• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.154-159
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• 2006

본 논문은 웹 서버에 의해 자동으로 수집되는 로그 파일로부터 고객 가치 판단 기준을 고객의 행동 기반에 두고 군집화 기법을 이용하여 고객을 세분화하고 세분화 결과에 의사결정나무를 적용함으로써 고객을 분류하는 통합 모형을 제안하였다. 또한, 분류된 고객들의 주 서비스 활용 패턴을 분석하기 위하여 연관규칙기법을 적용하여 고객의 과학기술정보 활용의 연관성을 분석함으로써, 과학정보포털 서비스를 제공하는 사이트 이용자의 분류군에 해당하는 정보와 인터페이스를 제공하는 새로운 방법에 대하여 연구하였다. 고객 관리 측면에서 본 논문은 정보 서비스를 제공하는 웹 사이트의 기존고객을 분류하여 패턴을 분석함으로써 고객 위주의 사이트 운영정책과 동적 인터페이스를 제공하기 위한 웹사이트 활용 방안을 제시하였다. 또한, 고객의 지속적인 관리라 각 고객 분류군별에 안는 서비스를 제공하고 고객의 관리에도 기여할 수 있을 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.111-111
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• 2020

하천환경과 기후의 변화로 인해 수질오염 과정의 메커니즘이 더욱 복잡해짐에 따라 다양한 요인을 고려한 불확실성 평가 연구가 요구되고 있다. 하천 수질 중에서도 부영양화 문제는 특히 개발로 인한 하천환경 변화 이후 사회 정치적 논점이 되어왔다. 본 연구에서는 지난 7년 동안의 수질 변화의 전반적인 양상을 조사하였으며, 클로로필-a(Chl-a, chlorophyll-a) 농도의 시공간적 의존성의 효과적으로 고려하기 위해 기계학습 기반 분류(classification) 접근법인 다변량 은닉 마코프 모형(MHMM, multivariate hidden Markov model)을 사용하였다. 월 단위 수질 및 수문 자료를 사용하여 Chl-a의 변동성을 군집화하여 수질 상태의 익월 천이확률을 효과적으로 추정하였다. Chl-a와 수질 및 수문기상 조건의 관계를 평가하였으며, 결과적으로 수질 상태의 시공간적 전이가 정확하게 식별되었고 이의 잠재적 원인에 대하여 논의하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.435-435
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• 2023

최근 기후변화의 영향으로 상대적으로 좁은 국가면적이라 할 수 있는 국내에서도 가뭄과 홍수가 지역적으로 동시에 발생하는 등 자연재해에 의한 피해가 빈번해지고 있다. 이 중 가뭄은 타 풍수해에 비하여 일반적으로 장기간의 무강우에 의해 발현되고, 피해가 발생할 경우 생활용수, 농업용수, 공업용수 등 다양한 지역의 용수사용특성에 따라 피해가 집중 및 가중되는 특징을 지닌다. 본 연구에서는 지역별 가뭄피해도에 영향을 주는 영향인자의 민감도 분석을 실시하고 그 결과를 분석하였다. "가뭄 피해도"는 용수별 직간접 피해의 정도를 점수 또는 등급 등의 정량적으로 나타낸 것으로 정의된다. 우선, 국가가뭄정보통계집(2018-2020)에서 제시된 지역별 가뭄피해정보자료와 용수사용특성을 기반으로 군집분석을 실시한 문기훈(2022)의 연구모형을 기반으로 최근 발행된 2021년의 피해정보를 추가적으로 반영하여 군집분석을 실시하였다. 그리고 지역별 가뭄피해도 군집등급에 영향을 주는 과거 피해인자와 용수사용특성을 함수화하고, 지역별 불확실성을 반영한 민감도 분석을 실시하였다. 분석 결과 지역별 과거의 가뭄피해경험여부 및 용수사용특성의 변동에 따라 지역적 가뭄피해도 군집등급이 달라짐을 확인할 수 있었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.439-449
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• 2016

The methodology of synthetic unit hydrograph using geomorphic characteristics was suggested. Six geomorphic components over 19 watersheds were used to estimate synthetic unit hydrograph and the test watersheds were classified into two groups on the basis of the area of $200km^2$. The regression formulas between standardized geomorphic characteristics for each group and peak quantities of specific streamflow and time of representative unit hydrograph were suggested and the Nash and the Clark unit hydrographs were derived. For verifying the derived unit hydrographs, the resulting hydrographs were compared with the ones using the existing Clark unit hydrographs based on the empirical parameter estimation for the 145 storm events during 2010 to 2011 for the additional six watersheds. The results showed the relatively higher performance over the existing synthetic unit hydrograph methods, which could be a contribution to the hydrologic estimation in ungauged watersheds.

• Industry Promotion Research
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• v.9 no.2
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• pp.45-58
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• 2024

This study modelled the social network structure characteristics between Innopolis Start-ups located in Daejeon and Innopolis Start-ups' customers scattered across the country as a tendency of regional clustering among homogeneous technologies, and the observed values were included within the 95% confidence interval of the ERGM(Exponential Random Graph Model) analysis model. If both the research institute and the customer company are located in Yuseong-gu, Daejeon, the probability of being connected is about 13 times higher than if they are located in other administrative districts, and there is a strong tendency of connection between firms with the same technology with a negative value of assortment and homogeneity (0.1904), especially among the six technology sectors, with a P value of 0.035. There was a negative value (-0.0035) among firms not located in Yuseong-gu, with less clustering tendency. This confirms that Yuseong-gu, Daejeon, where the Daedeok Innopolis is located, is forming the centre of an innovation cluster.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.263-272
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• 2016

Modular product design has contributed to flexible product modification and development, production lead time reduction, and increasing product diversity. Modular product design aims to develop a product architecture that is composed of detachable modules. These modules are constructed by maximizing the similarity of components based on physical and functional interaction analysis among components. Accordingly, a systematic procedure for clustering the components, which is a main activity in modular product design, is proposed in this paper. The first phase in this procedure is to build a component-to-component correlation matrix by analyzing physical and functional interaction relations among the components. In the second phase, network flow modeling is applied to find clusters of components, maximizing their correlations. In the last phase, a network flow model formulated with linear programming is solved to find the clusters and to make them modular. Finally, the proposed procedure in this research and its application are illustrated with an example of modularization for a vacuum cleaner.

• Journal of Environmental Impact Assessment
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• v.28 no.4
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• pp.413-426
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• 2019

Many factories indiscriminately located in the vicinity of residential areas need to be adjusted to quasi-industrial parks or new planning management area. In the present work, the changes of atmospheric $SO_2$ concentration according to clustering of individual location factories throughout Gimpo city into a new area were evaluated using a commercial dispersion model, AERMOD. As a result of the evaluation, it was suggested the possibility of improving the pollution through the relocation of individual factories. The combination of relocation and discharge regulation on the stack height may reduce the overall pollution from Gimpo approximately up to 70%, and some areas achieve maximum 87% decrease. However, the area selected as a cluster zone may show a relatively large increase compared to the change in the total pollution level of Gimpo.

• The Korean Journal of Applied Statistics
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• v.29 no.5
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• pp.949-960
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• 2016

This paper uses all sections of highway data (VDS) for two years (Jan. 2014-Dec. 2015), with 15 minute units. The first purpose of this study is to find clusters with similar patterns that appear repeatedly with time variables of month, week and hour. The cluster analysis results indicate a variety of patterns of average traffic speeds by time variables depending on the clusters; subsequently, these can be utilized to model for the forecast of the speed at a specific time. The second purpose is to do cluster analysis for grouping sections by effect nets that are closely related to each other. For the similarity measure we use cross-correlation functions calculated after pre-whitening the speed of each section. The cluster analysis gets 19 clusters, and sections within a cluster are geographically close. These results are expected to help to forecast a real-time speed.

• Journal of Wetlands Research
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• v.21 no.4
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• pp.281-289
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• 2019

In this study, the typhoon damage forecasting model was developed for southern inland district. The typhoon damage in the inland district is caused by heavy rain and strong winds, variables are many and varied, but the damage data of the inland district are not enough to develop the model. The hydrological data related to the typhoon damage were hour maximum rainfall amount which is accumulated 3 hour interval, the total rainfall amount, the 1-5 day anticipated rainfall amount, the maximum wind speed and the typhoon center pressure at latitude 33° near the Jeju island. The Multivariate Analysis such as cluster Analysis considering the lack of damage data and principal component analysis removing multi-collinearity of rainfall data are adopted for the damage forecasting model. As a result of applying the developed model, typhoon damage estimated and observed values were up to 2.2 times. this is caused it is difficult to estimate the damage caused by strong winds and it is assumed that the local rainfall characteristics are not considered properly measured by 69 ASOS.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.773-784
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• 2014

This study evaluated the applicability of the Modified Bartlett-Lewis Rectangular Pulse (MBLRP) rainfall generation model for modeling extreme rainfalls and floods in Korean Peninsula. Firstly, using the ISPSO (Isolated Species Particle Swarm Optimization) method, the parameters of the MBLRP model were estimated at the 61 ASOS (Automatic Surface Observation System) rain gauges located across Korean Peninsula. Then, the synthetic rainfall time series with the length of 100 years were generated using the MBLRP model for each of the rain gauges. Finally, design rainfalls and design floods with various recurrence intervals were estimated based on the generated synthetic rainfall time series, which were compared to the values based on the observed rainfall time series. The results of the comparison indicate that the design rainfalls based on the synthetic rainfall time series were smaller than the ones based on the observation by 20% to 42%. The amount of underestimation increased with the increase of return period. In case of the design floods, the degree of underestimation was 31% to 50%, which increases along with the return period of flood and the curve number of basin.