• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.154-155
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• 2017

With the recent development in construction industry, industrial by-products fly ash(FA) and blast furnace slag(BS) have been used in large quantities as an alternative to cement, as a solution for environmental problems and resource exhaustion. This study analyzed the basic characteristics according to the changes in replacement ratio and mixing ratio of FA and BS in high strength SCMs concrete, from which in turn it sought to find the optimal mixing ratio for high strength concrete The results showed that in unhardened concrete the more the replacement ratio and FA mixing ratio increases the slump flow will increase while amount of air decreases, and setting time is delayed. In hardened concrete the more the replacement ratio and FA mixing ratio increases the more the overall compression strength decreases, but until 28 days of material age the larger of the BS ratio displayed the best compression strength.

• 한국식품저장유통학회지
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• 제7권2호
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• pp.160-165
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• 2000

The study aimed to review linerboard compositions of corrugated fiberboard boxes for Oriental melons(Cucumis melon L. var makuwa), analyzing relationships among material compositions, price, weight of boxes, theoretical compression and bursting strength of various liner boards. 19 and 22 different liner boards were currently used for the bleached and the unbleached corrugated boards, respectively. The corrugated board containers with the bleached liners were mostly used in the market although the average price was 10 percents higher than the unbleached. The average compression strength of the bleached. We strongly recommend to redesign the boxes because the average compression and bursting strength of the current boxes were much higher than national packaging standards as much as 70 and 82, respectively.

• Steel and Composite Structures
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• 제29권4호
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• pp.509-526
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• 2018

The direct strength method adopted by the AISI Standard and AS/NZS 4600 is an advanced design method meant to substitute the effective width method for the design of cold-formed steel structural members accounting for local instability of thin plate elements. It was proven that the design strength formula for the direct strength method could predict the ultimate strength of medium strength steel welded section compressive and flexural members with local buckling reasonably. This paper focuses on the modification of the direct strength formula for the application to high strength and high performance steel welded section columns which have the nominal yield stress higher than 460 MPa and undergo local buckling, overall buckling or their interaction. The resistance of high strength steel welded H and Box section columns calculated by the proposed direct strength formulae were validated by comparison with various compression test results, FE results, and predictions by existing specifications.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.571-572
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• 2009

초고강도 콘크리트의 개발에 따라 철근 압축이음에 대한 연구 필요성이 높아지고 있다. 현행 설계 기준에서 콘크리트강도와 횡보강근의 영향을 고려하지 않기 때문에 압축이음길이가 인장이음길이보다 길어지는 기현상(奇現象)이 발생한다. 본 연구에서는 51개 실험체의 결과를 바탕으로 40MPa부터 70MPa까지 콘크리트에 대한 압축이음길이 설계식을 제안하였다. 본 연구에서 제안된 압축이음길이 설계식을 이용하여 고강도 콘크리트에서 압축이음길이가 인장이음길이보다 길어지는 이상 현상을 해소할 수 있다. 더불어 제안된 압축이음길이 설계식은 통계적 기법에 기반을 두어 재료강도와 동일한 수준의 신뢰성을 확보할 수 있다.

• Structural Engineering and Mechanics
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• 제12권5호
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• pp.459-474
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• 2001

The complete moment-curvature curves of doubly reinforced concrete beams made of normal- or high-strength concrete have been evaluated using a newly developed analytical method that takes into account the stress-path dependence of the constitutive properties of the materials. From the moment-curvature curves and the strain distribution results obtained, the post-peak behavior and flexural ductility of doubly reinforced normal- and high-strength concrete beam sections are studied. It is found that the major factors affecting the flexural ductility of reinforced concrete beam sections are the tension steel ratio, compression steel ratio and concrete grade. Generally, the flexural ductility decreases as the amount of tension reinforcement increases, but increases as the amount of compression reinforcement increases. However, the effect of the concrete grade on flexural ductility is fairly complicated, as will be explained in the paper. Quantitative analysis of such effects has been carried out and a formula for direct evaluation of the flexural ductility of doubly reinforced concrete sections developed. The formula should be useful for the ductility design of doubly reinforced normal- and high-strength concrete beams.

• 한국지반신소재학회논문집
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• 제7권2호
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• pp.1-5
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• 2008

일반적인 콘크리트 건축물이나 도로포장에서 발생되는 부등침하는 건물의 붕괴나 도로의 수명저하로 인한 비용을 증가시킨다. 이에 대하여 침하된 구조물 하부지반에 그라우팅 공법을 이용하여 지반침하복원을 실시한다. 그러나 기존 그라우트 공법의 경우, 강도발현기간이 길고, 보강효과가 지속적이지 못한 단점을 지니고 있다. 이를 보완하기 위한 주입재료로써, 고밀도 팽창 재료의 특성을 평가하였다. 지반상태와 팽창재료의 주입량의 변화에 따른 압축강도의 변화와 화학물질에 대한 안정성 시험 및 SEM 촬영을 통하여 특성을 연구하였다. 압축강도는 다른 물질과의 혼합으로 높은 강도가 발현되었으며, 화학적 저항성은 대부분의 조건에서 반응하지 않았으나 알코올계열에 변화가 발생하였다. SEM 촬영을 통하여 강도발현에 있어서 조직구성이 촘촘할수록 치밀하게 구성된다고 판단하였다.

• Steel and Composite Structures
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• 제17권4호
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• pp.497-516
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• 2014

The ultimate carrying capacity of axially loaded welded square box section members made of medium and high strength steels (nominal yield stresses varying from 345 MPa to 460 MPa), with large width-to-thickness ratios ranging from 35 to 70, is analyzed by finite element method (FEM). At the same time, the numerical results are compared with the predicted results using Direct Strength Method (DSM), modified DSM and Effective Yield Strength Method (EYSM). It shows that curve a, rather than curve b recommended in Code for design of steel structures GB50017-2003, should be used to check the local-overall interaction buckling strength of welded square section columns fabricated from medium and high strength steels when using DSM, modified DSM and EYSM. Despite all this, EYSM is conservative. Compared to EYSM and modified DSM, DSM provides a better prediction of the ultimate capacities of welded square box compression members with large width-thickness ratios over a wide range of width-thickness ratios, slenderness ratios and steel grades. However, for high strength steels (nominal yield strength greater than 460 MPa), the numerical and existent experimental results indicate that DSM overestimates the load-carrying capacities of the columns with width-thickness ratio smaller than 45 and slenderness ratio less than 80. Further, for the purpose of making it suitable for a wider scope, DSM has been modified (called proposed modified DSM). The proposed modified DSM is in excellent agreement with the numerical and existing experimental results.

• 한국공간구조학회논문집
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• 제1권2호
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• pp.67-74
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• 2001

This paper is to estimate the load carrying capacities of concrete-filled steel tubular columns and the important parameters are selected the size, length and concrete strength. he concrete-filled tube structures has many excellent structural properties, that is, high load capacity, good plastic deformation and high resistance local buckling. Under these background, this study Investigated to the structural compression behaviors, the maximum strength, the confinement effects, the fracture mechanism, local buckling failure and concrete strength effects.

• Korea-Australia Rheology Journal
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• 제18권4호
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• pp.183-189
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• 2006

High internal phase emulsions are highly concentrated emulsion systems consisting of a large volume of dispersed phase above 0.74. The rheological properties of high internal phase water-in-oil emulsions were measured conducting steady shear, oscillatory shear and creep/recovery experiments. It was found that the yield stress is inversely proportional to the drop size with the exponent of values between 1 and 2. Since the oil phase contains monomeric species, microcellular foams can easily be prepared from high internal phase emulsions. In this study, the microcellular foams combining a couple of thickeners into the conventional formulation of styrene and water system were investigated to understand the effect of viscosity ratio on cell size. Cell size variation on thickener concentration could be explained by a dimensional analysis between the capillary number and the viscosity ratio. Compression properties of foam are important end use properties in many practical applications. Crush strength and Young's modulus of microcellular foams polymerized from high internal phase emulsions were measured and compared from compression tests. Of the foams tested in this study, the foam prepared from the organoclay having reactive group as an oil phase thickener showed outstanding compression properties.

• Design & Manufacturing
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• 제17권1호
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• pp.48-55
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• 2023

In this study, on the structure simulation for manufacturing a high strength/light weight 48V battery housing for a mild hybrid vehicle was conducted. Compression analysis was performed in accordance with the international safety standards(ECE R100) for existing battery housings. The effect of plastic materials on compressive strength was analyzed. Three models of truss, honeycomb and grid rib for the battery housing were designed and the strength characteristics of the proposed models were analyzed through nonlinear buckling analysis. The effects of the previous existing rib, double-sided grid rib, double-sided honeycomb rib and double-sided grid rib with a subtractive draft for the upper cover on the compressive strength in each axial direction were examined. It was confirmed that the truss rib reinforcement of the battery housing was very effective compared to the existing model and it was also confirmed that the rib of the upper cover had no significant effect. In the results of individual 3-axis compression analysis, the compression load in the lateral long axis direction was the least and this result was found to be very important to achieve the overall goal in designing the battery housing. To reduce the weight of the presented battery housing model, the cell molding method was applied. It was confirmed that it was very effective in reducing injection pressure, clamping force and weight.