• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.347-354
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• 2013

Recently, crushed fine aggregates are being widely used due to the shortage of natural sand. In Korea, the amount of fine particles under 0.08 mm contained in crushed fine aggregates is restricted to be less than 7%, which is similar to the regulations of ASTM but is still very strict compared to the regulations of the other nations. In addition, the crushed aggregates already have in them about 20% of fine particles under 0.08 mm which occurs while they are crushed. The fine particles are not easy to wash out, and also to maximize the use of resources it is deemed necessary to review the possibility of enhancing the limit of the amount of fine particles. Therefore, this study conducted experiments to analyze the characteristics of fine particles under 0.08mm and their influence on the properties of concrete. Experiments using silt and cohesive soil were also done for comparison. In the experiments on fine particles, the methylene blue value was more in the soil dust contained in silt and cohesive soil than in the stone powder contained in crushed fine aggregates. Also, the methylene blue value had a close correlation with packing density and liquid & plastic limit. In the experiments done with concrete, the quantity of high range water reducing agent demanded to obtain the same slump increased as the fine particle substitution rate heightened. However, in the experiment which used stone powder testing the compressive strength and tensile strength of concrete in the same water-cement ratio, there was little change in strength with less than 20% addition of fine particles among the fine aggregates, and no meaningful difference in the amount of drying shrinkage of concrete.

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.561-567
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• 2001

It is reported that a lot of sludge powder is produced during the process of manufacturing crushed fine aggregate in mines. However, there is a limitation on the its use that most of them are disposed and wasted, which cause environmental pollution. Therefore, in this paper, tests are carried out in order to recycle sludge powder as filler for cement mortar products. Kinds of aggregates and mix proportion of mortar are varied under various contents of sludge powder. According to test results, it is found that cement mortar products using sludge powder as substitution of fine aggregate about 10% have better qualities than those without sludge powder.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.82-89
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• 2009

According to the great city development and the rapid growth of redevelopment project, waste concrete emission has been increased. Waste concrete powder is one of the by-product originated from the recycling of the waste concrete. The more making high quality recycled aggregate to use aggregate for concrete, the more waste concrete powder is producted relatively. Therefore, to realize the total recycling of waste concrete, development of recycling technology for waste concrete powder need very much. This technical note present the discharged process and the various properties of waste concrete powder. As the results, on the average, the maximum particle-size of waste concrete powder is less than $600{\mu}m$, and oven-dry density is less than $2.5g/cm^3$. And waste concrete powder contains more than 50% of $SiO_2$, 30% of CaO and 10% of $Al_2O_3$. Thus qualities of waste concrete powder is lower than those of high quality raw material for concrete. However, if it is processed by grading to the purpose, it will be used as resource of raw materials for construction field.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.88-94
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• 2011

To make recycling aggregate, quantity of fine particles increase due to multi-crushing. Though this particles were mixed with recycling aggregate, those have to be disparted from aggregate in the high quality recycling aggregate, because of the cause of low quality. Considering reactivity, fine particles is better than coarse one. Therefore, it needs to develop suitable usage. We try to make cement extruding material by using the fine particles from concrete recycling, as a silicious replacement. Test results are as follows ; 1) Waste concrete powder has major ingredients such as $SiO_2$ and CaO, its density is $2.45g/cm^3$ being similar to silica powder, its diameter is range 13 to $141{\mu}m$. 2) Considering to strength properties according to particle size, specimen was made using small particles is higher strength than large one. 3) Despite of exception in the autoclaved curing, when the replacement of waste fine particle increase, strength of extruding panel shows almost same level.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.341-342
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• 2009

In this study, various tests were performed such as setting time, flow, F1exural strength and compressive strength test to evaluate the effect according to the substitution of the replacement ratio of waste concrete powder and the change of particle size

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.116-117
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• 2021

This study examined basic mechanical properties by developing eco-friendly soil concrete using Masato particulate matter treated as waste. Experiments show that DG10 satisfies the compressive strength criterion, but for DG20, the criterion was not reached. As the mixing volume of Masato particulates increased, the compressive strength and slump decreased, and in the case of the compression strength test after freezing and melting, it was found that the standards were not met.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.231-235
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• 1989

Possibility of using microcarriers for the growth of a transformed human embryonic kidney cell line 293 was investigated. The cell grew well in a static culture such as T-flasks with medium of DME/F12 (3:1) mixture supplemented with 5% FBS, but it was most difficult to make the cells grow on microcarriers mainly due to the low attachment efficiency and poor spreading at initial stage of the culture. Consequently, 30-50% of the cells were lost upon inoculation into microcarrier suspension and significant fraction of the mirrocarrier became bald. The medium supplemented with the concentrated conditioned medium by hepatoma cell line HpG2 supported the active growth of the cells on microcarrier and the cells showed a very healthy and well spreading morphology. It was probable that some spreading and attachment factors of HpG2 conditioned medium were effective for 293 cells.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.4
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• pp.10-16
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• 1983

액체의 미립화는 기계산업분야 뿐만 아니라, 농약살포, 화학 공학의 분무건조, 반응의 촉진, 분 체제조, 식품공업 등 폭넓게 이용되며 또한 각분야에서 그 필요성이 강조되고 있다. 특히 기계 산업분야에서는 액체연료의 분무연소(boiler, gas turbine, 자동차용engine등) 원자로 노심의 spray cooling, spray drying, spray painting 등 그 이용도는 날로 증가되는 추세에 있다. 액체를 미 립화하는 이유는 각각의 분야나 사용하는 목적에 따라 다르지만, 대별하면 다음과 같다. (1) 액체의 단위 체적당 표면적을 증대시키기 위하여 (2) 직경이 작은 입자의 필요성 (3) 균일한 입경의 액적군을 얻기 위하여 등을 들 수 있다. 액체의 미립화에 대한 요구는 산업의 발당, 대기오염, 생energy 등의 문제가 중요시됨에 따라 다양화되고 있다. 따라서 응용면에서는 atomizer의 성능개선과 설계법, 새로운 미립화방법, 상업에의 분무이용기술, 분무계측법 등의 개발이 필요하게 된다. 액체미립화에서 취급하는 사항은 그 내용에 따라 다음과 같이 분류된다. (1) 액체의 미립화기구 : 기액계면의 불안정성과 분열기구에 관한 것으로, 액체형상으로써 액주, 액막 및 액적으로 나눌 수 있다. (2) 액체의 미립화 방법과 특성 : energy의 종유와 부가방식에 따랄 나누어진다. (3) 합체, 분산, 증발 등 분무의 운동이나 열적거동 (4) 분무입경이나 운동의 계측법과 특성도시 (5) 액체미립화의 각종응용 본보에서는 상기의 각 항목중, 특히 액체의 미립화방법과 분무특성에 대해서만 말하기로 한다.

• Resources Recycling
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• v.10 no.3
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• pp.14-22
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• 2001

For the recycle of coal fly ash generated from power stations, we developed an electrocyclone system which can separate unburned carbon form coal fly ash, based on the fact that coarse fly ash particles contain higher amount of unburned carbon and unburned carbon particles are charged positively, and pure ash particles are charged negatively on contacting each other. Additionally, guide vanes were installed in the cyclone to control the cut size. Two types of electrode, stick and grid type, were designed to investigate the effect of electrode type. Results show that by introducing an electric field inside the cyclone, the yield increases by 5 to 15e1o. But the content of unburned carbon in the clean ash does not change significantly.

• Magazine of RCR
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• v.4 no.2
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• pp.28-36
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• 2009