• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.23-29
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• 2020

The soil structures settle down continuously under cyclic dynamic loading after opening railway lines. This study examined the characteristics of the settlement and stiffness of cement-treated soils with the change in the content of fines under cyclic dynamic loading. Eighteen cases of the test were carried out with the changes in the fines content of soils, cement content, and curing days. Based on the test results, cement-treated soils containing more than 3% of cement could decrease settlement sufficiently even with a high portion of fines under cyclic dynamic loading. In addition, the elastic and plastic settlements could be reduced using 3 to 4% cement to the level of 1/4 and 1/6, respectively. In the viewpoint of stiffness, the resilient modulus of cement-treated soils increases with increasing cement content. Using more than 3% of cement, the 80MPa compaction stiffness standard for the upper subgrade of railways was satisfied, even with 40% of fines content of soils.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.4
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• pp.7-14
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• 2001

Recycled fibers usually give slow drainage in the paper forming process, which limits the application of more refining to the recycled fibers for improving paper strength and formation. To use recycled fibers more effectively, especially OCC, developing very efficient handling technique of short fibers and fines is inevitable. We tried to make hard flocs of fractionated short fibers and fines, which were the main cause of slow drainage, by adding excessive amount of retention aid selectively on them. This technique was proved to increase drainage considerably, but to decrease strength properties, compared to the conventional technique of adding the same amount of polymers to the whole furnish in the lab test. The bonding capability of short fibers and fines in Korean OCC was very poor. Various chemical treatment on the short fibers and fines of the Korean OCC did not improve their bonding and optical properties. One of the reasons of no improvement in their properties was their high amount of ashes.

• Advances in concrete construction
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• v.2 no.3
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• pp.209-227
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• 2014

The use of limestone fines (LF) in mortar and concrete can in certain ways improve performance and thus has become more and more commonplace. However, although LF is generally regarded as a filler, it is up to now not clear how much filling effect it could have and how best the filling effect could be utilized. Herein, the packing density and filling effect of LF were studied by measuring the packing densities of LF, (LF + cement) blends and (LF + cement + fine aggregate) blends under dry and wet conditions, and measuring the performance of mortars made with various amounts of LF added. It was found that the addition of LF would not significantly increase the packing density of (LF + cement) blends but would fill into the paste to increase the paste volume and paste film thickness, and improve the flow spread and strength of mortar.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.521-524
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• 2006

Recently, densified pollet fuel from wood biomass is widely used at North America and Europe as a regenerable and clean carbon neutral bioenergy. High-pressure compaction of sawdust of several species of wood to form a densified fuel was studied. Calorific and elemental analysis were carried out to assess pellet fuels Hot-press process was adopted for compact ion of sawdust and compaction was performed under prescribed condition. Densified fuels were evaluated by its oven-dry density and fines after 5-minute shaking test. The target density and fines of densified fuels were over $1.2g/cm^3$ and below 0.5%, respectively. When the press-temperature is over $60^{\circ}C$ densified fuels with density over $1.2g/cm^3$ and with fines below 0.5% can be produced. And the pressure over $1000kgf/cm^2$ was effect ive for this production.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.4 s.117
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• pp.10-16
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• 2006

The study was carried out to investigate how the refining of pulps affects the stress-strain characteristics and physical properties of paper. SwBKP and HwBKP were refined with Hollender laboratory beater to obtain three levels of freeness(500, 400 and 300 ml CSF) at the different consistencies(0.5% and 1.0%). The effects of fines were also evaluated. The stresses and strains of papers made from SwBKP and HwBKP were increased with refining. The absolute value of strain in paper made from SwBKP was higher than those of paper made from HwBKP. We also found that the presence of fines increased the stress and strain significantly in both pulp types. The refining at lower pulp consistency gave higher stress and strain properties. Most physical properties of paper were improved with refining, but the effect of refining consistency depended on the characteristics of each physical properties.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.2
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• pp.64-69
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• 1999

Drainage phenomena on the conventional fourdrinier table can be divided into two distinct zones based on the drainage mechanisms involved. In the forming zone, natural drainage is the principal water removal mechanism, while in the vacuum zone vacuum dewatering displaces water in the wet sheet with air. In this study to investigate the influence of polyelectrolyte addition on natural and vacuum dewatering a vacuum drainage tester was developed and used. Addition of PAM decreased the dryness of the wet sheet after vacuum dewatering since substantial reduction in vacuum level occurred due to flocculation of fibers. Addition of PAM, however, increased the wet web dryness when the fines content of the stock is greater than 35% indicating the presence of fines reduced the air permeability of the wet web to increase its response to vacuum dewatering. On the other hand, PEI, which flocculates the fibers and fines via patch formation, showed little impact on the drainage characteristics of the stocks.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.4
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• pp.18-26
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• 2000

In order to investigate the influencing factors in flotation fractionation, flotations were performed at varied conditions. The selectivity of fines fractionation was mainly affected by long fiber flocculation degree and if there were not sufficient flocculation of long fibers, more loss of long fibers could not be avoided. The amount of flotation rejects were totally dependent on the stability of froth floated on the stock surface. Only small size fines could stabilize the froth as they hindered the drainage of liquid lamella in flotation-froth. More flotation reject and better flocculation of long fibers were two important factors for improving flotation. Changing a flotation flux or an air-mixing ratio to increase the flocculation of fibers increased long fiber ratio in the reject. In order to satisfy the both conditions of reducing long fiber loss and of increasing flotation reject, search of fractionation promoter is needed.

• Journal of the Korean Geotechnical Society
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• v.34 no.4
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• pp.37-47
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• 2018

This paper described a results of direct shear test and pullout test by using soil supported by drilled shafts in order to evaluate the effect of relative density and fines content on pullout resistance performance of drilled shafts. The result of direct shear test showed that the variation characteristics of internal friction angle and cohesion could be confirmed quantitatively. The result of pullout test also showed that the effect of relative density and fines content on pullout resistance performance of drilled shafts was confirmed. That is, the contribution of the internal friction angle and cohesion of soils on the pullout resistance performance of drilled shafts was found to vary, when the fines content was about 13% based on results direct shear test and pullout test. Therefore, at design of drilled shafts, the effect of skin friction resistance should be considered on the influence factor of strength parameters ($c-{\phi}$) according to the fines content of soil.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.373-383
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• 1987

No-fines concrete is concrete from which the fine aggregate fraction has been omitted. The concrete so formed, consisting only of coarse aggregate, cement, and water, has large voids uniformly distributed through its mass. This study was performed to obtain the basic data which can be applied to the use of no-fines concrete. The data was based on the properties of no-fines concrete depending upon various mixing ratios. The results obtained were summarized as follows. 1. Test result of the consistency, suitable water-cement ratio was increased with the increasing of mixing ratio. 2. At the suitable water-cement ratio, the highest strengths were showed. But it gradually was decreased with the increasing of mixing ratio and strengths are considerably lower than that of conventional portland cement concrete. 3. The relations between compressive and tensile strength were highly singnificant as a straight line shaped. The strength ratio was decreased with the increasing of mixing ratio and considerably lower than of conventional portland cement concrete. 4. Bulk density was decreased with the increasing of the mixing ratio, and was similar to that of the conventional portland cement concrete at mixing ratio 1:4. 5. The relations between strength and bulk density were highly significant as a straight line shaped. The decreasing ratio of strengths was higher than that of bulk density.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3C
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• pp.93-102
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• 2011

Most experimental studies on soil liquefaction are related to clean sands. However, soils in the field or reclaimed grounds commonly contain some amounts of silt and clay rather than clean sand only. Many researchers investigated the effect of fine contents on liquefaction resistance and mainly used non-plastic fines such as silts. In this study, 10% of plastic fines with various plasticity index (PI) such as 8, 18, 50, and 377 were mixed with wet Nakdong River sand and then loose, medium, and dense specimens were prepared by undercompaction method. A series of undrained cyclic triaxial tests were carried out by applying three different cyclic stress ratios. As a result, the liquefaction resistance tended to decrease as a PI of fines in the specimens with equal fine content increased. On the other hand, the difference between loose specimens with low and high plasticity fines was not clearly observed in terms of liquefaction resistance. However, in the case of dense specimens, liquefaction resistance decreased up to 40% as a plasticity of fines increased.