• Computers and Concrete
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• 제9권4호
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• pp.257-273
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• 2012

Based on the heterogeneous characterization of concrete at mesoscopic level, Realistic Failure Process Analysis ($RFPA^{3D}$) code is used to simulate the failure process of concrete-filled tubular (CFT) stub columns. The results obtained from the numerical simulations are firstly verified against the existing experimental results. An extensive parametric study is conducted to investigate the effects of different concrete strength on the behaviour and load-bearing capacity of the CFT stub columns. The strength of concrete considered in this study ranges from 30 to 110 MPa. Both the load-bearing capacity and load-displacement curves of CFT columns are evaluated. In particular, the crack propagation during the deformation and failure processes of the columns is predicted and the associated mechanisms related to the increased load-bearing capacity of the columns are clarified. The numerical results indicate that there are two mechanisms controlling the failure of the CFT columns. For the CFT columns with the lower concrete strength, they damage when the steel tube yields at first. By contrast, for the columns with high concrete strength it is the damage of concrete that controls the overall loading capacity of the CFT columns. The simulation results also demonstrate that $RFPA^{3D}$ is not only a useful and effective tool to simulate the concrete-filled steel tubular columns, but also a valuable reference for the practice of engineering design.

• 대한토목학회논문집
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• 제26권5B호
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• pp.563-572
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• 2006

현재 해안구조물의 설계시에는 현지관측을 토대로 한 Goda식(Goda, 1974)과 같은 경험식이나 2차원적인 수리수치모형실험을 통한 파력값을 많이 사용하고 있다. 하지만, 이러한 2차원 해석결과들은 실해역에 설치된 구조물의 평면배치형상에 따라 변화하는 작용파력의 3차원 구조를 재현하기에는 무리가 있는 듯 하다. 특히, 혼성방파제와 같은 대형구조물의 항외측과 항내측에서 위상차가 발생하는 경우에는 구조물의 단면별로 파력이 각기 다르게 작용할 것으로 판단된다. 본 연구에서는, 해안구조물에 작용하는 파력의 3차원구조를 명확히 하기 위하여, 투과성구조물 및 쇄파현상에도 적용이 가능한 기존의 수치해석기법(Hur and Mizutani, 2003)에 Large Eddy Simulation(LES)기법을 도입한 새로운 3차원 수치해석기법을 제안하였으며, 이 기법을 이용하여 얻어진 잠제상 구조물에서의 작용파력 계산치를 기존의 수리모형실험치와 비교한 결과, 좋은 일치성을 확인하였다. 또한, 대형해안구조물 중 혼성방파제를 본 연구의 대상구조물로하여, 사석마운드로의 투과 및 개구부로의 회절의 영향으로 인해 발생하는 위상차를 고려한 3차원 파력구조에 관해 논의하였으며, 2차원 해석으로는 규명할 수 없었던 3차원적인 동적 파력특성을 파악할 수 있었다.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2004년도 학술발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
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• pp.40-45
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• 2004

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2001년도 학술발표회 논문집(II)
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• pp.1071-1076
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• 2001

• 복식문화연구
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• 제23권4호
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• pp.616-627
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• 2015

The purpose of this study was to develop slacks patterns for obese-schoolgirls aged 10~12 by using a 3D virtual garment simulation system. The criteria for subjects in this study were girls who had a BMI of over $25kg/m^2$. A total of 155 schoolgirls who met these criteria were enrolled. The results were as follows: First, by using 3D virtual garment simulation, a new slacks pattern considerate of obese-schoolgirls was developed. The basic numerical formulae were as follows: Front and back hip girth of H/4-0.5+1 and H/4+0.5+1.5, front waist girth of W/4+1+0.5, back waist girth of W/4+2+0.5, front crotch extension of H/16-0.5, back crotch extension of H/8-0.5, front dart amount of 1, and back dart amount of 2. Second, according to the new slacks pattern appearance evaluation, the new slacks pattern scored more highly than the existing pattern for silhouette and ease amount, confirming that the new slacks pattern is appropriate for obese-schoolgirls. Additionally, the new slacks pattern was evaluated allowing for the proper space length of the waist, abdomen and hips. This study is expected to serve as important basic data for ensuing studies that may utilize a 3D virtual garment simulation system with 2D patterns and for future 3D pattern production program development.

• 한국해양공학회지
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• 제25권3호
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• pp.19-27
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• 2011

In case of constructing submerged breakwaters for the purpose of preventing coastal erosion, the number of submerged breakwaters, as well as their asymmetry is dependent on the field conditions. The aim of the present study was to examine the 3-D hydrodynamic characteristics (3-D wave field, wave height, mean water level, and mean flow) around the asymmetric submerged breakwaters using a 3-D numerical model, LES-WASS-3D, which was validated through a comparison with existing experimental data and showed fairly nice agreement. From the numerical results, the wave height, mean water level, and mean flow are discussed in relation with the variation in the breakwater length ratio.

• 대한기계학회논문집A
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• 제26권3호
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• pp.576-585
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• 2002

A three-dimensional Lagrangian explicit time-integration finite element code for analyzing the dynamic impact phenomena was developed. It uses four node tetrahedral elements. In order to consider the effects of strain rate hardening, strain hardening and thermal softening, which are frequently observed in high-velocity deformation phenomena, Johnson-Cook model is used as constitutive model. For more accurate and robust contact force computation, the defense node contact algorithm was adopted and implemented. In order to evaluate the performance of the newly developed three-dimensional hydrocode NET3D, numerical simulations of the oblique impact of mild steel plate by mild steel sphere were carried out. Ballistic limit about various oblique angle between 0 degree and 80 degree was estimated through a series of simulations with different initial velocities of sphere. Element eroding by equivalent plastic strain was applied to mild steel spheres and targets. Ballistic limits and fracture characteristics obtained from simulation were compared with experimental results conducted by Finnegan et al. From numerical studies, the following conclusions were reached. (1) Simulations could successfully reproduce the key features observed in experiment such as tensile failure termed "disking"at normal impacts and outwards bending of partially formed plus segments termed "hinge-mode"at oblique impacts. (2) Simulation results fur 60 degrees oblique impact at 0.70 km/s and 0.91 km/s were compared with experimental results and Eulerian hydrocode CTH simulation results. The Lagrangian code NET3D is superior to Eulerian code CTH in the computational accuracy. Agreement with the experimentally obtained final deformed cross-sections of the projectile is excellent. (3) Agreement with the experimental ballistic limit data, particularly at the high-obliquity impacts, is reasonably good. (4) The simulation result is not very sensitive to eroding condition but slightly influenced by friction coefficient.

• Journal of Information Display
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• 제3권2호
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• pp.13-18
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• 2002

Numerical simulation is one of the most useful tools to study gas discharge phenomena that occur in alternating current plasma display panel (AC-PDP) cell. Most PDP cell simulations have been performed for two-dimensional cell, is cross-section along the address electrode. We developed a three-dimensional PDP simulator and applied it to a T-shaped electrode cell in order to show the effects of sustain electrode shape that cannot be included in two-dimensional simulation. The dependence of power consumption on electrode shape and area in the simulation showed the same trend as experiment.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.213-220
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• 2010

This study presents a numerical simulation model of vertical ground heat exchangers, considering unsaturated hydro static ground conditions induced by the ground water table fluctuation. Heat transfer in ground and grout is modeled by a 3-D FEM transient conductive heat transfer model, where heat transfer between circulating fluid and heat exchanging pipe is treated as 1-D quasi steady state forced convective elements. To take into account the unsaturated ground condition, soil thermal conductivity and heat capacity which are dependent on the matric suction are applied to ground elements. Parametric studies considering various ground water table conditions are conducted to investigate the influence of unsaturated hydro static ground condition on the mean heat exchange rate of ground heat exchanger. Simulation results considering water table fluctuation show 60~100% of mean heat exchange rate for a saturated soil condition and 125~208% of that for a dry soil condition. Thus consideration of unsaturated soil condition is substantially recommended for more accurate design and performance evaluation for ground heat exchangers.

• 한국유체기계학회 논문집
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• 제4권3호
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• pp.14-20
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• 2001

Numerical analysis of the three dimensional turbulent flow field in a complex valve trim is carried out to confirm the possibility whether this simulation tool can be used as a design tool or not. The simulation of the incompressible flow in a glove valve is performed by using the commercial code. CFD-ACEA utilizes the finite volume approach as a discretization scheme, and the pressure-velocity coupling is made from SIMPLEC algorithm in it. Four flow cases of the control valve are investigated, and the valve flow coefficient for each case is compared with the experimental data. Simulation results show a good agreement with the experiments, and it is observed that the cavitation model improves the simulation results.