• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.194-198
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• 2011

In this study, an efficient algorithm for Delaunay triangulation of a number of points which can be used on a GPU-based parallel computation is studied The developed algorithm is programmed using CUDA library. and the program takes full advantage of parallel computation which are concurrently performed on each of the threads on GPU. The results of partitioned triangulation collected from the GPU computation requires proper stitching between neighboring partitions and calculation of connectivities among triangular cells on CPU In this study, the effect of number of threads on the efficiency and total duration for Delaunay grid generation is studied. And it is also shown that GPU computing using CUDA for Delaunay grid generation is feasible and it saves total time required for the triangulation of the large number points compared to the sequential CPU-based triangulation programs.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.395-402
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• 2005

This paper deals with modeling and computer simulation of a full multibody vehicle model for a driving simulator. The multibody vehicle model is based on the recursive formulation and a corresponding simulation code is generated automatically from AUTOCODE, which is a symbolic computation package developed by the authors using MAPLE. The paper describes a procedure for automatically generating a highly efficient simulation code for the full vehicle model, while incorporating realistically modeled components. The following issues have been accounted for in the procedure, including software design for representing a mechanical system in symbolic form as a set of computer data objects, a multibody formulation for systems with various types of connections between bodies, automatic manipulation of symbolic expressions in the multibody formulation, interface design for allowing users to describe unconventional force-and torque-producing components, and a method for accommodating external computer subroutines that may have already been developed. The effectiveness and efficiency of the proposed method have been demonstrated by the simulation code developed and implemented for driving simulation.

• Structural Engineering and Mechanics
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• 제8권6호
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• pp.579-589
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• 1999

A new way to reduce the eigenvalue computation effort in structural dynamics is presented in this paper. The degrees of freedom of a structure may be classified into groups that are termed as sub-degrees of freedom. The eigenvalue analysis is performed with each of sub-degrees of freedom so that the computing time is much shortened. Since the dynamic coupling between sub-degrees of freedom is selected to be small and it may be considered as a perturbation, the perturbation algorithm is used to obtain an accuratae result. The accuracy of perturbation depends on the coupling between sub-degrees of freedom. The weaker the coupling is, the more accurate the result is. The procedure can be used to simplify a problem of three dimensions to that of two dimensions or from two dimensions to one dimension. The application to a truss and a space frame is shown in the paper.

• 한국정보통신학회논문지
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• 제8권4호
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• pp.955-959
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• 2004

공간 데이터 마이닝을 위한 기존의 클러스터링 기법들은 점 객체만을 대상으로 한다. 즉, 선이나 면 같은 다양한 공간 객체들을 지원하지 못한다. 이것은 클러스터링 과정에서 객체들 간의 거리 계산에 있어서, 점 객체는 용이하지만 선과 면인 경우에는 어렵기 때문이다. 본 논문에서는 이러한 문제점을 해결하기 위하여 균등 격자를 이용한 클러스터링 기법을 설계한다. 세부적으로 이 기법에서는 다각형 객체들 간의 거리 계산을 균등 격자를 이용하여 단순화시킴으로서 거리 계산에 따른 시간과 비용을 줄일 수 있다.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권7호
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• pp.453-457
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• 2005

With the expansion of Internet, a variety of image databases are widely used and it is needed to select the part of an image what he wants. In contents-based image retrieval system, Zernikie moment and ART Descriptors are used fur shape descriptors in MPEC-7. This paper presents a fast computation method to determine the radius of a bounding circle that encloses an object in a binary image. With conventional methods, the whole area of the image should be scanned first and the distance from every pixel to the center point be computed. The proposed 4-directional scan method and fast circle-drawing algorithm is utilized to minimize the scanning area and reduce the number of operations fur computing the distance. Experimental results show that proposed method saves the computation time to determine the radius of a bounding circle efficiently.

• 항공우주기술
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• 제7권1호
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• pp.61-67
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• 2008

무인항공기의 비행제어법칙 설계를 위하여 자동 제어기 이득 결정 프로그램을 개발하였다. 제어기 이득 결정 문제를 최적화 문제로 정식화 하고, 최적화 문제의 최적해로부터 제어기 이득을 결정하였다. 최적화 문제의 해를 계산하기 위해 진화연산기법의 하나인 PSO 알고리듬과 비선형 프로그래밍의 하나인 SQP 알고리듬을 연결하여 사용하였다. 이 방법을 통하여 최적해 계산 시간을 PSO 방법에 비하여 1/5로 감소시켰으며, 보다 정확한 최적해를 계산할 수 있었다.

• 한국정보처리학회논문지
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• 제4권3호
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• pp.880-894
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• 1997

본 논문에서는 양자화 계수가 0이 되는 위치를 예측하여 축소된 영역내에서 DCT (Discrete Cosine Trans-form)를 수행하는 새로운 알고리즘을 제안한다. 이 제안한 알고 리즘은 FDCT(Forward DCT)와 IDCT(Inverse DCT)의 계산량을 줄여 부호와 시간과 복호 화 시간을 감소시킬 뿐만 아니라, 허프만(huffiman) 부호화시에도 각각의 불럭에 대하여 분류된 블럭 크기에 따라 각기 다른 수평 수직 지그재그 스캔을 수행함으로써 압축률 을 증가시킨다. 기존의 영상 부호화 방법은 모든 블럭에 대하여 똑같은 DCT 계산과 지그재그 스캔을 행한다. 그렇지만, 제안한 알고리즘은 부호화시에 분류된 블럭 크기 밖의 양자화 계수에 대해 FDCT를 계산하는 대신 0을 대입함FDCT 계산 시간을 줄인다. 또한, 복호화시에는 분류된 블럭 크기내에 존재하는 역양자화 계수만 가지고 IDCT를 수행함으로써 IDCT 계산 시간을 줄인다. 추가하여, 제안한 알고리즘은 분류된 블럭 특성에 적합한 수평 수직 지그재그 스캔을 수행함으로써 Run-length를 줄여서, 향상된 압축률을 제공한다. 한편, 제안한 알고리즘은 DCT에서 압축률과 화질면에서는 최적이지만 부호와 시간과 복호화 시간이 많이 걸리는 16*16 블럭의 처리에도 적용되어질 수 있다. 또한, 실시간을 요구하는 동영상 부호화로 확장되어 질 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.514-537
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• 2020

Wireless sensor network (WSN) is a distributed network composed of many sensory nodes. It is precisely due to the clustering unevenness and cluster head election randomness that the energy consumption of WSN is excessive. Therefore, a many-objective optimization WSN energy balance model is proposed for the first time in the clustering stage of LEACH protocol. The four objective is considered that the cluster distance, the sink node distance, the overall energy consumption of the network and the network energy consumption balance to select the cluster head, which to better balance the energy consumption of the WSN network and extend the network lifetime. A many-objective optimization algorithm to optimize the model (LEACH-ABF) is designed, which combines adaptive balanced function strategy with penalty-based boundary selection intersection strategy to optimize the clustering method of LEACH. The experimental results show that LEACH-ABF can balance network energy consumption effectively and extend the network lifetime when compared with other algorithms.

• 한국태양에너지학회 논문집
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• 제36권6호
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• pp.47-59
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• 2016

As the usage of sun tracking system in solar energy utilization facility increases, requirement of more accurate computation of sun position has also been increased. Accordingly, various algorithms to compute the sun position have been proposed in the literature and some of them insist that their algorithms guarantee less than 0.01 degree computational error. However, mostly, the true meaning of accuracy argued in their publication is not clearly explained. In addition to that, they do not clearly state under what condition the accuracy they proposed can be guaranteed. Such ambiguity may induce misunderstanding on the accuracy of the computed sun position and ultimately may make misguided notion on the actual sun tracking system's sun tracking accuracy. This work presents some comments related to the implementation of sun position computational algorithm for the sun tracking system. We first introduce the algorithms proposed in the literature. And then, from sun tracking system user's point of view, we explain the true meaning of accuracy of computed sun position. We also discuss how to select the proper algorithm for the actual implementation. We finally discuss how the input factors used in computation of sun position, like time, position etc, affect the computed sun position accuracy.

• Journal of Ecology and Environment
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• 제33권4호
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• pp.275-288
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• 2010

Ecological modeling faces some unique problems in dealing with complex environment-organism relationships, making it one of the toughest domains that might be encountered by a modeler. Newer technologies and ecosystem modeling paradigms have recently been proposed, all as part of a broader effort to reduce the uncertainty in models arising from qualitative and quantitative imperfections in the ecological data. In this paper, evolutionary computation modeling approaches are introduced and proposed as useful modeling tools for ecosystems. The results of our case study support the applicability of an algal predictive model constructed via genetic programming. In conclusion, we propose that evolutionary computation may constitute a powerful tool for the modeling of highly complex objects, such as river ecosystems.