diagram) were introduced, but it enables the robot to decide only whether the current position is part of GVG branch or not in the GVG algorithm. In this paper, therefore, to overcome these problems, we present a method for updating a global topological map from the local topological maps. These local topological maps are created through a labeled Voronoi diagram algorithm from the local grid map built based on the sensor information at the current robot position. And the nodes of a local topological map can be utilized as the features of the environment because it is robust in light of visibility problem. The geometric information of the feature is applied to the extended Kalman filter and the SLAM in the indoor environment is accomplished. A series of simulations have been conducted using a two-wheeled mobile robot equipped with a laser scanner. It is shown that the proposed scheme can be applied relatively well.

• 한국통신학회논문지
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• 제36권9A호
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• pp.758-766
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• 2011

무선 협력 통신 기술은 유선 기간망과 연결 없이 설치 가능한 중계국(Relay Station)을 이용하여 추가적으로 기지국을 설치하지 않아도 커버리지 확장, 음영지역의 해소, 링크 전송률을 향상시킬 수 있다. 중계국은 중요한 이동 통신자원 중 하나로 등장하면서 많은 연구들이 최적의 중계국 선택 방안, 중계국 분배 알고리즘과 같은 주제에 초점을 맞추어 진행하여 왔다. 그러나 특정한 환경에 배치한 중계국 수와 획득할 수 있는 링크 전송률 이득사이 관계를 정확히 분석하는 수학적 모델에 대한 제안은 없었다. 본 논문에서는 Voronoi tessellation에 의한 중계국 기반 클러스터 기법을 제안한다. 또한 Voronoi tessellation에 기반하여 배치한 중계국 수와 사용자가 획득할 수 있는 링크 전송률 이득 사이 관계에 대한 수학적 분석 모텔을 추출한다. 본 논문에서 제안된 수학적 분석 모델의 정확성은 Erceg 경로 손실 모델에 기반한 시뮬레이션에 의해 검증되었다.

• 한국통신학회논문지
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• 제29권12C호
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• pp.1686-1691
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• 2004

본 논문에서는 기존의 고속 유클리디언 거리 변환법을 개선한 새로운 계산 방법을 제안한다. 기존의 고속 유클리디언 거리 변환법이 가지고 있는 단점인 특징점의 수에 비례하여 계산량이 늘어나는 단점을 극복하기 위해서, 본 논문에서는 특징점들 중에서 비특징점과 4방향으로 연결되어 있는 특징점만을 이용하여 보로노이 다이어그램을 계산함으로써 유클리디언 거리 변화도(Euclidean distance map)의 계산 시간을 기존의 방법보다 평균 40%로 감소시켰다. 본 논문에서 제안한 방법의 효율성을 검증하기 위해서 크기의 바이너리 영상 16장에서 대해서 기존의 방법과 제안한 방법으로 똑같이 유클리디언 거리 변화도를 계산하여 계산 시간을 비교함으로써 그 효능을 입증하였다.

• Computers and Concrete
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• 제27권3호
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• pp.283-295
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• 2021

Existing meso-scale models of concrete need to refine the mesh grids of aggregate and cement mortar, which may greatly reduce the computational efficiency. To overcome this problem, a novel meso-scale modeling strategy, which is based on rigid body spring method and Voronoi diagram, is proposed in this study to establish the meso-scale model of concrete. Firstly, establish numerical aggregate models according to user-defined programs. Circle aggregates are adopted due to their high efficiency in generation and packing process, and the grading of aggregate are determined according to the distribution curve proposed by Full and Thompson; Secondly, extract the centroids of aggregates, and then develop the Voronoi diagram in which aggregate centroids are defined as initial scatters; Finally, establish the rigid body spring model for concrete based on the Voronoi diagram. Aggregates are represented by rigid blocks, and assumed to be unbreakable. Cement mortar is concentrated into the interface between adjacent blocks and represented by two uniform springs. The number of grids is consistent with that of aggregates in specimens, and no mesh-refinement of aggregates and cement mortar is required. The accuracy and efficiency of the proposed modeling strategy are firstly identified by comparing the numerical results with the experimental ones, and then the applicability of the proposed strategy with different volume percentage occupied by aggregates is investigated.