• 대한기계학회논문집A
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• 제25권8호
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• pp.1206-1212
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• 2001

The kinematic analysis of Stewart platform manipulator(SPM) is carried out in order to reduce the calculation time for its forward kinematic solution when the iterative numerical method is employed. The kinematic equations for three substructures of the 6-3 SPM are newly derived by introducing Denavit-Hartenberg link parameters and using kinematic constraints associated with the SPM and substructure kinematics. It is shown that the forward kinematics can be easily solved from three nonlinear equations with three unknown variables only, leading to a great reduction in calculation time.

• 대한기계학회논문집
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• 제7권2호
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• pp.153-160
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• 1983

The flows in an axial flow turbomachine are calculated numerically in the two sets of flow surfaces of H-S and B-B surfaces assuming that the flow is axisymmetric. The calculation is performed by regarding the governing equations as the quasi-Poisson's equations and using the finite element method for the flow regions divided into triangular elements. The results of numerical calculation agree comparatively well with the experimental results and it has been found that the distribution of an axial velocity component at the rotor exit is not necessarily uniform under the influences of the inlet guide vanes and the front shape of the hub even if the rotor is designed by the free-vortex theory. Also it has been found that the existence of the optimum value of the blade number can be estimated from the results of calculation of deviation angles at rotor exit if we consider the viscous flow-loss, and that the flows of B-B surfaces are affected very sensitively by the degree of satisfaction of Kutta condition.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.633-637
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• 1995

Numerical calculation tool for forging of gear-like components based on kinematically admissible velocity fields for upper bound method applicable to various deformation features of workpiece in forging processes were suggested. Each one of them deals with unidirectional flow of metal on dies, such as external involute spur gear, sequare spline, internal serrations. A complex calcuation tool of gear-like component forging process was built up by combining these kinematically velocity fields. In this paper, the workpiece with both external and internal teeth is divided into two parts. The deformation of each part is analyzed simultaneously using numerical calculation tool form combined kinematically admissible velocity field. The experimental set-up was installed in a 200 ton hydraulic press. As a result, each kinematically admissible velocity field could be combined with other and the calculated solution are useful to predict the capacity of forging equipment.

• 설비공학논문집
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• 제10권6호
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• pp.658-665
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• 1998

This paper investigates local exhaust effectiveness in a room with a supply and an exhaust slots on the ceiling. The mean age of air is an indicator of supply effectiveness, while the mean residual life time can be used as an indicator of exhaust effectiveness. The distribution of local mean residual life time in a space is calculated by four different numerical procedures. The reverse-flow calculation method has been proved to show quite accurate results while it can save considerable amount of computation time and efforts, compared to the method by its original definition. It is concluded that the diffusion term in the equation of mean residual life time can be neglected. The spatial and temporal diffusion characteristics of the contaminant are also discussed.

• 한국환경과학회지
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• 제11권9호
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• pp.925-931
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• 2002

Land-use types should be included in air pollutant diffusion model because a complex mixture of various land-use patterns with computational grid can make errors in calculation of several parameters. However, the air pollutant diffusion model has generally been treated with a uniform component with land-use type in each mesh because of the complexity of the simulation. This study presents a numerical simulation of the horizontal distribution of $O_3$dry deposition velocity during summertime in Busan metropolitan city. The calculation of the meteorological field was conducted using the land cover data. Simulation has been performed by the following two scenarios : (1) one with current land cover data, and (2) the other with only land and sea for the surface characteristics. The results from each scenario reveals considerable differences on the meteorological fields and these differences can cause changes in the calculation values of $O_3$deposition velocity.

• 오토저널
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• 제6권4호
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• pp.54-61
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• 1984

Numerical calculation of the flow field past a passenger car was carried out by using a panel method with a small computer of 5Mbyte memory size. The shape of car body was simplified and reconstructed by 2180 panels on which a constant strength sink (or source) was distributed. The separation of flow from the surface and the wake flow were not considered in the calculation because of the computer memory limitation. All of the results of calculation were presented by using a 3-dimensional computer graphics. In spite of small memory size of computer, generally good agreements were obtained, except the separated region, from the comparison of pressure distribution between numerical analysis and wind tunnel experiment with 1/5 scaled model.

• 대한화학회지
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• 제60권3호
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• pp.163-168
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• 2016

비조화진동자의 진동에너지와 파동함수를 수치적으로 간단히 계산할 수 있는 Discrete Variable Representation 방법을 요약하고, Morse 진동자를 모형으로 활용하여 실제 분자계의 기본전이 및 들뜬 전이에너지를 구하는데 적용할 수 있는 최적의 변수 범위를 예측하였다.

• 대한기계학회논문집B
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• 제31권8호
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• pp.653-662
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• 2007

Due to the difficulty raised from the coupling of cavitation modeling with turbulent flow, numerical simulation for two phase flow remains one of the challenging issues in the society. This research focuses on the development of numerical code to deal with incompressible two phase flow around 2D hydrofoil by combing the cavitation model suggested by Kunz et al. with $k-{\varepsilon}$ turbulent model. The simulation results are compared to experimental data to verify the validity of the developed code. Also, the comparison of the calculation results is made with LES results to evaluate the capability of $k-{\varepsilon}$ turbulence model. The calculation results show very good agreement with experimental observations even though this code can not grasp the small scaled bubbles in the calculation wheres LES can hold the real physics. This code will be extended to 3D compressible two phase flow for the study on the fluid dynamics in the inducers and impellers.

• Steel and Composite Structures
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• 제20권3호
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• pp.599-621
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• 2016

In order to study the working mechanism of rectangular steel-concrete composite columns subjected to compression-bending load and further determine the seismic performance index, a bottom strengthened rectangular steel reinforced concrete (SRC) column with concealed steel plates and a bottom strengthened rectangular concrete filled steel tube (CFST) columns were proposed. Six column models with different configurations were tested under horizontal low cyclic loading. Based on the experiments, the load-bearing capacity, stiffness and degradation process, ductility, hysteretic energy dissipation capacity, and failure characteristics of the models were analyzed. The load-bearing capacity calculation formulas for a normal section and an oblique section of bottom strengthened rectangular steel-concrete composite columns were pesented and a finite element (FE) numerical simulation of the classical specimens was performed. The study shows that the load-bearing capacity, ductility, and seismic energy dissipation capacity of the bottom strengthened rectangular steel-concrete composite columns are significantly improved compared to the conventional rectangular steel-concrete composite columns and the results obtained from the calculation and the FE numerical simulation are in good agreement with those from the experiments. The rectangular steel-concrete composite column with bottom strengthened shows better seismic behavior and higher energy dissipation capacity under suitable constructional requirements and it can be applied to the structure design of high-rise buildings.

• 한국해양공학회지
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• 제16권1호
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• pp.22-26
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• 2002

In this paper, a finite element method is applied to the numerical calculation of the harbor calmness. The mild stop equation as the basic equation is used. The key of this model is that the bottom friction and boundary absorption are imposed. A numerical result is presented and compared with the results obtained from the other numerical analysis. These results are in very well agreement. This method calculating the calmness can be broadly utilized making the new design of harbor and fishing port in the future.