• 제목/요약/키워드: ranking algorithm

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An Estimated Closeness Centrality Ranking Algorithm and Its Performance Analysis in Large-Scale Workflow-supported Social Networks

  • Kim, Jawon;Ahn, Hyun;Park, Minjae;Kim, Sangguen;Kim, Kwanghoon Pio
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제10권3호
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    • pp.1454-1466
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    • 2016
  • This paper implements an estimated ranking algorithm of closeness centrality measures in large-scale workflow-supported social networks. The traditional ranking algorithms for large-scale networks have suffered from the time complexity problem. The larger the network size is, the bigger dramatically the computation time becomes. To solve the problem on calculating ranks of closeness centrality measures in a large-scale workflow-supported social network, this paper takes an estimation-driven ranking approach, in which the ranking algorithm calculates the estimated closeness centrality measures by applying the approximation method, and then pick out a candidate set of top k actors based on their ranks of the estimated closeness centrality measures. Ultimately, the exact ranking result of the candidate set is obtained by the pure closeness centrality algorithm [1] computing the exact closeness centrality measures. The ranking algorithm of the estimation-driven ranking approach especially developed for workflow-supported social networks is named as RankCCWSSN (Rank Closeness Centrality Workflow-supported Social Network) algorithm. Based upon the algorithm, we conduct the performance evaluations, and compare the outcomes with the results from the pure algorithm. Additionally we extend the algorithm so as to be applied into weighted workflow-supported social networks that are represented by weighted matrices. After all, we confirmed that the time efficiency of the estimation-driven approach with our ranking algorithm is much higher (about 50% improvement) than the traditional approach.

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.

연관규칙을 이용한 상품선택과 기대수익 예측 (Item Selection By Estimated Profit Ranking Based on Association Rule)

  • 황인수
    • Asia pacific journal of information systems
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    • 제14권4호
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    • pp.87-97
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    • 2004
  • One of the most fundamental problems in business is ranking items with respect to profit based on historical transactions. The difficulty is that the profit of one item comes from its influence on the sales of other items as well as its own sales, and that there is no well-developed algorithm for estimating overall profit of selected items. In this paper, we developed a product network based on association rule and an algorithm for profit estimation and item selection using the estimated profit ranking(EPR). As a result of computer simulation, the suggested algorithm outperforms the individual approach and the hub-authority profit ranking algorithm.

거리순위를 이용한 얼굴검출 (Face Detection using Distance Ranking)

  • 박재희;김성대
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2005년도 추계종합학술대회
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    • pp.363-366
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    • 2005
  • In this paper, for detecting human faces under variations of lighting condition and facial expression, distance ranking feature and detection algorithm based on the feature are proposed. Distance ranking is the intensity ranking of a distance transformed image. Based on statistically consistent edge information, distance ranking is robust to lighting condition change. The proposed detection algorithm is a matching algorithm based on FFT and a solution of discretization problem in the sliding window methods. In experiments, face detection results in the situation of varying lighting condition, complex background, facial expression change and partial occlusion of face are shown

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전압안정성를 고려한 전력계통의 상정사고 선택 앨고리즘 (Contingency Ranking Algorithm Using Voltage Stability)

  • 박규홍;조양행;정인학
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2002년도 하계학술대회 논문집 A
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    • pp.105-107
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    • 2002
  • This paper presents a algorithm for contingency ranking using the real power ratio. The fundamemtal cause of voltage collapse is considered due to excessive power trnsfer through the line. To obtain contingency ranking, maximum real power tansferred to the load is obtained when load impedance $Z_r$ equal to line impedance $Z_s$. This algorithm is verified by simulation on a 6-bus test system.

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전압안정성를 고려한 전력계통의 상정사고 선택 엘고리즘 (Contingency Ranking Algorithm Using Voltage Stability)

  • 박규홍;조양행;정인학
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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    • pp.146-148
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    • 2002
  • This paper presents a algorithm for contingency ranking using the real power ratio, The fundamemtal cause of voltage collapse is considered due to excessive power trnsfer through the line To obtain contingency ranking, maximum real power tansferred to the load is obtained when load $impedance^{Z_r}$ equal to line $impedance^{Z_s}$, This algorithm is verified by simulation on a 6-bus test system.

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절단기수의 나열을 통한 최대유통문제에서 모든 k-치명호를 찾는 방법 (A Method for Determining All the k Most Vital Arcs in the Maximum Flow Problem by Ranking of Cardinality Cuts)

  • 안재근;정호연;박순달
    • 대한산업공학회지
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    • 제25권2호
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    • pp.184-191
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    • 1999
  • The k most vital arcs (k-MVA) of a maximum flow problem is defined as those k arcs whose simultaneous removal from the network causes the greatest decrease in the throughput capability of the remaining system between a specified pair of nodes. In this study, we present a method for determining all the k-MVA in maximum flow problem using a minimal cardinality cut algorithm and k-th minimal cut ranking algorithm. For ranking cardinality cuts, we use Hamacher's ranking algorithm for cut capacity and by comparing present residual capacity of cardinality cut with expected residual capacity of next cardinality cut, we also present termination condition for this algorithm. While the previous methods cannot find all the alternatives for this problem, a method presented here has advantage of determining all the k-MVA.

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A Generic Multi-Level Algorithm for Prioritized Multi-Criteria Decision Making

  • G., AlShorbagy;Eslam, Hamouda;A.S., Abohamama
    • International Journal of Computer Science & Network Security
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    • 제23권1호
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    • pp.25-32
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    • 2023
  • Decision-making refers to identifying the best alternative among a set of alternatives. When a set of criteria are involved, the decision-making is called multi-criteria decision-making (MCDM). In some cases, the involved criteria may be prioritized by the human decision-maker, which determines the importance degree for each criterion; hence, the decision-making becomes prioritized multi-criteria decision-making. The essence of prioritized MCDM is raking the different alternatives concerning the criteria and selecting best one(s) from the ranked list. This paper introduces a generic multi-level algorithm for ranking multiple alternatives in prioritized MCDM problems. The proposed algorithm is implemented by a decision support system for selecting the most critical short-road requests presented to the transportation ministry in the Kingdom of Saudi Arabia. The ranking results show that the proposed ranking algorithm achieves a good balance between the importance degrees determined by the human decision maker and the score value of the alternatives concerning the different criteria.

대규모 워크플로우 소셜 네트워크의 추정 근접 중심도 랭킹 알고리즘 성능 분석 (Performance Analysis of an Estimated Closeness Centrality Ranking Algorithm in Large-Scale Workflow-supported Social Networks)

  • 김자원;안현;김광훈
    • 인터넷정보학회논문지
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    • 제16권3호
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    • pp.71-77
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    • 2015
  • 본 논문에서는 대규모 워크플로우 기반 소셜 네트워크를 위한 추정 근접 중심도 랭킹 알고리즘을 구현하고, 그에 대한 성능 분석을 수행한다. 기존의 근접 중심도 분석 방법은 특정 노드와 다른 모든 노드들 간의 최단거리를 구하므로 네트워크의 크기가 커짐에 따라 근접 중심도 분석 시간이 기하급수적으로 증가하는 문제점을 가진다. 이로 인해 대규모 소셜 네트워크의 근접 중심도 랭킹 과정에도 계산시간 문제를 가진다. 이러한 문제점을 개선하고자 본 논문에서는 추정기법을 활용한 근접 중심도 랭킹 알고리즘을 구현하며 기존 알고리즘과의 성능 분석을 수행한다. 이는 약 50%의 계산 시간 단축 결과를 보여주었다.

Performance Evaluations of Text Ranking Algorithms

  • Kim, Myung-Hwi;Jang, Beakcheol
    • 한국컴퓨터정보학회논문지
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    • 제25권2호
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    • pp.123-131
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    • 2020
  • 텍스트 순위 알고리즘은 키워드 추출을 위한 대표적인 방법이며 그 중요성이 강조되고 있다. 본 논문에서는 텍스트 랭킹 알고리즘에서 대표적으로 사용되는 TF-IDF, SMART, INQUERY, CCA 알고리즘이 적용된 최근 연구와 실험해비교한다. 먼저, 각 알고리즘을 설명한 후 뉴스와 트위터 데이터를 기반으로 알고리즘의 성능을 분석한다. 실험 결과에 따르면 네 가지 알고리즘 모두 뉴스 데이터에서 특정 단어의 추출 성능이 좋다는 것을 알 수 있다. 그러나 Twitter의 경우 CCA는 특정 단어를 추출하는 최고의 성능을 가지며 INQUERY는 가장 낮은 성능을 보여준다. 또한 6 가지 비교 메트릭을 통해 알고리즘의 정확성을 분석한다. 실험 결과 CCA가 뉴스 데이터에서 최고의 정확도를 보여주고, 트위터의 경우 TF-IDF와 CCA는 비슷한 성능을 보이며 높은 정확도를 보인다.