• 전기전자학회논문지
• /
• 제18권1호
• /
• pp.146-151
• /
• 2014

스마트 그리드는 기존 전력망에 ICT(Information Communication Technology)기술과 타산업간의 지속적인 융합으로 다양한 부가서비스를 제공한다. 다양한 프로토콜을 사용하고 있는 스마트 그리드 응용시스템이 상호간에 독립적으로 정보를 교환하기 위해서는 기존 프로토콜에 독립적인 미들웨어 사용이 필요하다. 스마트 그리드 응용시스템들은 대부분 All-IP 기반에서 정보 교환이 이루어진다. 현재 All-IP 기반의 미들웨어는 대표적으로 SOAP(Simple Object Access Protocol)과 RESTful(REpresentational State Transfer ful)이 있다. 본 논문에서는 SOAP과 RESTful의 성능을 비교 분석하여 향후 스마트 그리드 응용 시스템 구축 시 사용할 수 있는 SOAP와 RESTful의 성능을 비교분석하였다.

• 대한임베디드공학회논문지
• /
• 제9권2호
• /
• pp.101-107
• /
• 2014

Mobile robots use an environment map of its workspace to complete the surveillance task. However grid-based maps that are commonly used map format for mobile robot navigation use a large size of memory for accurate representation of environment. In this reason, grid-based maps are not suitable for path planning of mobile robots using embedded board. In this paper, we present the path planning algorithm that produce a secure path rapidly. The proposed approach utilizes a hybrid map that uses less memory than grid map and has same efficiency of a topological map. Experimental results show that the fast path planning uses only 1.5% of the time that a grid map based path planning requires. And the results show a secure path for mobile robot.

• 대한방사선기술학회지:방사선기술과학
• /
• 제41권2호
• /
• pp.149-155
• /
• 2018

Quantitative analysis was performed to confirm that moire artifact was removed without loss of image when using grid suppression software in the diagnosis of micro lesions. we showed that grid suppression images can be morphologically different from original images as they are significantly lower than those of the optimized grid in the similarity analysis with reference images in mammographic phantom images. We were confirmed that images of microcalcification with smaller signal than noise were lost because the pixel values of all lesions increased significantly after the grid suppression, The change in contrast using the NORMI 13 X-ray test phantom was reduced to 30% of the reference image, This result was significantly lower than the 90% when using the optimized grid. In conclusion, the use of grid suppression software in clinical images should be carefully considered because of the possibility of misdiagnosis due to micro lesion loss and morphological changes.

• Steel and Composite Structures
• /
• 제18권2호
• /
• pp.395-408
• /
• 2015

The paper considers the free vibration analysis of FGM grid systems. Up to now, very little work has been done on this type of system and the paper aspires to fill this gap. Based on the hybrid-stress finite element formulation free vibration solutions for FGM grid systems of various aspect ratios, different types of gradations functions, and support conditions are determined. The tabulation of these results, not available thus far, should be useful to designers and researchers who may use them.

• 한국컴퓨터산업학회논문지
• /
• 제6권2호
• /
• pp.345-354
• /
• 2005

그리드 사용자에게 시간과 장소에 상관없이 그리드 서비스를 이용할 수 있게 해주는 기술이 모바일 그리드이다. 이동환경에서 그리드 서비스를 제공하기 위해서는 단말기 배터리의 성능 및 이동성의 고려 등 여러 가지 제약사항이 따르며, 유선망에서의 그리드 기술을 이동 환경에 적용하기에는 많은 어려움이 있다. 따라서 본 논문에서는 모바일 그리드 서비스를 제공하기 위한 모바일 그리드 구조를 Ad-hoc 네트워크를 이용하여 설계를 하였으며, NS-2(Network Simulator)를 이용한 시뮬레이션을 통한 세 가지 방법의 라우팅 프로토콜의 지연시간에 대한 측정 및 이동 단말기 배터리의 성능을 고려한 비교를 통해, hybrid 방식의 라우팅 프로토콜이 효율적임을 제시하였다. 향후 모바일 그리드 서비스를 제공하기 위한 자원 할당 및 신뢰성 확보 방안에 대한 연구를 수행할 예정이다.

• 한국전산유체공학회지
• /
• 제10권1호
• /
• pp.24-30
• /
• 2005

Unstructured grid system is suitable for flows of complex geometries. For problems with moving boundary walls, the grid system must be time-dependently changing and deforming according to the movement of the boundaries when we use a body fitted grid system. In this paper, a new moving-grid finite-volume method on unstructured grid system is proposed and developed for unsteady compressible flows with shock waves. To assure geometric conservation laws on moving grid system, a control volume on the space-time unified domain is adopted for estimating numerical flux. The method is described and applied for two-dimensional flows.

• 전기학회논문지
• /
• 제64권1호
• /
• pp.35-40
• /
• 2015

This paper presents the optimal network configuration for electric stations using HOMER software. For the given data such as annual average wind speed and grid costs, this software calculates the NPC(Net Present Cost), operating cost and COE(Cost of Energy). Based on these simulation results, it is possible to find the optimal network configuration for electric stations depending on the grid cost and average wind speed. When the rising grid cost is considered, it is essential to use grid and renewable energy together. Depending on the increase of the grid cost, NPC of the configuration using renewable energy and grid can be gradually getting smaller than NPC of the configuration using only grid.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 1996년도 춘계 학술대회논문집
• /
• pp.105-110
• /
• 1996

In the present paper, flow fields around two dimensional single and two circular cylinders are analysed by a finite difference method. Navier-Stokes and the continuity equations an solved to simulate the flow fields. A overlapped grid system(the composite of a body boundary-fitted grid system near the body and a rectangular grid system for other flow fields) is used for this calculation. In the use of overlapped grid system, it is most significant thing to exchange the physical quantities from one grid system to the other one continuously, In this research, the linear interpolations of physical quantaties are done for this purpose in the overlapped region. The numerical calculations are carried out for the flows around a circular cylinder and two cylinders to verify the accuracy of present method. The flow fields around two cylinders facing the flow with side by side and tandem arrangement are analysed. The results are compared to other experimental and computational ones done in other single grid system.

• Journal of Electrical Engineering and Technology
• /
• 제7권6호
• /
• pp.918-925
• /
• 2012

This paper proposes a control method for grid-connected inverter systems under unbalanced and distorted grid voltage. The proposed method can reduce the power ripple caused by the unbalanced condition and compensate for the low-order harmonics of the output currents caused by the distortion of grid voltage. To reduce the power ripple, our method replaces the two conventional PI controllers with one PR controllers in the stationary frame. PR controllers can implement selective harmonic compensation without excessive computational requirements; the use of these controllers simplifies the method. Both the simulated and experimental results agree well with the theoretical analysis.

• Journal of Electrical Engineering and Technology
• /
• 제5권1호
• /
• pp.1-7
• /
• 2010

Recently, smart grid has been considered a very important new energy delivery technology, and one that can help ensure a cleaner environment by making use of information and communication technology (ICT) in countries around the world. The many technological benefits smart grid offers is expected to bring about a huge change in the electric energy supply chain. In particular, smart grid with advanced ICT is likely to allow market agents to participate in the decision-making process in the restructured electricity industry, easily facilitating Homeostatic Utility Control. In this paper, we examine smart grid as a market externality, and then illustrate issues from the commercial market perspective as it relates to electricity market design. Finally, our paper identifies some of the impacts of smart grid on electricity market design, which may possibly be incorporated into the evolution of the electricity market, thus ensuring market efficiency.