• 제목/요약/키워드: Rank algorithm

검색결과 283건 처리시간 0.029초

Affine Projection 알고리즘을 이용한 표면 부착형 영구자석 전동기의 온라인 파라미터 추정 (Online Parameter Estimation of SPMSM using Affine Projection Algorithm)

  • 문병훈;김형우;최준영
    • 전력전자학회논문지
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    • 제23권1호
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    • pp.66-71
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    • 2018
  • We propose an online parameter estimation method for surface-mounted permanent-magnet synchronous motor (SPMSM) using an affine projection algorithm (APA). The proposed method estimates parameters with two APAs based on the discrete-time model equation of SPMSM during motor operation. The first APA is designed to estimate inductance, and the second APA is designed to estimate resistance and flux linkage. However, in case when the d-axis current is controlled to 0A, the second APA cannot estimate resistance and flux linkage simultaneously because the matrix rank in APA becomes deficient. To overcome this problem, we temporarily inject a negative reference current input to the d-axis control loop, and the matrix in the APA then becomes full rank, which enables the simultaneous estimation of resistance and flux linkage. The proposed method is verified by PSIM simulation and an actual experiment, and the results reveal that SPMSM parameters can be estimated online during motor operation.

데이터 리터러시 연구 분야의 주경로와 지적구조 분석 (Analyzing the Main Paths and Intellectual Structure of the Data Literacy Research Domain)

  • 이재윤
    • 정보관리학회지
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    • 제40권4호
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    • pp.403-428
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    • 2023
  • 이 연구에서는 데이터 리터러시 분야 연구의 발전 경로와 지적구조 및 떠오르는 유망 주제를 파악하고자 하였다. 이를 위해서 Web of Science에서 검색한 데이터 리터러시 관련 논문은 교육학 분야와 문헌정보학 분야 논문이 전체의 60% 가까이를 차지하였다. 우선 인용 네트워크 분석에서는 페이지랭크 알고리즘을 사용해서 인용 영향력이 높은 다양한 주제의 핵심 논문을 파악하였다. 데이터 리터러시 연구의 발전 경로를 파악하기 위해서 기존의 주경로분석법을 적용해보았으나 교육학 분야의 연구 논문만 포함되는 한계가 있었다. 이를 극복할 수 있는 새로운 기법으로 페이지랭크 주경로분석법을 개발한 결과, 교육학 분야와 문헌정보학 분야의 핵심 논문이 모두 포함되는 발전 경로를 파악할 수 있었다. 데이터 리터러시 연구의 지적구조를 분석하기 위해서 키워드 서지결합 분석을 시행하였다. 도출된 키워드 서지결합 네트워크의 세부 구조와 군집 파악을 위해서 병렬최근접이웃클러스터링 알고리즘을 적용한 결과 대군집 2개와 그에 속한 소군집 7개를 파악할 수 있었다. 부상하는 유망 주제를 도출하기 위해서 각 키워드와 군집의 성장지수와 평균출판년도를 측정하였다. 분석 결과 팬데믹 상황과 AI 챗봇의 부상이라는 시대적 배경 하에서 사회정의를 위한 비판적 데이터 리터러시가 고등교육 측면에서 급부상하고 있는 것으로 나타났다. 또한 이 연구에서 연구의 발전경로를 파악하는 수단으로 새롭게 개발한 페이지랭크 주경로분석 기법은 서로 다른 영역에서 병렬적으로 발전하는 둘 이상의 연구흐름을 발견하기에 효과적이었다.

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.

유연생산시스템(FMS)에서의 기계-부품그룹 형성기법 (Machine-part Group Formation Methodology for Flexible Manufacturing Systems)

  • 노인규;권혁천
    • 대한산업공학회지
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    • 제17권1호
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    • pp.75-82
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    • 1991
  • This research is concerned with Machine-Part Group Formation(MPGF) methodology for Flexible Manufacturing Systems(FMS). The purpose of the research is to develop a new heuristic algorithm for effectively solving MPGF problem. The new algorithm is proposed and evaluated by 100 machine-part incidence matrices generated. The performance measures are (1) grouping ability of mutually exclusive block-diagonal form. (2) number of unit group and exceptional elements, and (3) grouping time. The new heuristic algorithm has the following characteristics to effectively conduct MPGF : (a) The mathematical model is presented for rapid forming the proper number of unit groups and grouping mutually exclusive block-diagonal form, (b) The simple and effective mathematical analysis method of Rank Order Clustering(ROC) algorithm is applied to minimize intra-group journeys in each group and exceptional elements in the whole group. The results are compared with those from Expert System(ES) algorithm and ROC algorithm. The results show that the new algorithm always gives the group of mutually exclusive block-diagonal form and better results(85%) than ES algorithm and ROC algorithm.

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Function Optimization Using Quadratically Convergent Algorithms With One Dimensional Search Schemes

  • Kim, Do-Il
    • 대한산업공학회지
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    • 제14권2호
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    • pp.25-40
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    • 1988
  • In this paper, a unified method to construct a quadratically convergent algorithm with one dimensional search schemes is described. With this method, a generalized algorithm is derived. As it's particular cases, three quadratically convergent algorithms are performed. They are the rank-one algorithm (Algorithm I), projection algorithm (Algorithm II) and the Fletcher-Reeves algorithm (Algorithm III). As one-dimensional search schemes, the golden-ratio method and dichotomous search are used. Additionally, their computer programming is developed for actual application. The use of this program is provided with the explanation of how to use it, the illustrative examples that are both quadratic and nonquadratic problems and their output. Finally, from the computer output, each algorithm was analyzed from the standpoint of efficiency for performance.

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An Improved Automated Spectral Clustering Algorithm

  • Xiaodan Lv
    • Journal of Information Processing Systems
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    • 제20권2호
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    • pp.185-199
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    • 2024
  • In this paper, an improved automated spectral clustering (IASC) algorithm is proposed to address the limitations of the traditional spectral clustering (TSC) algorithm, particularly its inability to automatically determine the number of clusters. Firstly, a cluster number evaluation factor based on the optimal clustering principle is proposed. By iterating through different k values, the value corresponding to the largest evaluation factor was selected as the first-rank number of clusters. Secondly, the IASC algorithm adopts a density-sensitive distance to measure the similarity between the sample points. This rendered a high similarity to the data distributed in the same high-density area. Thirdly, to improve clustering accuracy, the IASC algorithm uses the cosine angle classification method instead of K-means to classify the eigenvectors. Six algorithms-K-means, fuzzy C-means, TSC, EIGENGAP, DBSCAN, and density peak-were compared with the proposed algorithm on six datasets. The results show that the IASC algorithm not only automatically determines the number of clusters but also obtains better clustering accuracy on both synthetic and UCI datasets.

LSI를 이용한 차원 축소 클러스터 기반 키워드 연관망 자동 구축 기법 (Automatic Construction of Reduced Dimensional Cluster-based Keyword Association Networks using LSI)

  • 유한묵;김한준;장재영
    • 정보과학회 논문지
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    • 제44권11호
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    • pp.1236-1243
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    • 2017
  • 본 논문은 기존의 TextRank 알고리즘에 상호정보량 척도를 결합하여 군집 기반에서 키워드 추출하는 LSI-based ClusterTextRank 기법과 추출된 키워드를 Latent Semantic Indexing(LSI)을 이용한 연관망 구축 기법을 제안한다. 제안 기법은 문서집합을 단어-문서 행렬로 표현하고, 이를 LSI를 이용하여 저차원의 개념 공간으로 차원을 축소한다. 그 다음 k-means 군집화 알고리즘을 이용하여 여러 군집으로 나누고, 각 군집에 포함된 단어들을 최대신장트리 그래프로 표현한 후 이에 근거한 군집 정보량을 고려하여 키워드를 추출한다. 그리고나서 추출된 키워드들 간에 유사도를 LSI 기법을 통해 구한 단어-개념 행렬을 이용하여 계산한 후, 이를 키워드 연관망으로 활용한다. 제안 기법의 성능을 평가하기 위해 여행 관련 블로그 데이터를 이용하였으며, 제안 기법이 기존 TextRank 알고리즘보다 키워드 추출의 정확도가 약 14% 가량 개선됨을 보인다.

인덱스 이미지에서의 무손실 압축을 위한 적응적 순위 기반 재인덱싱 기법 (An Adaptive Rank-Based Reindexing Scheme for Lossless Indexed Image Compression)

  • 유강수;이봉주;장의선;곽훈성
    • 한국통신학회논문지
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    • 제30권7C호
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    • pp.658-665
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    • 2005
  • 인덱스 이미지를 구성하는 요소들을 재구성하는 기법을 재인덱싱이라 한다. 이는 무손실 압축의 효율을 높이기 위한 방법으로 잘 알려져 있다. 본 논문에서는 이웃하는 픽셀간의 발생빈도수에 대한 순위를 가지고 재인덱싱 기법을 보다 유연하게 처리하기 위한 적응적 방법을 소개한다. 제안한 방법을 통하여 획득한 순위로 구성된 이미지를 산술 부호화하여 무손실 압축을 행한다. 이때 발생하는 순위 정보를 송신측으로 보내지 않게 하기 위해 적응적으로 한 픽셀씩 처리한다. 순위 정보로 전환된 이미지를 순위 이미지라고 부른다. 이러한 순위 이미지는 동일한 순위에 포함되는 많은 픽셀들이 존재하게 되어 일반적인 이미지보다 데이터의 중복성을 높일 수 있고 데이터 분포가 한쪽으로 편중되어 있어 산술 부호화의 효율을 기대할 수 있다. 실험 결과, 제안한 적응적 순위 기반 재인덱싱 방법은 Zeng의 방법보다 최대 26$\%$의 비트율 절감 효과를 보였다.

분산 이기종 컴퓨팅 시스템에서 효율적인 리스트 스케줄링 알고리즘 (An Efficient List Scheduling Algorithm in Distributed Heterogeneous Computing System)

  • 윤완오;윤정희;이창호;김효기;최상방
    • 전자공학회논문지CI
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    • 제46권3호
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    • pp.86-95
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    • 2009
  • 이기종 컴퓨팅 환경에서 방향성 비순환 그래프(directed acyclic graph DAG)의 효율적인 스케줄링은 시스템의 성능을 높게 만드는데 매우 중요한 역할을 한다. 이기종의 컴퓨팅 환경에서 DAG로 표현되는 프로그램의 최적 스케줄링 방법을 찾는 것은 잘 알려진 '정해진 시간 내에 해결하기 어려운 문제(NP-complete)' 이다. 본 논문은 분산 이기종 컴퓨팅 시스템에서 병렬로 실행 가능한 프로그램을 위한 새로운 리스트 스케줄링 알고리즘인 HRPS(Heterogeneous Rank-Path Scheduling)를 제안하였다. HRPS의 가장 궁극적인 목적은 프로그램의 실행시간을 최소화하는 것이다. 알고리즘의 성능을 위해 DAG 입력 그래프를 이용하여 기존에 제안되어진 CPOP, HCPT, FLB 알고리즘과 스케줄의 길이를 비교한 결과 성능 향상의 결과를 얻을 수 있었다.

다중경로 환경에서 DOA를 추정하기 위한 Forward/Backward First Order Statistics Algorithm (Forward/Backward First Order Statistics Algorithm for the estimation of DOA in a Multipath environment)

  • 김한수
    • 한국음향학회:학술대회논문집
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    • 한국음향학회 1998년도 학술발표대회 논문집 제17권 1호
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    • pp.221-224
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    • 1998
  • 간섭신호가 원하는 신호에 coherent한 경우에는 원하는 신호와 간섭신호간의 cross correlation에 의해 공분산 행렬의 rank가 줄어들게 되어 coherent한 간섭신호의 도래각을 추정할 수 없게 된다. 이러한 문제를 해결하기 위해 발표된 기존의 방법중 대칭 어레이(Symmetric array)방법은 계산량이 많아지고 공간 스무딩(Spatial Smoothing)방법은 array aperture size에서 손해를 보게 되어 분해능이 떨어지는 단점이 있다[1,2,3].

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