• Transactions of the Korean hydrogen and new energy society
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• v.31 no.3
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• pp.314-321
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• 2020

In this work, a preliminary design of an inlet guide vane and runner for developing a 2.5 kW hydraulic turbine was conducted by using computational fluid dynamic analysis. Three-dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were used to analyze the fluid flow in the hydraulic turbine. The hexahedral grid system was used to construct computational domain, and the grid dependency test was performed to obtain the optimal grid system. Velocity triangle diagram considering the flow angles of the inlet guide vane and runner was analyzed to obtain a basic geometry of the inlet guide vane and runner. Through modification of the preliminary design, the hydraulic performances of the turbine have improved under overall drop conditions. Especially, the efficiency and power of the turbine increased by 0.95% and 1.45%, respectively, compared to those of the reference model.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.111-115
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• 2015

Recently, protection coordination issues can occur due to increased fault current in power system when power system being changed radial power system to grid system such as loop power system, micro grid and smart grid. This paper analyzed Recloser-Fuse coordination in loop power distribution system with Superconducting Fault Current Limiters(SFCLs) when single line ground fault occur in loop power distribution system with SFCLs. We analyzed Recloser-Fuse Coordination in radial power distribution system and changed coordination caused by increased Fault current because of loop system when single line ground fault occur in power distribution system. This paper simulated to improve changed coordination using SFCLs in loop power distribution system. Power distribution system, SFCLs and protective devices are modeled using PSCAD/EMTDC.

• KCID journal
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• v.21 no.1
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• pp.127-140
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• 2014

Recently drastic climate changes(e.g., extreme floods and droughts) are often taking place around the world. Even an increase in uncertainty, population, and mega cities has caused drastic changes in water recycle process. As in other countries, Korea has faced some issues relevant to water security. In response to these changes, Smart Water Grid(SWG) system combining the current water resources management with ICT (Information and Communications Technology) is considered as a new paradigm for the Korean water resources management. This study aims to explore and identify influential factors contributing to the SWG system's application to analyze the importance and role of those factors, and then to offer a policy suggestion for the successful application of the SWG system along with legislative improvements in Korea. In this study, we looked at different barriers related to the SWG application and also the complicated Korean water laws, enacted by different ministries and in order to efficiently apply the SWG system to the current Korean water resources management structures. This study employed qualitative research methods to analyze and identify the priorities of the tasks to be implemented by analyzing conditions for the SWG application, especially related to multi water sources and micro water grid, because legal and institutional measures can be more important to manage conflicts between different stakeholders once the SWG enters a phase of standardization and commercialization from its development stage.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.992-998
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• 2015

The ESS is composed of Battery Package, PCS(Power Conditioning System) Package, BCU(BESS Control Unit). In Jeju smart grid test-bed, we have developed a business model by ESS power system, renewable energy, transportation, such as customers, and have demonstrated above things. We have analyzed the EMS(Energy Management System) model of KPX where manages supply and demand of domestic electrical power system. We modified and launched EMS for microgrid but the cost was expensive and the system was large size. For releasing this system from industry as a whole, it is imperative to develop PMS(Power Management System) for microgrid. However, the cost of EMS for microgrid is expensive, some systems because it is a large development of the all of the first fruits in urgent PMS(Power Management System) for microgrid to be used in industry in general. Therefore, in this paper, we propose the ESS model considering the power systems characteristics and extensibility in korea. and also we propose the PMS to manage the ESS systems.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.39-41
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• 2006

The weld quality of spacer grids in Pressurized Water Reactors(PWR) fuel is extremely important for the fuel assembly performance in the nuclear renter. The spacer grid welds are currently evaluated mainly by the metallographic examination although it reveals only cross-points which are welded by the laser beam. This experiment is also to compare the weldability of Zircaloy-4 spacer grids using by the GTA and laser beam. The effect of node geometries of spacer grids for GTAW and LBW has been studied and optimum conditions of spacer grid welding have been found. Microstructures and micro-hardness of GTA and laser beam welded zones have been also compared.

• Information and Communications Magazine
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• v.30 no.12
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• pp.76-82
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• 2013

본 고에서는 전력시스템의 효율화를 위한 스마트그리드(Smart-grid) 통신 기술을 소개하고, 스마트그리드 통신의 다양한 문제를 해결하는데 사용될 수 있는 게임이론(Game theory)의 응용에 대해서 살펴보도록 한다. 스마트그리드는 에너지 ICT융합기술로써 전력의 수요와 공급에 대한 정보가 실시간으로 양방향 통신이 가능하기에 기존의 단방향 전력 시스템과 비교해서 에너지 효율적이고 안정적이라는 장점이 있다. 전통적인 전력시스템과는 달리 스마트그리드 환경에서는 다수의 분산전원 공급자가 존재할 수 있으며, 전력의 소비자 또한 전력시장에 영향력을 행사할 수 있는 메커니즘을 가지고 있다. 그에 따라 복수의 공급자와 소비자로 이루어진 합리적인 경제주체들이 어떤 의사결정을 하는가에 대하여 게임이론을 통해 분석하는 연구가 활발하다. 본 논문에서는 특별히 스마트그리드에서 중요한 역할을 담당할 것으로 예상되는 수요관리(DSM: Demand Side Management)및 마이크로그리드(Micro-grid)를 소개하고 게임이론과 접목시킨 연구들을 살펴보기로 한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.737-743
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• 2013

This paper describes the overvoltage through lightning surge analysis on underground system in DC combined distribution systems. It is considered that operating micro grid including distributed generation with smart grid can make possibility of composing new distribution system different from existing one. However, there are many papers about low voltage DC distribution in grids or buildings but not many about replacement or distributing 22.9kV AC distribution system to DC system. Among many research need for DC system development, overvoltage is studied in this paper. Overvoltage is simulated on DC cable when lightning strikes to overhead grounding wire which is installed at the nearest location from power cable section. Analysis as well as modeling is performed in EMTP/ATPDraw. It is evaluated that analysis results can be used to design of DC underground distribution power cable system.

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.30-37
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• 2001

A Numerical simulation for the propulsion of axisymmetric body by contractive and dilative motion is carried out. The present analysis shows that a propulsive force can be obtained in highly viscous fluid by a contractive and dilative motion of axisymmetric body. An axisymmetric analysis code is developed with unstructured grid system for the simulation of complicated motion and geometry. The developed code is validated by comparing with the results of stokes approximation with the problem of uniform flow past a sphere in low Reynolds number($R_n=1$). The validated code is applied to the simulation of contractive and dilative motion of body. The simulation is extended to the analysis of waving surface with projecting part for finding out the difference of hydrodynamic performance according to the variation of waving surface configuration. The present study will be the basic research for the development of the propulsor of an axisymmetric micro-hydro-machine.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.498_499
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• 2009

마이크로그리드는 소형 분산 에너지원(Micro-Source or Distributed Energy Resources: DER)으로 이루어진 분산전원항의 총칭으로, 다수의 수용가들을 위하여 수요지에서 전력을 생산 및 공급 하는 기술로 기본적으로 여러 수용가의 부하 및 분산발전기들이 하나의 덩어리(Cluster)를 형성하게 되는 새로운 개념의 배전망이다. 마이크로그리드를 간단하게 정의하면 "분산형 전원과 부하를 갖는 소규모 전력계통에서 복수의 전원 및 열원이 IT 관련 기술을 사용하여 일괄제어 및 관리되어 기존 전력계통으로부터 독립되어 운전할 수 있는 온사이트형 전력 공급 시스템"이라 할 수 있다.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.2
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• pp.55-59
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• 2017

An optical method to inspect the 3-D shape of surface of Micro BGA is proposed, where spatially arranged LED light sources and specular reflection are considered. The reflected image captured by a vision system was analyzed to calculate the relative displacements of LED's in the image. Also, the statistics for all BGA's contained in a captured image are used together to find out the criteria for the detection of existing defects, and the usefulness of the proposed method is shown via experiments.