• 한국안전학회지
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• 제31권4호
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• pp.75-81
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• 2016

This study presents the effect of urea and sulfur admixture on compressive strength, chloride diffusion coefficient, and internal void distribution of concrete. Compressive strength of concretes with urea admixture by 5% increased by 5% relative to Control. However, that of concretes with urea admixture over 10% decreased. Chloride diffusion coefficient of concrete with urea and sulfur admixture decreased by 40% relative to Control. Additionally, the volume of internal void of concrete with urea and sulfur admixture decreased by 20% relative to Control. Therefore, it can be mentioned from test results that the use of adequate urea and sulfur admixture improves the mechanical properties and durability of concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.185-188
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• 2005

This study selected three different specified concrete strength types of mixture which were applied to domestic seawater concrete structure and measured compressive strength and chloride diffusion coefficient and composed the formula of prediction model of chloride diffusion coefficient in order to provide the useful data for concrete mix decision of seawater structures. As a result, the formula of prediction model of chloride diffusion coefficient which set W/C and compressive strength as parameters and performed multiplex regression analysis which was based on the mathematical theory was confirmed more reliable than the formula of prediction which was composed existing water-cement ratio function.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.953-956
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• 2008

본 연구에서는 불포화폴리에스터 수지(U.P.)를 이용한 투수성 폴리머 콘크리트를 제조하여 투수성 및 강도 특성을 실험적으로 규명하였다. 그 결과 투수성 폴리머 콘크리트의 공극률 및 투수계수는 폴리머 결합재량의 증가에 따라 감소하는 경향을 나타내었다. 또한 투수성 폴리머 콘크리트의 압축강도는 폴리머 결합재량의 증가에 따라 감소하는 경향을 나타내었다. 투수성 폴리머 콘크리트의 압축강도는 투수계수가 증가함에 따라 감소하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술.기술논문발표회
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• pp.11-15
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• 2002

This study is intended to analyze the relationship between the rebound value of P type schmidt hammer and the compressive strength for a quality control of concrete. According to the results, the compressive strength of standard curing specimen increases in proportion to age, but that of air curing specimen hardly increases after 28 days. The rebound value of P type schmidt hammer, however, increases due to carbonation of concrete in air curing specimen. The correlativity between the rebound value and the compressive strength is very favorable in the case of standard curing specimen, but drops remarkably in the case of air curing specimen. Thus, as application of age coefficient is required for exact estimation of the compressive strength, the age coefficient is derived from this study. The age coefficient of P type schmidt hammer is higher at the age of 3 and 7days, and drops significantly, compared with the age of 28days. And it is lower before 28days than that of N type schmidt hammer suggested in Japan, and shows the similar tendency after 28days.

• 소성∙가공
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• 제22권4호
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• pp.223-228
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• 2013

The friction coefficients of advanced high strength steel sheets were experimentally determined. In the friction test, the pulling and holding forces acting on the sheet for various friction conditions, such as lubricant viscosity, pulling speed, blank holding pressure, sheet surface roughness, and hardness of the sheet were measured and the friction coefficient was calculated based on Coulomb's friction law. While the friction coefficient, generally, decreases as the value of friction factor increases, the factor associated with the sheet surface roughness shows U shape behavior for the friction coefficient. Furthermore, the relationship between friction coefficient and the wear volume, which was computed for the roughness of both sheet surfaces and the friction area, is linearly proportional.

• 콘크리트학회논문집
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• 제17권5호
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• pp.735-742
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• 2005

본 연구에서는 시멘트의 종류에 따른 콘크리트의 내해수성을 평가하기 위하여 실험을 통해 총 5종류의 시멘트를 사용한 콘크리트의 강도, 공극률 및 염화물 확산 특성을 평가하고, 이들의 상관관계를 분석하였다. 실험 결과, 장기재령에서 V종 시멘트를 사용한 콘크리트의 압축강도 및 공극률은 I종 시멘트를 사용한 콘크리트와 비슷하게 나타났으나 염화물 확산계수는 크게 나타났다. 그리고 I종 시멘트의 일부를 플라이애쉬로 치환해 사용한 콘크리트의 압축강도, 공극률 및 염화물침투 저항성은 재령 경과와 함께 I종 시멘트를 사용한 경우에 비하여 우수한 것으로 나타났다. 한편, 콘크리트의 압축강도 및 공극률과 염화물 확산계수는 시멘트의 종류에 관계없이 높은 상관계수 및 결정계수를 나타내어 높은 상관성을 가지고 있음이 확인되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제9권6호
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• pp.723-726
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• 1996

A water loaded pressure device using water as the breaking force was developed to evaluate eggshell strength and compared with a dropping ball techniques. Further, relationships of shell thickness and weight of eggs to shell strength were also studied. Values for both of the shell strength measuring methods showed a highly significant correlation (p < 0.001) with shell thickness. The water loaded pressure method had a much higher simple correlation coefficient for shell thickness (r = + 0.786) than the dropping ball method (r = + 0.577). The shell strength measured by the water loaded pressure method appeared not to be correlated to egg weight. On the other hand, the negative sign of the standard partial regression coefficient and the partial regression coefficient of egg weight in the estimated multiple regression equation implied that for a given shell thickness a larger egg tended to have less shell strength than a smaller egg.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1069-1080
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• 2008

The mechanical characteristic of Lightweight Foamed Soil(LWFS) are investigated in this research. LWFS is composed of the in-suit soil, cement and foam to reduce the unit-weight and increase compressive strength. The unconfined compressive tests are carried out on the prepared specimens of LWFS with various soil types to investigate the relationship between compressive strength of LWFS and physical properties of soil. The result indicate that coefficient of gradation($C_g$) and liquid limit(LL) are more important factor affecting compressive strength than other physical properties of soil and coefficient of gradation($C_g$) and liquid limit(LL) can standard to determine the optical soil among the in-situ soils for LWFS.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.11-12
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• 2017

The properties of concrete produced by ready mixed concrete company in Busan were tested. Because the concrete was mixed with blast furnace slag and fly ash, the compressive strength and chloride ion diffusion coefficient were lower than OPC concrete even though the specified concrete strength was same. If the durability about salt attack were satisfied, the concrete of lower specified concrete strength would be adopted to concrete mixing design.

• 한국구조물진단유지관리공학회 논문집
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• 제3권2호
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• pp.177-183
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• 1999

The major object of this study is to investigate experimentally the experimental equation by the non-destructive testing methods of ultrasonic pulse velocity, rebound number, combined method of ultrasonic pulse velocity and rebound number, maturity which are applicable to the evaluation of compressive strength of concrete at early ages. Also test result of mix are statistically analyzed to infer the correlation coefficient between the maturity and the compressive strength of concrete. The results show good application of Logistic curve for estimating strength development under various curing temperature. The relation between ultrasonic pulse velocity, rebound number, combined method of ultrasonic pulse velocity and rebound number and compressive strength of concrete have low correlation coefficient, but maturity method show good correlation coefficient.