• 한국지리정보학회지
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• 제11권3호
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• pp.151-165
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• 2008

지형경사와 사면방향은 BROOK90 Model과 같은 물리 결정 물수지 모델에서 증발산과 융설, 순복사 등을 계산하기 위해서 사용하는 중요한 매개변수가 된다. 본 연구에서는 수치표고모형(DEM)을 제작하고, DEM의 해상도가 달라짐에 따라서 유역 평균 지형경사와 유역 평균 사면방향이 어떻게 달라지는지, 그리고 이 차이는 물리 결정 일괄 매개변수 물수지 모델인 BROOK90의 물수지 모의 결과에 어떤 영향을 미치는지를 평가하였다. 충청도 병천천 유역을 대상으로, DEM은 1:25,000 수치지형도를 이용하여 TIN과 Topo To Raster 방법으로 제작하였다. 각각의 방법으로 10m~100m 해상도의 DEM을 10m 간격으로 10개씩 총 20개의 DEM을 제작하였다. DEM의 해상도가 높아지면 병천천 유역의 평균 지형경사가 커져서 이는 병천천 유역의 증산량을 증가시키고 하천유출량을 감소시켰다. 이것은 평지보다 경사지가 직달복사량을 많이 받는 물리적 특성이 모델에 반영되어 있기 때문이다. 한편, DEM의 해상도가 낮아지면 병천천 유역에서는 평균 사면방향이 남동방향에서 남향으로 이동하는 경향이 있었다. 이에 따라 증발산량이 증가하고 하천유출량은 감소하는 것으로 나타났다.

• 한국전자파학회논문지
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• 제25권8호
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• pp.838-848
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• 2014

본 논문에선 Interferometric Synthetic Aperture Radar(InSAR) 고도계의 측정값인 거리와 도래각(Angle of Arrival: AOA)을 실제 수치 표고 자료(Degital Elevation Model: DEM)상에서 모의실험하여 얻었다. 이 때 거리 측정값을 얻기 위해서 필요한 원시 데이터 및 압축 데이터의 결과도 나타냈다. 도래각은 안테나 간의 위상 차이로부터 Deterministic Maximum Likelihood Estimator(DMLE)를 사용하여 구했다. 거리 빈(range bin)의 크기와 펄스 반복 주기(PRI: Pulse Repetition Interval)가 실제 수치 표고 자료의 셀 크기에 비해 작기 때문에 모의실험에 적합하지 않다. 따라서 본 논문에서는 선형 보간법을 이용하여 해상도가 높은 수치 표고 자료를 생성하여 모의실험하였다. 서론 부분에서 InSAR 고도계를 소개하였고, 고도와 각도를 구하는 방법에 대해서 설명하였으며, 모의실험 부분에서 위에 소개된 방법의 성능을 보였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.290-295
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• 1999

Lineament extraction from mountain area often provides valuable geological information. In many cases, the lineaments correspond to a series of continuous large valleys. This paper introduces a new lineament extraction method from Digital Elevation Model (DEM) using Raindrop Tracing Algorithm (RTA). The main advantage of this algorithm over conventional Segment Tracing Algorithm (STA) is that it utilizes DEM directly unlike the STA Which utilizes the shaded relief of DEM. The RTA simulates the real life of raindrops that converge into a large valley. The simulation has been done by sprinkling the randomized raindrops over DEM and counting the number of raindrop path that follows the negative gradient of the DEM. The large counting number indicates the location of a big valley where the raindrops converge. With the help of the counting number array (accumulator array) recording the flowing path information, RTA can produce perfectly unbiased binary image of the lineament.

• 한국도로학회논문집
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• 제15권5호
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• pp.31-45
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• 2013

PURPOSES : Determination of particle packing model variables that can be used for formulation of new DEM based particle packing model by examining existing particle packing models METHODS : Existing particle packing models are thoroughly examined by analytical reformulation and sensitivity analysis in order to set up DEM based new particle packing model and to determine its variables. All model equations considered in this examination are represented with consistent expressions and are compared to each others to find mathematical and conceptual similarity in expressions. RESULTS : From the examination of existing models, it is observed that the models are very similar in their shapes although the derivation of the models may be different. As well, it is observed that variables used in some existing models are comprehensive enough to estimate particle packing but not applicable to DEM simulation. CONCLUSIONS : A set of variables that can be used in DEM based particle packing model is determined.

• 한국지리정보학회지
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• 제13권4호
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• pp.50-66
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• 2010

본 논문에서는 보다 합리적이고 객관적인 토석류 방재대책 수립에 도움을 주기 위하여 고정밀 LiDAR DEM을 이용한 GIS 기반의 토석류 시뮬레이션 방법을 제시하였다. 매우 극단적인 산악지형 분포를 보이는 강원도 평창군 일원을 연구대상지역으로 설정하고, 유한차분법을 적용한 GIS 기반의 수치해석 프로그램을 이용하여 토석류의 발생 가능성을 시뮬레이션 하였다. 그 후 해석된 토석류 시뮬레이션 결과의 신뢰성을 검증하기 위하여 동일한 대상지역에 대하여 SINMAP 및 지형해석 방법에 의한 토석류 해석을 수행하고, 그 해석결과를 본 연구에서 제안된 GIS 기반의 토석류 시뮬레이션 결과와 비교 분석하였다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.117-123
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• 2000

Using the modified DEM (Discrete Element Method), which we proposed in order to improve the accuracy of the simulation, soil behavior and reaction by lugs of rotating wheel and a soil cutting process by a high speed blade were calculated and compared with experimental data. The DEM is one of computational mechanics, where the object body is supposed as an assembly of small particles called elements and not a continuum as in the case of FEM. We can easily treat some discrete phenomena such as cracking, separating and sliding by the DEM. We had to modify the original mechanical model, which induced too free movement of elements, adding a tension spring, which would display the role of soil adhesion. The results of DEM simulations were successful from both the soil behavior and reaction points of view.

• 한국안전학회지
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• 제24권6호
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• pp.1-6
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• 2009

This study describes a construction procedure of 3D virtual space using the NGIS data and its application to simulation. 3D space topography is modeled by using DEM consisted with triangular regular network. The elevations of nodal points of DEM are calculated through the interpolation with contour line and elevation points from the NGIS. Also, data for 2D roads and their environments, such as trees, lamps, and traffic signals, were extracted from the NGIS and projected on the DEM surfaces to get 3D virtual space. To give a reality to 3D virtual space and accelerate its graphic speed, data were converted into the directX format. It is believed that the virtual space constructed in this work can be applicable to the ubiqutous because DEM data can be converted to the AutoCAD format and ASCII code.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.14-19
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• 2021

Aim of this research was to investigate the effects of Digital Elevation Model (DEM) for sensitivity analysis with two types of DEMs: 1 to 24,000 and 1 to 250,000 DEM. Another emphasis was given to the development of methodology for processing DEMs to create ArcGIS Pro and GRASS layers. This was done while developing water quality system modeling using DEMs which were used to model hydrological processes and SWAT model. Sensitivity analysis with DEMs resulted in different runoff volumes in the model simulation. Runoff volume was higher for the 1:24,000 DEM than 1:250,000 DEM, probably due to the finer resolution and slope which increased the estimated runoff from the watershed. Certainly the DEMs were factors in precision of the simulations and it was obvious during sensitivity analysis that DEMs had significant effect on runoff volumes. We suggest, however, that additional comparative research could be conducted involving more parameters such as soil and hydrologic parameters to provide insight into the overall physical system which the SWAT model represents.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.191-203
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• 2018

이 연구는 각각 크기와 재질이 다른 3 가지 종류의 분쇄 매체를 이용하여 회전속도와 밀링 시간의 따른 구리 (Cu) 분말의 형상변화의 과정에 미치는 영향을 관찰하고, 볼 움직임의 DEM시뮬레이션을 행하였다. 전동볼밀에서 볼 움직임의 3차원 시뮬레이션을 통해 분쇄 메커니즘을 규명하기 위하여 분쇄매체의 힘, 운동에너지, 매체 운동속도 등을 계산하였다. 시뮬레이션에서는 회전속도, 볼 재질, 운동속도, 마찰계수 등을 실제 실험조건과 동일하게 조건을 맞추어 투입되는 에너지의 변화량도 계산하였다. 주사전자현미경 결과를 살펴보면 볼 직경이 작을 때 입자형상이 불규칙한 형태에서 구형 형태로 변화하는 것을 알 수 있었다.

• 드라이브 ㆍ 컨트롤
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• 제20권4호
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• pp.71-79
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• 2023

In the field of agricultural machinery, various on-field tests are conducted to measure design load for optimal design of agricultural equipment. However, field test procedures are costly and time-consuming, and there are many constraints on field soil conditions due to weather, so research on utilizing simulation to overcome these shortcomings is needed. Therefore, this study aimed to model agricultural soils using discrete element method (DEM) software. To simulate draft force, predictions are made according to travel speed and compared to field test results to validate the prediction accuracy. The measured soil properties are used for DEM modeling. In this study, the soil property measurement procedure was designed to measure the physical and mechanical properties. DEM soil model calibration was performed using a virtual vane shear test instead of the repose angle test. The DEM simulation results showed that the prediction accuracy of the draft force was within 4.8% (2.16~6.71%) when compared to the draft force measured by the field test. In addition, it was confirmed that the result was up to 72.51% more accurate than those obtained through theoretical methods for predicting draft force. This study provides useful information for the DEM soil modeling process that considers the working speed from the perspective of agricultural machinery research and it is expected to be utilized in agricultural machinery design research.