• 한국유체기계학회 논문집
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• 제15권4호
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• pp.55-60
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• 2012

The purpose of this study is to investigate the buckling load of filament-wound composite towers for large scale wind-turbine using finite element method(FEM). To define material properties, we used both the effective property method and the stacking properties method. The effective properties method is to assume that composite consists of one ply. The stacking properties method is to assume that composite consists of some stacked plies. First, linear buckling analysis of the tower, filament-wounded with angles of [${\pm}30$] was carried out by two methods for composite material properties, the stacking method and the effective method. and FE analysis was performed for the composite towers according to filament winding angles of [${\pm}30$], [${\pm}45$], [${\pm}60$]. FE analysis results using the stacking properties of the composite were in good agreement with the results by the effective properties. The difference between FEM results by material properties methods was approximately 0~2.3% in buckling Analysis and approximately 0~0.6% in modal analysis. And above the angle of [${\pm}60$], there was a little change of buckling load.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.306-313
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• 2005

For seismic response analysis of rockfill dam, dynamic material properties, by field test, are needed. Density and elastic wave profiles have to be known to get an information of the material properties of structure. In this study, various field tests are applied to the example of rockfill dam to get an information of dynamic material properties and seismic safety is evaluated by seismic response analysis with the result of field tests.

• 한국농공학회논문집
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• 제54권4호
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• pp.39-46
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• 2012

The objectives of this study is intended to analyze stresses using the boundary element method and probability analysis for agricultural structure. Loads and material properties are an important factor when analyzing the structure. Until now, designing structure, loads and material properties are applied deterministic value. However, load and material properties involve uncertainties due to those change probabilistic and deterministic methods could not consider uncertainties. To solve these problems, the reliability analysis based on probability properties scheme was developed. Reliability analysis is easy to approach to analysis frame structure, however it has limitation when solving plane stress strain problems a kind of agricultural structures. The BEM (Boundary Element Method) is able to analysis plane strain problems by boundary conditions. Thus, this study applied boundary element method to analysis plane strain problem, load and material properties as a probabilistic value to calculate the analytical model using Monte Carlo simulations were developed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.31-36
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• 2003

In this study a relationship between SP curves and tensile properties was investigated by FE analysis on SP test with various assumed tensile properties. For the accuracy of FE analysis, SP test and tensile test were performed and those results were compared with FE analysis results. The yield load(Py) defined from the intersection point of two lines tangent to the elastic bending region and plastic bending region. And it was related specifically with yield stress(${\sigma}_0$) in FE analysis result curves. The slopes of FE analysis result curves normalized by yield stress(${\sigma}_0$) reflected the change of tensile properties regardless of yield stress(${\sigma}_0$) variation. Empirical relations were derived from these results. Tensile properties from these relations showed good agreement in FE analysis curve and tested curve.

• 한국군사과학기술학회지
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• 제6권4호
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• pp.63-72
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• 2003

This paper deals with the analysis of composite sabot of APFSDS projectile. Unlike conventional composite parts, the sabot is composed of thick-sectioned lamination, and thus requires 3-dimensional properties in the analysis. In this study, a model was formulated to calculate the equivalent composites properties. The equivalent properties were then used in the finite element analysis and the results were compared with those by the full 3-dimensional analysis with ply-by-ply modeling. The results generally agreed with each other in the bound of 20% error, indicating that the formulated model produced the equivalent properties with reasonable accuracy. It was thought to be an efficient approach to use the model in global analysis and then perform the full 3-dimensional analysis in regions of interest for detailed evaluation in designing the composite sabot structure.

• 전기학회논문지
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• 제61권12호
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• pp.1813-1819
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• 2012

This paper presents vector magnetic properties of an electrical steel sheet (ESS) employed for electric machine and iron loss analysis considering the vector magnetic properties of the ESS. The vector magnetic properties of the ESS are measured by using a two-dimensional single sheet tester and modeled by an E&S vector hysteresis model to be applied to finite element method. The finite element analysis considering the vector magnetic properties is applied to iron loss analysis of a three-phase induction motor model, and the influences of the vector magnetic properties on the iron loss distribution are verified by comparing with numerical results from a typical B-H curve model.

• Geomechanics and Engineering
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• 제37권3호
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• pp.253-262
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• 2024

Dynamic properties are pivotal in soil analysis, yet their experimental determination is hampered by complex methodologies and the need for costly equipment. This study aims to predict dynamic soil properties using static properties that are relatively easier to obtain, employing machine learning techniques. The static properties considered include soil cohesion, friction angle, water content, specific gravity, and compressional strength. In contrast, the dynamic properties of interest are the velocities of compressional and shear waves. Data for this study are sourced from 26 boreholes, as detailed in a geotechnical investigation report database, comprising a total of 130 data points. An importance analysis, grounded in the random forest algorithm, is conducted to evaluate the significance of each dynamic property. This analysis informs the prediction of dynamic properties, prioritizing those static properties identified as most influential. The efficacy of these predictions is quantified using the coefficient of determination, which indicated exceptionally high reliability, with values reaching 0.99 in both training and testing phases when all input properties are considered. The conventional method is used for predicting dynamic properties through Standard Penetration Test (SPT) and compared the outcomes with this technique. The error ratio has decreased by approximately 0.95, thereby validating its reliability. This research marks a significant advancement in the indirect estimation of the relationship between static and dynamic soil properties through the application of machine learning techniques.

• Composites Research
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• 제16권4호
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• pp.59-65
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• 2003

샌드위치 구조물의 응용된 형태인 스마트 스킨 구조물을 ABAQUS로 유탄요소 해석하였다. 심재로 쓰이는 하니컴은 일반적으로 두께 방향 강성 및 전단 강성만 제작회사에 의하여 제공된다. 이를 바탕으로 하니컴 재료의 물성을 추정하여 다른 방향의 제공되지 않는 물성을 계산하였고, 이를 유탄요소 해석시 물성 자료로 적용하였다. 또한, 스마트 스킨 구조물의 좌굴 및 3점 굽힘 거동을 유한요소 해석하였으며, 기존의 실험결과 및 이론값과 비교 분석하였다. 비교적 결과가 잘 일치하였다. 본 연구를 통하여서 하니컴의 물성을 상용 패키지에 적용하는 방법 및 타당한 근거를 제시하였고, 이 결과를 바탕으로 스마트 스킨 구조물을 상용패키지로 유한요소 해석시 지침을 제시할 수 있다

• 한국해양공학회지
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• 제25권2호
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• pp.73-78
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• 2011

The purpose of this study was to investigate the natural frequency of filament-wound composite towers for large scale wind-turbines using the finite element method (FEM). To define the material properties, we used both the effective property method and the stacking properties method. The effective properties method assumes that a composite consists of one ply. The stacking properties method assumes that a composite consists of several stacked plies. First, a modal analysis of the tower, filament-wound with angles of $[{\pm}30]$, was carried out using the two methods for composite material properties, the stacking method and effective method. Then, an FE analysis was performed for composite towers using filament winding angles of $[{\pm}30]$, $[{\pm}45]$, and $[{\pm}60]$. The FE analysis results using the stacking properties of the composite were in good agreement with the results from the effective properties method. The difference between the FEM and material properties methods was approximately 0~0.6%

• 한국해양공학회지
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• 제25권2호
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• pp.79-84
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• 2011

The purpose of this study was to investigate the buckling load of filament-wound composite towers for large scale wind-turbines using the finite element method (FEM). To define the material properties, we used both the effective property method and stacking properties method. The effective properties method assumes that a composite consists of one ply. The stacking properties method assumes that a composite consists of several stacked plies. First, a linear buckling analysis of the tower, filament-wound with angles of $[{\pm}60]$, was carried out using the two methods for composite material properties: the stacking method and effective method. An FE analysis was also performed for the composite towers using the filament winding angles of $[{\pm}30]$, $[{\pm}45]$, and $[{\pm}60]$. The FE analysis results using the stacking properties of the composite were in good agreement with the results from the effective properties method. The difference between the FEM results and material properties method was approximately 0~2.3%. Above the angle of $[{\pm}60]$, there was little change in the buckling load.