• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1996년도 춘계 학술대회논문집
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• pp.27-32
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• 1996

A previously developed pressure based calculation procedure for incompressible flows was modified and applied to transonic and supersonic flows. It uses pressure as a primary variable in preference to density and body fitted coordinate and non-staggered grid system. The discretized momentum equations were rearranged as a system of equations with respect to covariant velocity components. Three different discretization schemes, QUICK hybrid and first order upwind, were used to approximate the convective terms and compared. Present approach was tested far two transonic flow and one supersonic flow problems. Comparison with previous results show that present approach can be used as a solver for compressible flows.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권12호
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• pp.3096-3117
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• 2013

To execute the performance driven Grid applications, an effective and scalable workflow scheduling is seen as an essential. To optimize cost & makespan, in this paper, we propose a Scalable Cost-Time Trade-off (SCTT) model for scheduling workflow tasks. We have developed a heuristic algorithm known as Scalable Cost-Time Trade-off Scheduling (SCTTS) with a lower runtime complexity based on the proposed SCTT model. We have compared the performance of our proposed approach with other heuristic and meta-heuristic based scheduling strategies using simulations. The results show that the proposed approach improves performance and scalability with different workflow sizes, task parallelism and heterogeneous resources. This method, therefore, outperforms other methods.

• 한국인터넷방송통신학회논문지
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• 제21권3호
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• pp.7-14
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• 2021

자동화된 스마트 그리드의 등장은 이러한 문제에 대응을 위한 필수적인 장치가 되고 있으며 스마트 그리드 기반 사회로의 진전을 가져오고 있다. 스마트 그리드는 전기 공급 업체와 소비자 간의 양방향 통신을 가능하게 하는 새로운 패러다임이다. 스마트 그리드는 전력 그리드를 보다 안정적이고 신뢰할 수 있으며 효율적이고 안전하게 만들기 위한 엔지니어의 이니셔티브로 인해 등장했다. 스마트 그리드는 전력 소비자가 전력 사용에서 더 큰 역할을 할 수 있는 기회를 창출하고 전력을 현명하고 효율적으로 사용하도록 동기를 부여한다. 이에 본 연구에서는 기계 학습을 통한 전력 수요 관리에 중점을 둔다. 기계 학습을 사용한 수요 예측과 관련하여 현재 다양한 기계 학습 모델이 소개되어 적용되고 있는 데 이에 관한 체계적인 접근이 요구되고 있다. 특히 GP 학습 모델의 경우에 일반 소비 예측 및 데이터의 가시화와 관련해서 다른 학습 모델보다 장점이 있지만, 스마트 미터 데이터의 예측과 관련해서는 데이터 독립성에 강한 영향을 받는다.

• 한국건설관리학회논문집
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• 제23권4호
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• pp.65-77
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• 2022

공정관리는 건설 프로젝트에서 가장 중요한 프로젝트 성공 요인 중 하나이다. 그러나, 기존의 공정계획 기법은 건설 프로젝트에서 상당한 수작업과 관리자의 판단이 필요하기 때문에 신속한 공정계획과 운영에 많은 어려움이 있다. 본 연구는 공정계획을 자동화하고 시각화하기 위한 새로운 공정계획 기법과 알고리즘을 제안하는 것을 목적으로 하며, 이를 가산 그리드 공정계획 기법(CSM)이라고 한다. 이 기법은 시각화된 도구를 통해 작업 범위를 정의하면 각 작업의 생산성과 작업 가능 조건에 따라 일정계획이 자동으로 생성된다. 날짜별 작업의 위치를 그리드 기반 접근방식으로 시각화할 수 있다. 또한 작업 일정은 진행 상황에 따라 자동으로 갱신할 수 있다. 제안된 기법의 산업적 활용 가능성을 건설프로젝트의 샘플 데이터를 가지고 사례 연구를 통해 검증하였다. 본 연구는 공정관리 프로세스를 자동화하여 건설 산업에 기여할 수 있을 깃으로 기대한다.

• 한국전산유체공학회지
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• 제13권3호
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• pp.35-43
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• 2008

A methodology for the simulation of compressible high Reynolds number flow over rigid and moving bodies on a structured Cartesian grid is described in this paper. The approach is based on a modified version of the Brinkman Penalization method. To avoid oscillations in the vicinity of the body and to simulate shcok-containing flows, a Weighted Essentially Non-Oscillatory scheme is used to discretize the spatial flux derivatives. For high Reynolds number viscous flow, two turbulence models of the two-equation Menter's SST URANS model and a two-equation Detached Eddy Simulation are implemented. Some simple flow examples are given to assess the accuracy of the technique. Finally, a moving grid capability is demonstrated.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.200-208
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• 2007

A methodology for the simulation of compressible high Reynolds number flow over rigid and moving bodies on a structured Cartesian grid is described in this paper. The approach is based on a modified version of the Brinkman Penalization method. To avoid oscillations in the vicinity of the body and to simulate shcok-containing flows, a Weighted Essentially Non-Oscillatory scheme is used to discretize the spatial flux derivatives. For high Reynolds number viscous flow, two turbulence models of the two-equation Menter's SST URANS model and a two-equation Detached Eddy Simulation are implemented. Some simple flow examples are given to assess the accuracy of the technique. Finally, a moving grid capability is demonstrated.

• 대한기계학회논문집
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• 제19권8호
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• pp.1854-1868
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• 1995

An effective nesting algorithm has been proposed to allocate the arbitrary shapes on one or several raw sheets by applying the well-known simulated annealing algorithm as the optimization technique. In this approach, both the shapes to be allocated and the raw sheets are represented as the grid-based models. This algorithm can accommodate every possible situations encountered in cutting apparel parts from the raw leather sheets. In other words, the usage of the internal hole of a shape for other small shapes, handling of the irregular boundaries and the interior defects of the raw sheets, and the simultaneous allocation on more than one raw sheets have been tackled on successfully in this study. Several computational experiments are presented to verify the robustness of the proposed algorithm.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.483-488
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• 1998

A pressure drop model for the PWR grids with and without mixing device is proposed at single phase based on the fluid mechanistic approach. Total pressure loss is expressed in additive way for form and frictional losses. The general friction factor correlations and form drag coefficients available in the open literatures are used to the model. As the results, the model shows better predictions than the existing ones for the non-mixing grids, and reasonable agreements with the available experimental data for mixing grids. Therefore it is concluded that the proposed model for pressure drop can provide sufficiently good approximation for grid optimization and design calculation in advanced grid development.

• 한국CDE학회논문집
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• 제14권3호
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• pp.197-206
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• 2009

In a finite element analysis of the metal forming processes having large plastic deformation, largely distorted elements are unstable and hence they influence upon the result toward negative way so that adaptive remeshing is required to avoid a failure in the numerical computation. Therefore automatic mesh generation and regeneration is very important to avoid a numerical failure in a finite element analysis. In case of generating quadrilateral mesh, the automation is more difficult than that of triangular mesh because of its geometric complexity. However its demand is very high due to the precision of analysis. Thus, in this study, an automatic quadrilateral mesh generation and regeneration method using grid-based approach is developed. The developed method contains decision of grid size to generate initial mesh inside a two dimensional domain, classification of boundary angles and inner boundary nodes to improve element qualities in case of concave domains, and boundary projection to construct the final mesh.

• Journal of Power Electronics
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• 제16권3호
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• pp.1122-1130
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• 2016

This paper presents a novel approach for achieving both a tight DC voltage regulation and a power factor control by applying the Reaching Law Sliding Mode Control (RL-SMC) and the conventional Sliding Mode Control (SMC). Applying these strategies on a matrix rectifier (MR) can achieve a unity grid side power factor when the DC load changes widely and it can provide a ripple-free output voltage that is easily affected by distortions of the three-phase ac voltage supply. Furthermore, by employing the reaching law on the SMC can solve the chatting problem of the sliding motion. Comparative Matlab simulations and experimental verifications for these strategies have been presented and discussed in this paper. The results show that by applying the SMC and RL-SMC on a MR can achieve a unity grid side power factor and a regulated ripple-free DC output.