• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.713-722
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• 1991

본 연구에서는 graphite/epoxy와 glass/epoxy 그리고 graphite/epoxy와 kevl- ar/epoxy의 혼합적층된 복합재료 평판의 저속충격에 대한 응답을 유한요소 모델을 사 용하여 수치해석 한후, 각각의 단일적층판들의 결과와 비교하였으며, 이때의 접촉력 관계식은 Yang과 Sun이 제안한 수정된 접촉법칙을 이용하였다. 또한, 수치해석 결과 에서의 충격자의 속도변화로써 혼합적창판 배열에 따른 에너지 흡수율을 계산하였고, 이를 충격특성이 취약한 graphite/epoxy 단일 적층판의 결과와 비교 고찰하였다.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.399-404
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• 2000

Functionally graded materials(FGMs) involve dual-phase graded layers in which two different constituents are mixed continuously and functionally according to a given volume fraction. For the analysis of their thermo-mechanical response, conventional homogenized methods have been widely employed in order to estimate equivalent material properties of the graded layer. However, such overall estimations are insufficient to accurately predict the local behavior. In this paper, we compare the thermo-elastic behaviors predicted by several overall material-property estimation techniques with those obtained by discrete analysis models utilizing the finite element method, for various volume fractions and loading conditions.

• Journal of Industrial Technology
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• v.19
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• pp.253-260
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• 1999

Two thermodynamic models were used to predict the partial molar volumes of solutes in supercritical carbon dioxide at infinite dilution: (1) the Peng-Robinson equation of state with various mixing rules including those based on $EOS/G^E$ (2) the Kirkwood Buff fluctuation integral with the hard sphere expansion (HSE) method. The Kirkwood-Buff fluctuation integral method, in which an equation of state for pure component and molecular parameters are required, produced better results especially near the critical point than the Peng-Robinson equation of state with the several mixing rules based an $EOS/G^E$. When the $EOS/G^E$ mixing rules were used, poorer results were obtained compared with the classical mixing rule and Kirkwood-Buff model.

• Clean Technology
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• v.15 no.3
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• pp.172-179
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• 2009

The thermoplastic polyurethane waste (TPU-S) with good tensile properties, hardness, NBS abrasion resistance, specific gravity and low wet coefficient of kinetic friction was melt-blended with ethylene propylene diene monomer rubber (EPDM) with high wet slip resistance and low mechanical properties to form EPDM/TPU-S blend films, and their composition-property relationship was investigated to find the optimum composition for shoe outsole material. The properties except the wet slip resistance increased with increasing TPU-S contents in the blend. All the properties except elongation at break, specific gravity and the wet coefficient of kinetic friction in the range of $0{\sim}65\;wt%$ of TPU-S did not attain the values predicted by the simple additive rule. The optimum weight ratio of EPDM/TPU-S for the application to the typical shoe outsole material was found to be 30/70.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.661-669
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• 1997

This paper presents a theoretical analysis for a velocity profile of fluid-granule mixed flow and a sheet erosion of an embankment having noncohesive materials due to overflow. The velocity profile were obtained using the stress-strain relationships based on a grain-inertia regime and an erosion depth was obtained using dynamic Coulomb criterion. Experiments were performed to compare with theoretical values and fairly good agreements were found. Theoretical results on velocity profiles, which can be applied to any type of velocity profiles in a fluid-granule mixed flow, showed a considerable improvement for the existing theories on a debris flow. for a design purpose, formulas and figure diagrams for obtaining a velocity profile, an erosion depth, an overflow depth and a granular discharge were proposed for given values of a flood discharge, particle properties and embankment scale.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.23-31
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• 2012

Present work deals three families of $SiO_2$ gelling agents which have been used to produce gel fuel based on Kerosene. Jet A-1 is chosen as fuel where power-law rheological model is used to confirm whether or not the gelification is achieved depending on the %wt of gellant. It was confirmed that the produced jelly-like substance have shear-thinning effect, and that its apparent viscosity increases as $SiO_2$ concentration increases. Compared to other gellants, gel with Aerosil(R) R972 fits most to the power-law model, while gels with Silica 230 and Silica 530 deviate from the power-law model. The rheological characteristics behaved differently depending on the mixing method(vortex mixing and manual mixing) when gellant concentration is increased.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.1
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• pp.13-20
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• 2008

Graded layers in which two different constituent particles are mixed are inserted into functionally graded material such that the volume fractions of constituent particles vary continuously and functionally over the entire material domain. The material properties of this dual-phase graded region, which is essential for the numerical analysis of the thermo-mechanical behavior of FGM, have been predicted by traditional homogenization methods. But, these methods are limited to predict the global equivalent material properties of FGMs because the detailed geometry information such as the particel shape and the dispersion structure is not considered. In this context, this study intends to investigate the characteristics of these homogenization methods through the finite element analysis utilizing the discrete micromechanics models of the graded layer, for various volume fractions and external loading conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.3
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• pp.319-326
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• 1985

본 연구에서는 준 3차원 유한요소법(quasi 3-D finite element method)을 사 용하여 균일한 변위하중뿐 아니라 적층판의 제작 공정상 필연적인 열하중(thermal loading)의 영향을 동시에 고려하여 층간균열의 발생 및 성장에 대한 특성을 밝히고자 한다. 끝으로 층간 균열이 인장강도에 미치는 영향을 혼합법칙(rule of mixtures)의 개념을 사용하여 평가하고자 한다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.3
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• pp.79-84
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• 1998

It is very difficult to analyze the transient temperature distribution during quenching of the steel because of coupled effects among temperature, structures and stresses. In this paper, using Inoue's equation of evolution and mixture rule, transient temperature distribution is calculated by the finite element method considering latent heat of transformation structure and temperature dependence of physical and mechanical prperties for the 0.45% carbon cylindrical steel bar with 40mm diameter and 20mm height during end-quenching.

• Journal of Energy Engineering
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• v.10 no.2
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• pp.153-160
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• 2001

본 연구에서는 고온 분위기 온도 및 대기압 하에서 액적의 급속가열과 연소가 가능한 고온 연소로 장치와 고속도 비디오 카메라를 이용하여 다조성 단일 액적 연소에 대해 고찰하였다. 그 결과 저비점 성분을 혼합한 경유의 액적은 기본적으로 입경의 2승 법칙에 의해서 감소되었으며, 그 과정에서 입경이 일시적으로 급속히 감소하는 현상이 보여짐과 더불어 연소기간도 단축되었다. 즉, 저비점 성분을 혼합한 경유의 액적은 미세폭발 현상에 의해 기존 디젤 연료에 비해 더 빨리 증발되고 연소가 되었다. 또한, 순수 파라핀계 및 함산소계 연료의 화염은 전체 연소기간동안 기존 경유의 화염에 비해 푸른색을 띠고 있어, 매연이 없는 연소를 입증해 주었다.