• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.231-238
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• 2011

A role of Distribution Automation System(DAS) is required to be changed from observing and control to complex and various new system including functions which monitoring, control, prediction, operation and management of EMS type according to be gradually Smart Grid of distribution operation system for development of further power system industrial. IEC(International Electrotechnical Commission) published communication standards which interface and data model of distribution operation system to IEC 61968 and of host system like EMS(Energy Management System) to IEC 61970. So far, each standards are emphasizing themselves, but if they are applied by designed integration of the standards, it could be more efficiency system. So, in this paper, integration application of IEC standards and structure of further distribution operation system to use them are proposed by gradually increasing importance of communication protocols, functions and roles in further distribution management system considering Smart Grid.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.848-854
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• 2006

In this study, a computational analysis system has been developed in order to investigate flow-induced vibration(FIV) phenomenon for general stator-rotor cascade configurations. Relative movement of the rotor with respect to stator is reflected by modeling independent two computational domains. Fluid domains are modeled using the unstructured grid system with dynamic moving and local deforming methods. Unsteady, Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation SST $k-\omega$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used flow computing the coupled governing equations of the fluid-structure interaction problem. Detailed FIV responses for different flow conditions are presented with respect to time and vibration characteristics are also physically investigated in the time domain.

• Journal of Information Technology Services
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• v.16 no.2
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• pp.85-96
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• 2017

The revised "Software Industry Promotion Law" has been effective from 2013. This law is to be basis of the domestic public information sector and increases the opportunities for small and medium-sized firms in participating the public IT projects. The shortcomings of this law may be the increase of the risk and the decrease of quality of projects. These suggest that the competencies of project manager (PM) s are critical. Also, in general, an SI (System Integration) project is a one that provides a customer with a customer-tailored system for system integration. Particularly, in an SI project involved in a public institution or a large corporation, the ripple effect of success or failure of a project is becoming greater as the system requires higher cost and more time due to high complexity and large scale. One of the solutions to address these problems is to investigate the competencies of a PM. Thus, in this paper, we derived the major competencies using the RGT (Repertory Grid Technique) and categorized the resultant constructs using the content analysis. In addition, we analyzed the level of importance of competencies by applying the AHP (Analytic Hierarchy Process). The conclusion was that Problem-solving Skill and Leadership were the most important competencies of a project manager.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.10 s.115
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• pp.1082-1089
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• 2006

In this study, advanced computational analysis system has been developed in order to investigate flow-induced vibration(FIV) phenomenon for general stator-rotor cascade configurations. Relative movement of the rotor with respect to stator is reflected by modeling Independent two computational domains. Fluid domains are modeled using the unstructured grid system with dynamic moving and local deforming methods. Unsteady, Reynolds-averaged Wavier-stokes equations with one equation Spalart-Allmaras and two-equation SST ${\kappa}-{\varepsilon}$ turbulence models are solved for unsteady flow problems and also relative moving and vibration effects of the rotor cascade are fully considered. A coupled implicit time marching scheme based on the Newmark integration method is used for computing the governing equations of fluid-structure interaction problems. Detailed vibration responses for different flow conditions are presented and then vibration characteristics are physically investigated in the time domain as computational virtual tests.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.1
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• pp.74-85
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• 2002

The numerical experiment has been conducted to investigate the unsteady shock wave reflecting phenomena. The cell-vertex finite-volume, Roe's upwind flux difference splitting method with unstructured grid is implemented to solve unsteady Euler equations. The $4^{th}$-order Runge-Kutta method is applied for time integration. A linear reconstruction of the flux vector using the least-square method is applied to obtain the $2^{nd}$-order accuracy for the spatial derivatives. For a better resolution of the shock wave and slipline, the dynamic grid adaptation technique is adopted. The new concept of grid adaptation technique, which is much simpler than that of conventional techniques, is introduced for the current study. Three error indicators (divergence and curl of velocity, and gradient of density) are used for the grid adaptation procedure. Considering the quality of the solution and the numerical efficiency, the grid adaptation procedure was updated up to $2^{nd}$ level at every 20 time steps. For the convenience of comparison with other experimental and analytical results, the case of interaction between the straight incoming shock wave and a sharp wedge is simulated for various flow conditions. The numerical results show good agreement with other experimental and analytical results, in the shock wave reflecting structure, slipline, and the trajectory of the triple points. Some critical cases show disagreement with the analytical results, but these cases also have been proven to show hysteresis phenomena.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.6
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• pp.538-548
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• 2014

This study provides a robust control of a grid-connected three-phase two-level photo voltaic inverter. The introduced control method uses the cascade control strategy to regulate AC-side current and DC-link voltage. A robust controller with integration action is used for the inner-loop AC-side current control, which maximizes the convergence rate using a linear matrix inequality-based optimization design method and eliminates the offset error. The robust controller design method considers the parameter uncertainty set to accommodate parameter mismatch and un-modeled components in the inverter model. An outer-loop proportional-integral controller is used to regulate DC-link voltage with linearization of DC/AC relation. The proposed control strategy is applied to a grid-connected 100 kW photo voltaic inverter.

• Journal of the Semiconductor & Display Technology
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• v.13 no.1
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• pp.73-81
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• 2014

In this paper, high-speed Hybrid MAC (Medium Access Control layer) implementation suitable for smart grid applications is researched. MB-OFDM (Multi-Band Orthogonal Frequency Division Multiplexing) is considered for high-speed communication method in smart grid application. In this paper, the MAC adopts the distributed network managing method. Also, the MB-OFDM merit of high-speed transfer rate of up to 480Mbps must be supported. Hence, this paper presents an efficient hardware-software integration (co-design) method in order to realize a high- speed transmission, and a realizing method of distribution network. Finally, MAC performance and reliability based on MB-OFDM PHY (PHYsical layer) are confirmed through simulation and emulation.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.97-102
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• 2005

Because of the limited fossil resources and the need to avoid emissions and toxic waste the future energy supply will be based on a large portion of renewable energies: wind-, solar-, biomass- and geothermal energy. Focus is on the utilization of wind energy coming from onshore- and offshore-sites. Generating electricity from wind is state of the art and feeding large amounts of wind power into the electrical grid will create some additional problems. Suggestions concerning energy storage will be made and the problem of power quality is discussed.

• Journal of Internet Computing and Services
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• v.13 no.6
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• pp.55-62
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• 2012

Grid web applications by standard Web technology are increasingly used to provide grid service to users as normal Web user interface and service. It is however difficult to integrate a grid security system such as Grid Security Infrastructure (GSI) into Web applications because the delegation way of standard Web security is not the same as the one of Grid security. This can be solved by allowing Web applications to get a Grid credential by using an online credential repository system such as MyProxy. In this paper, we investigate the problem that occurs when MyProxy, which assumes mutual trust between a user and Grid web application, is adapted for achieving security integration between Web and Grid, and we propose a new Grid proxy delegation service to delegate a Grid credential to the Web without assuming mutual trust. In the service, the X.509 proxy delegation process is added to OAuth protocol for credential exchange, and authentication can be done by an external service such as OpenID. So, users can login onto the Grid web application in a single sign-on manner, and are allowed to securely delegate and retrieve multiple credentials for one or more Virtual Organizations.

• Spatial Information Research
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• v.23 no.6
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• pp.43-55
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• 2015

Currently, each organization has developed its gridded data in the form of respective grid system for its own purpose. Interoperability among the organization had been limited and resulted in inconvenient data access and application across domains. In this study, we investigated potential standards for National grid system and their strength and weakness. We also reviewed existing gridding schemes and had a survey of demand about grid system to those who have used or would plan to use gridded data in academic and business sectors. As the result of survey of demand, we suggested national grid system for national grid data integration management system which has the mutual compatibility and also proposed sharing scheme of the grid type for users who need to grid data.