• 농업과학연구
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• 제48권3호
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• pp.515-526
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• 2021

The frequency of typhoons and torrential rainfalls has increased due to climate change, and the concurrent risk of breakage of dams and reservoirs has increased due to structural aging. To cope with the risk of dam breakage, a more accurate emergency action plan (EAP) must be established, and more advanced technology must be developed for the prediction of flooding. Hence, the present study proposes a method for establishing a more effective EAP by performing flood and inundation analyses using one- and two-dimensional models. The probable maximum flood (PMF) under the condition of probable maximum precipitation (PMP) was calculated for the target area, namely the Gyeong-cheon reservoir watershed. The breakage scenario of the Gyeong-cheon reservoir was then built up, and breakage simulations were conducted using the dam-break flood forecasting (DAMBRK) model. The results of the outflow analysis at the main locations were used as the basis for the one-dimensional (1D) and two-dimensional (2D) flood inundation analyses using the watershed modeling system (WMS) and the FLUvial Modeling ENgine (FLUMEN), respectively. The maximum inundation area between the Daehari-cheon confluence and the Naeseong-cheon location was compared for each model. The 1D flood inundation analysis gave an area of 21.3 km², and the 2D flood inundation analysis gave an area of 21.9 km². Although these results indicate an insignificant difference of 0.6 km² in the inundation area between the two models, it should be noted that one of the main locations (namely, the Yonggung-myeon Administrative and Welfare Center) was not inundated in the 1D (WMS) model but inundated in the 2D (FLUMEN) model.

• Structural Engineering and Mechanics
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• 제6권5호
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• pp.497-516
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• 1998

A relatively simple two-dimensional multilayered shell model is presented for predicting both global quantities and stress distributions across the thickness of multilayered thick shells, that is based on a third-order zig-zag approach. As for any zig-zag model, the layerwise kinematics is accounted for, with the stress continuity conditions at interfaces met a priori. Moreover, the shell model satisfies the zero transverse shear stress conditions at the upper and lower free surfaces of the shell, irrespective of the lay-up. By changing the parameters in the displacement model, some higher order shell models are obtained as particular cases. Although it potentially has a wide range of validity, application is limited to cylindrical shell panels in cylindrical bending, a lot of solutions of two-dimensional models based on rather different simplyfying assumptions and the exact three-dimensional elasticity solution being available for comparisons for this benchmark problem. The numerical investigation performed by the present shell model and by the shell models derived from it illustrates the effects of transverse shear modeling and the range of applicability of the simplyfying assumptions introduced. The implications of retaining only selected terms depending on the radius-to-thickness ratio are focused by comparing the present solutions to the exact one and to other two-dimensional solutions in literature based on rather different simplyfying assumptions.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.155-158
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• 2008

A practical modeling approach of a small slinger combustor is proposed and a 2-dimensional axisymmetric computational model is developed. Based on numerical results from the full 3-dimensional configuration, model reduction is achieved toward 2-dimensional axisymmetric configuration. By simplifying the complex model, computing time can be significantly reduced and it makes easy to find effects of geometry modification. Numerical results show that the flow characteristic of 2-D model is quite similar to that of the 3-D configuration.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.174-180
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• 2010

Conductive and radiative thermal model configurations of an imager of a geostationary satellite are presented. A two-plane method is introduced for three dimensional conductive coupling which is not able to be treated by thin shell plate thermal modeling technique. Especially the two-plane method is applied to massive matters and PIP(Payload Interface Plate) in the imager model. Some massive matters in the thermal model are modified by adequate correction factors or equivalent thickness in order to obtain the numerical results of thermal modeling to be consistent with the analytic model. More detailed nodal breakdown is specially employed to the object which has the rapid temperature gradient expected by a rule of thumb. This detailed thermal model of the imager is supposed to be used for detailed analyses and test predictions, and be correlated with the thermal vacuum test results before final in-flight predictions.

• 대기
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• 제30권4호
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• pp.319-333
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• 2020

Aircraft observations constitute one of the major sources of temperature observations which provide three-dimensional information. But it is well known that the aircraft temperature data have warm bias against sonde observation data, and therefore, the correction of aircraft temperature bias is important to improve the model performance. In this study, the algorithm of the bias correction modified from operational KMA (Korea Meteorological Administration) global model is adopted in the preprocessing of aircraft observations, and the effect of the bias correction of aircraft temperature is investigated by conducting the two experiments. The assimilation with the bias correction showed better consistency in the analysis-forecast cycle in terms of the differences between observations (radiosonde and GPSRO (Global Positioning System Radio Occultation)) and 6h forecast. This resulted in an improved forecasting skill level of the mid-level temperature and geopotential height in terms of the root-mean-square error. It was noted that the benefits of the correction of aircraft temperature bias was the upper-level temperature in the midlatitudes, and this affected various parameters (winds, geopotential height) via the model dynamics.

• 한국지반신소재학회논문집
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• 제20권3호
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• pp.11-20
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• 2021

본 논문에서는 유한요소법과 경계요소법을 결합하여 기하학적으로 급변 부위가 있는 이차원 탄성 정적 문제에 대하여 효율적이고 정확한 해석 결과를 얻기 위한 유한요소법과 경계요소법의 근사 결합 방법을 제시한다. 이차원 문제의 유한요소로서는 3절점, 4절점 평면응력 요소를 적용하고, 이차원 문제의 경계요소로는 3절점 경계요소를 적용한다. 모델링 단계에서는 우선 전체 해석 대상을 유한요소로 모델링한 후에 기학학적 급변 부위를 경계요소로 모델링 하는데, 유한요소의 모델링을 위하여 정의된 절점을 이용하여 경계요소를 정의한다. 해석 단계에서는 전체 해석 대상에 대하여 유한요소 해석을 우선적으로 수행하고, 이후에 경계요소 해석을 자동으로 수행하는데, 경계부에서의 경계조건은 유한요소 해석 결과인 변위 조건과 응력 조건을 적용한다. 수치예제로서 이차원 탄성 정적 문제인 균열이 있는 평판에 대한 해석 결과를 제시하고 고찰한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.319-324
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• 2001

A finite element model for the process of squeeze casting for metal matrix composites (MMCs) in cylindrical mold is developed. The fluid flow and the heat transfer are the fundamental phenomena in the squeeze casing process. To describe heat transfer with solidification of molten aluminum, the energy equation in terms of temperature and enthalpy are applied to two dimensional axisymmetric model which is similar to the experimental system. And one dimensional flow model is employed to simulate the transient metal flow. The direct iteration technique was used to solve the resulting nonlinear algebraic equations. A computer program is developed to calculate the enthalpy, temperature and fluid velocity. Cooling curves and temperature distribution during infiltration and solidification are calculated for pure aluminum. The temperature is measured and recorded experimentally. At two points of the perform inside and one point of the mold outside, thermocouple wire are installed. The time-temperature data are compared with the calculated cooling curves. The experimental results show that the finite element model can estimate the solidification time and predict the cooling process.

• 자원환경지질
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• 제25권1호
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• pp.73-77
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• 1992

본 논문에서는 2차원 전기비저항 모델링에서 후리에역변환을 계산하는 수치구적법을 비교하였다. 지수함수 및 큐빅스프라인 보간을 사용한 구적법을 균질대지 모델에 대하여 검토하였다. 이들 기술적용시, ${\lambda}_{min}$을 최소의 샘플링파수라고 할 때 0에서 ${\lambda}_{min}$까지 간격에 대한 적분은 후리에변환된 포텐샬을 대수 함수로 근사함으로써 계산하였다. 이러한 방법은 ${\lambda}=0$에서의 대수적인 불연속성에 기인한 후리에역변환의 오차를 크게 줄일 수 있다. 수치계산 결과, 샘플링간격이 적당하다면 큐빅스프라인 보간법이 지수함수 보간법보다 더 정확함을 알았다.

• Advances in Computational Design
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• 제9권2호
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• pp.137-150
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• 2024

Paper shows the problems of numerical modeling of nonlinear physical processes of elements stress-strain state of construction are considered. Elastic-plastic environment of homogeneous solid material is investigated. The results of computational experiments of physically nonlinear strain process study of isotropic elements of three-dimensional constructions with a system of one - and doubly periodic spherical cavities under uniaxial compression are presented. The effect and mutual influence of stress concentrators in the form of a spherical cavities, vertically located two cavities and a horizontally located system of two cavities on the strain of construction is studied.

• The Journal of the Acoustical Society of Korea
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• 제20권4E호
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• pp.17-23
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• 2001

To develop the code of predicting flow-field and aeroacoustic noise by an electrical cable, a combined CFD-Acoustic analogy approach is selected. The two dimensional, unsteady and incompressible Reynolds-averaged Navier-Stokes solver with κ-ω and κ-ω SST turbulence modeling is used to calculate the near flow-field around an electric cable. Near-field results are then coupled with two-dimensional Curle's integral formulation based upon Lighthill's acoustic analogy with the assumption of acoustic compactness. To validate this code, numerical results are compared with experimental data for a circular cylinder. The simulation shows an overprediction on acoustic amplitudes, but overally speaking, the spectrum pattern of sound pressure agrees well with experiment within an acceptable amount of error. In addition, a few cross-sections of the cable were selected and tested with each other in terms of drag and radiated noise