• 한국재난정보학회 논문집
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• 제14권2호
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• pp.182-193
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• 2018

연구목적: 연구의 목적은 통행행태와 도시공간특성관계를 위계적으로 분석하는데 있다. 연구방법: 본 연구는 2010년 우리나라 83개 도시에 대한 통행행태와 도시공간특성과의 관계를 위계선형모형으로 분석하였다. 연구결과: 도시속성이 교통수단선택과 통행시간에 개인속성과 더불어 영향을 미치는 것으로 나타났다. 그러나 도시속성을 변화시키는 정책을 통해서 수단선택과 소요시간에 영향을 미치는 정도가 비교적 낮은 것으로 나타나 교통을 위해서 토지이용정책을 동원하는 정책효과는 이론적으로 있으나 그 규모에 대해서는 기대보다는 크지 않다. 결론: 고밀개발 또는 도시규모가 클수록 대중교통체계가 많이 공급되어 이용을 많이 하지만 승용차에 비해 시간이 많이 소요되는 단점을 극복하지 못하고 있다.

• 한국공간구조학회논문집
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• 제22권3호
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• pp.25-32
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• 2022

In this paper, the instability of the domed spatial truss structure using wood and the characteristics of the buckling critical load were studied. Hexagonal space truss was adopted as the model to be analyzed, and two boundary conditions were considered. In the first case, the deformation of the inclined member is only considered, and in the second case, the deformation of the horizontal member is also considered. The materials of the model adopted in this paper are steel and timbers, and the considered timbers are spruce, pine, and larch. Here, the inelastic properties of the material are not considered. The instability of the target structure was observed through non-linear incremental analysis, and the buckling critical load was calculated through the singularities and eigenvalues of the tangential stiffness matrix at each incremental step. From the analysis results, in the example of the boundary condition considering only the inclined member, the critical buckling load was lower when using timber than when using steel, and the critical buckling load was determined according to the modulus of elasticity of timber. In the case of boundary conditions considering the effect of the horizontal member, using a mixture of steel and timber case had a lower buckling critical load than the steel case. But, the result showed that it was more effective in structural stability than only timber was used.

• Spatial Information Research
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• 제5권2호
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• pp.177-183
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• 1997

토지이용 분류 체계상에서의 종류라는 개념은 토지이용 변화의 분류 체계성에 그대로 적용시킬 수가 있다. 본 연구에서는 선형 판별 함수를 원용하는 최우법(Maximum likelihood method)으로 산출되는 토지이용분류의 공간적 결과와 Markov 전이 행렬 방법으로 산출되는 정량적 결과가 상호 보완하는 의미에서 합성모형으로 통합되었다. 본 연구에서는 다변수 판별 함수의 계산법과 Markov 연쇄행렬 계산법에 관하여 토의되고 그 합성 모형을 대상 지역에 실제 적용하여 그 결과 '90년, '95년 토지이용도가 예측 작성되었다. 모형화의 문제 및 예측의 정확도 역시 더욱 토의 되어야 하며 추후 개선의 여지를 남긴다.

• Geomechanics and Engineering
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• 제13권3호
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• pp.475-488
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• 2017

Geotechnical data contributes substantially to the cost of engineering projects due to increasing cost of site investigations. Existing information in the form of soil maps can save considerable time and expenses while deciding the scope and extent of site exploration for a proposed project site. This paper presents spatial interpolation of data obtained from soil investigation reports of different construction sites and development of soil maps for geotechnical characterization of Multan area using ArcGIS. The subsurface conditions of the study area have been examined in terms of soil type and standard penetration resistance. The Inverse Distance Weighting method in the Spatial Analyst extension of ArcMap10 has been employed to develop zonation maps at different depths of the study area. Each depth level has been interpolated as a surface to create zonation maps for soil type and standard penetration resistance. Correlations have been presented based on linear regression of standard penetration resistance values with depth for quick estimation of strength and stiffness of soil during preliminary planning and design stage of a proposed project in the study area. Such information helps engineers to use data derived from nearby sites or sites of similar subsoils subjected to similar geological process to build a preliminary ground model for a new site. Moreover, reliable information on geometry and engineering properties of underground layers would make projects safer and economical.

• Geomechanics and Engineering
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• 제23권3호
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• pp.207-215
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• 2020

This paper presents a kinematic limit analysis for passive earth pressure of rigid retaining structures considering the unsaturation of the backfill. Particular emphasis in the current work is focused on the effects of the spatial change in the degree of saturation on the passive earth pressure under different steady-infiltration/evaporation conditions. The incorporation of change of effective unit weight with degree of saturation is the main contribution of this study. The problem is formulated based on the log-spiral failure model rather than the linear wedge failure model, in which both the spatial variations of suction and soil effective unit weight are taken into account. Parametric studies, which cover a wide range of flow conditions, soil types and properties, wall batter, back slope angle as well as the interface friction angle, are performed to investigate the effects of these factors on the passive pressure and the corresponding shape of potential failure surfaces in the backfill. The results reveal that the flow conditions have significant effects on the suction and unit weight of the clayey backfill, and hence greatly impact the passive earth pressure of retaining structures. It is expected that present study could provide an insight into evaluation of the passive earth pressure of retaining structures with unsaturated backfills.

• Journal of Information Processing Systems
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• 제16권3호
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• pp.688-698
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• 2020

Point clouds have ability to express the spatial entities, however, the point clouds redundancy always involves some uncertainties in computer recognition and model construction. Therefore, point clouds thinning is an indispensable step in point clouds model reconstruction and other applications. To overcome the shortcomings of complex classification index and long time consuming in existing point clouds thinning algorithms, this paper proposes a point clouds fast thinning algorithm. Specifically, the two-dimensional index is established in plane linear array (x, y) for the scanned point clouds, and the thresholds of adjacent point distance difference and height difference are employed to further delete or retain the selected sample point. Sequentially, the index of sample point is traversed forwardly and backwardly until the process of point clouds thinning is completed. The results suggest that the proposed new algorithm can be applied to different targets when the thresholds are built in advance. Besides, the new method also performs superiority in time consuming, modelling accuracy and feature retention by comparing with octree thinning algorithm.

• Journal of the Korean Data and Information Science Society
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• 제28권1호
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• pp.29-37
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• 2017

산림경영 계획을 위한 필요한 산림재적을 보다 효율적으로 추정하기 위해서 다양한 연구가 요구되어져 왔는데, 이러한 산림구조에 관한 연구는 주로 현장조사와 위성영상을 이용하여 이루어진다. 현장조사를 통한 연구는 비교적 정확하나 시간과 비용이 많이 들 뿐 아니라 접근의 용이성이 떨어지는 지역이 있기 때문에, 넓은 지역의 조사가 어렵다는 단점이 있다. 최근에는 항공기에서 발사된 레이저 펄스가 반사되어 돌아오는 시간을 측정하여 대상의 3차원 좌표를 얻는 LiDAR (Light Detection and Ranging) 기술을 활용하여 획득한 정밀한 수치형자료를 이용한 산림의 구조에 관한 연구가 이루어지고 있다. 일반적으로 산림재적을 추정하기 위해서 LiDAR자료를 이용한 수고자료와 산림 재적에 대한 회귀모형의 중요성이 점차 높아지는데, 국내의 경우 수목의 종류와 그 분포가 다르기 때문에 회귀모형만으로 재적을 추정하는 데 한계가 있다. 따라서 본 논문에서는 산림의 수고와 흉고직경을 측정하여 재적값을 추정하고 산림의 공간효과를 고려한 계층적 베이지안 분석을 통해 관측되지 않은 전체 산림재적에 대한 추정을 하고자 한다.

• Steel and Composite Structures
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• 제50권1호
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• pp.25-43
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• 2024

In this article, a mathematical model is developed to predict the dynamic behavior of bio-inspired composite beam with helicoidal orientation scheme under variable axial load using a unified higher order shear deformation beam theory. The geometrical kinematic relations of displacements are portrayed with higher parabolic shear deformation beam theory. Constitutive equation of composite beam is proposed based on plane stress problem. The variable axial load is distributed through the axial direction by constant, linear, and parabolic functions. The equations of motion and associated boundary conditions are derived in detail by Hamilton's principle. Using the differential quadrature method (DQM), the governing equations, which are integro-differential equations are discretized in spatial direction, then they are transformed into linear eigenvalue problems. The proposed model is verified with previous works available in literatures. Parametric analyses are developed to present the influence of axial load type, orthotropic ratio, slenderness ratio, lamination scheme, and boundary conditions on the natural frequencies of composite beam structures. The present enhanced model can be used especially in designing spacecrafts, naval, automotive, helicopter, the wind turbine, musical instruments, and civil structures subjected to the variable axial loads.

• Journal of the Korean Data and Information Science Society
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• 제25권4호
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• pp.941-949
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• 2014

Unit level logistic regression model with mixed effects has been used for estimating small area proportions, which treats the spatial effects as random effects and assumes linearity between the logistic link and the covariates. However, when the functional form of the relationship between the logistic link and the covariates is not linear, it may lead to biased estimators of the small area proportions. In this paper, we relax the linearity assumption and propose two types of kernel-based logistic regression models for estimating small area proportions. We also demonstrate the efficiency of our propose models using simulated data and real data.

• 보건행정학회지
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• 제23권4호
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• pp.387-396
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• 2013

Background: The purpose of this study was to analyze the association between areas of Korea Train Express (KTX) region and external medical service use in Korean society using spatial statistical model. Methods: The data which was used in this study was extracted from 2011 regional health care utilization statistics and health insurance key statistics from National Health Insurance Corporation. A total spatial units of 229 districts (si-gun-gu) were included in this study and spatial area was all parts of the country excepted Jeju, Ulleungdo island. We conducted Kruskal-Wallis test, correlation, Moran's I and hot-spot analysis. And after, ordinary linear regression, spatial lag, spatial error analysis was performed in order to find factors which were associated with external medical service use. The data was processed by SAS ver. 9.1 and Geoda095i (windows). Results: Moran's I of health insurance patients' external medical service use was 0.644. Also, population density, Seoul region, doctor factors positively associated with health insurance patients' external medical service. In contrast, average age, health care organization per 100 thousand were negatively associated with health insurance patients' external medical service use. Conclusion: The finding of this study suggested that health insurance patient's external medical service use correlated for seoul region in korea. The study results imply the need for more attention medical needs in the region (si-gun-gu unit) for health insurance patients of seoul region. It is important to adapt strategy to activation of primary health care as well as enhancing public health institution for prevent leakage of patients to other areas.