• Journal of Power Electronics
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• v.18 no.3
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• pp.746-756
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• 2018

Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1203-1212
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• 2004

The purpose of this study is to predict and understand the hydrodynamic forces and their nonlinear behaviors of fluid motion around the submerged plate oscillating near a free surface. To achieve this objective, we have developed a composite grid method for the solution of a radiation problem. The domain is divided into two different grids; one is a moving grid system and the other is a fixed grid system. The moving grid is employed for the body fitted coordinate system and moves with the body. This numerical method is applied to calculation of radiation forces generated by the submerged plate oscillating near a free surface. In order to investigate the characteristics of the radiation forces, the forced heaving tests have been performed with several amplitudes and different submergences near a free surface. These experimental results are compared with the numerical ones obtained by the present method and a linear potential theory. As a result, we can confirm the accuracy of the present method. Finally, the effect of nonlinear and viscous damping has been evaluated on the hydrodynamic forces acting on the submerged plate.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.579-586
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• 2006

The paper introduces the grid technology currently applied intensively to civil engineering around the world. Basic concepts of grid technology and its application areas are summarized. Some of available grid systems in foreign countries and also in Korea are introduced and their main goals and functions aye compared. Through reviewing the KOCED program currently under development in Korea, the future of the grid technology in civil engineering is groped.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.65.3-65
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• 2002

$\textbullet$ Introduction $\textbullet$ Grid-connected power system $\textbullet$ Current Control $\textbullet$ Simulation $\textbullet$ Conclusion

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.7
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• pp.440-447
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• 2006

Grid computing is the complex deployments of various hardware and software components. The Grid environment should provide a mechanism for real-time monitoring and notification. It is very important to implement a monitoring mechanism in the Grid environment. Most existing monitoring systems only focus on their own requirements. With the development of Grid computing technology, the extensible monitoring systems become more and more feasible and popular. In this paper, we describe our research and development works on M-Mon, a novel framework for the flexible and adaptive Grid monitoring system. M-Mon system focuses on some critical issues like scalability, reusability, runtime extensibility, protocol transparency and uniform data representation. To provide interoperability with other monitoring systems and to reuse legacy facilities with a minimum effort, our monitoring system has been developed using service-oriented architecture.

• Journal of Electrical Engineering and Technology
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• v.6 no.6
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• pp.731-741
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• 2011

Conventional methodologies (empirical, analytical, numerical, hybrid, etc.) for sizing photovoltaic (PV) systems cannot be used when the relevant meteorological data are not available. To overcome this situation, modern methods based on artificial intelligence techniques have been developed for sizing the PV systems. In the present study, the optimum PV/inverter sizing ratio for grid-connected PV systems with orientation due south and inclination angles of $45^{\circ}$ and $60^{\circ}$ in selected Algerian locations was determined in terms of total system output using type-2 fuzzy logic. Because measured data for the locations chosen were not available, a year of synthetic hourly meteorological data for each location generated by the PVSYST software was used in the simulation.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.145-151
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• 1999

An Interactive grid generation program(KGRID) with graphical user interface(GUI) has been improved. KGRID works on the UNLX environment and GUI has been implemented with OSF/Motif and X Toolkit and the graphics language is Open GL for visualization of the 3D objects. It supports more convenient user environment to generate 2D and 3D multi-block structured grid systems. It provides various useful field grid generation methods, which are the algebraic methods, the elliptic partial differential equations method and the predictor-corrector method. It also supports 3D surface grid generation with NURBS(Non-Uniform Rational B-Spline) and various stretching functions to control grid points distribution on curves and surfaces. And some menus are added to perform flexible management, for the objects. We generated surface and field grid system about full aircraft configuration using KGRID. The performance and stability of the KGRID is verified through the generation of the grid system about a complex shape.

• Journal of the Korean Solar Energy Society
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• v.24 no.2
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• pp.9-15
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• 2004

3kW grid connected PV(photovoltaic) systems have been constructed for evaluating and analyzing performance of PV system at FDTC(field demonstration test center) in Korea, PV systems installed in FDTC have been operating and monitored since November 2002. As climatic and irradiation conditions have been varied through long-term field test, data acquisition system has been constructed for measuring performance of PV system to observe the overall effect of environmental conditions on their operation characteristics. The performance of PV systems has been evaluated and analyzed for component perspective(PV array and power conditioning system) and global perspective(system efficiency, capacity factor, and electrical power energy) by field test. By the results, it is very important to develop optimal design technology of grid connected PV system.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.4
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• pp.255-259
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• 2009

In this paper, we present AGE(Automatic Grid Environments), which is a middleware system in which Grid resources can automatically participate in a Grid environment. While other existing systems need the configuration of each Grid node to deploy a Grid environment, AGE offers automatic installation and execution of necessary middleware for participating in a Grid environment. And Grid applications in AGE do not need to be pre-installed and pre-configured. When an application is to be executed in participating Grid nodes, this system can download, install, and execute the application automatically. Therefore, AGE provides users with convenience such as deploying a Grid environment, executing the application, and releasing nodes or resources from the Grid environment automatically.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.1
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• pp.76-84
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• 2013

The renewable energy sources is raising for use of grid connected systems, for which higher power quality requirements are being issued. A grid connected converter requires a LC-filter stage, this one is lightly damped for efficiency constraints. Hence, it is subject to resonance if excited by the converter current harmonics or pre-exciting grid voltage harmonics. In this paper, an active damping technique employing notch filter for damping of the resonance frequency is introduced. This technique doesn't need to additional sensors. In addition, it is simple to apply for various systems. Monitoring of the resonance frequency ensures the stable operation of the proper connection and disconnection of the grid. This paper proposes the estimating method of a resonant frequency to determine the cut-off frequency of the notch filter. This method is validated by both simulation and experimental results.