• 제목/요약/키워드: Cluster index

검색결과 539건 처리시간 0.024초

A Cluster validity Index for Fuzzy Clustering

  • Lee, Haiyoung
    • 한국지능시스템학회논문지
    • /
    • 제9권6호
    • /
    • pp.621-626
    • /
    • 1999
  • In this paper a new cluster validation index which is heuristic but able to eliminate the monotonically decreasing tendency occurring in which the number of cluster c gets very large and close to the number of data points n is proposed. We review the FCM algorithm and some conventional cluster validity criteria discuss on the limiting behavior of the proposed validity index and provide some numerical examples showing the effectiveness of the proposed cluster validity index.

  • PDF

고차원 (유전자 발현) 자료에 대한 군집 타당성분석 기법의 성능 비교 (Comparison of the Cluster Validation Methods for High-dimensional (Gene Expression) Data)

  • 정윤경;백장선
    • 응용통계연구
    • /
    • 제20권1호
    • /
    • pp.167-181
    • /
    • 2007
  • 유전자 발현 자료(gene expression data)는 전형적인 고차원 자료이며, 이를 분석하기 위한 여러 가지 군집 알고리즘(clustering algorithm)과 군집 결과들을 검증하는 군집타당성분석 기법(cluster validation technique)이 제안되고 있지만, 이들 군집 타당성을 분석하는 기법의 성능에 대한 비교, 평가는 매우 드물다. 본 논문에서는 저차원의 모의실험 자료와 실제 유전자 발현 자료에 대하여 군집 타당성분석 기법들의 성능을 비교하였으며, 그 결과 내적 측도에서는 Dunn 지수, Silhouette 지수 순으로 뛰어났고 외적 측도에서는 Jaccard 지수가 성능이 가장 우수한 것으로 평가되었다.

PROPERTIES AND SPECTRAL BEHAVIOUR OF CLUSTER RADIO HALOS

  • FERETTI L.;BRUNETTI G.;GIOVANNINI G.;KASSIM N.;ORRU E.;SETTI G.
    • 천문학회지
    • /
    • 제37권5호
    • /
    • pp.315-322
    • /
    • 2004
  • Several arguments have been presented in the literature to support the connection between radio halos and cluster mergers. The spectral index distributions of the halos in A665 and A2163 provide a new strong confirmation of this connection, i.e. of the fact that the cluster merger plays an important role in the energy supply to the radio halos. Features of the spectral index (flattening and patches) are indication of a complex shape of the radiating electron spectrum, and are therefore in support of electron reacceleration models. Regions of flatter spectrum are found to be related to the recent merger. In the undisturbed cluster regions, instead, the spectrum steepens with the distance from the cluster center. The plot of the integrated spectral index of a sample of halos versus the cluster temperature indicates that clusters at higher temperature tend to host halos with flatter spectra. This correlation provides further evidence of the connection between radio emission and cluster mergers.

The Classification of Forest Communities by Cluster Analysis in Mt. Seokbyung Experimental Forest of Gangwon-Do

  • Chung, Sang-Hoon;Kim, Ji-Hong
    • 한국산림과학회지
    • /
    • 제99권5호
    • /
    • pp.736-743
    • /
    • 2010
  • This study examined the ecological attributes of classified forest community by cluster analysis in the mixed forest of Mt. Seokbyung Experimental Forest of Gangwon-Do. The vegetation data were collected in randomly established 51 sample plots (2.04 ha) and analysis adopted the cluster analysis, importance value index, and Shannon's diversity index. Main results were as follows; 1) the study area was classified into 4 clusters (A, B, C and D). 2) The cluster A was dominated by Pinus densiflora with an importance value of 71.6%. The most dominant species in the cluster B and cluster C were Larix leptolepis (57.1%) and Quercus mongolica (40.2%), respectively. Finally, The cluster D was dominated by P. densiflora (30.6%) and Q. mongolica (31.0%) with the mixed forest. 3) In the P. densiflora community (cluster A), distribution of DBH class showed a reverse J-shaped curve. In the L. leptolepis community (cluster B), individuals of dominant species had the bell-shaped distribution. Oak species indicated uniform distribution of DBH class (under 25 cm) in the mixed P. densiflora - Q. mongolica community (cluster D). 4) The species diversity index of the communities in descending order were: Pinus densiflora - Q. mongolica community > Larix leptolepis community > Pinus densiflora community > Quercus mongolica community.

클러스터 타당성 평가기준을 이용한 최적의 클러스터 수 결정을 위한 고속 탐색 알고리즘 (Fast Search Algorithm for Determining the Optimal Number of Clusters using Cluster Validity Index)

  • 이상욱
    • 한국콘텐츠학회논문지
    • /
    • 제9권9호
    • /
    • pp.80-89
    • /
    • 2009
  • 클러스터링 알고리즘에서 최적의 클러스터 수를 결정하기 위한 효율적인 고속 탐색 알고리즘을 소개한다. 제안하는 방법은 클러스터링 적합도의 척도로 사용되는 클러스터 타당성 평가기준을 토대로 한다. 데이터 집합에 클러스터링 프로세스를 진행하여 최적의 클러스터 형상에 도달하게 되면 클러스터 타당성 평가기준은 최대 혹은 최소값을 가질 것으로 기대한다. 본 논문에서는 최적의 클러스터 개수를 찾기 위한 고속의 비소모적 탐색 방법을 설계하고 실제 클러스터링과 접목한다. 제안하는 알고리즘은 k-means++ 클러스터링 알고리즘에 적용하였고, 클러스터 타당성 평가기준으로써 CB 및 PBM 타당성 평가기준 방법을 사용하였다. 몇몇의 가상 데이터 집합과 실제 데이터 집합에 실험한 결과, 제안하는 방법은 정확도의 손실 없이 계산 효율을 획기적으로 증가시킴을 보여주었다.

변동계수를 이용한 반도체 결점 클러스터 지표 개발 및 수율 예측 (Development of a New Cluster Index for Semiconductor Wafer Defects and Simulation - Based Yield Prediction Models)

  • 박항엽;전치혁;홍유신;김수영
    • 대한산업공학회지
    • /
    • 제21권3호
    • /
    • pp.371-385
    • /
    • 1995
  • The yield of semiconductor chips is dependent not only on the average defect density but also on the distribution of defects over a wafer. The distribution of defects leads to consider a cluster index. This paper briefly reviews the existing yield prediction models ad proposes a new cluster index, which utilizes the information about the defect location on a wafer in terms of the coefficient of variation. An extensive simulation is performed under a variety of defect distributions and a yield prediction model is derived through the regression analysis to relate the yield with the proposed cluster index and the average number of defects per chip. The performance of the proposed simulation-based yield prediction model is compared with that of the well-known negative binomial model.

  • PDF

A Variable Selection Procedure for K-Means Clustering

  • Kim, Sung-Soo
    • 응용통계연구
    • /
    • 제25권3호
    • /
    • pp.471-483
    • /
    • 2012
  • One of the most important problems in cluster analysis is the selection of variables that truly define cluster structure, while eliminating noisy variables that mask such structure. Brusco and Cradit (2001) present VS-KM(variable-selection heuristic for K-means clustering) procedure for selecting true variables for K-means clustering based on adjusted Rand index. This procedure starts with the fixed number of clusters in K-means and adds variables sequentially based on an adjusted Rand index. This paper presents an updated procedure combining the VS-KM with the automated K-means procedure provided by Kim (2009). This automated variable selection procedure for K-means clustering calculates the cluster number and initial cluster center whenever new variable is added and adds a variable based on adjusted Rand index. Simulation result indicates that the proposed procedure is very effective at selecting true variables and at eliminating noisy variables. Implemented program using R can be obtained on the website "http://faculty.knou.ac.kr/sskim/nvarkm.r and vnvarkm.r".

METALLICITY DETERMINATION FOR A GLOBULAR CLUSTER BY SPECTRAL INDICES

  • LEE SANG-GAK
    • 천문학회지
    • /
    • 제29권2호
    • /
    • pp.157-170
    • /
    • 1996
  • In order to determine the metallicity of a globuar cluster, M3,by using the spectral indices, a kind of index grid has been establshed by stars in globular clusters, M3, M15, M71 and old open cluster, NGC 188. The indices were measured from the medium resolution spectra of about $2{\AA}$. The summed indices were used to determine metallicity in order to increase signals. It is found that the core depth index is measured more accurately and leads result more accurate than the pseudo-equivalent width index. This method can be further improved by including many more calibration globular clusters of various metallicity to make finer grids. By this method, the metallicity of M3 is determined as $[Fe/H] = -1.46\pm0.15$.

  • PDF

중국 주요 50개 도시의 전자상거래 발전성과에 대한 평가 (Evaluation on Development Performances of E-Commerce for 50 Major Cities in China)

  • 정동빈;왕강
    • 유통과학연구
    • /
    • 제14권1호
    • /
    • pp.67-74
    • /
    • 2016
  • Purpose - In this paper, the degree of similarity and dissimilarity between pairs of 50 major cities in China can be shown on the basis of three evaluation variables(internet businessman index, internet shopping index and e-commerce development index). Dissimilarity distance matrix is used to analyze both similarity and dissimilarity between each fifty city in China by calculating dissimilarity as distance. Higher value signifies higher degree of dissimilarity between two cities. Cluster analysis is exploited to classify 50 cities into a number of different groups such that similar cities are placed in the same group. In addition, multidimensional scaling(MDS) technique can obtain visual representation for exploring the pattern of proximities among 50 major cities in China based on three development performance attributes. Research design, data, and methodology - This research is performed by the 2013 report provided with AliResearch in China(1/1/2013~11/30/2013) and utilized multivariate methods such as dissimilarity distance matrix, cluster analysis and MDS by using CLUSTER, KMEANS, PROXIMITIES and ALSCAL procedures in SPSS 21.0. Results - This research applies two types of cluster analysis and MDS on three development performances based on the 2013 report of Aliresearch. As a result, it is confirmed that grouping is possible by categorizing the types into four clusters which share similar characteristics. MDS is exploited to carry out positioning of both grouped locations of cluster and 50 major cities belonging to each cluster. Since all the values corresponding to Shenzhen, Guangzhou and Hangzhou(which belong to cluster 1 among 50 major cities) are very large, these cities are superior to other cities in all three evaluation attributes. Twelve cities(Beijing, ShangHai, Jinghua, ZhuHai, XiaMen, SuZhou, NanJing, DongWan, ZhangShan, JiaXing, NingBo and FoShan), which belong to cluster 3, are inferior to those of cluster 1 in terms of all three attributes, but they can be expected to be the next e-commerce revolution. The rest of major cities, in particular, which belong to cluster 4 are relatively inferior in all three attributes, so that this automatically evokes creative innovation, which leads to e-commerce development as a whole in China. In terms of internet businessman index, on the other hand, Tainan, Taizhong, and Gaoxiong(which belong to cluster 2) are situated superior to others. However, these three cities are inferior to others in an internet shopping index sense. The rest of major cities, in particular, which belong to cluster 4 are relatively inferior in all three evaluation attributes, so that this automatically evokes innovation and entrepreneurship, which leads to e-commerce development as a whole in China. Conclusions - This study suggests the implications to help e-governmental officers and companies make strategies in both Korea and China. This is expected to give some useful information in understanding the recent situation of e-commerce in China, by looking over development performances of 50 major cities. Therefore, we should develop marketing, branding and communication relevant to online Chinese consumers. One of these efforts will be incentives like loyalty points and coupons that can encourage consumers and building in-house logistics networks.

전라지역 응급실 환자의 유출입 분석 및 지역유형 변화 추이 (Analysis of Change Transitions in Regional Types in Emergency Department Patient Flows of in Jeonlado (2014-2018))

  • 이재현;이성민;김성중;오미라
    • 융합정보논문지
    • /
    • 제10권12호
    • /
    • pp.126-131
    • /
    • 2020
  • 본 연구는 전라도 지역 시·군·구의 지역 유형 변화를 파악하기 위하여 응급실 환자들의 유출입 현황을 분석하였다. 2014-2018년의 국가응급진료정보망에서 전라도 지역의 자료를 추출하였고, 환자의 주소와 응급의료기관 주소를 활용하여 지역친화도(Relevance index, RI)와 지역환자구성비(Commitment index CI)를 계산하였다. 계산된 지표들을 적용하여 군집분석으로 지역유형을 분류하였고, 비모수적 방법인 크루스칼-왈리스 검정을 사용하여 지역유형에 대한 RI와 CI의 연도별 차이를 살펴보았다. RI와 CI를 활용한 군집분석 결과는 3개의 지역유형으로 구분되었고, 군집 1은 유출형, 군집 2는 유입형, 군집 3은 자체충족형으로 분류되었다. 각 군집(지역유형)에 대한 RI와 CI의 연도별 차이에서는 군집 2(유입형)와 군집 3(자체충족형)은 유의한 차이가 없었다. 군집 1(유출형)은 CI에서는 유의한 차이가 없었고, RI에서 2004년은 2017년과 2018년에 유의한 차이가 있었다. 이는 응급의료 집중화가 심해진 반면, 응급의료 환경이 개선되었다고 보기는 어려운 것으로 해석된다.