• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1587-1590
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• 2012

인터넷의 활용이 보편화 됨에 따라 정보의 양은 급격히 늘어나고 있다. 이에 취업을 희망하는 구직자의 경우 IR 로부터 원하는 정보를 검색하기 위해 과거보다 더 많은 시간과 노력이 필요하게 되었다. 이에 본 논문에서는 TF(Term Frequency)기법을 통해 문서를 추출하고 추출된 문서의 Doc_ID 빈도수를 기준으로 한 내용기반과 군집기법을 혼합한 하이브리드 검색 시스템을 제안한다. 구직자들이 클릭한 취업정보들의 링크번호들을 K-means 알고리즘을 이용하여 군집화를 한다. 생성된 군집들은 각기 하나의 문서로 가정하고, 기존 문서과 더불어 검색 주제와 연관성을 갖고 있는 문서들을 동적비율로 검색 랭킹 하는 방식이다. 기존의 IR 기술과의 비교 실험을 통해 성능을 평가하였다. 실험결과 본 논문에서 제안한 방법이 기존의 방법보다 우수함을 확인할 수 있었다

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.290-293
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• 2009

바이오 칩 분석 시스템은 유전자와 실험의 두 축으로 이루어진 바이오 칩에서 자료를 추출하고 필요한 정보를 얻기 위해 데이터를 분석하는 시스템이다. 유전자 데이터를 효율적으로 분석할 수 있는 방법으로 바이오 칩 분석 시스템이 각광받으면서 데이터의 양과 종류가 방대해지고 메모리의 효율적인 사용과 이에 따른 속도 개선을 위해 임베디드 시스템이 필요해지고 있다. 이에 따라 본 연구에서는 임베디드 시스템을 위한 PSO 기반의 군집화 알고리즘을 구현하였다. 방대한 양의 유전자 데이터를 분석하기 위해 생태계 모방 알고리즘인 Particle Swarm Optimization 알고리즘과 비슷한 유전자의 분류를 위한 기법으로 군집화를 사용하여 유전자 데이터의 통합 분석 시스템을 구현, 사용자에게 더욱 효율적으로 정보를 제공한다. 본 논문에서는 방대한 양의 데이터의 최적화에 효율적인 생태계 모방 알고리즘 Particle Swarm Optimization 을 이용하여 데이터들을 군집화하는 알고리즘을 임베디드 시스템을 위해 구현한 방법을 기술하고 있다.

• The KIPS Transactions:PartB
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• v.13B no.3 s.106
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• pp.337-344
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• 2006

In this paper, we describe the design and the implementation of word clustering system using a definition of an entry word in the dictionary, called a dictionary definition. Generally word clustering needs various features like words and the performance of a system for the word clustering depends on using some kinds of features. Dictionary definition describes the meaning of an entry in detail, but words in the dictionary definition are implicative or abstractive, and then its length is not long. The word clustering using only features extracted from the dictionary definition results in a lots of small-size clusters. In order to make large-size clusters and improve the performance, we need to transform the features into more general words with keeping the original meaning of the dictionary definition as intact as possible. In this paper, we propose two methods for extending the dictionary definition using ontology. One is to extend the dictionary definition to parent words on the ontology and the other is to extend the dictionary definition to some words in fixed depth from the root of the ontology. Through our experiments, we have observed that the proposed systems outperform that without extending features, and the latter's extending method overtakes the former's extending method in performance. We have also observed that verbs are very useful in extending features in the case of word clustering.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.595-603
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• 2018

This study was conducted to understand the growth of attached microbial community in small and medium streams of Gyeonggi-do and the removal efficiency of fluoride with changes in growth. The sites monitoring were carried out for 12 weeks at the P1 and P2(P1 is the point where the discharge water flows. P2 is the downstream point of about 2 km flow), and investigated the water quality and the biomass analysis of the attached microbial community. The growth of the attached microbial community increased up to the 7th investigation, and it was observed that detachment phenomenon occurred. Influencing factors about growth of the attached microbial community were flow rate, velocity, and organic material(T-N & T-P). Meanwhile, fluoride content of attached microbial community also tended to increase until the 7th investigation, and decrease from the 8th. It is assumed that fluoride content has also be reduced with the detachment phenomenon of the attached microbial community. It is expected that this will contribute to the evaluation and management of the use of attached microbial community as a means of stream management. The application of techniques using the attached microbial community should include basic investigation of factors that may affect the growth of the attached microbial community and replacement of the attachment plate according to the time of removal.

• Journal of Korean Society of Forest Science
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• v.81 no.4
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• pp.310-319
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• 1992

Vegetational data obtained from 24 quadrats of Mt. Paekdu area were analysed by applying two multivariate methods : two-way indicator species analysis(TWIMSPAN) for classification and detrended canonical correspondence analysis(DCCA) for ordination. DCCA technique allowed to extract the ordination axes that could be related to 9 environmental factors. The dominant tree species distributed in the region between 1,700-1,950m from sea level were Betula ermanii, Larix olgensis, Abies nephrolepis, and Picea jezoensis in descending order. The dominant tree species distributed in the region between 1.300-1.500m were Abies nephrolepis, Pinus koraiensis, Larix olgensis, Betula mandshurica, and Picea jezoensis in descending order. The available phosphorus content in forest soil ranged from 7 to 1.153ppm. The distribution of the major communities showed a close relationship with elevation gradient. From high to low elevation, the communities of Alnus fruticosa var. mandshurica, Betula ermanii, Larix olgensis, Abies nephrolepis, Picea jezoensis, Pinus koraiensis, and Quercus mongolica were found in descending order. At the communities where Betula ermanii was dominant, Betula ermanii forest was distributed in the high elevation area, Betula ermanii-Larix olgensis forest in the good nutrition of organic matter and $K^+$, and Abies nephrolepis forest in the good nutrition of $Mg^{{+}{+}}$ and $Ca^{{+}{+}}$. The most dominant factor influencing community distribution was elevation.

• The KIPS Transactions:PartB
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• v.14B no.7
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• pp.513-522
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• 2007

Clustering is to divide given data and automatically find out the hidden meanings in the data. It analyzes data, which are difficult for people to check in detail, and then, makes several clusters consisting of data with similar characteristics. On-Line Document Clustering System, which makes a group of similar documents by use of results of the search engine, is aimed to increase the convenience of information retrieval area. Document clustering is automatically done without human interference, and the number of clusters, which affect the result of clustering, should be decided automatically too. Also, the one of the characteristics of an on-line system is guarantying fast response time. This paper proposed a method of determining the number of clusters automatically by geometrical information. The proposed method composed of two stages. In the first stage, centers of clusters are projected on the low-dimensional plane, and in the second stage, clusters are combined by use of distance of centers of clusters in the low-dimensional plane. As a result of experimenting this method with real data, it was found that clustering performance became better and the response time is suitable to on-line circumstance.

• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.446-455
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• 2004

The ichthyofauna and community structure in Hongcheon river, Korea, was investigated from April to October 2002. During the surveyed period, 52 species belonging 11 families were collected. There were 23 Korean endemic species (44.23%), including Rhodeus uyekii, Acheilognathus signifer, A. yamatsutae, Coreoleuciscus splendidus, Koreocobitis rotundicaudata and Silurus microdorsalis. Dominant species were Zacco platypus (20.38%), and subdominant species were Z. temmincki (19.62%). Also, Rhynchocypris oxycephalus (8.45%), Pungtungia herzi (8.01%), C. splendidus (6.63%) were numerous. Of the 6 introduced fishes in Hongcheon river Carassius cuvieri, Lepomis macrochirus and Micropterus salmoides were originated from foreign countries but Anguilla japonica, Gymnogobius urotaenia, Rhinogobius giurinus were introduced from other native river systems. According to the fish distribution, the fish community of Hongcheon river was divided into 4 groups by principle component analysis (PCA).

• Korean Journal of Environment and Ecology
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• v.27 no.4
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• pp.487-497
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• 2013

This study was conducted to suggest vegetation management plan for Gugok landscape maintenance and improvement by deducing the vegetation landscape factors inherent in Yongha Gugok and understanding vegetation structure through the investigate of existing vegetation and plant community structure of Yongha valley in Woraksan National Park. There were broad and flat rocks, natural layered stones, clear water, light stones, stream, valleys, waterfalls, Pinus densiflora and Acer pseudosieboldianum as a result of deducing natural factors on poetry. There were P. densiflora and A. pseudosieboldianum appeared as one of main vegetation landscape elements. The actual vegetation analysis results were as followed. The natural vegetation occupied 67.5% and it was classified as P. densiflora community, Quercus variabilis community, Q. variabilis-P. densiflora community, Q. variabilis-Q. serrata community, Q. serrata community, Q. mongolica community, Q. mongolica-P. densiflora community, Deciduous broad-leaved tree community. The artificial vegetation(18.7%) was classified as Q. serrata community-Larix kaempferi community, Q. mongolica- Castanea crenata community, L. kaempferi community, L. kaempferi-C. crenata community, fruticeta, L. kaempferi-Q. mongolica community. The grassland area(2.0%) was classified as Miscanthus sinensis community, Phragmites communis community, and other areas were classified as landscape tree planting area, farm, orchard, residential area. The representative vegetation were P. densiflora community, Q. variabilis-Q. serrata community, L. kaempferi community, Deciduous broad-leaved tree community in Yongha Gugok. The species diversity index of Shannon was 0.6274~0.9908 on the whole. Yongha Gugok, as a symbol of succession on confucianism and reverence for nature, should be preserved natural valley landscape being clean and wijungchuksa at the end of Joseon Dynasty and Japanese Colonial era. In this historical and cultural Gugok, vegetation landscape management plan is needed to landscape maintenance with P. densiflora community, density control with L. kaempferi community. And it is considered when natural disasters and artificial damages happened, P. densiflora-oriented vegetation restoration plan should be applied in order to restore.

• Korean Journal of Environment and Ecology
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• v.26 no.4
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• pp.593-603
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• 2012

This study was carried out to investigate the ecological succession sere and conservative value, and to provide the basic data for the planning of the Provincial Park Management in Seonamsagol(Valley), Jogyesan(Mt.) Provincial Park(altitude 884m), Suncheon City, Korea by analysing the structure of the plant community. Twenty plots(size is $20m{\times}20m$) were set up at an altitude of range from 315m to 480m. As a result of analysis of TWINSPAN which is one of the ordination technique, the plant communities were divided into four groups which are community I(Quercus variabilis community), community II(Q. serrata community), community III(Decideous broad-leaved plant community), and community IV(Carpinus tschonoskii community). The warmth index is $104^{\circ}C{\cdot}month$ based on the data of monthly mean temperature during the past thirty years(1981~2010), so we found out that the vegetation of the study site located in the South Temperate Climate Zone. We supposed that the ecological succession sere of the study site is in the early stage of developing from Q. serrata community to Carpinus tshonoskii community, however we should do a long-term monitoring to investigate the changes of the ecological succession each plant community, meanwhile Sasa borealis was dominant species in the shrub layer. The diameter at breast height of specimen tree is range from 20 to 55cm(average 36cm) and the height of that is range from 14 to 35m(average 23cm). The age of community I was 64 years old, that of community II was from 59 to 64 years old, that of community III was from 51 to 62 years old, and that of community IV was from 41 to 68 years old, thus the age of the study site is about from 38 to 72 years old. According to the index of Shnnon's diversity(unit: $400m^2$), community IV was ranged from 0.8452 to 1.2312, community III was ranged from 0.8044 to 1.1404, community II was ranged from 0.8221 to 0.9971, and community I was 0.8324.

• Korean Journal of Environment and Ecology
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• v.23 no.2
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• pp.208-219
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• 2009

This study is to establish a management method for conservation through comparison and analysis on vegetation structures of Pinus densiflora forest around Beopjusa area for past 17-year. The spatial range of the study was $3.6km^2$ from maintenance office to Beopjusa area. The analysis results of the actual vegetation showed that the ratio of vegetation were composed of 64.7% of Pinus densiflora forest, 3.2% of mixed forest of P. densiflora and deciduous broadleaf trees and 5.9% of deciduous broadleaf tree community out of overall area, 360ha. The type of P. densiflora forest were categorized into four communities; community having high potential of succession, community having low potential of it, the community being in the process of succession and community being in the process of natural selection. The succession tendency was in order of the community having low potential of succession(P. densiflora forest), having high potential of it(P. densiflora forest which is deciduous broadleaf trees are dominating in sub-canopy layer), being in the process of succession(P. densiflora-Prunus sargentii and P. densiflora-Quercus serrata community) and being in the process of natural selection(Q. serrata-P. densiflora and Q. aliena-P. densiflora community). In terms of vegetation management, P. densiflora forest having high potential of succession was needed to remove deciduous broadleaf trees in the sub-canopy layer and the community being in the process of succession was required to be pruning the branch in the canopy layer. Lastly, the community being in the process of natural selection was suggested to let it be in succession, since it is hard to be in the status of P. densiflora Forest.