• Journal of information and communication convergence engineering
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• 제6권4호
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• pp.434-438
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• 2008

Massive data are continuously produced with a data rate of over several terabytes every day. These applications need effective clustering algorithms to achieve an overall high performance computation. In this paper, we propose ancestor as cluster center based approach to clustering, the K-means algorithm using ancestor. We modify the K-means algorithm. We present a clustering architecture and a clustering algorithm that minimize of I/Os and show a performance with excellent. In our experimental performance evaluation, we present that our algorithm can improve the I/O speed and the query processing time.

• Communications for Statistical Applications and Methods
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• 제27권4호
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• pp.431-443
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• 2020

The K-means clustering algorithm has had successful application in sufficient dimension reduction. Unfortunately, the algorithm does have reproducibility and nestness, which will be discussed in this paper. These are clear deficits for the K-means clustering algorithm; however, the hierarchical clustering algorithm has both reproducibility and nestness, but intensive comparison between K-means and hierarchical clustering algorithm has not yet been done in a sufficient dimension reduction context. In this paper, we rigorously study the two clustering algorithms for two popular sufficient dimension reduction methodology of inverse mean and clustering mean methods throughout intensive numerical studies. Simulation studies and two real data examples confirm that the use of hierarchical clustering algorithm has a potential advantage over the K-means algorithm.

• Communications for Statistical Applications and Methods
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• 제22권4호
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• pp.321-331
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• 2015

The K-means clustering algorithm is a popular and widely used method for clustering. For covariance matrices, we consider a geodesic clustering algorithm based on the K-means clustering framework in consideration of symmetric positive definite matrices as a Riemannian (non-Euclidean) manifold. This paper considers a geodesic clustering algorithm for data consisting of symmetric positive definite (SPD) matrices, utilizing the Riemannian geometric structure for SPD matrices and the idea of a K-means clustering algorithm. A K-means clustering algorithm is divided into two main steps for which we need a dissimilarity measure between two matrix data points and a way of computing centroids for observations in clusters. In order to use the Riemannian structure, we adopt the geodesic distance and the intrinsic mean for symmetric positive definite matrices. We demonstrate our proposed method through simulations as well as application to real financial data.

• 한국산업정보학회논문지
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• 제17권2호
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• pp.57-64
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• 2012

본 논문에서는 텍스트 마이닝 분야에서 중요한 부분을 차지하고 있는 문서 클러스터링을 위하여 다목적 유전자 알고리즘을 제안한다. 문서 클러스터링에 있어 중요한 요소 중 하나는 유사한 문서를 그룹화 하는 클러스터링 알고리즘이다. 지금까지 문서 클러스터링에는 k-means 클러스터링, 유전자 알고리즘 등을 사용한 연구가 많이 진행되고 있다. 하지만 k-means 클러스터링은 초기 클러스터 중심에 따라 성능 차이가 크며 유전자 알고리즘은 목적함수에 따라 지역 최적해에 쉽게 빠지는 단점을 갖고 있다. 본 논문에서는 이러한 단점을 보완하기 위하여 다목적 유전자 알고리즘을 문서 클러스터링에 적용해 보고, 기존의 알고리즘과 정확성을 비교 및 분석한다. 성능 시험을 통해 k-means 클러스터링(약 20%)과 기존의 유전자 알고리즘(약 17%)을 비교할 때 본 논문에서 제안한 다목적 유전자 알고리즘의 성능이 월등하게 향상됨을 보인다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.671-672
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• 2008

K-means is a popular one in clustering algorithms, and it minimizes the mutual euclidean distance among the sample points. But K-means has some demerits, such as depending on initial condition, unsupervised learning and local optimum. However mahalanobis distancecan deal this case well. In this paper, the author proposed a new clustering algorithm, named exponential probability clustering, which applied Mahalanobis distance into K-means clustering. This new clustering does possess not only the probability interpretation, but also clustering merits. Finally, the simulation results also demonstrate its good performance compared to K-means algorithm.

• 응용통계연구
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• 제34권6호
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• pp.969-977
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• 2021

본 연구에서는 Hierarchical K-means 군집화 알고리즘을 이용해 서울의 A아파트 가구들의 전력 사용량 패턴을 군집화 하였다. 차원을 축소해주면서 패턴을 파악할 수 있는 Hierarchical K-means 군집화 알고리즘은 기존 K-means 군집화 알고리즘의 단점을 보완하여 최근 대용량 전력 사용량 데이터에 적용되고 있는 방법론이다. 본 연구에서는 여름 저녁 피크 시간대의 시간당 전력소비량 자료에 대해 군집화 알고리즘을 적용하였으며, 다양한 군집 개수와 level에 따라 얻어진 결과를 비교하였다. 결과를 통해 사용량에 따라 패턴이 군집화 됨을 확인하였으며, 군집화 유효성 지수들을 통해 이를 비교하였다.

• Journal of Information Processing Systems
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• 제4권2호
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• pp.67-76
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• 2008

This research proposes a new strategy where documents are encoded into string vectors and modified version of k means algorithm to be adaptable to string vectors for text clustering. Traditionally, when k means algorithm is used for pattern classification, raw data should be encoded into numerical vectors. This encoding may be difficult, depending on a given application area of pattern classification. For example, in text clustering, encoding full texts given as raw data into numerical vectors leads to two main problems: huge dimensionality and sparse distribution. In this research, we encode full texts into string vectors, and modify the k means algorithm adaptable to string vectors for text clustering.

• 한국인터넷방송통신학회논문지
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• 제13권1호
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• pp.83-88
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• 2013

본 연구의 목적은 유사 블로그 추천 시스템을 통해서 특정 주제의 유사도에 따라 주제를 찾아 주는 것이다. 유사 추천 시스템을 실현하기 위해서는 대규모 데이터 집합에서 유사항목을 가진 그룹을 찾을 수 있도록 군집해야 한다. 군집화(clustering) 기법은 군집하고자 하는 목적에 따라 적합한 기법과 군집수가 결정되어야 한다. 군집기법으로는 가장 많이 사용되는 K-means 알고리즘을 사용 하였고 추천 알고리즘은 흰개미 군집 알고리즘을 사용하였다. 흰개미 습성 모델을 이용한 군집화 기법은 K-means 알고리즘이 갖고 있는 적절한 군집 갯수 문제점을 해결하고, 군집화 시간을 단축하며, 군집을 위한 군집 평균 이동횟수를 개선한다.

• 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.

• Communications for Statistical Applications and Methods
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• 제19권2호
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• pp.213-217
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• 2012

Fuzzy k-means clustering is an attractive alternative to the ordinary k-means clustering in analyzing multivariate data. Fuzzy versions yield more natural output by allowing overlapped k groups. In this study, we modify a fuzzy k-means clustering algorithm to be used for undirected social networks, apply the algorithm to both real and simulated cases, and report the results.