• 제어로봇시스템학회논문지
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• 제14권4호
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• pp.381-384
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• 2008

In this paper, we consider the problem of designing decentralized sliding mode static output feedback control laws for a class of large scale systems with mismatched uncertainties. We derive a sufficient condition for the existence of a linear switching surface in terms of constrained linear matrix inequalities(LMIs), and we parameterize the linear switching surfaces in terms of the solution matrices to the given constrained LMI existence conditions. We also give an LMI-based algorithm for designing decentralized switching feedback control laws. Finally, we give a design example in order to show the effectiveness of our method.

• 대한기계학회논문집A
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• 제30권5호
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• pp.595-601
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• 2006

Design space optimization using design space adjustment and refinement is used to optimize a knuckle in the suspension system of an automobile. This approach is a new efficient method for large-scale topology optimization by virtue of two reasons. First, design space adjustment including design space expansion and reduction is suitable for large-scale problems. Second, the design space refinement can be done globally or locally where and when necessary and thus is very effective in obtaining a target resolution with much less number of elements. Compliance minimization for a knuckle is considered with a realistic working condition to show the effectiveness and superiority of the new approach.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 춘계 학술대회논문집
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• pp.41-44
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• 2007

A large eddy simulation method with unstructured mesh is presented. Two explicit filtering procedures are adopted for reducing the aliasing error of the nonlinear convective term and measuring the level of subgrid scale velocity fluctuation, respectively. The developed subgrid scale model is basically an eddy viscosity model which depends on both local velocity fluctuation level and local grid scale. As a validation problem, the flows around a sphere of several Reynolds numbers are simulated and some characteristic quantities are compared to experimental data and numerical results in the literature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.5197-5218
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• 2019

Large-scale retrieval algorithm is problem for visual analyses applications, along its research track. In this paper, we propose a high-efficiency region division-based image retrieve approaches, which fuse low-level local color histogram feature and texture feature. A novel image region division is proposed to roughly mimic the location distribution of image color and deal with the color histogram failing to describe spatial information. Furthermore, for optimizing our region division retrieval method, an image descriptor combining local color histogram and Gabor texture features with reduced feature dimensions are developed. Moreover, we propose an extended Canberra distance method for images similarity measure to increase the fault-tolerant ability of the whole large-scale image retrieval. Extensive experimental results on several benchmark image retrieval databases validate the superiority of the proposed approaches over many recently proposed color-histogram-based and texture-feature-based algorithms.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권1호
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• pp.26-32
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• 2000

In this paper, we consider to robust controller design problem for the linear large scale systems with the uncertainties and the time-delays. The considered time-delays are that exist in the state and the input of the subsystems and the interconnected subsystems. And the considered uncertainties are two general types that exist in the system, input and interconnected matrices. Based on the linear matrix inequality(LMI) and Lyapunov theorem, we present sufficient conditions for the existence of a controller that guarantees the asymptotic stability of systems regardless of the uncertainties and the time-delays. Also, the controller can be easily obtained by checking the feasibility of the LMI's. Finally, we show the usefulness of our results by an example.

• 제어로봇시스템학회논문지
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• 제11권8호
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• pp.651-655
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• 2005

In this paper, we consider the problem of designing decentralized sliding mode control laws far a class of large scale systems with mismatched uncertainties. We derive a sufficient condition far the existence of a linear switching surface in terms of a linear matrix inequalities(LMIs), and we parameterize the linear switching surfaces in terms of the solution matrices to the given LMI existence conditions. We also give an algorithm for designing decentralized switching feedback control laws. Finally, we give a design example in order to show the effectiveness of our method.

• 한국정보통신학회논문지
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• 제23권8호
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• pp.1011-1017
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• 2019

본 논문은 무선 애드혹 네트워크에서 신뢰성이 보장되는 데이터 전송을 위해 다중 경로를 설정하는 노드분리 경로문제를 해결하기 위한 강화학습을 제안한다. 노드분리 경로문제는 소스와 목적지사이에 중간 노드가 중복되지 않게 다수의 경로를 결정하는 문제이다. 본 논문에서는 기계학습 중 하나인 강화학습에서 Q-러닝을 사용하여 노드의 수가 많은 대규모의 무선 애드혹 네트워크에서 전송거리를 고려한 최적화 방법을 제안한다. 특히 대규모의 무선 애드혹 네트워크에서 노드분리 경로 문제를 해결하기 위해서는 많은 계산량이 요구되지만 제안된 강화학습은 효율적으로 경로를 학습함으로써 적절한 결과를 도출한다. 제안된 강화학습의 성능은 2개의 노드분리경로를 설정하기 위한 전송거리 관점에서 평가되었으며, 평가 결과에서 기존에 제안된 시뮬레이티드 어널링과 비교평가하여 전송거리면에서 더 좋은 성능을 보였다.

• 한국경영과학회지
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• 제39권4호
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• pp.75-84
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• 2014

In this paper, we dealt with feature selection problem of large-scale and high-dimensional biological data such as omics data. For this problem, most of the previous approaches used simple score function to reduce the number of original variables and selected features from the small number of remained variables. In the case of methods that do not rely on filtering techniques, they do not consider the interactions between the variables, or generate approximate solutions to the simplified problem. Unlike them, by combining set covering and clustering techniques, we developed a new method that could deal with total number of variables and consider the combinatorial effects of variables for selecting good features. To demonstrate the efficacy and effectiveness of the method, we downloaded gene expression datasets from TCGA (The Cancer Genome Atlas) and compared our method with other algorithms including WEKA embeded feature selection algorithms. In the experimental results, we showed that our method could select high quality features for constructing more accurate classifiers than other feature selection algorithms.

• 대한산업공학회지
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• 제25권4호
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• pp.500-509
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• 1999

In this paper, we consider an optimal routing problem when point-to-point and point-to-multipoint connection traffics are offered in an ATM network. We propose a mathematical model for cost-minimizing configuration of a logical network for a given ATM-based BISDN. Our model is essentially identical to the previous one proposed by Kim(Kim, 1996) which finds a virtual-path configuration where the relevant gains obtainable from the ATM technology such as the statistical multiplexing gain and the switching/control cost-saving gain are optimally traded-off. Unlike the Kim's model, however, ours explicitly considers the VP's QoS(Quality of Service) for more efficient utilization of bandwidth. The problem is a large-scale, nonlinear, and mixed-integer problem. The proposed algorithm is based on the local linearization of equivalent-capacity functions and the relaxation of link capacity constraints. As a result, the problem can be decomposed into moderate-sized shortest path problems, Steiner arborescence problems, and LPs. This fact renders our algorithm a lot faster than the previous nonlinear programming algorithm while the solution quality is maintained, hence application to large-scale network problems.

• 한국지반환경공학회 논문집
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• 제13권2호
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• pp.49-57
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• 2012

과거에는 굴착공사 중 사고발생의 경우 대부분 대규모 붕괴로 연결되는 경우가 많았다. 그러나 최근에는 설계검토 수준의 향상 및 공사 중 적극적인 계측계획의 수립 등으로 대규모 붕괴로 연결되기 전 문제발생 징후를 사전 감지, 피해를 최소화하여 공사를 안전하게 완료하는 경우가 많아지고 있다. 본 논문은 먼저 과거 붕괴사례 조사를 통해 과거의 붕괴원인에 대해 정리하였다. 다음으로 최근에 중요하게 대두되고 있는 계측관리에 대한 일반사항 및 활용방법에 대해 살펴보고 굴착공사 중 문제발생 유형 및 원인에 대해 검토하였다. 또한 실제 시공 중 계측결과 이상 징후가 나타난 현장을 대상으로 계측결과와 연계하여 문제발생 원인 및 보강대책을 검토하였다. 본 연구를 통해 굴착공사 중 대규모 붕괴사고를 사전에 방지하기 위해서 계측관리 및 지반조사가 매우 중요한 사항이라는 인식이 증대될 것으로 판단된다.