• 한국산업융합학회 논문집
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• 제26권6_2호
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• pp.1135-1144
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• 2023

In this paper, bending strength and permeability tests were conducted on concrete permeable blocks manufactured by recycling industrial by-products of oyster shell and blast furnace slag to measure and compare bending strength and permeability coefficient, and present experimental research results. To this end, a total of 54 specimens with a size of 200x200x60mm for surface layer and base layer were manufactured, and bending strength and permeability test were carried ourt accoridng to KS F 4419. Eighteen types of mixing designs were implemented by varying the mixing and replacement rates of oyster shells and blast furnace slag. As a result of the experiment, the higher the mixing ratio of oyster shell, the lower the bending strength and the permeability coefficient. Thereafter, a total of three permeable blocks with dimensions of 200x200x60mm were manufactured and subjected to bending strength and permeability tests according to KS F 4419. As a result of the test, the bending strength satisfies the standard of KS F 4419, and the permeability coefficient is 12 times higher than the standard of KS F 4419. It seems that the proper mixing of oyster shells and blast furnace slag increases the amount of air, and further research on durability and economic feasibility of materials used to manufacture permeable blocks is required.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.69-72
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• 2011

The purpose of this study is to identify basic property of porous concrete using cooper slag as fine aggregate. The specimens were made with cooper slag with various mixing ratio(10, 20, 30, 50%), porous concrete and porous concrete containing river fine aggregate and crushed fine aggregate, which W/B ratio fixed 0.25. Compressive strength, Flexural strength, coefficient of permeability. From the test results, various fine aggregate mixing ratio improves compressive strength and flexural strength, but cooper slag fine aggregate mixing ratio over 20%, concrete indicates trend to decrease performance of permeability. Concrete containing fine aggregate is improved the performance of permeability and strength compared to other specimen, when age 28days, and cooper slag mixing ratio less than 20% concrete indicates better performance than cooper slag mixing ratio 20% over.

• 하천과문화
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• 제9권4호
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• pp.70-73
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• 2013

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제16회 학술발표회 논문개요집
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• pp.182-182
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• 1999

• Journal of the Korean Wood Science and Technology
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• 제51권6호
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• pp.470-480
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• 2023

This study aimed to develop a sound-absorbing composite using sugarcane bagasse (SB) and coffee silver skin (CS) as raw materials. The composite boards were manufactured by bonding the fibers with Melamine Urea-Formaldehyde adhesive, ensuring a consistent thickness of 30 mm. Various densities were employed, namely 380, 450, and 520 kg/m³. The samples were fabricated with different fiber ratios, including SB100%, SB75% with CS25%, and SB50% with CS50%. The sound absorption coefficient (SAC) and noise reduction coefficient (NRC) were measured using the impedance tube method within a frequency range of 63-6,300 Hz. The experimental results revealed that the mixing ratio of CS exerted a notable influence on enhancing the SAC, while the density of the composite board exhibited a significant impact on increasing both the SAC and NRC. Among the densities tested, the optimal value was observed at 520 kg/m³, yielding a SAC value of 0.65 at a frequency of 1,000 Hz and an NRC value of 0.55 for the SB50-CS50 composite plate. These findings underscore the importance of considering the CS mixing ratio and composite board density when aiming to optimize sound absorption properties.

• 한국건설순환자원학회논문집
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• 제10권4호
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• pp.475-481
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• 2022

순환골재는 생산과정에서 발생하는 미세균열 및 순환골재 표면에 존재하는 시멘트 페이스트 성분의 존재로 인해, 천연골재에 비해 높은 흡수율을 가지며, 이로 인해 콘크리트에 골재로서 사용할 경우 작업성 저하, 강도의 저하 등의 문제가 발생하게 된다. 골재의 수급이 점점 어려워지고 있는 현 상황에, 골재 수급의 대안이 될 수 있는 순환골재를 적극적으로 활용하기 위한 방법으로, 본 연구에서는 Tam et al.이 제안한 2단계 배합과정을 활용하였고, 이를 이용해 제조한 콘크리트의 압축강도, 탄성계수, 및 염소이온 확산계수를 일반 배합과정을 적용한 천연골재 콘크리트 및 100 % 치환율의 순환골재 콘크리트와 비교 분석하였다. 실험 결과에 따르면, 압축강도와 탄성계수는 물시멘트비에 관계없이, 2단계 배합방법으로 제작한 순환골재 콘크리트가 일반배합과정으로 배합된 순환골재 콘크리트에 비해 높게 나타났으며, 천연골재 콘크리트에 근접하는 역학적 성능을 발휘하였다. 그러나 염소이온 확산계수의 경우 순환골재 콘크리트가 천연골재 콘크리트보다 높게 측정되었으며, 2단계 배합과정의 적용에 따른 염소이온 확산계수의 감소는 확인할 수 없어, 2단계 배합이 내구성에는 크게 기여하지 않는 것으로 판단된다.

• Tribology and Lubricants
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• 제17권2호
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• pp.130-137
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• 2001

In this paper, the thermal effects on the performance of floating ring journal bearing are investigated theoretically. The numerical analyses include pressure drop at inner film due to a centrifugal force, fluid momentum effects of supply oil into inner film and thermal effects in lubricating films. All performance data are presented as the rotating speed of journal from 10,000 rpm to 70,000 rpm.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2303-2308
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• 2007

Experiments were performed to determine the thermal (or turbulent) diffusion coefficient (TDC) and to investigate the critical heat flux (CHF) performance in the 5${\times}$5 rod bundle with 5 unheated rods which are supported by Hybrid Mixing Vane. In this study, HFC-134a fluid was used as working fluid and the fluid temperature were measured in the important subchannels. To determine the TDC value, the measured fluid temperatures were compared with the predicted values obtained from the MATRA code. The best optimized value of ${\beta}$ was found to be 0.02 by considering prediction statistics, i.e., average and standard deviations of the differences between the experimental results and code calculations. Using the best optimized value of ${\beta}$ as 0.02, the MATRA code predicts the test results of the fluid temperature within ${\pm}$1.0 % of error. According to the experimental results on CHF of 5 non-heating guide tubes, the case with non-heating guide tube showed a little good performance in terms of CHF.

• Elastomers and Composites
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• 제46권4호
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• pp.324-328
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• 2011

신발 밑창용 CIIR에 BR, SBR 및 NBR을 다양한 조성으로 혼합하여 블렌드물의 내마모성과 마찰계수에 미치는 영향을 고찰하였다. CIIR이 BR에 블렌딩됨에 따라 CIIR이 BR의 결정 형성을 방해하며, 이것이 BR/CIIR 블렌드물의 내마모성을 급격히 감소하는 요인 중의 하나로 작용하는 것으로 이해된다. BR/CIIR 블렌드물에서 BR의 함량이 증가함에 따라 $tan{\delta}$ 피크 면적이 저하하였으며, 블렌드물의 마찰계수도 유사하게 저하하는 경향을 나타내었다. CIIR에 BR을 첨가함에 따라 블렌드물의 응력완화율 및 반발탄성이 감소하였으며, 블렌드물의 반발탄성에 영향을 미치는 것으로 추정된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.1126-1131
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• 2006

This study is part of the project that develops the permeable preactive barrier to be applied in a landfill. The geotechnical applicability of the permeable preactive barrier that filters the leachate from the landfill was evaluated. Dry specimens were made using a mixture of sand, loess and bentonite. A series of experiments are performed to determine the unconfined compressive strength and permeability of various mixing ratio of bentonite, loess, and sand. The laboratory test indicate that the optimum-mixing ratio that satisfied the regulation of unconfined compressive strength(490kPa) and coefficient of permeability$(10^{-3}\sim10^{-4}cm/s)$ of the landfill was when the ratio of sand and loess was 8:2 with bentonite content of 2%. The permeable preactive barrier is different from an impermeable barrier in that it permits a limited diffusion of the leachate, which will be directly purified biologically and chemically in the landfill.