• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.1
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• pp.15-20
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• 2017

The purpose of this study is to present the intellectual structure of Assistive Technology Journal using co-word analysis of keywords. The articles of Assistive Technology Journal were collected from Web of Science citation database. 255 articles during the period from 2003 to 2015 were selected for the analysis. And 1,359 author keywords were extracted from the articles. In order to analyze the intellectual structure of Assistive Technology Journal, clustering analysis was conducted and 5 clusters were determined. Next, 5 clusters are presented in the map of multidimensional scaling. The results of this study are expected to assist in exploring the future directions of the researches on assistive technology.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.2
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• pp.205-211
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• 2012

The retrieved documents have to be transformed into proper data structure for the clustering algorithms of statistics and machine learning. A popular data structure for document clustering is document-term matrix. This matrix has the occurred frequency value of a term in each document. There is a sparsity problem in this matrix because most frequencies of the matrix are 0 values. This problem affects the clustering performance. The sparseness of document-term matrix decreases the performance of clustering result. So, this research uses the factor score by factor analysis to solve the sparsity problem in document clustering. The document-term matrix is transformed to document-factor score matrix using factor scores in this paper. Also, the document-factor score matrix is used as input data for document clustering. To compare the clustering performances between document-term matrix and document-factor score matrix, this research applies two typed matrices to self organizing map (SOM) clustering.

• The Journal of the Korea Contents Association
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• v.20 no.8
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• pp.674-684
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• 2020

To investigate the differences of bacterial- and archaeal communities depending on kind of wastewater (municipal/livestock) and on treating conditions of basins, sludges were sampled from 10 basins of 3 municipal wastewater treatment plants(WWTP) with A2O and a activated sludge sample from a livestock WWTP. The metagenomic DNAs of the sludge samples were extracted and amplified with primers, 27F/518R for bacteria and Arch519F/A958R for archaea, and pyrosequenced with Roche 454 GS-FLX Titanium. As results, the bacterial communities in basins of municipal WWTPs were quite different from those of livestock WWTP, but within the same municipal WWTP their community structures were similar to each other regardless of different environmental conditions such as O₂. And their archaeal communities resulted from anaerobic·anoxic basins were clustered only within communities originated from the same WWTP. Furthermore Seo-bu WWTP with high bacterial diversity and species richness performed better N/P-removal compared to the orther WWTPs.

• Korean Journal of Environment and Ecology
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• v.6 no.2
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• pp.147-153
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• 1993

The Dalbatjae-Birobong ridge forest in Mt. Sobaek area was studied to investigate forest community structure. Twenty 20m $\times$ 25m plots were set up in the studied ridge forest along altitude of 770m to 1,410m and vegetation analysis for tree stratum of the trees above 1cm DBH was carried out. The leading dominant tree species were Pinus densiflora in the lower elevation and Quercus mongolica in the higher elevation. According to importance value and cluster analysis, the studied ridge forest was classified into four forest communities of Pinus densiflora community, Pinus densiflora-Quercus mongolica community. Quercus mongolica community and Quercus mongolica-deciduous tree species community. According to importance value of major tree species in canopy and understory, the present community type seems to continue for a relatively long time. Species diversity of Pinus densiflora community, Pinus densiflora-Quercus mongolica community, Quercus mongolica community and Quercus mongolica-deciduous tree species community were 0.6791, 0.6850, 0.5296 and 0.7136, respectively.

• Journal of agriculture & life science
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• v.50 no.3
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• pp.69-80
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• 2016

The present study was to survey the site environment, vegetation structure and soil characteristics in the wild habitats of Acer tegmentosum Maxim. and offers basic information for habitats conservation and restoration. Most of the wild habitats were located at altitudes between 605~1,413m with inclinations ranged as 8~30°. The bare rock rate were 8~50%. The vegetation structure by the PC-ORD based on the Two Way Cluster Analysis were divided into three groups Community I(Acer tegmentosum - Quercus mongolica), Community II(Acer tegmentosum - Carpinus cordata), Community III(Quercus mongolica - Tilia amurensis). The species diversity(H') was highest in Community II as 1.474, Community I was 1.471, Community III was 1.219. The soil textures were Clay loam, The average soil pH was 4.8, Soil organic matter was 15.15% and available phosphorus was 2.33ppm. Ordination analysis result by soil characteristics, community, characteristic species showed that the greatest effect factors were slope, altitude, tree and shrub's cover rate, organic matter, total-nitrogen, calcium, magnesium. Correlation analysis between environment factor result showed that O.M. - (T.N., K+, Mg2+, CEC, EC), T.N. - (K+, Mg2+, CEC, EC) were positive correlations.

• Korean Journal of Environment and Ecology
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• v.5 no.1
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• pp.54-67
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• 1991

To investigate the structure of the plant community of Daewon valley forest in Mt. Chiri, eighty-nine plots were set up by the dumped sampling method. The classification by TWINSPAN and DCA ordination were applied to the study area in order to classify item into several groups based on woody plants and environmental variables. The classification had been successfully overlayed on an ordination of the same data using DCA. The plots can be classified into five groups by TWINSPAN and DCA. There are Pinus densiflora community. Quercus variabilis-Q. serrata community. Carpinus laxiflora community. Q. monogolica community and Cornus controversa-Q. mongolica community. The successional trends of tree species by both techniques seem to be from P. densiflora through Q. variabilis, Q. serrata to C. laxiflora on the low altitude and from Q. mongolica to C. controversa on the high altitude in the canopy layer. As a result of the analysis for the relationship between the stand scores of DCA and environmental variables. they had a tendancy to increase significantly from the P. densiflora community to C. laxiflora community that was soil moisture. the amount of soil humus and soil nutrients.

• Korean Journal of Environment and Ecology
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• v.14 no.1
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• pp.28-37
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• 2000

지리산국립공원의 아고산지대를 중심으로 분포하고 있는 한국특산종 구상나무의 생육현화과 구상나무림의 군집구조를 파악하여 앞으로의 구사나무림 관리의 기초자료를 마련하고자 구상나무가 생육하고 있는 지역에 42개의 방형구(20m$\times$20m)를 설치하여 식생을 조사하였다 분석한 결과 조사대상지는 세 개의 군집인 신갈나무-당단풍군집 구상나무-신갈나무군집 구상나무군집으로 분류되었다 수종간의 상관관계에서는 물들메나무와 함박꽃나무 함박꽃나무와 층층나무 구상나무와 잣나무 거제수나무와 노각나무 물들메나무와 말발도리 거제수나무와 물들메나무 거제수나무와 물갬나무 거제수나무와 함박꽃나무 철쭉과 회나무 주목과 미역줄나무 물갬나무와 노각나무, 잣나무와 마가목, 진달래와 명자순 명자순과 시닥나무, 가문비나무와 마가목 등의 수종들간에는 높은 정의 상관관계가 인정되었고 당단풍과 미역줄나무 등의 수종들간에는 높은 부의 상관관계가 인정되었다 본 조사지의 종다야도는 1.2389-1.2552으로 높게 나타났다 구상나무의 활력은 저조한 것으로 나타났으며 12.92%가 고사목이었다 생육현황표의 점수 평균은 13.88이었다.

• Journal of the Korean Society for information Management
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• v.29 no.2
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• pp.45-70
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• 2012

There have been many methods and algorithms proposed for multidimensional scaling to mapping the relationships between data objects into low dimensional space. But traditional techniques, such as PROXSCAL or ALSCAL, were found not effective for visualizing the proximities between objects and the structure of clusters of large data sets have more than 50 objects. The CLUSCAL(CLUster-oriented SCALing) technique introduced in this paper differs from them especially in that it uses cluster structure of input data set. The CLUSCAL procedure was tested and evaluated on two data sets, one is 50 authors co-citation data and the other is 85 words co-occurrence data. The results can be regarded as promising the usefulness of CLUSCAL method especially in identifying clusters on MDS maps.

• Proceedings of the Korean Society for Information Management Conference
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• 2013.08a
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• pp.23-26
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• 2013

지식기반사회와 정보홍수시대로 갈수록, 도서관의 존속여부에 대한 고민으로 도서관경영의 중요성은 심화되며, 관련 연구가 많이 이루어지고 있다. 이에 본 연구는 동시출현단어 분석을 통해 도서관경영 분야의 지적구조를 분석하였다. 데이터 수집은 2001~2013년도까지 한국연구재단에 등재된 5개의 문헌정보학 관련 학회지를 대상으로 하였으며, 해당 논문 수는 413건이다. 데이터 처리후 군집분석을 실시하여 9개의 군집을 형성하였으며, 해당 군집은 장서개발, 디지털도서관, 공공도서관, 마케팅 및 조직관리, 국립중앙도서관 및 작은도서관, 인사관리(직무/자격제도), 대학도서관, 학교도서관, 서비스 품질평가이다. 이러한 연구 결과는 기존의 도서관경영 분야의 주제영역과 비교하였다.

• Korean Journal of Environment and Ecology
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• v.5 no.1
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• pp.32-41
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• 1991

A survey of subalpine zone (altitude is 1,360-1,410m) in Mt. Chiri, was conducted using 25 sample plots of 500$m^2$ size. The classification by TWINSPAN and DCA ordination were applied to the study area in order to classify them into several groups based on woody plants and environmental variables. By TWINSPAN techniques, the plant community were divided into five groups by importance value of Abies nephrolepis. The dividing groups are Fraxinus rhynchophylla - Magnolia sieboldii community, Quercus mongolica - Rhododendron schlippenbachii community, Q. mongolica - F. rhynchophylla - Acer pseudo-sieboldianum community, Q. mongolica- A. nephrolepis- Rh. schlippenbachii community, and A. nephrolepis- Pinus densiflora - Rh. schlippenbachii community. The successional trends of tree species by both techniques seem to be from Q. mongolica to A. nephrolepis in the canopy layer. It was no difference between the stand scores of DCA and environmental variables.