• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.99-104
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• 1998

A study is carried out to investigate the characteristics of concrete various level(0~60%) of fly ash. These results indicate that compressive strength of fly ash concrete seems to be slightly higher than that of ordinary concrete between 7 and 28 days, thereafter the strength of fly ash concrete is significantly higher. In fresh properties of the fly ash concrete, the loss of slump and air content with time up to 120 minutes is lower, but the setting time is increased with increasing fly ash content.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.410-417
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• 2000

The strength properties of Light-Weighted Soils(LWS) mixed with Expanded Polystrene(E.P.S.) using uniaxial and triaxial tests are studied. Test results show that when the initial water contents of dredged soils are under 135% and the cement contents are above 1%, Light-Weight Soils are in the appropriate strength range of 2.0 lo 4.0kg/$\textrm{cm}^2$. However. E.P.S. contents had a little effects on the strength properties of LWS.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.330-335
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• 1999

The objective of this stu요 was to develop a polymer mortar guide block for the blind handicapped people. A high strength and a long durability polymer concrete using unsaturated polyester resin was used to developed the block and to improve the exiting cement mortar guide bloc. Physical and mechanical properties of the polymer mortar guide block were investigated with respect to absorptivity, impact strength, bending strength compared to those of the conventional cement guide block. The polymer mortar guide block was proven to have properties , indication that the block have better industrial applications.

• Computers and Concrete
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• 제21권6호
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• pp.623-635
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• 2018

In order to research the influence of different recycled aggregate contents on the mechanical properties of pervious concrete, the experimental study and numerical simulation analysis of the mechanical properties of pervious concrete with five kinds of recycled aggregates contents (0%, 25%, 50%, 75% and 100%) are carried out in this paper. The experimental test were first performed on concrete specimens of different sizes in order to determine the influence of recycled aggregate on the compressive strength and splitting tensile strength, direct tension strength and bending strength. Then, the development of the internal cracks of pervious concrete under different working conditions is studied more intuitively by $PFC^{3D}$. The experimental results show that the concrete compressive strength, tensile strength and bending strength decrease with the increase of the recycled aggregate contents. This trend of reduction is not only related to the brittleness of recycled aggregate concrete, but also to the weak viscosity of recycled aggregate and cement paste. It is found that the fracture surface of pervious concrete with recycled aggregate is smoother than that of natural aggregate pervious concrete by $PFC^{3D}$, which means that the bridging effect is weakened in the stress transfer between the left and right sides of the crack. Through the analysis of the development of the internal cracks, the recycled aggregate concrete generated more cracks than the natural aggregate concrete, which means that the recycled aggregate concrete is easier to form a coalescence fracture surface and eventually break.

• 품질경영학회지
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• 제42권4호
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• pp.757-768
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• 2014

Purpose: In this paper we present a case study of developing fast curing adhesives for insulation material of LNG carriers using an extreme vertices design with four mixture components. Three material properties are considered - shear strength, viscosity, and tensile strength. In the optimization experiment, we used hardness instead of tensile strength due to shortage of specimens. Methods: We employ four-factor extreme vertices design with 19 runs and desirability function approach for simultaneously optimizing three responses. After selecting optimal condition of the mixture components, we do confirmation experiments to verify the reproducibility of the optimal condition under manufacturing circumstance. Results: Simultaneous optimal condition for the three responses, that is, shear strength, viscosity, and harness is obtained. At the optimal condition, confirmation experiments are executed in manufacturing circumstance. The variation for the shear strength is not satisfactory, which is due to the variation of the humidity. Conclusion: At the optimal condition three material properties are satisfactory. To reduce the variability for the shear strength, robust design is needed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.232-238
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• 1996

In this paper, the properties of high-strength concrete are described with respect to materials and mix conditions(water-cement ratio, chemical admixture, replacement of fly ash). As primary purposes of this study, the optimum mix design method of high-strength concrete to decrease unit cement contents is investigated, and the properties of fresh and hardened concretes are tested in terms of slump, air content and compressive strength. As results of this study, workability and strength development of the high-strength concrete depend on the water-cement ratio, replacement ratio of fly ash and dosage of the chemical admixture. The conditions which are proposed optimum mix design of the high-strength concrete show W/C 37%, S/A 42~45% and unit cement content 470~480kg/$\textrm{m}^3$. Based on the results, the applicability of high-strength concrete in site is clearly proved.

• 소성∙가공
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• 제23권2호
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• pp.110-115
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• 2014

Low cycle fatigue characteristics are very important in the development of automobile suspension parts. Fatigue properties using the strain life approach are usually obtained from low cycle fatigue tests. However, low cycle fatigue testing requires a lot of time and cost. In the current study, an attempt to estimate low cycle fatigue properties of high strength steel sheet from tensile test and tensile simulations is performed. In addition, low cycle fatigue testing was conducted to compare the fatigue properties obtained from tensile testing and simulations. In conclusion, the results effectively predict the low cycle fatigue properties. However, some deviations still exist.

• 콘크리트학회지
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• 제8권5호
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• pp.156-162
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• 1996

고강도콘크리트에 매립된 철근의 부착특성을 실험적으로 규명하기 위하여 80개의 보단부형 시험체에 대한 부착실험을 수행하였다. 실험의 변수로는 콘크리트의 압축강도를 주변수로 선정하고 그 외 부착특성에 영향을 미치는 여러 요인 중 부착길이, 피복두께, 철근 직경 등을 변수로 선정하여 각 변수의 영향을 콘크리트의 압축강도와 비교하도록 하였다. 본 연구의 주요 결과를 살펴보면 고강도콘크리트에서의 부착강도는 부착길이의 증가에 직접적으로 비례하지는 않는 것으로 나타났다. 이러한 결과는 콘크리트의 강도가 증대함에 따라 더욱 큰 영향을 미치게 되는데 고강도콘크리트에서는 부착길이를 증가시키더라도 철근과의 부착강도는 상당히 제한된 증가를 나타나는데 불과하였다. 한편 부착강도와 피복두께와의 관계는 콘크리트의 강도에 관계없이 선형으로 비례하는 것으로 나타났으며, 특히 콘크리트의 강도가 증가함에 따라 그 비례상수는 오히려 더 증가함을 알 수 있었다.

• 한국재료학회지
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• 제13권7호
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• pp.453-459
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• 2003

In this paper the effect of interstitial heat treatment on the microstructure and mechanical properties was examined both in the 0.15C-6Mn steels and 0.15C-6Mn steels added with Nb or Ti. This result will be applied into the development of a steel which has the properties of high strength and high ductility resulted from the transformation induced plasticity. The strength-elongation combination was increased as the holding time was increased when the temperature is at $625^{\circ}C$. However, the strength-elongation combination was decreased sharply as the holding time was increased when the temperature is at $675^{\circ}C$. The tensile strength and elongation of a reverse transformed steels added with Ti or Nb was 93 kg/$\textrm{mm}^2$ and 40%, respectively. This steel shows higher strength more than 10% of the 0.15C-6Mn steel without loss of ductility. The autenite formed from the reverse transformed treatment has a fine lath type, which has the width size of 0.1-0.3 $\mu\textrm{m}$. The TRIP sequence normally transforms the austenite to martensite, however, some of the sequence will produce retained austenite \longrightarrow deformation twin \longrightarrow martensite

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.9-12
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• 2007

Recently, research and development related to high strength concrete for the high rise and large scale reinforced concrete building has been actively promoted in worldwide by national and private research project. But, it is reported that violent explosive explosion would be happened when it was exposed in fire. In the existed study, a explosion in a reinforced concrete structure looses the organism by the different contraction and expansion of hardened cement paste and aggregate, and causes crack by thermal stress. In case of the Europe, Japan and America, they have studied the explosion for a long time. However it would hardly study the explosion in domestic, So it is needed base on mechanical properties of fire deterioration in high strength concrete. Therefore, this study is intend as an mechanical properties of specimen to high heating by heating and load test machine and $700^{\circ}C$. As a result, it is willing to propose fundamental data for quick and accurate diagnosis of deteriorated concrete structure by fire damage with experiment according to the design high strength concrete.