• 한국해안해양공학회지
• /
• 제10권1호
• /
• pp.27-36
• /
• 1998

물의 유동을 해석하기 위한 3차원 수치모형이 개발되었다 모형은 균질류에 대한 $\sigma$-좌표에서 방정식들 을 유한요소법을 사용하여 해석한다. 모형의 정확성을 정토하기 위하여 1차원 수로에서 취송류 분포, 정사각형 호수에서 취송류 분포를 해석하고 해석해와 비교 검증하였으며, 마산-진해만에서 조류분포를 계산하고 현장 관측자료와 비교 검증하였다. 계산결과가 비교된 해석해 및 관측치와 대체로 일치하는 양호한 결과를 보였다. 따라서, 개발된 모형은 복잡한 육지경계를 갖는 자연 수괴의 3차원적 순환현상을 해석하는 데 널리 활용될 수 있을 것이다

• Interaction and multiscale mechanics
• /
• 제1권3호
• /
• pp.369-379
• /
• 2008

A combined stochastic diffusion and mean-field model is developed for a systematic study of the grain growth in a pure single-phase polycrystalline material. A corresponding Fokker-Planck continuity equation is formulated, and the interplay/competition of stochastic and curvature-driven mechanisms is investigated. Finite difference results show that the stochastic diffusion coefficient has a strong effect on the growth of small grains in the early stage in both two-dimensional columnar and three-dimensional grain systems, and the corresponding growth exponents are ~0.33 and ~0.25, respectively. With the increase in grain size, the deterministic curvature-driven mechanism becomes dominant and the growth exponent is close to 0.5. The transition ranges between these two mechanisms are about 2-26 and 2-15 nm with boundary energy of 0.01-1 J $m^{-2}$ in two- and three-dimensional systems, respectively. The grain size distribution of a three-dimensional system changes dramatically with increasing time, while it changes a little in a two-dimensional system. The grain size distribution from the combined model is consistent with experimental data available.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집E
• /
• pp.748-753
• /
• 2001

The objective of the present study is to visualize the pulsatile flow fields by using three-dimensional computer simulation and the PIV system. A closed flow loop system was built for the steady and unsteady experiments. The Harvard pulsatile pump was used to generate the pulsatile pressure and velocity waveforms. Conifer powder as the tracing particles was added to water to visualize the flow field. Two consecutive particle images were captured by a CCO camera for the image processing at several cross section. The range validation and the area interpolation methods were used to obtain the final velocity vectors with high accuracy. The finite volume predictions were used to analyze three-dimensional flow patterns in the bifurcation model. The results of the PIV experiment and the computer simulation are in good agreement and the results show the recirculation zones and formation of the paired secondary flow distal to the apex of the bifurcated model. The results also show that the branch flow is pushed strongly to the inner wall due to the inertial force effect and helical motions are generated as the flow proceeds toward the outer wall.

• 한국물환경학회지
• /
• 제28권1호
• /
• pp.26-37
• /
• 2012

Multi-dimensional hydrodynamic and water quality models are widely used to simulate the physical and biogeochemical processes in the surface water systems such as reservoirs and estuaries. Most of the models have adopted the Eulerian grid modeling framework, mainly because it can reasonably simulate physical dynamics and chemical species concentrations throughout the entire model domain. Determining the optimum grid cell size is important when using the Eulerian grid-based three-dimensional water quality models because the characteristics of species are assumed uniform in each of the grid cells and chemical species are represented by concentration (mass per volume). The objective of this study was to examine the effect of grid-size of a three dimensional hydrodynamic and water quality model (EFDC) on hydrodynamics and mass transport in the Saemangeum Reservoir. Three grid resolutions, respectively representing coarse (CG), medium (MG), and fine (FG) grid cell sizes, were used for a sensitivity analysis. The simulation results of numerical tracer showed that the grid resolution affects on the flow path, mass transport, and mixing zone of upstream inflow, and results in a bias of temporal and spatial distribution of the tracer. With the CG, in particular, the model overestimates diffusion in the mixing zone, and fails to identify the gradient of concentrations between the inflow and the ambient water.

• 한국수소및신에너지학회논문집
• /
• 제28권3호
• /
• pp.308-314
• /
• 2017

Jet pump in automotive fuel tank module is used to deliver fuel to fuel pump so that the pump is operated without aeration in suction side. In this study, three dimensional simulation model of jet pump is developed to understand performance variation over design parameters. Performance of jet pump is also investigated experimentally in terms of operating pressures. The experimental data is used to verify the three dimensional simulation model of jet pump. Verification results show that the three dimensional simulation model of jet pump is about 1% error with experiment. The simulations are conducted in terms of throat ratio and primary flow induction angle. As the throat ratio is increased, the flux ratio is trade-off at 3 times of throat diameter. On the other hand, as primary flow induction angle is increased, vapor pressure inside the nozzle is decreased. In summary, the results show that liquid jet pump has to be optimized over design parameters. Additionally, high velocity of induced flow is able to evolve cavitation phenomena inside the jet pump.

• 대한금속재료학회지
• /
• 제47권11호
• /
• pp.699-706
• /
• 2009

Deformation behavior of pure aluminum during equal channel angular pressing (ECAP) was simulated using a three-dimensional version of the finite element method in conjunction with a constitutive model based on the dislocation density and cell evolution. The three-dimensional finite element analyses for the prediction of microstructural features, such as the variation of the dislocation density and the cell size with the number of ECAP, are reported. The calculated stress and strain and their distributions are also investigated for the route Bc ECAP processed pure aluminum. The results of finite element analyses are found to be in good agreement with experimental results for the dislocation cell size. Due to the accumulation of strain throughout the workpiece and an overall trend to saturation in cell size, a decrease of the difference in cell size with the number of passes (1~4) was predicted.

• 한국해양공학회지
• /
• 제12권2호통권28호
• /
• pp.121-129
• /
• 1998

A quantitative non-contact multi-point measurement system is proposed to the measurement of three-dimensional movement of floating vessels by using digital image processing. The instantaneous three-dimensional movement of a floating structure which is floating in a small water tank is measured by this system and its three-dimensional movement is reconstructed by the measurement results. The validity of this system is verified by position identification for spatially distributed known positional values of basic landmarks set for the camera calibration. It is expected that this system is applicable to the non-contact measurement for an unsteady physical phenomenon especially for the measurement of three-dimensional movement of floating vessels in the laboratory model test.

• 국제초고층학회논문집
• /
• 제13권1호
• /
• pp.57-67
• /
• 2024

With the requirement of high quality and three-dimensional urban development, the public space areas city-center rail transit stations is expanded from the plots defined by the road network density to the plots defined by the three-dimensional public space density, covering the internal and external paths of the plots, which brings about the resilient pattern of plot utilization. This paper uses the isochronous three-dimensional influence realm model around the station areas to quantitatively analyze and compare the surrounding three-dimensional path density of public space, and initially proposes flexible use patterns of differently scaled plots under the multi-scale plots linkage, to effectively promote the overall accessibility of the station realm space.

• Structural Engineering and Mechanics
• /
• 제22권1호
• /
• pp.33-52
• /
• 2006

Three-dimensional description of building structure taking into consideration soil-structure interaction is a very complex problem and solution of this problem is often obtained by using finite element method. However, this method takes a significant amount of computational time and memory. Therefore, an efficient computational model based on subdivision of the structure into building elements such as wall and floor slab elements, plane and three-dimensional joints and lintels, that could provide accurate results with significantly reduced computational time, is proposed in this study for the analysis three-dimensional structures subjected to dynamic load. The examples prove the efficiency and the computing possibilities of the model.

• 대한기계학회논문집
• /
• 제12권6호
• /
• pp.1207-1216
• /
• 1988

본 연구에서는 이 염색격자법을 이용하여 가장 기본적인 복합재인 탄성계수가 서로 다른 두 물체로 구성된 2상적합재를 제작할 수 있는가를 검토하였고, 또한 제작 완성된 접합재를 이용하여 접합경계면 부근의 국소영역에서의 3차원적인 변형거동을 관찰한 것이다.