• International Journal of Computer Science & Network Security
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• 제21권1호
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• pp.6-11
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• 2021

Routing protocols play a pivotal role in the energy management and lifespan of any Wireless Sensor Network. Lower network lifetime has been one of the biggest concerns in LEACH protocol due to dead nodes. The LEACH protocol suffers from uneven energy distribution problem due to random selection of a cluster head. The cluster head has much greater responsibility compared to other non- cluster head nodes and consumes greater energy for its roles. This results in early dead nodes due to energy lost for the role of cluster- head. This study proposes an approach to balance the energy consumption of the LEACH protocol by using a semi-deterministic opportunity coefficient to select the cluster head. This is calculated in each node with the battery energy level and node ID. Ultimately, based on the opportunity cost, cluster head will be selected and broadcasted for which other nodes with higher opportunity cost will agree. It minimizes the chances of nodes with lower battery level being elected as cluster head. Our simulation experiments demonstrate that cluster heads chosen using our proposed algorithm perform better than those using the legacy LEACH protocol.

• 한국동물학회지
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• 제24권2호
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• pp.91-98
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• 1981

Deer mice, Peromyscus maniculatus, 의 성체 571마리의 30개 morphometric 형질들을 이용한 cluster analyses에서 두가지의 similarity 행렬식 (Average taxonomic distance와 Correlation coefficient 행렬식)을 이용한 dendrogram이 서로 다르다는 것이 확인되었다. 이들 두가지의 행렬식 중에서 taxarks의 형태적인 유연관계를 나타내는 하나의 dendrogram만을 선택하기 위한 한 객관적방법이 제안되었다. 즉 principal component analysis에 의한 결과를 비교할 표준결과로 이용하는 방법이다.

• 천문학회보
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• 제36권2호
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• pp.53.1-53.1
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• 2011

We analyze the halo and galaxy catalogs from the Millennium simulations at redshifts z=0, 0.5, 1 to determine the alignment profiles of cluster galaxies in terms of the matter density correlation coefficient and discuss a cosmological implication our result has for breaking parameter degeneracies. For each selected cluster, we measure the alignment between the major axes of the pseudo inertia tensors from all satellites within cluster's virial radius and from only those satellites within some smaller radius. Then we average the measured values over the similar-mass sample to determine the cluster galaxy alignment profile as a function of top-hat scale difference at each redshift. It is shown that the alignment profile of cluster galaxies is well approximated by a power-law of the nonlinear density correlation coefficient that is independent of the power spectrum normalization and bias factor. The alignment profile of cluster galaxies is found to have higher amplitude and lower power-law index when averaged over the larger-mass sample and to have rather weak redshift-dependence. This result is consistent with the picture that the satellite galaxies retain the memory of the external tidal fields right after merging and infalling into the clusters but they gradually lose the initial alignment tendency as the cluster's relaxation proceeds. Demonstrating that the nonlinear density correlation coefficient varies sensitively with the density parameter and neutrino mass fraction, we discuss a potential power of the cluster galaxy alignment profile as an independent probe of cosmology.

• Communications for Statistical Applications and Methods
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• 제25권4호
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• pp.373-383
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• 2018

The spatial scan statistic is a widely used method to detect spatial clusters. The method imposes a large number of scanning windows with pre-defined shapes and varying sizes on the entire study region. The likelihood ratio test statistic comparing inside versus outside each window is then calculated and the window with the maximum value of test statistic becomes the most likely cluster. The results of cluster detection respond sensitively to the shape and the maximum size of scanning windows. The shape of scanning window has been extensively studied; however, there has been relatively little attention on the maximum scanning window size (MSWS) or maximum reported cluster size (MRCS). The Gini coefficient has recently been proposed by Han et al. (International Journal of Health Geographics, 15, 27, 2016) as a powerful tool to determine the optimal value of MRCS for the Poisson-based spatial scan statistic. In this paper, we apply the Gini coefficient to normal-based spatial scan statistics. Through a simulation study, we evaluate the performance of the proposed method. We illustrate the method using a real data example of female colorectal cancer incidence rates in South Korea for the year 2009.

• 천문학회보
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• 제16권
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• pp.19.2-19.2
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• 1991

• 대기
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• 제16권4호
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• pp.259-267
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• 2006

In the present study, the neural network (NN) model with cluster analysis method was developed to predict storm surge in the whole Korean coastal regions with special focuses on the regional extension. The model used in this study is NN model for each cluster (CL-NN) with the cluster analysis. In order to find the optimal clustering of the stations, agglomerative method among hierarchical clustering methods was used. Various stations were clustered each other according to the centroid-linkage criterion and the cluster analysis should stop when the distances between merged groups exceed any criterion. Finally the CL-NN can be constructed for predicting storm surge in the cluster regions. To validate model results, predicted sea level value from CL-NN model was compared with that of conventional harmonic analysis (HA) and of the NN model in each region. The forecast values from NN and CL-NN models show more accuracy with observed data than that of HA. Especially the statistics analysis such as RMSE and correlation coefficient shows little differences between CL-NN and NN model results. These results show that cluster analysis and CL-NN model can be applied in the regional storm surge prediction and developed forecast system.

• 한국작물학회지
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• 제49권4호
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• pp.337-341
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• 2004

Morphological and genetic diversity of thirty nine safflower germplasm were collected and evaluated by Principal Component Analysis (PCA) and Random Amplified Polymorphic DNA (RAPD) method. Stem length and seeding to flowering days of the safflower germplasm showed $26\~117cm\;and\;76\~179$ days of variation respectively. USA originated germplasm showed higher oil content as $39\%$, but that of Japanese showed lower as $26\%$. PCA made three different cluster groups according to some agronomic characteristics of safflower. Korea originated germplasm showed similar cluster group with that of collected from USA in the PCA of stem length. But in the seeding to flowering days, it showed similar cluster pattern with that of collected from Japan rather than USA. In the experiment of RAPD analysis, total five primers showed polymorphism at the several chromosomal loci. Korea, China Japan and South Central Asia originated germplasm were differently classified with USA and South West Asia originated germplasm with lower similarity coefficient value (0.47). Most of Korea originated germplasm were grouped with South Central Asia originated germplasm with higher similarity coefficient value (0.74) conferring similar genetic background between both of them. China and Japan originated germplasm were dendrogramed with Korea originated germplasm at the 0.65 and 0.50 similarity coefficient values respectively. Some common results were expected from both of PCA and RAPD analysis, but lower genetic heritability caused by relative higher portion of environmental variance and environment by genotype interaction at the expression of those of agronomic characteristics made constraint to find any reliable results.

• 한국해안해양공학회지
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• 제19권1호
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• pp.1-15
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• 2007

서해연안역의 폭풍해일고 산정을 위한 초기 연구 단계로, 8 node 병렬 리눅스 클러스터의 효율성과 함께 황해 조석 모의결과의 신뢰성을 검토하였다. NPB 벤치마크 결과 7배에 이르는 계산 효율의 성능향상을 보였다. pADCIRC 모델을 이용한 황해 조석재현 결과는 선행된 연구들과 비교하여 만족스런 신뢰성을 나타냈다. 모델 변수 선정에 따른 영향을 살펴본 바에 따르면, 우리나라 서해연안과 같은 천해역의 조석수동역학 해석에는 수심에 따른 바닥마찰계수의 적절한 사용이 필수적인 것으로 분석되었다.

• 대한산업공학회지
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• 제21권3호
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• pp.371-385
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• 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.

• Journal of Plant Biotechnology
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• 제42권4호
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• pp.401-408
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• 2015

멜론(Cucumis melo L.) 유전자원 83 품종에 대한 형질특성 및 유전적 다양성을 분석하였다. 형질은 유묘, 잎, 줄기, 화기, 과실, 종자에 대해 총 35개 세부특성을 조사하고, 다변량(MANOVA) 분석을 하였다. 주성분 분석(PCA, principal component analysis) 결과 과중, 과장, 과경, 자엽길이, 종자직경, 종자길이 등 8개의 주성분이 전체 변량의 76.3% 를 나타내었다. 평균연관법(Average linkage method)을 사용한 83개의 멜론의 군집분석(Cluster analysis) 결과 coefficient 0.7에서 5개의 cluster로 분류되었다. Cluster I은 과특성에 있어 가장 높은 측정치를, Cluster II는 당도, Cluster V는 과의 성숙기간이 긴 품종들로 주로 구성되었다. 유전자형 분석은 Cucurbit Genomics Initiative (ICuGI) database에 공시된 15개의 Expressed-sequence Tag-Simple Sequence Repeat (EST-SSR) 마커를 이용하였으며 비가중평균결합법(UPGMA)을 통해 품종간 유연관계를 분석하고 6개의 군으로 분류하였다. 형태적 군집분석 결과와 유전적 군집분석 결과의 상관관계를 조사한 결과 상관계수(r) 값이 -0.11으로 매우 낮게 나타났다.