• 제목/요약/키워드: Ranking System

검색결과 544건 처리시간 0.029초

날씨효과를 고려한 전력계통의 상정사고 순위 결정 (A Determining Contingency Ranking Using the Weather Effects of the Power System)

  • 김경영;이승혁;김진오;김태균;전동훈;차승태
    • 대한전기학회논문지:전력기술부문A
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    • 제53권9호
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    • pp.487-493
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    • 2004
  • The electric power industry throughout the world is undergoing considerable changes from the vertically integrated utility structure to the deregulated market. However, the deregulated electricity market is operated with respect to theory of economical efficiency, and therefore, the system operator requires data with fast contingency ranking for security of the bulk power system. This paper compares the weather dependant probabilistic risk index(PRI) with the system performance index for power flow in the IEEE-RTS. The system performance index for power flow presents the power system stability. This paper presents fast calculation method for determining contingency ranking using the weather dependant probabilistic risk index(PRI). The probabilistic risk index can be classified into the case of normal and adverse weather. This paper proposes calculation method using the probabilistic risk index in determining contingency ranking required for security under the deregulated electricity market.

화학물질 우선순위선정 시스템에서 고려되는 노출.독성인자 비교연구 (Comparative Study of Exposure Potential and Toxicity Factors used in Chemical Ranking and Scoring System)

  • 안윤주;정승우;김민진;양창용
    • Environmental Analysis Health and Toxicology
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    • 제24권2호
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    • pp.95-105
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    • 2009
  • Chemical Ranking and Scoring (CRS) system is a useful tool to screen priority chemicals of large body of substances. The relative ranking of chemicals based on CRS system has served as a decision-making support tools. Exposure potential and toxicity are significant parameters in CRS system, and there are differences in evaluating those parameters in each CRS system. In this study, the parameters of exposure potential, human toxicity, and ecotoxicity were extensively compared. In addition the scoring methods in each parameter were analyzed. The CRS systems considered in this study include the CHEMS-1 (Chemical Hazard Evaluation for Management Strategies), SCRAM (Scoring and Ranking Assessment Model), EURAM (European Union Risk Ranking Method), ARET (Accelerated Reduction/Elimination of Toxics), and CRS-Korea. An comparative analysis of the several CRS systems is presented based on their assessment parameters and scoring methods.

한국기원 기사 랭킹과 덤에 관한 분석 (Analysis of Korean Baduk rating system and dum)

  • 조성훈;장원철
    • 응용통계연구
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    • 제32권6호
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    • pp.783-794
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    • 2019
  • 현재 한국기원의 기사랭킹제도는 체스 계에서 널리 사용되는 Elo rating system에 기반을 두고 있다. 또한 대국에서 6집반의 덤에도 불구하고 여전히 많은 기사들이 흑을 선호하며 실제로 흑을 든 기사가 높은 승률을 보이고 있다. 이 연구에서는 Bradley-Terry model을 통하여 실제 흑의 효과를 고려한 랭킹을 산출하여 현재 사용되고 있는 Elorating system과 비교 분석한다.

인체 및 수생태 보호를 위한 지표수 우선관리대상 항목 선정기법: CRAFT (Chemical RAnking of surFacewater polluTants) (Chemical Ranking and Scoring Methodology for the Protection of Human Health and Aquatic Ecosystem in Korean Surfacewater: CRAFT (Chemical RAnking of surFacewater polluTants))

  • 남선화;곽진일;윤성지;정승우;안윤주
    • 한국물환경학회지
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    • 제27권6호
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    • pp.804-812
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    • 2011
  • To prevent the overflow of various harmful chemicals, it is necessary to modify the chemical management system with an expansion to institutionally regulated substances. This modification should be preceded by selection of the priority chemicals, with a diverse chemical ranking system (CRS) applied to select the chemicals in developed countries. In Korea, a systematic CRS was used in a project related to soil and groundwater, however, it is inadequate to compare soil and groundwater CRS to that of surfacewater. In this study, a priority chemical ranking system for surfacewater was proposed through the analysis of international and domestic CRS cases. This was then applied to 161 chemicals to derive the priority list of harmful chemicals. As a result, Chemical RAnking of surFacewater polluTants (CRAFT) is presented for the protection of human health and the aquatic ecosystem from surfacewater pollutants. The components of CRAFT are the human health toxicity, aquatic ecosystem toxicity and reliability assessment factors. Three lists were derived from the 161 priority harmful chemicals for the protection of human health, aquatic ecosystem or both. It is expected that this result can be useful to prioritize harmful chemicals for the protection of human health and the aquatic ecosystem from Korean surfacewater.

태그쌍의 의미유사도 기반 태그 랭킹 시스템 (Tag Ranking System based on Semantic Similarity of Tag-pair)

  • 이시화;황대훈
    • 한국멀티미디어학회논문지
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    • 제16권11호
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    • pp.1305-1314
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    • 2013
  • 기존의 태그 기반 시스템들은 콘텐츠에 태깅된 태그들을 활용한 단일 태그 매칭을 통해 검색결과를 제공함에 따라 정확도가 낮은 검색결과를 제공하고 있으며, 또한 사용자들이 콘텐츠에 태깅 시 태그간의 연관관계 및 우선순위는 고려하지 않아 태그가 가지고 있는 콘텐츠와 관련된 정보들을 효율적으로 제공하지 못하고 있다. 이에 본 논문에서는 위의 문제점을 해결하기 위해 태그 기반 시스템에 적합한 태그간 의미 유사도를 추출하여 콘텐츠에 태깅된 태그들을 재 랭킹하기 위한 태그 랭킹 시스템을 제안하였다. 제안 시스템의 성능 평가는 이미지에 태깅된 태그(baseline)와 태그 동시출현 빈도수 기법을 적용한 랭킹(frequency) 결과를 본 논문에서 제안한 태그 랭킹 시스템에 의해 추출된 랭킹 결과와 비교 실험하였다.

포토톡 : 사용자 선호 기반 멀티미디어 콘텐츠 랭킹 시스템의 구현 (PhotoToc: an Implementation of a Ranking System by using User Favor-Based Metrics)

  • 이진수;박알음;최송아;안후영;박영호
    • 디지털콘텐츠학회 논문지
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    • 제8권2호
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    • pp.113-119
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    • 2007
  • 최근 UCC의 등장으로 인터넷을 이용한 멀티미디어의 활용이 증가 하고 있다. 이러한 환경에서 사진, 동영상, 음악 등 멀티미디어의 검색은 시간과 접촉 이용성을 증가시켜줄 수 있는 중요한 이슈가 되고 있다. 그러나 현재 제안되어 있는 멀티미디어 활용 시스템들은 전체 사용자를 기반으로 우선순위를 적용하여 단일화된 매트릭을 통한 랭킹 시스템을 제안함으로 사용자 중심의 실용적인 랭킹 시스템을 제공하지 못하고 있다. 본 연구에서는 이러한 문제점에 기반 하여 사용자 중심의 차별화된 뷰(view)를 제공해 줄 수 있는 사용자 선호 기반(User Favor-Based) 멀티미디어 랭킹 시스템 '포토톡'을 제안한다. 제안하는 시스템은 현실적인 랭킹시스템을 통해서 사용자 중심의 결과를 도출할 수 있는 장점을 가진다.

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전력계통에 있어서 직접법을 활용한 상정사고 위험순위 결정 (Contingency Severity Ranking Using Direct Method in Power Systems)

  • 이상근
    • 전기학회논문지P
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    • 제54권2호
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    • pp.67-72
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    • 2005
  • This paper presents a method to select contingency ranking considering voltage security problems in power systems. Direct method which needs not the detailed knowledge of the post contingency voltage at each bus is used. Based on system operator's experience and knowledge, the membership functions for the MVAR mismatch and allowable voltage violation are justified describing linguistic representation with heuristic rules. Rule base is used for the computation of severity index for each contingency by fuzzy inference. Contingency ranking harmful to the system is formed by the index for security evaluation. Compared with 1P-1Q iteration, this algorithm using direct method and fuzzy inference shows higher computation speed and almost the same accuracy. The proposed method is applied to model system and KEPCO pratical system which consists of 311 buses and 609 lines to show its effectiveness.

폭소노미 사이트를 위한 랭킹 프레임워크 설계: 시맨틱 그래프기반 접근 (A Folksonomy Ranking Framework: A Semantic Graph-based Approach)

  • 박현정;노상규
    • Asia pacific journal of information systems
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    • 제21권2호
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    • pp.89-116
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    • 2011
  • In collaborative tagging systems such as Delicious.com and Flickr.com, users assign keywords or tags to their uploaded resources, such as bookmarks and pictures, for their future use or sharing purposes. The collection of resources and tags generated by a user is called a personomy, and the collection of all personomies constitutes the folksonomy. The most significant need of the folksonomy users Is to efficiently find useful resources or experts on specific topics. An excellent ranking algorithm would assign higher ranking to more useful resources or experts. What resources are considered useful In a folksonomic system? Does a standard superior to frequency or freshness exist? The resource recommended by more users with mere expertise should be worthy of attention. This ranking paradigm can be implemented through a graph-based ranking algorithm. Two well-known representatives of such a paradigm are Page Rank by Google and HITS(Hypertext Induced Topic Selection) by Kleinberg. Both Page Rank and HITS assign a higher evaluation score to pages linked to more higher-scored pages. HITS differs from PageRank in that it utilizes two kinds of scores: authority and hub scores. The ranking objects of these pages are limited to Web pages, whereas the ranking objects of a folksonomic system are somewhat heterogeneous(i.e., users, resources, and tags). Therefore, uniform application of the voting notion of PageRank and HITS based on the links to a folksonomy would be unreasonable, In a folksonomic system, each link corresponding to a property can have an opposite direction, depending on whether the property is an active or a passive voice. The current research stems from the Idea that a graph-based ranking algorithm could be applied to the folksonomic system using the concept of mutual Interactions between entitles, rather than the voting notion of PageRank or HITS. The concept of mutual interactions, proposed for ranking the Semantic Web resources, enables the calculation of importance scores of various resources unaffected by link directions. The weights of a property representing the mutual interaction between classes are assigned depending on the relative significance of the property to the resource importance of each class. This class-oriented approach is based on the fact that, in the Semantic Web, there are many heterogeneous classes; thus, applying a different appraisal standard for each class is more reasonable. This is similar to the evaluation method of humans, where different items are assigned specific weights, which are then summed up to determine the weighted average. We can check for missing properties more easily with this approach than with other predicate-oriented approaches. A user of a tagging system usually assigns more than one tags to the same resource, and there can be more than one tags with the same subjectivity and objectivity. In the case that many users assign similar tags to the same resource, grading the users differently depending on the assignment order becomes necessary. This idea comes from the studies in psychology wherein expertise involves the ability to select the most relevant information for achieving a goal. An expert should be someone who not only has a large collection of documents annotated with a particular tag, but also tends to add documents of high quality to his/her collections. Such documents are identified by the number, as well as the expertise, of users who have the same documents in their collections. In other words, there is a relationship of mutual reinforcement between the expertise of a user and the quality of a document. In addition, there is a need to rank entities related more closely to a certain entity. Considering the property of social media that ensures the popularity of a topic is temporary, recent data should have more weight than old data. We propose a comprehensive folksonomy ranking framework in which all these considerations are dealt with and that can be easily customized to each folksonomy site for ranking purposes. To examine the validity of our ranking algorithm and show the mechanism of adjusting property, time, and expertise weights, we first use a dataset designed for analyzing the effect of each ranking factor independently. We then show the ranking results of a real folksonomy site, with the ranking factors combined. Because the ground truth of a given dataset is not known when it comes to ranking, we inject simulated data whose ranking results can be predicted into the real dataset and compare the ranking results of our algorithm with that of a previous HITS-based algorithm. Our semantic ranking algorithm based on the concept of mutual interaction seems to be preferable to the HITS-based algorithm as a flexible folksonomy ranking framework. Some concrete points of difference are as follows. First, with the time concept applied to the property weights, our algorithm shows superior performance in lowering the scores of older data and raising the scores of newer data. Second, applying the time concept to the expertise weights, as well as to the property weights, our algorithm controls the conflicting influence of expertise weights and enhances overall consistency of time-valued ranking. The expertise weights of the previous study can act as an obstacle to the time-valued ranking because the number of followers increases as time goes on. Third, many new properties and classes can be included in our framework. The previous HITS-based algorithm, based on the voting notion, loses ground in the situation where the domain consists of more than two classes, or where other important properties, such as "sent through twitter" or "registered as a friend," are added to the domain. Forth, there is a big difference in the calculation time and memory use between the two kinds of algorithms. While the matrix multiplication of two matrices, has to be executed twice for the previous HITS-based algorithm, this is unnecessary with our algorithm. In our ranking framework, various folksonomy ranking policies can be expressed with the ranking factors combined and our approach can work, even if the folksonomy site is not implemented with Semantic Web languages. Above all, the time weight proposed in this paper will be applicable to various domains, including social media, where time value is considered important.

Stability Index Based Voltage Collapse Prediction and Contingency Analysis

  • Subramani, C.;Dash, Subhransu Sekhar;Jagdeeshkumar, M.;Bhaskar, M. Arun
    • Journal of Electrical Engineering and Technology
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    • 제4권4호
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    • pp.438-442
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    • 2009
  • Voltage instability is a phenomenon that could occur in power systems due to stressed conditions. The result would be an occurrence of voltage collapse leading to total blackout of the system. Therefore, voltage collapse prediction is an important part of power system planning and operation, and can help ensure that voltage collapse due to voltage instability is avoided. Line outages in power systems may also cause voltage collapse, thereby implying the contingency in the system. Contingency problems caused by line outages have been identified as one of the main causes of voltage instability in power systems. This paper presents a new technique for contingency ranking based on voltage stability conditions in power systems. A new line stability index was formulated and used to identify the critical line outages and sensitive lines in the system. Line outage contingency ranking was performed on several loading conditions in order to identify the effect of an increase in loading to critical line outages. Correlation studies on the results obtained from contingency ranking and voltage stability analysis were also conducted, and it was found that line outages in weak lines would cause voltage instability conditions in a system. Subsequently, using the results from the contingency ranking, weak areas in the system can be identified. The proposed contingency ranking technique was tested on the IEEE reliability test system.