• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.471-479
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• 2004

In this study, a time-dependent constitutive model was developed for cohesive soils. A damage law was included in the model, using which the undrained creep behavior was predicted. The mathematical and physical derivation of the model was performed in the sense of adopting only few model parameters. The model prediction was well agreed with the experimental result of creep testing including creep rupture.

• Journal of the Korean GEO-environmental Society
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• v.25 no.4
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• pp.5-12
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• 2024

In the case of creating a site in the reclaimed land (public waters), due to the nature of the coastal sedimentary ground, large-scale construction materials are required, It is necessary to utilize soft clay, which is inevitably generated during construction of the complex, as a fill material in terms of resource recycling and economic aspects (reducing the amount of embankment required). In this study, changes in the consolidation characteristics of cut-out disturbed soft clay due to the recycling of soft clay soil were identified, and a consolidation settlement design plan was proposed. Through the results of the consolidation test of the study site, the change in consolidation characteristics (compression index reduction, precede load uncountable) due to disturbance (cutting) was confirmed, the method of calculating (consolidation settlement) the filling clay layer as the composite target layer (consolidation target layer, loading load layer) was analyzed as a result consistent with the actual behavior.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5A
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• pp.861-872
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• 2006

The element free Galerkin method is extended by the local partition of unity method to model the cohesive cracks in two dimensional continuum. The shape function of a particle whose domain of influence is completely cut by a crack is enriched by the step enrichment function. If the domain of influence contains a crack tip inside, it is enriched by a branch enrichment function which does not have the LEFM stress singularity. The discrete equations are obtained directly from the standard Galerkin method since the enrichment is only for the displacement field, which satisfies the local partition of unity. Because only particles whose domains of influence are influenced by a crack are enriched, the system matrix is still sparse so that the increase of the computational cost is minimized. The condition for crack growth in dynamic problems is obtained from the material instability; when the acoustic tensor loses the positive definiteness, a cohesive crack is inserted to the point so as to change the continuum to a discontiuum. The crack speed is naturally obtained from the criterion. It is found that this method is more accurate and converges faster than the classical meshless methods which are based on the visibility concept. In this paper, several well-known static and dynamic problems were solved to verify the method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.2
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• pp.77-81
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• 1981

1200.deg.C-1300.deg.C 의 열간 단조작업에서의 강철은 스트레인 속도에 민감하고 그 기계적인 특성방정식은 .delta.=.delta.$_{0}$ .epsilon.$^{m}$ 이다. 이 연구는 열간압출시 필요고 하는 작용력을, 상계이론을 사용하여 해석하고 쟤료의 기계적 특성상수들을 대입하여, 계산한다. 이 결과를 실험치와 비교하고 압출각, 마찰계수, 스트레인 속도와 점성계수등의 일반적인 영향에 대해서도 토의하였다.특히 변형역내의 평균스트레인 속도에 의한 일정 항복용력을 사용하였을 경우에 대해서도 비교 검토되었다.

• The Korean Journal of Rheology
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• v.9 no.2
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• pp.47-52
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• 1997

식품유변학은 식품재료로 사용하는 생물체와 세포내외의 생체고분자물질의 물성을 주로 대상으로 하는 학문영역이다. 이들 물질들의 가공적성을 평가하고 공정관리를 수행하 기 위하여 점성, 소성, 점탄성 등유변학적 파라메터들이 사용된다. 또한 제춤의 관능적, 특성 특히 조직감(texture)특성을 나타내는 지표로서 유변학적 성질들이 자주 사용되고 있다. 본 고에서는 식품 유변학의 특징가 발전역사를 개관하고 1990년도 이후 국내에서 연구 발표된 식품유변학 분야의 연구내용을 액상식품, 젤화식품, 식물세포조직으로 구분하여 소개하였다.

• Geotechnical Engineering
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• v.10 no.1
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• pp.71-82
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• 1994

According to the field measurement of dredging-reclaimed land, the actual self-weight consolidation settlement has been frequently reported to be less than the predicted values based on the laboratory tests results. The author estimates that one of the reasons is the reduction of the compressibility due to the sedimentation of the dredging material, Furthemore, the aging effect is ignored in the consolidation characteristics of the very low stress range as a pump dredging-reclaimed land. In this paper, a series of seepage consotidation tests has been carried out by applying the seepage force to the specimen prepared by sedimentation in consolidmeter in order to clarflfy the aging-effect on the compressibility of dredging clayey soil, Also, with a view to overcome unstable consolidation solution occurring in the case where the initial water content is higher as pumpdredging reclaimed land, the finite difference analysis technique using predictorforrector method is suggested that it gets good agreement with ezperimental results. Finally, the compressibility of the dredging clayey soil is depended on self-weight consolidation time.

• Journal of the Korean GEO-environmental Society
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• v.12 no.5
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• pp.29-36
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• 2011

In this study, settling experiment was performed about cohesive and sandy soils among representative sample expected to dredge and dump for analysis of settling and consolidation characteristic. The analysis showed the definite difference between cohesive soils and sandy soils of relationships with settling and consolidation coefficient, a water content, interfacial heights. But directly after a dredged reclamation, prediction results about a initial volume change showed that cohesive soil of a water content change was decreased rapidly as time goes by, but sandy soils made no difference in a water content change. Results were compared and analyzed with the settling and consolidation coefficient and a initial settling velocity by real soil amounts for a feasibility check about test conditions applied to these experiment: we judge that test conditions are appropriate, each material by such these analyses suggests the scope of settling and consolidation coefficient, average and the representative relational formula.

• Geotechnical Engineering
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• v.5 no.2
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• pp.45-56
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• 1989

The influence of stress path on the deformation characteristics of clay has been studied through a series of stress-path controlled triaxial tests on artificially sedimented and normally con- solidated Kaolinite. It has been found that there exists a critical stress increment ratio, Kc, in which stress·strain characteristics possesses a linear relationships and beyond Kc, strain hardening. A modified hyperbolic constitutive model for the strain hardening behavior has been formulated based on the Drnevich's hyperbolic function. And, a method of settlement analyses has been Proposed wherein the effect of stress path during consolidation is taken into account.

• Composites Research
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• v.12 no.1
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• pp.11-18
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• 1999

The compression molding is widely used in the automotive industry to produce products that are large, thin, lightweight and stiff. The molded product is formed by squeezing a fiber-reinforced plastic composites. During a molding process of fiber reinforced thermoplastic composites, control of filling patterns in mold, orientation and distribution of fibers are needed to predict the effects of molding parameters on the flow characteristics. It is the objective of this paper to develop an isothermal compression molding simulation that can handle both thin and thick charges and motion of the flow front, and can predict pressure distributions and accurate velocity gradients. The composites are treated as an incompressible Newtonian fluid. The effects of slip parameter $\alpha$ and extensional/shear viscosity ratio $\zeta$ on the mold filling parameters are also discussed.

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.37-45
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• 2010

The particle size of microfine cement(MC) is so small that it can be injected into silt layer. But the more particle size is miniaturized, the more the cohesion increases. This phenomenon results in the decrease of the perviousness of MC. In this study, the grouting effects of microfine cement with superplasticizer to maintain cohesion low and that of normal cement were investigated in rock. To estimate the grouting effects, TCR/RQD test for rock quality, lugeon test, borehole loading test for coefficients of elastic and deformative stress, borehole shear test for shear stress, detection p~q~t(pressure~flow~time) chart tests were carried out. The results using MC show a better permeability, modulus of elasticity, deformation, charge per unit, and recover efficiency of grouting material than those of ordinary portland cement except shear stress.