• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.196-199
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• 2010

본 연구는 판에 존재하는 유공형상에 따른 응력 집중 해석이다. 일반으로 판은 가공이 쉽고 제작이 편리하여 그 사용이 많다. 이러한 판의 연결에는 원형의 유공을 이용하는 경우가 많고 구조물의 중량감소를 목적으로 유공을 만드는 경우도 있다. 그러나 판에 존재하는 유공의 경우 응력 집중으로 인한 균열생성과 같은 단점을 가진다. 이를 보완하기 위해 유공부의 최적설계 및 응력해석과 같은 많은 연구들이 수행되고 있다. 본 연구에서는 원형, 정사각형과 정삼각형의 유공을 유한 요소 프로그램을 이용하여 시뮬레이션하고 유공형상에 따라 판에 발생하는 응답을 알아보았다. 또한 원형유공의 응답을 기준으로 정사각형과 정삼각형 유공의 모서리의 곡률반경을 변화시켰을 때 발생하는 응답을 비교하였다. 상용 유한 요소 프로그램인 ANSYS/Workbench를 사용하여 인장응력하의 유공판의 응답 해석을 수행하였으며 얻어진 결과를 유공의 형상, 곡률반경의 변화에 따라 분석하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.291-297
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• 2006

In this study, the equivalent physical properties of the shielded slot plate having a lot of very tiny bridge shape structures on its plane were determined by tensile tests and structural analyses. With those results, numerical analyses for the deflection profile by gravity effect were carried out to compare with experimental results. The two results were shown coincident very well so that the estimated equivalent physical properties were verified enough for further studies such as curvature reduction for the shielded slot plate.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.930-932
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• 2017

In this paper, prediction of progressive interlaminar fracture in curved composite laminates under mode I loading was described. The prediction of progressive interlaminar fracture in curved composite laminates was conducted using cohesive zone model(CZM) in ABAQUS V6.13. Interlaminar fracture toughness used as input parameters in CZM was obtained through mode I, mode II and mixed mode I/II tests. The behaviors of progressive interlaminar fracture for curved composite laminates showed a good agreement between experimental and numerical results.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.377-388
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• 2010

The flexural behavior of composite HSB600 and HSB800 I-girders under a positive moment was investigated using the material non-linear moment-curvature analysis method. Three representative composite sections with different ductility properties were selected as the baseline sections in this study. Using these baseline sections, the moment-curvature program was verified by comparing the flexural strength and the moment-curvature curve obtained from the program with those obtained using the non-linear FE analysis of ABAQUS. In the FE analysis, the composite girders were modeled three-dimensionally with flanges, the web, and the concrete slab as thin shell elements, and initial imperfections and residual stresses were imposed on the FE model. In the moment-curvature and FE analyses, the 28-day compressive strength of the concrete slab was assumed to be 30-50 MPa, and the HSB600 and HSB800 steels were modeled as elasto-plastic strain-hardening materials, with the concrete as the CEB-FIP model. The effects of the ductility ratio of the composite girder, the type of steel, the compressive strength of the concrete deck, and the location of the plastic neutral axis on the flexural characteristics were analyzed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.367-373
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• 2008

In the design of horizontally curved plate girder web panels, it is required to evaluate accurately the elastic buckling strength under pure shear. Currently, elastic shear buckling coefficients of curved web panels stiffened by transverse intermediate stiffeners are determined by assuming conservatively that straight web panels without curvature are simply supported at the juncture between the flange and web. However, depending upon the geometry and the properties of the curved plate girder, the elastically restrained support may behave rather closer to a fixed support. The buckling strength of curved girder web is much greater (maximum 38%) than that of a straight girder calculated under the assumption that all four edges are simply supported in Lee and Yoo (1999). In the present study, a series of numerical analyses based on a 3D finite element modeling is carried out to investigate the effects of geometric parameters on both the boundary condition at the juncture and the horizontal curvature of web panel, and the resulting data are quantified in a simple design equation.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.299-307
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• 2009

In this study, the acoustical properties of micro-speaker had been studied as a function of diaphragm patterns. The diaphragm was divided into two sections, such as edge and dome sides. The pattern change at each side affected the tensile strength of diaphragm. As a result, the resonance frequency was varied with the change. With increasing the number of pattern at the edge side, it was increased at the first, but it reversed to the exponential decrease of that. It increased due to the increase of tensile strength to be caused by using "U" type of drill and whirlwind pattern, and decreasing of drill angle at the edge side. However, it was decreased due to the decrease of tensile strength to be by increasing the number of radiation pattern and dome hight, and decreasing the dome radius at the dome side.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.420-425
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• 2000

The room-temperature shapes of cured unsymmetric composite laminates have out-of-plane warping after autoclave processing. In addition, they exhibit two stable room-temperature configurations due to snap-through phenomena when the side length of laminates exceeds a critical value. The cured shapes of unsymmetric laminates are influenced by many environmental factors. Experiments show that the effect of too-plate cannot be ignored and has significant influence on the cured shape of unsymmetric laminates. In this present study, approximations to the strain fields are used in the expression for the total potential energy and the Rayleigh-Ritz method is applied. The slippage effects resulting from the interaction between the laminates and the tool-plate are considered. By introducing a dimensionless slippage coefficient and correlating the corresponding value with experimental results, the influence of processing parameters is investigated. Modeling is extended to predict curvatures of plate configurations with various aspect ratio.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.385-395
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• 2011

The flexural strength of composite HSB hybrid I-girders under positive moment is investigated by the moment-curvature analysis method to evaluate the applicability of the current AASHTO LRFD design specification to such girders. The hybrid girders are assumed to have the top flange and the web fabricated from HSB600 steel and the bottom flange made of HSB800 steel. More than 6,200-composite I-girder sections that satisfy the section proportion limits of AASHTOL RFD specifications are generatedby the random sampling technique to consider a statistically meaningful wide range of section properties. The flexural capacities of the sections are calculated by the nonlinear moment-curvature analysis in which the HSB600 and HSB800 steels are modeled as an elastoplastic, strain-hardening material and the concrete as CEB-FIP model. The effects of ductility ratio and compressive strength of concrete slab on the flexural strength of composite hybrid girders make of HSB steels are analyzed. Numerical results indicated that the current AASHTO-LRFD equation can be used to calculate the flexural strength of composite hybrid girders fabricated from HSB steel.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.499-500
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• 2004

일반적으로 진동판의 크기와 형태는 스피커의 음파 방출 효율과 재생대역 및 왜곡특성을 결정하는 중요한 요인이다. 지금까지 대부분의 연구결과들은 직경 25mm 이상, 두께 0.1mm 이상의 다양한 소재의 진동판으로 이루어진 스피커들을 대상으로 하였다. 그러나 현재 수요가 급증하고 있는 마이크로스피커에 사용되는 진동판들은 직경이 20mm 이하이고, 그 두께는 수십 ${\mu}m$ 필름 소재를 사용하고 있다. 이러한 이유로 마이크로스피커의 동작특성은 일반적인 스피커에 비해 재생대역이 좁고, 고조파 왜가 크게 나타난다. 본 논문은 수 십 ${\mu}m$ 두께의 필름 진동판을 사용하는 마이크스피커의 설계 시, 기본적인 특성을 예측할 수 있도록 하기 위해 진동판의 두께 변화, 단면의 곡률변화에 따른 스피커의 특성 변화를 조사하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.38-47
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• 2013

For the joint connection of the precast steel grid composite decks, the prefabricated joint which is composed of concrete shear key and high-tension bolts was already proposed. In this study, for the purpose of increasing the bending stiffness and bending strength of the proposed prefabricated joint section details of the proposed joint are modified, and through experimental tests the bending performance, such as stiffness and strength of a modified joint, is compared with those of the proposed joint. Test and analysis results show that the shear cracks in the concrete shear key are clearly reduced by the strengthening of the shear key using shear studs and additional rebars. According to analysis results of the moment-curvature relationship, bending stiffness of the modified joint is about 47% greater than the stiffness of the proposed joint. Furthermore, the modified joint has about 32% greater bending strength than the proposed joint. Compared to specimens without the joint the modified joint has same or slightly higher bending strength, but about 37% lower bending stiffness.