• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1942-1947
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• 2003

The valve is the key part which governs the efficiency, noise and reliability of the compressor, so the development of analytical model about valve performance is necessary. As the valve leed is opened and closed by pressure pulsation, the flow characteristic of the refrigerant passing the valve is very important. In the present study, a circular disk with inclination is assumed to be the valve reed of a reciprocating compressor and numerical analysis of three dimensional velocity fields are perfomed for the radial flow through the valve model. The effective flow and force area which are required to predict the efficiency of the valve are measured and compared with the numerical analysis in this research.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.157-162
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• 2003

This study is analysis on the heat transfer of exhaust gas into the muffler at passenger Car. Numerical analysis with Computational fluid Dynamics(CFD) was carried out to investigate exhaust gas flow. The STAR-CD S/W used for the three dimensional steady state CFD analysis in a muffler. The Navier-Stokes Equation is solved with the SIMPLE method in a general cartesian coordinates system. Result of numerical simulation; Inlet and outlet temperature shown about ${\Delta}T=239K$, 216K, 202K at in the muffler. Heat transfer was progressed quickly by atmospheric temperature of muffler external at in the near wall.

• Structural Engineering and Mechanics
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• 제12권4호
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• pp.377-396
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• 2001

The excessive cracking of RC cantilever decks, which often requires special attention for structural engineers, is studied using a three-dimensional crack analysis model. The model is based on a fracture energy approach for analyzing cracks in concrete, and the numerical analysis is carried out using a modified load control method. The problem of excessive cracking is then studied with four different span-ratios. Based on the numerical results, the crack behavior with respect to the patterns of crack propagation, dissipation of the fracture energy, and effects on the structural integrity are discussed. The mechanisms which cause the excessive cracking are also explained.

• Structural Engineering and Mechanics
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• 제27권1호
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• pp.1-16
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• 2007

In the present study, a spline finite strip with higher-order shear deformation is formulated for the stability and free vibration analysis of composite plates. The analysis is conducted based on Reddy's third-order shear deformation theory, Touratier's "Sine" model, Afaq's exponential model and Cho's higher-order zigzag laminate theory. Consequently, the shear correction coefficients are not required in the analysis, and an improved accuracy for thick laminates is achieved. The numerical results, based on different shear deformation theories, are presented in comparison with the three-dimensional elasticity solutions. The effects of length-to-thickness ratio, fibre orientation, and boundary conditions on the critical buckling loads and natural frequencies are investigated through numerical examples.

• 한국유체기계학회 논문집
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• 제12권3호
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• pp.13-18
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• 2009

This paper describes flow characteristics in a piping system having various duct shapes on refuse collecting system. A simulator for the refuse collecting system is designed to analyze the flow characteristics in the piping system. The simulator consists of an air intake, a waste chute, circular duct having various shapes, cyclone and turbo blower. The simulator has four different duct shapes: straight, curved, inclined and Y-shaped ducts. Three-dimensional Navier-Stokes analysis is introduced to analyze the pressure loss in the piping system. Throughout the numerical simulation, pressure loss obtained by numerical simulation has a good agreement with the results of experimental measurements. The selected length of curved and Y-ducts for the pressure loss is determined using pressure distributions on the duct. Flow and pressure characteristics in the piping system of the simulator are evaluated by numerical simulation and discussed in detail.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.490-496
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• 2006

In order to design accurately plastic board drain (PBB) method, it is important to determine the equivalent circle of PBD. In this paper, a series of numerical analyses on soft ground improved by PBD were carried out, in order to investigate the resonable equivalent circle of PBD considering consolidation behavior of improved soft ground by PBD. The applicability of numerical analyses, in which an elasto-viscoplastic three-dimensional consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of soft ground improved by PBD. And, through the results of the numerical analyses, consolidation behaviors of soft ground during consolidation was elucidated, together with the equivalent circle of PBD considering consolidation behaviors.

• 대한기계학회논문집B
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• 제21권9호
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• pp.1230-1243
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• 1997

A numerical technique for simulating incompressible viscous flow with free surface is presented. The flow field is obtained by penalty finite element formulation. In this work, a modified volume of fluid (VOF) method which is compatible with 4-node element is proposed to track the moving free surface. This scheme can be applied to irregular mesh system, and can be easily extended to three dimensional geometries. Numerical analyses were done for two benchmark examples, namely the broken dam problem and the solitary wave propagation problem. The numerical results were in close agreement with the existing data. Illustrative examples were studied to show the effectiveness of the proposed numerical scheme.

• 한국유체기계학회 논문집
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• 제7권4호
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• pp.40-46
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• 2004

This paper is concerned with the numerical analyses of an S-shaped duct for the inter-channel between compressor spools. For the compactness and lightweight of an engine, the length of the S-shaped duct is desired to be minimized. Shortening the S-shaped duct, however, flow separation is likely to occur. Numerical investigation using a three-dimensional Navier-Stokes flow solver was performed to determine the availability of the minimization of an S-shaped duct. Computations were performed introducing the experimental data as the inlet flow condition of the OGV in determining the minimum length of the S-shaped duct. Also, the leaning effect of the OGV which assists the flow to turn radially inward was studied adopting mixing-plane method to consider the rotor/OGV interaction.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3472-3484
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• 2023

The objective of this research is to assess the seismic performance of different types of electrical cabinets in nuclear power plants. The cabinets under investigation are: (a) Case 1: a short single cabinet; (b) Case 2: a tall single cabinet; (c) Case 3: separated cabinets; and (d) Case 4: a combined cabinet with coupling effects. To accurately capture the real behavior of the cabinet, three-dimensional finite element models are developed using ANSYS with connection non-linearity. Frequency domain decomposition (FDD) is used to determine the dynamic properties of the cabinets from shaking table testing data, and these results are utilized to validate the numerical model. The close match between the experimental and numerical results obtained from the modal analysis demonstrates the accuracy of the numerical model. Subsequently, transient structural analysis is performed on the validated models to explore seismic performance. The results show that the acceleration response of the combined cabinet is lower than the single cabinet and the separated cabinet. This observation suggests that top anchors used to combine two different types of cabinets play a crucial role in assessing the efficiency and seismic resistance of electrical cabinets in a nuclear power plant.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.211-218
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• 2000

Hot spot behaviors on the disk-pad contact surface during a braking operation have been analyzed for a ventilated disk brake using the finite element method. Hot spots which were studied using a coupled thermal-mechanical analysis technique are influenced by all of the mechanical, thermal, elastic and plastic processes that are involved in braking cycles, but their temperature gradients are most affected by rubbing speeds, braking forces, and design parameters between the disk and the pad. Undesirable hot spots that are generated by local thermoelastic instabilities are intended to be removed by optimized design parameters and material properties. In this study, a three-dimensional numerical method for the demonstration of hot spot behaviors has been applied to the rubbing surfaces between the disk and the pad.