• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.913-914
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• 2010

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2008년도 춘계학술발표대회 개요집
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• pp.16-16
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• 2008

• Structural Engineering and Mechanics
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• 제43권2호
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• pp.253-271
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• 2012

To analyze the bending and transverse shear effects of laminated composite plates, a thirteen nodes triangular element will be presented. The suggested formulations consider a parabolic variation of the transverse shear strains through the thickness. As a result, there is no need to use shear correction coefficients in computing the shear stresses. The proposed element can model both thin and thick plates without any problems, such as shear locking and spurious modes. Moreover, the effectiveness of $w_{,n}$, as an independent degree of freedom, is concluded by the present study. To perform the accuracy tests, several examples will be solved. Numerical results for the orthotropic materials with different boundary conditions, shapes, number of layers, thickness ratios and fiber orientations will be presented. The suggested element calculates the deflections and stresses more accurate than those available in the literature.

• Steel and Composite Structures
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• 제8권4호
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• pp.281-296
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• 2008

Visco-elastic material and thin metals were adhered to plate structures, forming the composite components that are similar to the sandwich plates, called constrained layered damped (CLD) plates. Constrained layer damping has been utilized for years to reduce vibration, and advances in computation and finite element analysis software have enabled various problems to be solved by computer. However, some problems consume much calculation time. The vibration equation for a constrained layered damped plate with simple supports and an impact force is obtained theoretically herein. Then, the results of the vibration equation are compared with those obtained using the finite element method (FEM) software, ABAQUS, to verify the accuracy of the theory. Finally, the 3M constrained layer damper SJ-2052 was attached to plates to form constrained layered damped plates, and the vibration equation was used to elucidate the damping effects and vibration characteristics.

• Steel and Composite Structures
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• 제44권1호
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• pp.91-104
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• 2022

The purpose of the present work is to study the parametric nonlinear vibration behavior of three layered symmetric laminated plate. In the analytical formulation; both normal and shear deformations are considered in the core layer by means of the refined higher-order zig-zag theory. Harmonic balance method in conjunction with Galerkin procedure is adopted for simply supported laminate plate, to obtain its natural and damping properties. For these aims, a set of complex amplitude equations governed by complex parameters are written accounting for the geometric nonlinearity and viscoelastic damping factor. The frequency response curves are presented and discussed by varying the material and geometric properties of the core layer.

• 한국축산시설환경학회지
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• 제19권1호
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• pp.33-38
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• 2013

We conducted investigations of the information and welfare of broiler chickens in Korea. The livestock housing of all broiler chicken farms were windowless type, bell feeder and nipple waterer were used, and stocking density was relatively higher (ranging from 18.2 $birds/m^2$ to 24.2 $birds/m^2$) than RSPCA's welfare standards for chicken hens (less than 19 $birds/m^2$). The ratios of sandwich panel, urethane form, slate, and steel plate in roofing materials were 61%, 21%, 13%, and 5%, respectively. The ratios of sandwich panel, urethane form, brick, and steel plate in wall materials were 61%, 21%, 13%, and 5%, respectively. The ratios of soil and concrete in flooring materials were 10% and 90%. The mist spray, fan, and cooling pad in cooling facilities were 42%, 32%, and 26%, respectively. Thus we believe that present data contribute to develop the animal welfare certification for broiler chickens and to improve animal welfare in Korea.

• Steel and Composite Structures
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• 제48권1호
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• pp.1-17
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• 2023

The main goal of this paper is to study vibration of damaged core laminated sectorial plates with Functionally graded (FG) face sheets based on three-dimensional theory of elasticity. The structures are made of a damaged isotropic core and two external face sheets. These skins are strengthened at the nanoscale level by randomly oriented Carbon nanotubes (CNTs) and are reinforced at the microscale stage by oriented straight fibers. These reinforcing phases are included in a polymer matrix and a three-phase approach based on the Eshelby-Mori-Tanaka scheme and on the Halpin-Tsai approach, which is developed to compute the overall mechanical properties of the composite material. Three complicated equations of motion for the sectorial plates under consideration are semi-analytically solved by using 2-D differential quadrature method. Using the 2-D differential quadrature method in the r- and z-directions, allows one to deal with sandwich annular sector plate with arbitrary thickness distribution of material properties and also to implement the effects of different boundary conditions of the structure efficiently and in an exact manner. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. The sandwich annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free. Several parametric analyses are carried out to investigate the mechanical behavior of these multi-layered structures depending on the damage features, through-the-thickness distribution and boundary conditions.

• 복합신소재구조학회 논문집
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• 제1권2호
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• pp.44-50
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• 2010

본 연구에서는 노후교량 바닥판 대체용으로 단품(Modular) GFRP 바닥판 구조에 대한 거동분석을 실험을 통행 실시하였다. 그 바닥판의 성능평가로서 축소모형(1/5)의 시험편 3개에 대한 실험적 연구를 수행하였다. 시험편은 박스튜브를 갖는 샌드위치 판이다. 교량바닥판의 구성재료는 유리섬유와 에폭시 레진이다. 모든 시험편에 대한 실험결과로서 최대강도, 강성 및 변형능력으로 나타내었다. 실험적 결과의 타당성을 검증하기 위해 유한요소해석을 하여 비교하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.189-190
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• 2006

A patient table considering x-ray transparency, mechanical safety and compact multi-axis moving mechanism has been developed. The goal of medical imaging technology is to keep radiation exposure of patients during x-raying to a minimum. In order to obtain clear pictures at low dose, however, the x-ray table which supports the patient must be sufficiently permeable to radiation to allow good image resolution. The table top is made of low density foam for x-ray transparent effective area and structural aluminum plate to connect moving mechanism under the table, covered with thin carbon fiber. This sandwich construction is very rigid and lightweight, so the table top can handle relatively heavy load comparing to its cantilevered structure which is unavoidable as long as cooperate with C-arm radiography. To verify the design results finite element static analysis and experimental tests have been done. According to the verification the results well satisfy certification guide lines as a medical device.

• Advances in Computational Design
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• 제5권1호
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• pp.55-89
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• 2020

For the first time, an accurate analytical solution, based on coupled three-dimensional (3D) piezoelasticity equations, is presented for free vibration analysis of the angle-ply elastic and piezoelectric flat laminated panels under arbitrary boundary conditions. The present analytical solution is applicable to composite, sandwich and hybrid panels having arbitrary angle-ply lay-up, material properties, and boundary conditions. The modified Hamiltons principle approach has been applied to derive the weak form of governing equations where stresses, displacements, electric potential, and electric displacement field variables are considered as primary variables. Thereafter, multi-term multi-field extended Kantorovich approach (MMEKM) is employed to transform the governing equation into two sets of algebraic-ordinary differential equations (ODEs), one along in-plane (x) and other along the thickness (z) direction, respectively. These ODEs are solved in closed-form manner, which ensures the same order of accuracy for all the variables (stresses, displacements, and electric variables) by satisfying the boundary and continuity equations in exact manners. A robust algorithm is developed for extracting the natural frequencies and mode shapes. The numerical results are reported for various configurations such as elastic panels, sandwich panels and piezoelectric panels under different sets of boundary conditions. The effect of ply-angle and thickness to span ratio (s) on the dynamic behavior of the panels are also investigated. The presented 3D analytical solution will be helpful in the assessment of various 1D theories and numerical methods.