• 제목/요약/키워드: Grid

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Grid Management System and Information System for Semantic Grid Middleware

  • Kim, Hyung-Lae;Han, Byong-John;Jeong, In-Yong;Jeong, Chang-Sung
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.4 no.6
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    • pp.1080-1097
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    • 2010
  • Well organized and easy usable Grid management system is very important for executing various Grid applications and managing Grid computing environment. Moreover, information system which can support Grid management system by providing various Grid environment related information is also one of the most interesting issue in the Grid middleware system area. Effective cooperation between Grid management system and information system can make a novel Grid middleware system. Especially, service oriented architecture based Grid management system is flexible and extensible for providing various type of Grid services. Also, information system based on data mining process which comprises various different kinds of domains such as users, resources and applications can make Grid management system more precise and efficient. In this paper, we propose semantic Grid middleware system which is a combination of Grid management system and semantic information system.

Third Party Grid Service Maketplace Model using Virtualization (가상화를 이용한 위탁형 그리드 서비스 거래망 모델)

  • Jang Sung-Ho;Lee Jong-Sik
    • Proceedings of the Korea Society for Simulation Conference
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    • pp.45-50
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    • 2005
  • Research and development of grid computing ware mainly focused on high performance computing field such as large-scale computing operation. Many companies and organizations concentrated on existing computational grid. However, service grid focusing on enterprise environments has been noticed gradually. Grid service providers of service grid construct diverse and specialized services and provide service resources that have economic feasibility to grid users. But, service resources are geographically dispersed and divided into many classes and have individual owners and management policies. In order to utilize and allocate resources effectively, service grid needs a resource management model that handles and manages heterogeneous resources of service grid. Therefore, this paper presents the third party grid service marketplace model using virtualization to solve problems of grid service resource management. Also, this paper proposes resource dealing mechanism and pricing algorithms applicable for service grid. Empirical results show usefulness and efficiency of the third party grid service marketplace model in comparison with typical economic models for grid resource management such as single auction model and double auction model.

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Grid Current Control Scheme at Thee-Phase Grid-Connected Inverter Under Unbalanced and Distorted Grid Voltage Conditions (계통전압 왜곡 및 불평형시 3상 계통연계인버터의 계통전류제어 기법)

  • Tran, Thanh-Vu;Chun, Tae-Won
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.11
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    • pp.1560-1565
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    • 2013
  • This paper proposes the control method for compensating for unbalanced grid current and reducing a total harmonic distortion (THD) of the grid current at the three-phase grid-connected inverter systems under unbalancd and distorted grid voltage conditions. The THD of the grid current caused by grid voltage harmonics is derived by considering the phase delay and magnitude attenuation due to the hardware low-pass filter (LPF). The Cauchy-Schwarz inequality theory is used in order to search more easily for a minimum point of THD. Both the gain and angle of a compensation voltage at the minimum point of THD of the grid current are derived. The negative-sequence components in the three-phase unbalanced grid voltage are cancelled in order to achieve the balanced grid current. The simulation and experimental results show the validity of the proposed control methods.

A Detection Method of Grid Voltage for Grid Support Operation of an Inverter-based Renewable Energy Generation System (인버터 기반 신재생 에너지 발전 시스템의 계통 지원 운전을 위한 계통 전압 검출 방법)

  • Ahn, Hyun-Chul;Song, Seung-Ho
    • New & Renewable Energy
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    • v.9 no.2
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    • pp.51-57
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    • 2013
  • The Grid code is being strengthen as increase of renewable energy ratio. Especially, the grid connection regulations are continuously being updated for stable operation of power grids. Static grid support and Dynamic grid support must make an accurate measure at Grid connected point because they needs control algorithm individually. It has to exactly measure voltage including switching ripple at the output of the inverter generating system. In addition, it is necessary to have an accurate voltage measurement when the situation rapidly changing the grid impedance is caused by the input of serial impedance of transformer and line impedance as well as Grid Fault Device. In this paper, We propose a new detection method of grid voltage to calculate accurately the r.m.s voltage of the grid connection point along the standard required by the low voltage regulation. We verified performance through simulation grid fault device.

Numerical Analysis of Free-Surface Flows Using Improved Adaptable Surface Particle Method Based on Grid System (개선된 격자기반 적합 표면입자법을 이용한 자유표면유동 수치해석)

  • Shin, Young-Seop
    • Journal of the Society of Naval Architects of Korea
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    • v.58 no.2
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    • pp.90-96
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    • 2021
  • In this study, the method of determining the state of grid points in the adaptable surface particle method based on grid system developed as a free-surface tracing method was improved. The adaptable surface particle method is a method of determining the state of the grid point according to the shape of the free-surface and obtaining the intersection of the given free-surface and grid line where the state of the grid point changes. It is difficult to determine the state of grid points in the event of rapid flow, such as collision or separation of free-surfaces, and this study suggests a method for determining the state of current grid points using the state of surrounding grid points where the state of grid point are known. A grid layer value was assigned sequentially to a grid away from the free-surface, centering on the boundary cell where the free-surface exists, to identify the connection information that the grid was separated from the free-surface, and to determine the state of the grid point sequentially from a grid away from the free-surface to a grid close to the free-surface. To verify the improved method, a numerical analysis was made on the problem of dam break in which a sudden collision of free-surface occurred and the results were compared, and the results were relatively reasonable.

Mobile Resource Reliability-based Job Scheduling for Mobile Grid

  • Jang, Sung-Ho;Lee, Jong-Sik
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.5 no.1
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    • pp.83-104
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    • 2011
  • Mobile grid is a combination of grid computing and mobile computing to build grid systems in a wireless mobile environment. The development of network technology is assisting in realizing mobile grid. Mobile grid based on established grid infrastructures needs effective resource management and reliable job scheduling because mobile grid utilizes not only static grid resources but also dynamic grid resources with mobility. However, mobile devices are considered as unavailable resources in traditional grids. Mobile resources should be integrated into existing grid sites. Therefore, this paper presents a mobile grid middleware interconnecting existing grid infrastructures with mobile resources and a mobile service agent installed on the mobile resources. This paper also proposes a mobile resource reliability-based job scheduling model in order to overcome the unreliability of wireless mobile devices and guarantee stable and reliable job processing. In the proposed job scheduling model, the mobile service agent calculates the mobile resource reliability of each resource by using diverse reliability metrics and predicts it. The mobile grid middleware allocated jobs to mobile resources by predicted mobile resource reliability. We implemented a simulation model that simplifies various functions of the proposed job scheduling model by using the DEVS (Discrete Event System Specification) which is the formalism for modeling and analyzing a general system. We also conducted diverse experiments for performance evaluation. Experimental results demonstrate that the proposed model can assist in improving the performance of mobile grid in comparison with existing job scheduling models.

An Improved Method for Mesh Grounding System Using Spaced Arrangement of Grounding Conductor (접지도체의 간격배치에 따른 개선된 접지설비 모델)

  • Song, Young-Joo;Choi, Hong-Kyoo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.3
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    • pp.57-65
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    • 2005
  • No matter how well the equally spaced grounding grid is designed, there we questions keep rising, such as leakage of current from comer conductor, high voltage of touch voltage in comers of grid than in center, and high material cost for grounding grid. The best-fitted design for unequally spaced grounding grid is a part that must be considered. Explain advantages of unequally spaced grounding grid and lead formula by dividing the number of grid division, j, into 20, instead of 7. Then, present Dij, which is optimum rate for unequally spaced grounding grid and verify safety and economy of the unequally spaced grounding grid by computer simulation with a poly-nominal function form.

Image Analysis Using Grid Suppression Software to Remove Moire Artifact from Micro Lesions of Sprague Dawley Rat (Sprague Dawley Rat의 미세병변에서 Moire Artifact를 제거하기 위한 Grid suppression software 사용 후 영상분석)

  • Lee, Sang-Ho
    • Journal of radiological science and technology
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    • v.40 no.4
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    • pp.575-580
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    • 2017
  • Because moire artifacts overlap with fine lesions and frequency bands, image processing software that removes moire artifacts can lead to loss of micro lesions. In this study, microscopic lesions such as microcalcification and microfracture were randomly formed on SD (Sprague Dawley) rats and image and optimized grid images were compared and analyzed using reference image and grid suppression software. The images were read by two consecutive radiologists using a McNemar's test. Among the 73 microcalcifications, in the 13 cases after grid suppression, the image of the optimized grid shows the loss of image in 3 cases, and the image after grid suppression shows statistically significant image loss (p=0.021). In all 53 fracture lines, there were 19 cases of image loss after the grid suppression, and only one case of the optimized grid showed no image loss. Therefore, the use of grid suppression software to remove moire artifacts should be carefully considered in the diagnosis of micro lesions.

Grid Voltage Estimation Scheme without Phase Delay in Voltage-sensorless Control of a Grid-connected Inverter (전압센서를 사용하지 않는 계통연계 인버터의 제어 및 위상지연을 개선한 계통전압 추정 기법)

  • Kim, Hyun-Sou;Kim, Kyeong-Hwa
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.1
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    • pp.89-93
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    • 2017
  • This study proposes a grid voltage estimation scheme without a phase delay in the voltage-sensorless control of a grid-connected inverter to enhance its economic feasibility, such as manufacturing cost and system complexity. The proposed scheme estimates grid voltages using a disturbance observer (DOB)-based current controller to control the grid-connected inverter without grid-side voltage sensors. The proposed voltage-sensorless control scheme can be applied successfully to grid-connected inverters, which should be operated with synchronization to the grid, considering the phase angle of the grid can be effectively detected through estimating the grid voltages by DOB. However, a problem associated with the phase delay in estimated grid voltages remains because the DOB has dynamic behavior similar to low-pass filter. Hence, the estimated grid voltages are compensated by a phase lead compensator to overcome the limitation. The effectiveness of the proposed control and estimation schemes is proven through simulations and experiments using a 2 kVA prototype inverter.

Proposed measure for Smart Grid's Personal Information Security Issue (스마트 그리드 개인정보 보안이슈 방안 제시)

  • Choi, Heesik;Cho, Yanghyun
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.12 no.4
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    • pp.41-49
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    • 2016
  • Smart Grid is a next generation of new power growth electrical grid which provide high quality of electrical service by using Information Technologies to increase intelligence and performance. By using Smart Grid system, it can support energy management such as increase quality of electrical power, decrease energy and decrease emissions. However, Smart Grid uses information of energy consumption and when Smart Grid collects information, it will create private information. In this thesis, it will address issues of security private information which caused by Smart Grid for administrative measure and efficiency of Smart Grid in domestic. Also, cryptographic module algorithm, latest security solutions and strong wireless security policy for network environment such as wireless communication Iinternet are require for Smart Grid perform successfully and protect national power network equipment from cyber-attack and can stop leakage of user's personal information. Finally, it is urgent to prepare protection measures of National industrial facilities and power grid which can prepare for a cyber terrorism and penetration attacks and build emergency countermeasure management team for Smart Grid are require for safe Smart Grid environment.