• The Journal of Engineering Geology
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• v.3 no.1
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• pp.51-61
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• 1993

Restricted maximum likelihood(RML) method was used to determine the parameters of generalized covariance, and universal krigig with RML was applied to estimate a groundwater level distribution of nonstationarv random function. Universal kriging with RML was compared to IRF-k with weighted least squares method for the comparison of their accuracies. Cross validation shows that two methods have nearly the same ability for the estimation of groundwater levels. Scattergram of estimates versus true values and contour maps of groundwater levels have nearly the same results. The reason why two methods produced the same results is thought to be the non-Gaussian distribution and the snaall number of sample data.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10a
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• pp.511-515
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• 2006

집합이나 배열의 원소, 트리의 노드, 그래프의 정점과 간선 등과 같은 이산 객체는 일반적으로 주기억장치의 논리적 주소 값과 같은 정수로 표현되어 왔다. Succinct 표현은 이와 같은 n개의 이산 객체를 O(n) 비트에 표현하는 방법이다. 대부분의 succinct 표현은 rank와 select라는 함수를 기본적으로 사용하며, 다양한 연구들에 의해 현재 rank와 select 함수는 o(n)?? 비트만을 사용하여 ??O(1) 시간에 수행될 뿐만 아니라, 실제로도 실용적으로 구현되었다. 본 논문에서는 $n{\times}n$ 배열, 즉 2차원 비트 스트링에 대한 Rank 및 Select 함수를 새롭게 정의한다. 또한, $O(n^2log\;n)$ 비트를 사용하여 O(1) 시간에 Rank 질의를 수행하고 O(log n) 시간에 Select 질의를 수행하는 방법과, 보다 적은 $O(n^2)$ 비트를 사용하면서 O(log n) 시간에 Rank 질의를 수행하고 $O(log^2\;n)$ 시간에 Select 질의를 수행하는 방법을 제안한다. 본 논문에서 정의하는 2차원 배열 상의 Rank와 Select 함수는 이미 개발된 2차원 상의 써픽스 트리 등을 기반으로 향후 개발될 2차원 상의 압축된 인덱스 자료구조나 이미지 프로세싱 등에 유용하게 사용된다.

• Journal of the Korea Society for Simulation
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• v.32 no.1
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• pp.1-11
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• 2023

Smart factory environments and digital twin environments are established, and today's factories accumulate vast amounts of production data and are managed in real time as visualized results suitable for user convenience. Production simulation techniques are in the spotlight as a way to prevent delays in delivery and predict factory volatility in situations where production schedule planning becomes difficult due to the diversification of production products. With the development of the digital twin environment, new packages are developed and functions of existing packages are updated, making it difficult for users to make decisions on which packages to use to develop simulations. Therefore, in this study, the concept of Discrete Event Simulation (DES) performed based on discrete events is defined, and the characteristics of various simulation packages were compared and analyzed. To this end, studies that solved real problems using discrete event simulation software for 10 years were analyzed, and three types of software used by the majority were identified. In addition, each package was classified by simulation technique, type of industry, subject of simulation, country of use, etc., and analysis results on the characteristics and usage of DES software were provided. The results of this study provide a basis for selection to companies and users who have difficulty in selecting discrete event simulation package in the future, and it is judged that they will be used as basic data.

• Journal of Internet Computing and Services
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• v.1 no.1
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• pp.47-62
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• 2000

Geographic Information System(GIS) deal with data which can potentially be useful for a wida range of applications. However, the information needs of each application usually vary, specially in resolution, detail level, and representation style, as defined in the modeling phase of the geographic database design. To be able to deal with such diverse needs, the GIS must after features that allow multiple representations for each geographic entity of phenomenon. This paper addresses the problem of formal definition of the objects and their relationships on geographical information systems. The geographical data is divided in two main classes: geo-objects and geo-fields, which describe discrete and continuous representations of spatial reality. I will study the classes and the roles of relationships over geo-fields, geo-objects and nongeo-objects. Therefore, this paper will contribute the efficient design of geographical class hierarchy schema by means of formalizing attribute-domains of classes.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.339-339
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• 2022

본 연구는 최신 강우 자료를 사용하여 자료의 기간을 네 가지 경우로 나누어 기간별 확률강우량을 산정하고 각 기간에 따른 확률강우량의 변화 특성을 파악하고자 하였다. 2020년을 기준으로 시강우 자료 관측기간이 40년 이상이 되는 62개 국내 강우관측소를 연구 대상으로 선정하였으며, 지점별 강우자료의 분석 기간은 최근 10년, 20년, 30년, 40년의 경우로 나누어 분석하였다. 분석기간에 따른 확률강우량은 Gumbel 분포형에 확률가중모멘트법을 적용하여 산정하였고, 이를 연강수량과 함께 공간적으로 분포시킨 결과, 연강수량의 분포에서 나타나지 않는 변화들이 확률강우량의 분포에서 명확히 드러나는 것을 확인할 수 있었다. 또한, 지속기간의 시간이 증가되고 재현기간이 커질수록 경기 북부와 전라남북도 경계 및 영동지방의 확률강우량이 증가하는 경향을 보였고, 최근 40년과 비교하였을 경우, 최근 10년, 20년, 30년 확률강우량의 변화량 결과에서 전라남도 지역은 지속기간 길어질수록 변화 양상이 뚜렷하게 보였으며, 강원도 지역은 최근 10년, 20년 변화량이 상이하게 나타났다. 기간에 따라 확률강우량의 변화량이 크거나 작은 대표 지역들을 선정하여 기간별 확률강우량의 IDF 곡선을 도시하여 비교 및 분석하였다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.6
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• pp.1-17
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• 2001

Nowadays, spatiotemporal data models deal with objects which can be potentially useful for wide range applications in order to describe complex objects with spatial and/or temporal facilities. However, the information needed by each application usually varies, specially in the geographic information which depends on the kind of time oriented views, as defined in the modeling phase of the spatiotemporal geographic data design. To be able to deal with such diverse needs, geographic information systems must offer features that manipulate geometric, space-dependent(i.e, thematic), and spatial relationship positions with multiple time oriented views. This paper addresses problems of the formal definition of relationships among spatiotemporal objects and their properties on geographic information systems. The geographical data are divided in two main classes : geo-objects and geo-fields, which describe discrete and continuous representations of the spatial reality. I study semantics and syntax about the temporal changes of attributes and the relationship roles on geo-objects and non-geo-objects, This result will contribute on the design of object oriented spatiotemporal data model which is distinguishied from the recent geographic information system of the homogeneously anchored spatial objects

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.575-578
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• 2009

자연하천에 적용가능한 수치모형은 지형의 변화를 합리적으로 계산할 뿐 아니라, 하도의 초기상태가 마름상태이거나 혹은 계산과정 중에 마름상태가 나타나더라도 충분히 계산할 수 있을 만큼 안정적이어야 한다. 본 연구에서는 비정형 및 비구조적 격자를 사용하여 지형변화를 고려한 흐름해석의 정확성과 효율성을 높이기 위해 보존변수의 재구성을 수면경사법과 MUSCL 기법을 연계하였으며, 하상경사항은 발산정리를 이용하여 이산화 하였다. 개발 모형의 정확성, 적용성 그리고 보존특성 등을 검증하기 위하여 해석해가 존재하는 불규칙 하상이 존재하는 하도 및 실험자료가 존재하는 실험하도에서의 댐 및 제방 붕괴와 같은 다양한 조건의 흐름에 적용하였다. 그리고 자연하천에 대한 적용 및 검증을 위해 Malpasset 댐 붕괴 모의를 수행하여 계산결과를 관측자료와 비교하였다.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.353-360
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• 2015

Various statistical models have been proposed over the last decade for spatially correlated Gaussian outcomes. The spatial linear mixed model (SLMM), which incorporates a spatial effect as a random component to the linear model, is the one of the most widely used approaches in various application contexts. Employing link functions, SLMM can be naturally extended to spatial generalized linear mixed model for non-Gaussian outcomes (SGLMM). We review popular SGLMMs on non-Gaussian spatial outcomes and demonstrate their applications with available public data.

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.15-22
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• 2003

In general, the linear regression model has been used to estimate trip generation in the travel demand forecasting procedure. However, the model suffers from several methodological limitations. First, trips as a dependent variable with non-negative integer show discrete distribution but the model assumes that the dependent variable is continuously distributed between -$\infty$ and +$\infty$. Second, the model may produce negative estimates. Third, even if estimated trips are within the valid range, the model offers only forecasted trips without discrete probability distribution of them. To overcome these limitations, a poisson model with a assumption of equidispersion has frequently been used to analyze count data such as trip frequencies. However, if the variance of data is greater than the mean. the poisson model tends to underestimate errors, resulting in unreliable estimates. Using overdispersion test, this study proved that the poisson model is not appropriate and by using Vuong test, zero inflated negative binomial model is optimal. Model reliability was checked by likelihood test and the accuracy of model by Theil inequality coefficient as well. Finally, marginal effect of the change of socio-demographic characteristics of households on trips was analyzed.

• Journal of Korea Water Resources Association
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• v.31 no.3
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• pp.347-360
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• 1998

Numerical simulations for fluid flow and solute transport in a fracture rock masses are performed by using a transient flow model, which is based on the three-dimensional stochastic and discrete fracture network model (DFN model) and is coupled hydraulic model with mechanical model. In the numerical simulations of the solute transport, we used to the particle following algorithm which is similar to an advective biased random walk. The purpose of this study is to predict the response of the tracer test between two deep bore holes (GPK1 and GPK2) implanted at Soultz sous Foret in France, in the context of the geothermal researches.l The data sets used are obtained from in situcirculating experiments during 1995. As the result of the transport simulation, the mean transit time for the non reactive particles is about 5 days between two bore holes.