• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.899-901
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• 1998

Continuation power flow is a tool that can trace the path of the solution from the base stable solution. However, the base stable solution cannot be calculated when the initial system load is too large to operate at a stable operating point. This case is called as unsolvable case. This paper presents implementation of the optimal load shedding algorithm on continuation power flow. It performs steady-state analysis of power systems at unsolvable case that can occur in contingency analysis. Numerical simulation on 20-bus test system demonstrates that the continuation power flow applying the optimal load shedding algorithm is robust at solvable and unsolvable cases.

• Proceedings of the KIEE Conference
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• summer
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• pp.162-164
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• 2004

Electrical power peak demand of Republic of Korea is annually growing and the peak demand has occurred in the summer. It is difficult that we handle with constructing power plants and increasing generation capacity to cope with a suddenly increased demand due to the cost problem, difficulty to find the new plant site, and the spread of the NIMBY. The alternative of the above problem is to efficiently manage demand of electrical power. Accordingly, load shedding of a section of demand side management is investigated. First we surveyed a trend of research in the domestic and overseas, for load curtailment and demand response program. After reviewing several demand response programs, the future research direction for load shedding in emergency and normal operation is introduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8370-8377
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• 2015

In spatial data stream management systems, it is needed appropriate load shedding algorithm because real-time input spatial data streams could exceed the limitation of main memory. However previous researches, lack regard for input ratio and spatial utilization rates of spatial data streams, or the characteristics of data source which generates data streams with spatial information efficiently, can lead to decrease the performance and accuracy of spatial data stream query. Therefore, multi-level load shedding scheme for spatial data stream management systems is proposed to increase the spatial query performance and accuracy. This proposed scheme limits overloads in relation to the input rate and the characteristics of data source first, and then, if needed, query data representing low query participation probability based on spatial utilizations are dropped relatively. Our experiments show that the proposed method could decrease load shedding frequency for previous researches by more than 11% despite query results accuracy and query performance are superior at 0.04% and 3%.

• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.89-98
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• 2009

As data stream is entered into system continuously and the memory space is limited, the data exceeding the memory size cannot be processed. In order to solve the problem, load shedding methods which drop a part of data to prevent exceeding the storage space have been researched. Generally, a traditional load shedding method uses random sampling with optimized rate according to data deviation. The method samples data not to distinguish those used in spatial query because the method uses only a random sampling with optimized rate according to data deviation. Therefore, the accuracy of query was reduced in u-GIS environment including spatial query. In this paper, we researched a new load shedding method improving accuracy of the query in u-GIS environment which runs spatial query and aspatial query simultaneously. The method uses a new sampling method that samples data having low probability used in query. Therefore proposed method improves spatial query accuracy and query processing speed as applying spatial filtering operation to sampling operator.

• The KIPS Transactions:PartD
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• v.13D no.6 s.109
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• pp.755-764
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• 2006

In recent, data streams are generated in various application fields such as a ubiquitous computing and a sensor network, and various algorithms are actively proposed for processing data streams efficiently. They mainly focus on the restriction of their memory usage and minimization of their processing time per data element. However, in the algorithms, if data elements of a data stream are generated in a rapid rate for a time unit, some of the data elements cannot be processed in real time. Therefore, an efficient load shedding technique is required to process data streams effcientlv. For this purpose, a load shedding technique over a data stream is proposed in this paper, which is based on the predicting technique of the frequency of data element considering its current frequency. In the proposed technique, considering the change of the data stream, its threshold for tuple alive is controlled adaptively. It can help to prevent unnecessary load shedding.

• 전기의세계
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• v.28 no.5
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• pp.49-55
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• 1979

During severe emergencies which result in insufficient generation to meet load, an automatic load shedding method considering the spinning and operating reserve can establish the optimum system operation. This paper presents methods and results of a study on the optimum operating scheme with spinning and operating reserve power in case of outage of large generator units to prevent frequency decay and continue stable operation. This study covers following three parts 1) Analysis of spinning reserve characteristics 2) Determination of operating reserve requirements 3) Development of the optimum load shedding programs By this study the optimum system operating method was recommended for reliable operation of power system.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.68-71
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• 2005

In the case of wind turbine design, Optimization of tower structure is very important because tower generally takes about $20\%$ of overall turbine cost. In this paper, we calculated wind loads considering vortex shedding, and optimized tower flange using the calculation results. For optimization, we used FEM to analyze structural strength of the flange and blade momentum theory to calculate wind loads.

• 전기의세계
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• v.24 no.2
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• pp.84-91
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• 1975

This paper describes the results of a study for the system characteristics, especislly for the abnormal frequency drop of power system, when a large generation unit such as Kori Nuclear 1 (595MW) pulls out from the system. The automatic load shedding method now adopted in our system was re-studied to ameliorate the above problem. From the results of the study, a new under-frequency relay with an element for detecting the slope of frequency change and with time delay element to raise the lowered frequency to a desired value, was found to be effective, and should be purchased and utilized. By this study, an optimal and concrete load shedding method was recommended for reliable operation of power system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.6
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• pp.381-389
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• 1987

This paper presents a method for optimal load shedding in preserving a system security following abnormal condition as well as a sudden major supply outage. The method takes account of static characteristic of generators control and voltage and system frequency characteristic of loads. The optimization problem is solved by a gradient technique to get the maximal effect by the least quantity of load shedding considering line overloads as well as voltage disturbances and system frequency. The method is illustrated on a 8-bus system. It has been found that the use of the proposed algorithm for model systems alleviate the line overload more efficiently than the former method. It is believed that this method will be useful in security studies and operational planning.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.70-72
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• 1993

This paper presents an expert system that sheds loads considering priority in the localized SCADA power systems during an emergency states. The proposed algorithm uses neural networks to detect local load shedding location and heuristic rules to determine load shedding amounts. The proposed expert system is demonatrated at one of the model system which incorporates two localized SCADA power system. It is operated under workstation.