• Proceedings of the Technology Innovation Conference
• /
• 2005.06a
• /
• pp.69-91
• /
• 2005

나노 기술은 국가와 기업 차원에서 전략적으로 활발하게 연구, 개발되고 있는 분야로 기술과 산업 전 분야에 걸쳐 있으며 계속 확대되고 있다. 이중 탄소나노튜브는 약 10년여 전부터 활발히 연구되고 있으며, 소재, 소자 등 나노 기술의 전 분야에 걸쳐서 적용될 수 있는 물질로 현재까지 실용화된 기술이나 제품이 많이 나오지는 않았으나 앞으로 다양한 적용분야가 창출될 전망이다. 그러나 전략적인 기술 개발을 위한 연구는 미비한 실정이다. 전략적이고 효과적인 기술 개발의 대안으로 특허 분석(patent analysis)이 제시되고 있으며 나노 기술에 대한 전반적인 특허 분석은 각 기업 연구소나 국가 연구소에서 진행되어 왔으나, 여기서 도출된 정보만으로는 전략적인 문제들을 분석하기에는 미흡하였다. 따라서 전략적인 기술 개발을 위한 특허 분석의 필요성이 제기되고 있다. 이에 본 연구에서는 특허의 인용(citation) 정보를 이용하여 특허와 특허 사이의 관계를 분석하고 이를 바탕으로 관련된 특허를 군집화(clustering) 하여 각 군집의 특성을 살펴보았다. 먼저 탄소나노튜브에 관한 특허를 USPTO 자료를 통해 추출하고, 이 특허들이 인용한 특허들을 추출하여 각 특허들이 어느 정도로 관련이 되어 있는가를 상관 행렬(correlation matrix)을 이용하여 조사하였다. 인용 특허의 분석은 기초 기술 분야에 이르기까지 광범위하게 조사하여 기술별로 특허를 군집화 하였을 뿐만 아니라, 특허 출원인 정보도 활용하여 군집화 하였다. 이를 통하여 기술별, 특허 출원인 별로 특허의 군집을 만들어서 각 군집의 특성을 도출하였고, 마지막으로 각 군집의 특성에 맞게 기술 개발측면에서 전략적인 시사점을 도출하였다. 각각의 군집들은 시간이 지날수록 확대, 통합되는 결과를 보이고 있으며, 융합기술화 되고 있다. 군집을 이루는 주요한 특성으로는 출원인 정보가 큰 비중을 차지하였으며, 이는 출원인의 기술 개발 전략과 이에 따른 기술개발경로나 특허 전략과 관련이 있는 것으로 나타났다. 다양한 기술에 관하여 군집의 크기가 계속 확대되고 있는 경향을 보이고 있기 때문에, 앞으로 지속적인 연구를 통하여 향후 특허 관리와 특허 전략에 적용할 수 있도록 하는 것이 중요하다.

• Ecology and Resilient Infrastructure
• /
• v.2 no.1
• /
• pp.22-32
• /
• 2015

This study investigated the difference in fish community structures in a main channel and an isolated former channel, considering the environmental factors in the Mangyeong River, Korea. Principal component analysis (PCA) with environmental factors showed that former channels were composed of a fine substrate covered by in-stream vegetation, whereas the main channel was covered by a wide range of substrates with a higher dissolved oxygen and conductivity. The result of the hierarchical cluster analysis with species abundance delineated to the four main groups; three abandoned channel groups and one main channel group. Non-metric multidimensional scaling (NMDS) showed that fish community structures of each study site differed from environmental factors: former channel fish communities were positively related to in-stream vegetation cover, whereas main channel fish communities were positively associated with dissolved oxygen and conductivity. The results indicated that channelization, where there was a separation between the former channel and the main channel, had detrimental effects on fish community structures of both the main channel and the abandoned channel in the Mangyeong River. In conclusion, this study suggested that the connectivity between the main channel and abandoned channel were required to enhance both habitat structural diversity and species diversity of the Mangyeong River.

• Journal of Digital Convergence
• /
• v.14 no.4
• /
• pp.459-469
• /
• 2016

The purpose of this study is to classify the subtypes of perpetrators of school violence based on their psychological characteristics. In order to classify the students, questionnaires/interviews which consist of 6 factors (Cognitive Impulsivity, Unplanned Impulsivity, Depression, Anxiety, Peer Conformity, and Self assertion) and 19 questions were administered to 86 perpetrators of school violence. Then, a two-step cluster analysis was performed with the survey results of 74 perpetrators. As a result, three clusters were identified and named as follows: 1) Impulsive Vulnerability, 2) Emotional Vulnerability, and 3) Social Vulnerability. Scrutinizing the detailed characteristics of each cluster, the first cluster, Impulsive Vulnerability, showed higher scores on Cognitive Impulsivity and Unplanned Impulsivity, compared to the other two clusters, while Depression and Anxiety scores were lower. The second cluster, Emotional Vulnerability, showed higher scores on Depression and Anxiety, while Cognitive Impulsivity and Unplanned Impulsivity scores were lower. The third cluster, Social Vulnerability, showed the highest score on Peer Conformity among the three clusters. However, Self assertion scores were the lowest in this cluster, and Cognitive Impulsivity, Unplanned Impulsivity, depression, and anxiety scores were lower than in the others. This study will provide a useful insight for facilitating teachers and parents' understanding of the psychological characteristics of school violence perpetrators and thereby contributing to effective intervention.

• Journal of KIISE:Software and Applications
• /
• v.32 no.7
• /
• pp.581-591
• /
• 2005

Collaborative filtering systems have problems involving sparsity and the provision of recommendations by making correlations between only two users' preferences. These systems recommend items based only on the preferences without taking in to account the contents of the items. As a result, the accuracy of recommendations depends on the data from user-rated items. When users rate items, it can be expected that not all users ran do so earnestly. This brings down the accuracy of recommendations. This paper proposes a collaborative recommendation method for extracting typical group preferences using user-item matrix optimization and user profiles in collaborative tittering systems. The method excludes unproven users by using entropy based on data from user-rated items and groups users into clusters after generating user profiles, and then extracts typical group preferences. The proposed method generates collaborative user profiles by using association word mining to reflect contents as well as preferences of items and groups users into clusters based on the profiles by using the vector space model and the K-means algorithm. To compensate for the shortcoming of providing recommendations using correlations between only two user preferences, the proposed method extracts typical preferences of groups using the entropy theory The typical preferences are extracted by combining user entropies with item preferences. The recommender system using typical group preferences solves the problem caused by recommendations based on preferences rated incorrectly by users and reduces time for retrieving the most similar users in groups.

• Korean Journal of Environmental Biology
• /
• v.29 no.3
• /
• pp.212-224
• /
• 2011

The Yeongsan River estuary, located in the south west coast, was a typical estuary before a dike was constructed in December 1981. After the construction, the water quality and plankton communities are expected to change. We investigated the change of phytoplankton community and environmental properties in the Yeongsan River estuary by comparing the data collected recently with the results reported before and/or shortly after the construction. Concentrations of $NH_4$-N were significantly increased in the freshwater zone. Concentrations of DO at the surface, $NO_2+NO_3$ and $NH_4$-N were increased while the concentrations of $PO_4$ at the surface were decreased in the seawater zone. The number of green algae species was decreased in the freshwater zone. The number of diatom species was decreased while the numbers of green algae and dinoflagellates were increased in the seawater zone. This study can provide information for better management of the Yeongsan River estuary since no comparison study has been documented between the phytoplankton community before and after the construction of the dike in the estuary.

• Journal of Korean Society of Forest Science
• /
• v.105 no.1
• /
• pp.122-131
• /
• 2016

This study was conducted to analyze the effect of climatic variables on tree-ring growth of Larix leptolepis distributed in Korea by dendroclimatological method. For this, annual tree-ring growth data of Larix leptolepis collected by the $5^{th}$ National Forest Inventory were first organized to analyze yearly growth patterns of the species. To explain the relationship between tree-ring growth of Larix leptolepis and climatic variables, monthly temperature and precipitation data from 1950 to 2010 were compared with tree-ring growth data for each county. When tree-ring growth data were analyzed through cluster analysis based on similarity of climatic conditions, six clusters were identified. In addition, index chronology of Larix leptolepis for each cluster was produced through cross-dating and standardization procedures. The adequacy of index chronologies was tested using basic statistics such as mean sensitivity, auto correlation, signal to noise ratio, and expressed population signal of annual tree-ring growth. Response function analysis was finally conducted to reveal the relationship between tree-ring growth and climatic variables for each cluster. The results of this study are expected to provide valuable information necessary for estimating local growth characteristics of Larix leptolepis and for predicting changes in tree growth patterns caused by climate change.

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

• The Journal of Bigdata
• /
• v.5 no.2
• /
• pp.135-143
• /
• 2020

This paper proposes a pre-processing method and a dimensional reduction method in the analysis of shopping carts where there are many correlations between variables when dividing the types of consumers in the agri-food consumer panel data. Cluster analysis is a widely used method for dividing observational objects into several clusters in multivariate data. However, cluster analysis through dimensional reduction may be more effective when several variables are related. In this paper, the food consumption data surveyed of 1,987 households was clustered using the K-means method, and 17 variables were re-selected to divide it into the clusters. Principal component analysis and factor analysis were compared as the solution for multicollinearity problems and as the way to reduce dimensions for clustering. In this study, both principal component analysis and factor analysis reduced the dataset into two dimensions. Although the principal component analysis divided the dataset into three clusters, it did not seem that the difference among the characteristics of the cluster appeared well. However, the characteristics of the clusters in the consumption pattern were well distinguished under the factor analysis method.

• The Korean Journal of Applied Statistics
• /
• v.28 no.6
• /
• pp.1209-1216
• /
• 2015

Competing-risks events are often observed in a clustered clinical study such as a multi-center clinical trial. We propose a joint modelling approach via a shared frailty term for competing risks survival data from a cluster. For the inference we use the hierarchical likelihood (or h-likelihood), which avoids an intractable integration. We derive the corresponding h-likelihood procedure. The proposed method is illustrated via the analysis of a practical data set.

• Journal of Soil and Groundwater Environment
• /
• v.7 no.3
• /
• pp.19-32
• /
• 2002

This study is objected to identify the relations between surface- and shallow ground-water and the seasonal variation of their qualities in watersheds near Muju area. The water type shows mainly Ca-$HCO_3$type. Heavy-metal contamination of surface water is locally detected, due to the mixing with mine drainage. In October nitrate concentration is especially high in densely populated area. Cluster Analysis and Principal Component Analysis are implemented to interpret the complexity of the chemical variation of surface- and ground-water with large amount of chemical data. Based on the cluster analysis, surface-water was divided into five groups and ground-water into three groups. Principal Component Analysis efficiently supports the result of cluster analysis, allowing the identification of three main factors controlling the water quality. There are (1) hydrogeochemical factor, (2) anthropogenic factor and (3) heavy metal contaminated by mine drainage.