• Geomechanics and Engineering
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• 제12권2호
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• pp.223-238
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• 2017

In this study, bearing capacities and settlement profiles of six irregularly shaped footings located on sand have been experimentally and analytically investigated under the effect of axial loading. The main variable considered in the study was the geometry of the footings. The axial loads were applied from the center of gravities of the test specimens. Consequently, the effect of footing shape on the variation of the bearing capacities and settlement profiles have been investigated in this paper. The three dimensional finite element analyses of the test specimens were conducted using the PLAXIS 3D software. The finite element model results are in acceptable agreement with the results obtained using experimental investigation. In addition, the usability of the finite element technique by design engineers to determine the bearing capacities and settlement profiles of irregularly shaped footings was investigated. From the results of the study, it was observed that the geometric properties of the footings significantly influenced the variation of the bearing capacities and settlement profiles.

• Geomechanics and Engineering
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• 제31권4호
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• pp.375-384
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• 2022

The variation of the undrained shear strength (c_u) is an important consideration for assessing slope stability in engineering practice. Previous studies focused on the three-dimensional (3D) stability of slopes in normally consolidated clays generally assume the undrained shear strength increases linearly with depth but does not vary in the horizontal direction. To assess the 3D stability of slopes with spatially varying undrained shear strength, the kinematic approach of limit analysis was adopted to obtain the upper bound solution to the stability number based on a modified failure mechanism. Three types failure mechanism: the toe failure, face failure and below-toe failure were considered. A serious of charts was then presented to illustrate the effect of key parameters on the slope stability and failure geometry. It was found that the stability and failure geometry of slopes are significantly influenced by the gradient of c_u in the depth direction. The influence of c_u profile inclination on the slope stability was found to be pronounced when the increasing gradient of c_u in the depth direction is large. Slopes with larger width-to-height ratio B/H are more sensitive to the variation of c_u profile inclination.

• 대한기계학회논문집A
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• 제33권9호
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• pp.903-912
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• 2009

This study is focused on simulation-based dimensional tolerance optimization process (DTOP) to minimize vehicle pulls by reduction of dimensional variation in front suspension system. In previous studies, the effect of tires and wheel alignment sensitivity have mainly been investigated to eliminate vehicle pulls in nominal design condition without allocating optimal tolerance level for selected components, among various factors regarding vehicle pulls such as vehicle design parameters, vehicle weight balance, tires, and environmental factors. Unfortunately, there are wide variations in the real vehicle, and these have impacted actual vehicle pulls, especially wheel alignment effects from suspension geometry variation has not been considered in the previous studies. In the tolerance design of suspension, tolerance variables with the uncertainty such as parts dimensional variation, assembly process, datum position and direction, and assembly tool tolerance has a great influence on the variation of the suspension dimensional performances. This study introduces total vehicle pull prediction model in considering major key factors for vehicle pull sensitivity. The Monte Carlo-based tolerance analysis model using Taguchi robust method is developed to optimize dimensional tolerance parameters, satisfying on the target variation level.

• 한국자동차공학회논문집
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• 제8권4호
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• pp.93-99
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• 2000

It is well known that an automotive muffle strongly influences engine efficiency and noise reduction. The performance of a muffler system is determined by the geometrical parameters such as the relative location of an inlet and outlet pipe size and cross sectional geometry of a chamber. In this study numerical analysis was performed to examine the flow characteristics in the simple automotive muffler for the variation of volumetric rate and offset. The computational grid generation was carried out. The RNG k-$\varepsilon$ turbulence model was applied. To provide the boundary condition for numerical analysis the experimental measurement wes carried out. As a result of this study we could understand that there was a recirculation flow inside muffler and pressure loss depends on the variation of volumetric rate and offset.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.583-584
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• 2006

This paper presents transistor matching in 70 nm nMOS. To adopt radio frequency(RF) applications, the RF performance, especially the current gain cutoff frequency($f_T$), is examined experimentally through a wafer. It is proved that the RF performance variation of 70 nm nMOS is dependent to the device geometry, the total width(W). The RF performance variation of 70 nm nMOS is inversely proportional to square root of total width(W). Also, decreasing of the number of fingers($N_f$) is helpful to decrease the variation of 70 nm nMOS.

• 대한기계학회논문집A
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• 제30권1호
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• pp.52-59
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• 2006

The vibration of hydraulic piston pumps is induced by the periodically changing cylinder chamber pressure whose waveform is significantly influenced by valve plate geometry. In this study, the force input to the housing of a bent-axis type hydraulic piston pump was computed by deriving the dynamic equations of its piston and cylinder barrel. The vibration intensity of the pump was represented by the acceleration amplitude of its housing. In order to comparatively evaluate the influence of valve plate geometry on the vibration of pump housing, two different types of valve plate were tested. The computed results showed good agreement with the experimental data, indicating that the vibration acceleration of pump housing is rather dependent on the variation amplitude of balance coefficient than the changing slope or overshoot of cylinder chamber pressure. It was also confirmed that the design effect of valve plates could be directly examined out by monitoring the vibration acceleration of pump housing.

• 대한기계학회논문집B
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• 제21권6호
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• pp.725-734
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• 1997

The effect of helical intake port geometry on in-cylinder swirl flow characteristics was studied. Two helical intake ports were selected to change swirl ratio, mean flow coefficient with the variation of valve lifts, valve eccentricity ratios and axial distance. The measurements were made by using an impulse swirl meter. The port B modified to increase the swirl ratio( $R_{s}$) had the tendency of the increased non-dimensional rig swirl ( $N_{r}$) distribution in comparison with that of the port A. And the $N_{r}$ distribution was remarkably improved at low valve lifts. The modification of the geometry to increase the swirl ratio ( $R_{s}$) in helical intake port resulted in the decrease of the mean flow coefficient ( $C_{f(mean)}$) regardless of valve eccentricity ratio ( $N_{y}$). And also non-dimensional rig swirl ( $N_{r}$) in the high valve lift affected the calculation of swirl ratio considerably.onsiderably.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.14-17
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• 1999

The wrinkling behavior of a thin sheet with perfect geometry is a kind of compressive instability. The compressive instability is influenced by many factors such as stress state mechanical properties of the sheet material geometry of the body contact conditions and plastic anisotropy. The analysis of compressive instability in plastically deforming body is difficult considering all the factors because the effects of the factors are very complex and the instability behavior may show wide variation for small deviation of the factors. In this study the bifurcation theory is introduced for the finite element analysis of puckering initiation and growth of a thin sheet with perfect geometry. All the above mentioned analysis and the post-bifurcation behavior is analyzed by introducing the branching scheme proposed by Riks. The finite element formulation is based on the incremental deformation theory and elastic-plastic material modeling. in order to investigate the effect of plastic anisotropy on the compressive instability a square plate that is subjected to compression in one direction and tension in the other direction is analyzed by the above-mentionedfinite element analysis. The critical stress ratios above which the buckling does not take place are found for various plastic anisotropic modeling method and discussed. Finally the effect of plastic anisotropy on the puckering behavior in the spherical cup deep drawing process is investigated.

• 한국기계가공학회지
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• 제12권6호
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• pp.101-108
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• 2013

An aircraft fuel hose is a kind of high pressure hose, and generally consists of a nipple, a socket, an inner tube, and a reinforcement layer to increase the tensile strength. Especially the nipple supports the other components in manufacturing stages such as the swaging or crimping processes however, the nipple also serves to prevent leakage in cases of hose engagement with a hydraulic system. To ensure the seal of the hose assembly, a beam seal fitting with metal-to-metal contact is usually adopted at the end of a nipple. Therefore, the geometry of the beam is an important parameter to be determined to make sure there is sufficient contact force. This study aims to investigate the effects of beam seal geometry on the contact force by changing the inclined angle and the thickness of the beam. The results reveal that the proper thickness and inclined angle of the beam seal are 0.45 mm and $8.5^{\circ}$, respectively.

• 한국지반공학회지:지반
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• 제1권2호
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• pp.7-16
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• 1985

성토 하에 매설된 강성관에 있어서 관의 두께, 매설상태, 성토높이, 성토흙의 탄성계수, 트렌치의 폭 및 깊이 등이 매설관에 작용하는 응력에 미치는 영향에 대해서 유한요소법의 선형해석을 이용하여 검토하였다. 관 주위의 수직접촉헌력의 분포와 수직하중을 선형중도귀식으로 나타내었으며, Marston-Spangler 이론에 의해서 구한 수직하중은 유한요소해석에 의한 값보다 일반적으로 크다. 그리고 Marston Spangler이론에서 이용되는 침하비는 항상 일정하지 않고 위에서 언급한 여러가지 요인의 유기에 따라서 달라진다는 사실을 알았다.