• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.41-44
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• 2009

데이터 마이닝의 대표적인 기법인 군집화는 군집내의 유사성을 최대화하고, 군집들간의 유사성을 최소화 시키도록 데이터의 집합을 분할하는 것이다. 대용량의 데이터베이스에서 최적의 효율화를 내기 위해서는 원시데이터에 대한 접근 횟수를 줄이고, 이것을 알고리즘 적용 대상이 데이터 구조의 크기를 줄이는 군집화 기법에 많은 관심이 보이고 있다. 본 논문에서는 유전자 알고리즘을 이용하여 자동으로 군집의 개수를 결정하는 군집화 알고리즘을 제안하는 적합도 함수는 보다 양질의 군집을 찾아내는 것으로 평가 되었다. 또한 유전자 알고리즘 중 8가지를 세부 분석하여 평가하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.331-333
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• 2002

협력적 여과 방법은 사용자의 평가 데이터를 이용하므로, 항상 초기 평가 문제(First-Rating Problem)와 희박성 문제(Sparsity Problem)가 발생한다. 최근 이러한 문제를 해결하기 위해 많은 연구가 진행되고 있는 데, 본 논문에서는 연관 규칙을 이용하여 이러한 문제를 해결하고자 한다. 사용자의 평가 데이터를 이용하여 아이템간의 연관성을 산출하고, 연관성이 높은 아이템끼리 군집한다. 사용자와 군집간에 피어슨 상관 계수(Pearson Correlation Coefficient)를 이용하여 가중치를 구하고, 이것으로 선호도를 예측한다. 이러한 방법을 기존의 협력적 여과 방법과 함께 속성에 의한 군집 방식과 비교 평가하였다. 또한, 효율적인 군집을 위한 Split Cluster Method를 제안하고, 기존의 트리 방식의 군집과 비교 평가하였다.

• Korean Journal of Environment and Ecology
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• v.11 no.1
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• pp.111-125
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• 1997

To investigate the climax forest structure and to construct the ecological basic data, forty nine plots were set up and surveyed in Mt. Minjuji, Chungchongpukdo. According to the analysis of classification by TWINSPAN, the community was divided by seven groups of Pinus densiflora-Carpinus laxiflora-Quercus serrata(community I), Q. mongolica-Q. serrata-Platycarya strobilacea(community II), Q. mongolica(community III), Fraxinus mandshurica-Acer mono(community IV), Cornus controversa-F. mandshurica(community V), F. mandshurica-Carpinus cordata(community VI), and F. mandshurica-C. laxiflora(community VII). In the results of the analysis of species structure, similarity, diversity and DBH, except for community I~III, it was founede out broadleaves-mixed-climax forest. Constructed basic data will be applied to sustainable development such as ecotourism, nature trail etc.

• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.233-243
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• 2015

The bimodal flocculation of cohesive sediments in water environments describes the aggregation and breakage process developing a bimodal floc size distribution with dense flocculi and floppy flocs. A two class population balance equation (TCPBE) was tested for simulating the bimodal flocculation by a model-data fitting analysis with two sets of experimental data (low and high turbulent flows) from 1-D flocculation-settling column tests. In contrast to the Single-Class PBE (SCPBE), the TCPBE could simulate interactions between flocculi and flocs and the flocculation mechanism by differential settling in a low turbulent flow. Also, the TCPBE could perform the same quality of simulation as the elaborate Multi-Class PBE (MCPBE), with a small number of floc size classes and differential equations. Thus, the TCPBE was proven to be the simplest model that is capable of simulating the bimodal flocculation of cohesive sediments in water environments and water, wastewater treatment systems.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.274-283
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• 2019

Beta diversity is an efficient means of assessing the spatial variation in community composition among sites. To present fish community variation and LCBD (Local Contribution to Beta Diversity) among sites in stream, 6 sampling sites were selected in Cheonggye stream. Fish communities, environmental and habitat variables were collected at sites from April 2014 to October 2015. We used the total variance of the fish community data table (site-by-species community table) based on different forms, presence-absence, abundance, and Hellinger transformation, to estimate and compare beta diversity and LCBD. Fish community data table transformed by Hellinger distance showed the higher values of beta diversity than presence-absence and abundance data table. A similar patterns of LCBD were observed with presence-absence and Hellinger transformed data table. Low value of beta diversity calculated by community data table with abundance was due to the non-normality of fish assemblage data. Additionally, correlation coefficients were calculated to evaluate the relationships among LCBD, community indices and physicochemical variables. LCBD showed negative correlation coefficients with Shannon diversity. Overall, application of beta diversity analysis is an efficient method of addressing spatial variation of fish communities and ecological uniqueness of the sites in stream.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.480-490
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• 2018

This study investigated the profiles of anger expression (anger control, anger in, anger out) and their variation in forms, and determined the differences in depression, aggression, and negative affect intensity of middle school students. For this purpose, the survey responses of 296 middle school students in Seoul were analyzed. The major study results are as follows. (1) Cluster analyses yielded four anger expression profiles: cluster 1 was characterized by high scores for anger control, anger in and anger out, cluster 2 by low scores for anger control, high scores for anger in and anger out, cluster 3 by low scores for anger control, anger in and anger out, and cluster 4 by low scores for anger in, high scores for anger control and anger out. (2) Between-cluster differences in depression, aggression, and negative affect intensity were all significant. The posteriori test indicated that cluster 4 was higher than the other three clusters in terms of depression. Cluster 3 was higher than the other three clusters on aggression, cluster 2 was higher than cluster 4 in terms of aggression. The interventions by aggression expression cluster are discussed and the implications of this research to education and counseling are explained.

• Korean Journal of Culture and Social Issue
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• v.28 no.1
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• pp.1-22
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• 2022

The purpose of this study was to explore natural groupings among adults based on gender role conflict, ambivalent sexism and aggression, and find differences in their acceptance of rape myths. 372 male and female adults in the Daegu and Gyeongsang province were surveyed and 350 were analyzed on their gender role conflict, ambivalent sexism, aggression and acceptance of rape myths. The cluster analysis divided participants into sub-groups such as 'unaggressive but conflicted about gender stereotypes', 'receptive to adaptive gender notions ' and 'compliant to aggressive gender stereotypes'. The sub-groups had differing levels of gender, age and education. There were differences in acceptance of rape myths among these groups, Post-hoc testing showed that the 'compliant to aggressive gender stereotype' subgroup showed the highest level of acceptance of rape myths, following by 'unaggressive but with gender stereotype conflicts' and 'receptive of adaptive gender notions'. Finally, needs for assessing individual characteristics according to their subgroup types and developing psychoeducational programs focused on the subgroup characteristics were addressed. Then, recommendations for future study were discussed.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.952-955
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• 2014

본 논문에서는 정보 검색 분야에서 잘 알려진 잠재 의미 분석 방법과 계층적 군집화 방법의 단점을 상호 보완하여 보다 효율적인 정보 검색을 위한 혼합형 군집화 방법을 제안한다. 먼저, 잠재 의미 분석 방법은 벡터 연산을 통하여 자동적으로 문서 내에 있는 잠재적인 의미를 찾는 정보 검색분야에서 많이 사용되는 고전적인 방법이다. 그러나 이 방법은 언어의 유의성이나 다의성으로 인하여 발생되는 백-오브-워드(bag-of-word) 문제를 가지고 있다. 두 번째 방법인 문서 군집화를 위하여 범용적으로 사용되고 있는 계층적 군집화 방법이다. 이 방법은 이를 통하여 분석된 군집의 질적 측면에서 볼 때, 여전히 단층적 군집들이 많이 형성되어 세부적인 분석을 통한 추가적인 군집화가 필요함을 알 수 있다. 따라서, 본 논문에서는 앞서 언급한 문제점을 해결하기 위하여 혼합적인 방법으로 잠재 의미 분석 방법을 이용한 응집 계층 군집화 방법을 제안한다. 제안한 방법을 이용하여 잘 알려진 두 개의 데이터에 적용하고 기존의 방법과 그 결과를 비교함으로써 군집의 질적 측면에서의 우수함을 보인다.

• Korean Journal of Environment and Ecology
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• v.14 no.4
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• pp.217-237
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• 2001

본 연구는 계룡산국립공원 갑사 계곡에 위치하는 낙엽활엽노거수군집의 식생군집구조를 부석하기 위하여 18개의 Belt-transect를 설정하여 조사하였다. 노거수군집 전체면적은 $46.442\m^2$이었고, 이 중 노거수가 차지하는 면적은 $35.246\m^2$이었으며, 대표적인 현존식생은 느티나무군집, 팽나무군집, 회화나무군집, 소나무군집, 말채나무군집이었다. 노고수의 규 은 흉고직경이 50~120cm, 수고가 18~22m 이었으며, 흉고직경 70cm이상되는 수종은 소나무(1주), 느티나무(9주), 갈참나무(8주), 졸참나무(1주), 회화나무(2주), 말채나무(1주)이었고, 본 조사 대상지의 평균수령은 150년생 내외이었다. 18개 조사구에 대하여 DCA의 ordination 분석결과 소나무군집, 느타나무-낙엽활엽수군집, 검팽나무-낙엽활엽수군집, 회화나무군집, 말채나무군집, 팽나무군집으로 분리되었다. 교모측의 우점종감의 평균거리는 8~12m이었고, Shannon의 종다양도는 0.7~0.9(단위면적:$200\m^2$_이었다.X>_이었다.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.1
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• pp.12-17
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• 2003

Optimal determination of cluster size has an effect on the result of clustering. In K-means algorithm, the difference of clustering performance is large by initial K. But the initial cluster size is determined by prior knowledge or subjectivity in most clustering process. This subjective determination may not be optimal. In this Paper, the genetic algorithm based optimal determination approach of cluster size is proposed for automatic determination of cluster size and performance upgrading of its result. The initial population based on attribution is generated for searching optimal cluster size. The fitness value is defined the inverse of dissimilarity summation. So this is converged to upgraded total performance. The mutation operation is used for local minima problem. Finally, the re-sampling of bootstrapping is used for computational time cost.