• Steel and Composite Structures
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• 제23권6호
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• pp.623-631
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• 2017

Present paper deals with the temperature-dependent buckling analysis of sandwich nanocomposite plates resting on elastic medium subjected to magnetic field. The lamina layers are reinforced with carbon nanotubes (CNTs) as uniform and functionally graded (FG). The elastic medium is considered as orthotropic Pasternak foundation with considering the effects of thermal loading on the spring and shear constants of medium. Mixture rule is utilized for obtaining the effective material properties of each layer. Adopting the Reddy shear deformation plate theory, the governing equations are derived based on energy method and Hamilton's principle. The buckling load of the structure is calculated with the Navier's method for the simply supported sandwich nanocomposite plates. Parametric study is conducted on the combined effects of the volume percent and distribution types of the CNTs, temperature change, elastic medium, magnetic field and geometrical parameters of the plates on the buckling load of the sandwich structure. The results show that FGX distribution of the CNTs leads to higher stiffness and consequently higher buckling load. In addition, considering the magnetic field increases the buckling load of the sandwich nanocomposite plate.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.550-553
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• 2008

In this paper, experiments of air-breathing proton exchange membrane fuel cell (PEMFC) for mobile devices were carried out according to the cathode conditions. These conditions are defined by the cathode flow field plate type (the channel type, the open type) and the cathode surface direction. Single cell and 6-cell stack were used in this experiments. The experimental results showed that the open type cathode flow field plate gave better performance for small size PEMFCs because the open type cathode plate allowed better air convection than the channel type cathode plate. In the experiments related to the direction of the slits on the cathode flow field plate, the horizontal slit cell was better than the vertical slit cell. With respect to the cathode surface direction, when the cathode surface is placed in the direction normal to the ground, PEMFC generated more stable power in the mass transport loss region.

• Earthquakes and Structures
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• 제15권3호
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• pp.285-294
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• 2018

In this study, nonlinear dynamic response of a concrete plate retrofit with Aluminium oxide ($Al_2O_3$) under seismic load and magnetic field is investigated. The plate is a composite reinforced by Aluminium oxide with characteristics of the equivalent composite being determined using Mori-Tanka model considering agglomeration effect. The plate is simulated with higher order shear deformation plate model. Employing nonlinear strains-displacements, stress-strain, the energy equations of column was obtained and using Hamilton's principal, the governing equations were derived. Differential quadrature method (DQM) in conjunction with Newark method is applied for obtaining the dynamic response of structure. The influences of magnetic field, volume percent of nanoparticles, geometrical parameters of column, agglomeration and boundary conditions on the dynamic response were investigated. Results showed that with increasing volume percent of nanoparticles, the dynamic deflection decreases.

• 소음진동
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• 제7권3호
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• pp.457-466
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• 1997

The experimental and analytical study was conducted to determine the noise transmission characteristics of acoustically loaded steel plate of rectangular enclosure and to investigate the sound radiation characteristics through out the enclosure. The vibrations of acoustically loaded plate give rise to sound radiations and generate the reverberant space that the sound field exists very close to a vibrating plate. Acoustic transmission loss is measured from the incident intensity into the plate and the transmitted intensity through out the plate. Sound radiation patterns are measured from both acoustic intensity technique and surface intensity technique. Those resultant patterns and vibrational modes are vital in understanding the relations between vibration and noise in the near field out of vibrating plate.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.375-376
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• 2006

Turbulent structure of a boundary-layer over a flat plate coated with micro riblet film(MRF) has been investigated experimentally. The turbulent structure was visualized using a dynamic particle image velocimetry (Dynamic PIV) system. We identified the vortex structures from 2-D velocity field data by applying the complex eigenvalue definition. The velocity field images acquired by using the complex eigenvalue definition showed the whole 2-D vortex structures clearly. In addition, the spatial distributions of small-scale vortices as well as large-scale vortices were obtained with high accuracy. The difference of vortex structures between the MRF coated flat plate and the smooth flat plate was analysed in detail. With varying upstream flow speed, the characteristics of vortex structure over the MRF coated flate plate was compared with those over the smooth flat plate.

• 한국지반공학회논문집
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• 제21권6호
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• pp.67-79
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• 2005

현장 평판재하시험은 평판에 작용하는 하중과 변위를 동시에 측정하기 때문에 역학적인 특성치 결정의 가능성이 높은 시험방법이다. 그러나 지금까지 평판재하시험으로부터 추정한 탄성계수는 일정 변위를 유발한 하중강도하에서의 지지력계수로부터 구한 하나의 상수값으로서, 이는 포장구조에서 노상이 경험하는 사용하중 단계에서의 대표적인 변형특성치로 결정하기에는 어려움이 있다. 포장설계시 사용되는 회복탄성계수 개념의 변형계수는 중간변형률$(0.01\%\sim0.1\%)$ 영역에서의 값으로서, 현장 노상토의 경우에도 이와 같은 변형률 범위에서의 변형계수를 평가하는 것이 중요하다. 본 논문에서는 노상 현장에서 반복평판재하시험을 이용하여 중간변형률 영역에서의 변형계수를 산정하는 방법을 제안하였다. 이의 신뢰성을 검토하기 위하여 현장에서 크로스홀 시험과 실내에서 공진주시험을 수행하여 전체변형률 영역에서의 현장의 변형특성을 평가하여 평판재하시험 결과와 비교하였다. 두 시험결과 사이의 응력상태를 고려하면 변형률에 따른 변형계수의 값과 경향이 비교적 일치하였고, 제안된 반복식 평판재하시험을통해 현장변형계수의 평가가 가능함을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제53권6호
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• pp.1201-1214
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• 2015

This paper introduces the combined effect of electric field, magnetic field and thermal field on edge wave propagating in a homogeneous isotropic prestressed plate of finite thickness and infinite length. The dispersion relation of edge wave has been obtained by using classical dynamical theory of thermoelasticity. The phase velocity has been computed and shown graphically for various initial stress parameter, electro-magneto parameter, electric parameter and thermoelastic coupling parameter.

• 대한기계학회논문집B
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• 제30권2호
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• pp.177-185
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• 2006

This study aims deriving analysis the flow characteristic of kitchen hood system with using 3-D numerical analysis method and improving the system to expel pollutes more efficiently. To understand the flow characteristics of four models, this study only focuses on velocity field, temperature field, and concentration field varying with followings whether separation plate is set or not and the shapes of separation plates. The quantity of air, speed of exhaust fan and temperature and concentration of heating source are concerned as constant values. The three models having different shapes have one exhaust port and the model which has the vent at the closest position to where pollutes are generated is discovered to be the most efficient model. Compare to the initial model (having no separation plate), it was $1.4-1.9\%$ more efficient at temperature distribution and $9.4-11.9\%$ more at $CO_2$ concentration distribution.

• 한국환경복원기술학회지
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• 제10권6호
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• pp.44-52
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• 2007

Recently, oystershell wastes cause serious environmental problem and the need for the researches on the recycling of oystershell have been increased and various methods are already in operation. Field plate bearing tests and numerical analysis were performed to investigate the bearing capacity of oystershell filled geotextile gabion which utilized the waste oystershell at the coastal oyster farm site. The waste oystershell mixed soil specimens were prepared for the laboratory test and field test in terms of varying blending ratio of granite soil and oystershell. Based on the cyclic plate load test results, the spring constant, subgrade modulus of ground, and the reinforcing parameters were determined. The field plate load test results indicate that the bearing capacity of the soil ground with the oystershell mixed ratio of 20% is greater than that of the original ground. Two-dimensional numerical analysis was evaluated the expected deformation in the given conditions. Analysis results show a similar characteristics on bearing capacity with the results of the field plate load test. These findings suggest that the oystershells are very promising construction materials for landfill and earth embankment in coastal area.

• Structural Engineering and Mechanics
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• 제34권2호
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• pp.143-157
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• 2010

This paper presents theoretical solutions for the three-dimensional (3D) stress field in an infinite isotropic elastic plate containing a through-the-thickness circular hole subjected to far-field in-plane loads by using Kane and Mindlin's assumption. The dangerous position, where the premature fracture or failure of the plate will take place, the expressions of the tangential stress at the surface of the hole and the out-of-plane stress constraint factor are found in a concise, explicit form. Based on the present theoretical solutions, a comprehensive analysis is performed on the deviated degree of the in-plane stresses from the related plane stress solutions, stress concentration and out-of-plane constraint, and the emphasis has been placed on the effects of the plate thickness, Poisson's ratio and the far-field in-plane loads on the stress field. The analytical solution shows that the effects of the plate thickness and Poisson's ratio on the deviation of the 3D in-plane stress components is obvious and could not be ignored, although their effects on distributions of the in-plane stress components are slight, and that the effect of the far-field in-plane loads is just on the contrary of that of the above two. When only the shear stress is loaded at far field, the stress concentration factor reach its peak value about 8.9% higher than that of the plane stress solutions, and the out-of-plane stress constraint factor can reach 1 at the surface of the hole and is the biggest among all cases considered.