• 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.12 no.1
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• pp.18-27
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• 2010

In u-GIS environment, GeoSensor environment requires that dynamic data captured from various sensors and static information in terms of features in 2D or 3D are fused together. GeoSensors, the core of this environment, are distributed over a wide area sporadically, and are collected in any size constantly. As a result, storage space could be exceeded because of restricted memory in DSMS. To solve this kind of problems, a lot of related studies are being researched actively. There are typically 3 different methods - Random Load Shedding, Semantic Load Shedding, and Sampling. Random Load Shedding chooses and deletes data in random. Semantic Load Shedding prioritizes data, then deletes it first which has lower priority. Sampling uses statistical operation, computes sampling rate, and sheds load. However, they are not high accuracy because traditional ones do not consider spatial characteristics. In this paper 'Pre-Filtering based Post Load Shedding' are suggested to improve the accuracy of spatial query and to restrict load shedding in DSMS. This method, at first, limits unnecessarily increased loads in stream queue with 'Pre-Filtering'. And then, it processes 'Post-Load Shedding', considering data and spatial status to guarantee the accuracy of result. The suggested method effectively reduces the number of the performance of load shedding, and improves the accuracy of spatial query.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2158-2164
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• 2015

In u-GIS environments, various load shedding techniques have been researched in order to balance loads caused by input spatial data streams. However, typical load shedding methods on aspatial data lack regard for characteristics of spatial data, also previous load shedding approaches on spatial, which still lack regard for spatial data density or dynamic input data stream, give rise to troubles on spatial query processing performance and accuracy. Therefore, dynamic load shedding scheme over spatial data stream is proposed through stored spatial data deviation and load ratio of input data stream in order to improve spatial continuous query accuracy and performance in u-GIS environment. In proposed scheme, input data which are a big probability related to spatial continuous query may be a strong chance to be dropped relatively.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05a
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• pp.363-366
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• 2003

인터넷 인구의 증가와 인프라의 발전은 새로운 인터넷 서비스들을 요구하게 되었고, 이러한 서비스의 대부분은 멀티캐스팅을 사용하고 데이터는 용량이 많은 멀티미디어 데이터들을 전송하는 서비스들이다. 멀티캐스팅은 데이터를 여러 목적지로 보내기 때문에 데이타의 복사가 필수적이어서 노드의 부하 가 많아지며, 데이터의 용량이 클 경우 노드의 부하는 더욱 커지게 된다. 이러한 이유로 멀티캐스트 라우팅 알고리즘의 연구가 필요하게 되었다. 노드에서 데이터를 복사하는데 노드의 용량 때문에 발생하는 노드연결도제한은 멀티캐스트 라우팅 연구에 고려하여야 할 기본적인 요소이다. 연결도제한을 고려한 멀티캐스트 라우팅 알고리즘이 현실적으로 의미를 갖고 있으나 이에 대한 연구는 제한이 없는 멀티캐스팅 알고리즘을 단순히 수정하여 제공하는 것뿐이었다. 따라서 본 연구에서는 노드연결도제한을 고려한 효율적인 알고리즘을 개발하기 위해 유전자 알고리즘 (Genetic Algorithm)과 개미 알고리즘 (Ant Algorithm)을 비교하고자 한다. 이 문제는 NP-hard 에 속하는 문제로 다항시간에 문제를 해결할 수 없음이 밝혀져 있다.

• Journal of Korea Fair Competition Federation
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• no.7
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• pp.76-81
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• 1996

독일의 독점금지관련 법제는 크게 기업의 불공정 경쟁행위를 규제하기 위하여 1909년에 제정된 부정경쟁방지법(UWG:Gesetz gegenden Unlauteren Wettbewerb, AUC:Act against Unfair Competition)과 제 2차대전 후 금융자본에 의한 기업의 카르텔과 콘체른의 성행으로 독과점의 폐해가 심해지자 독과점 규제의 실효성을 위하여 1957년 제정된 경쟁제한금지법(GWB:Gesetz gegen Wettbewerbs Beschrankungn, ARC: Act against Restraints of Competition)이다. 부정경쟁방지법은 부당한 거래거절이나 부당한 거래방해 행위, 부당한 차별적 취급 및 기만적인 광고 등 기업의 영업활동과 관련한 불공정경쟁행위 규제가 주된 목적으로서 민사절차에 의한 손해배상소송 등에서 활용되고 있으며 경쟁제한금지법과 중복되는 분야(부당한 거래거절 등)에 대하여는 행정벌의 부과를 규정하고 있어 경쟁제한금지법과 상호보완적 관계를 유지하고 있다. 따라서 본고에서는 독일의 경쟁제한금지법의 내용에 대해서만 살펴보기로 한다.

• 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.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1707_1708
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• 2009

Unit master control(UMC)는 발전소의 요구 부하신호를 설정하는 최상위의 제어레벨이며 UMC의 설정값은 자동급전 지령신호(Automatic Dispatch System : ADS) 또는 운전원이 설정하는 값에 따라 보일러 및 터빈 Master에 Unit 요구 신호를 출력하여 하위제어 레벨인 공기, 연료, 급수 등을 조절할 수 있는 기기에 Unit 부하 요구 신호(Unit Load Demand : ULD)에 따라 제어 되도록 하는 방법으로서, Unit 목표부하 설정, Unit 목표부하 상/하한 제한, 목표부하 변화율 제한, 주파수 보정, Runback/Rundown/ Runup, 보일러 및 터빈 Demand 신호생성의 기능을 가지고 있다.

• The Journal of the Korea Contents Association
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• v.20 no.9
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• pp.430-438
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• 2020

Many local governments are reducing speed limits according to the "Safe Speed 5030" policy implemented by the government to reduce traffic accident deaths. In the urban road sections in many metropolitan cities where speed limit reduction is applied as a pilot project, the decrease effect of the traffic accident number and death count is shown; however, no study of the effect analysis on the road sections of medium and small cities (basic local government unit) is found. Therefore, this study investigated the travel speed, number of traffic accidents, and death count before and after the implementation of speed limit reduction, targeting some urban road sections in Pyeongtaek city and some provincial road sections in Icheon city among basic local governments, namely among medium and small cities in Seoul Metropolitan Area.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.905-911
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• 2005

We propose an efficient adaptive subcarrier selection scheme, in which the active subcarriers and their modulation and coding schemes (MCSs) are selected at the receiver, and subsequently conveyed to the transmitter using limited feedback We theoretically show that capacity maximization can be achieved by selecting subcarriers with highest signal-to-noise ratios (SNRs) and adapting the number of active subcarriers according to channel environments. Furthermore, an ordering based adaptive subcarrier selection algorithm is proposed to select the optimal active subcarriers with low complexity. Numerical results show that the proposed adaptive subcarrier selection scheme provides higher capacity than that obtained by water-filling approaches, even with limited feedback.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06c
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• pp.193-195
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• 2006

인터넷 사용자의 급격한 증가와 기업들의 서비스 통합으로 다양한 시스템으로 구성된 온라인 웹 환경의 서비스가 제공되고 있다. 시간제한성의 서비스를 사용할 경우 예측하지 못한 부하발생으로 시스템의 폭주상태가 발생하게 된다. 예측하지 못한 부하에 대해 서비스 품질을 보장할 수 있는 부하제한 방법이 연구되었으나 웹 사용자의 사용패턴을 고려하지 못하고 있다. 본 논문에서는 폭주하는 서비스 상태에서 연계된 시스템 간 부하균형 상태를 유지하면서 사용자에게 동등한 만족도의 서비스 품질을 제공하는 방안을 제안하고 모의실험을 통해 서비스 성공률과 사용 평등성 비율을 분석하였다.