• Current Research on Agriculture and Life Sciences
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• v.16
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• pp.15-23
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• 1998

This experiment did comparison and analysis that protected soil particle migration have affect on function of the filter and therefore fall function of the filter. Results obtained are as follows: 1.High water head makes to be much movement of fine sand and out flow of particle to the outside. The filter have large opening size that reached stability an early stage, but much fine sand is washed away. If the velocity turns fast and becomes small, blocking phenomenon is remarkable nearby the filter-sand interface. 2. The movement of fine sand that effect on function of filter depend on opening size and change of water head. Under the same condition, USCE filter and USSPL filter is reached earlier than other filter that is stability of stage, because it's opening size is large. 3. Residual quantity of fine sand migration was largly come out in order of USSPL, USCE, USBR, Newton & Hurley, Bertram filter. 4. The time required to stability of flow was taken less in order of Bertram, Newton & Hurley, USBR, USSPL, USCE filter and coefficient of permeability was highly come out in order of USBR, Bertram, Newton & Hurley, USSPL, USCE filter. 5. It proved that USCE and USSPL is suitable for the filter criteria.

• Resources Recycling
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• v.21 no.1
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• pp.30-40
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• 2012

Electric arc furnace slag is made in ironworks during steel refining, it is been increasing chemical and physical resistibility using ageing method of unstable state of melting steel slag for using concrete's fine aggregates. Which is been changing stable molecular structure of aggregates, it restrains moving of ion and molecule. In Korea, KS F 4571 has been prepared for using the electric arc furnace oxidizing slag to concrete aggregates(EFS). In this study, Electric arc furnace oxidizing slag is used in the PRCC(Polymer Rapid setting Cement Concrete) which is applied a bridge pavement of rehabilitation, largely. The results showed that the increment of compressive strength development by 10- 20%. The flexural strength of EFS-Con increased greatly as the electric arc furnace oxidizing slag changed. The compressive strength and flexural strength developed enough for opening the overlayed EFS-Con to the traffic after 4 hours of EFS-Con placement. The permeability of EFS-Con was evaluated as negligible due to its very low charge passed. Thus, EFS-Con could be used at repairing or overlaying the concrete at fast-track job sites.

• Food Science and Preservation
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• v.6 no.4
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• pp.351-356
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• 1999

To develop and extend the shelf-life of vitamin C enriched fresh-cut apples using CA stored Fuji apples, dipping in 10% L-ascorbic acid and packaging with 0.03 mm LDPE, 0.04 mm PP and 0.08 mm Nylon/PE film(N$_2$displacement) were carried out. The changes of gas concentrations in the packaging and quality attributes of fresh-cut apples were examined during storage at 10$^{\circ}C$. The concentrations of O$_2$was maintained lower in Nylon/PE film than the other film, the level of O$_2$was in the range of 1∼3%. The increase of C$_2$H$_4$ concentrations in Nylon/PE film bag was more suppressed than the others. The vitamin C content of fresh-cut apples was enriched by dipping in L-ascorbic acid solution up to 241 mg$.$100 g-1 f.w., and the loss or that content was retarded differently by the package conditions of lower O$_2$level during storage. Browning in fresh-cut apples was shown after 6 days of storage in LDPE and PP film. but it was not shown by 14 days of storage in Nylon/PE film. Spoilage and off odor in fresh-cut apples were not detected up to 14 days of storage in Nylon/PE film. The results indicated that the vitamin C enriched fresh-cut apples can be processed from the long-term CA stored apples, and maintaining high quality of the products ill be possible in cases of the application of sealing packaging after O$_2$removal with film having low O$_2$permeability.

• Tunnel and Underground Space
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• v.29 no.3
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• pp.197-213
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• 2019

We simulated the fault reactivation experiment conducted at 'Main Fault' intersecting the low permeability clay formations of Mont Terri Underground Research Laboratory in Switzerland using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. We formulate the hydro-mechanical coupling relation of hydraulic aperture to consider the elastic fracture opening and failure-induced dilation for reproducing the abrupt changes in injection flow rate and monitoring pressure at fracture opening pressure. A parametric study was conducted to examine the effects of in-situ stress condition and fault deformation and strength parameters and to find the optimal parameter set to reproduce the field observations. In the best matching simulation, the fracture opening pressure and variations of injection flow rate and monitoring pressure showed good agreement with field experiment results, which suggests the capability of the numerical model to reasonably capture the fracture opening and propagation process. The model overestimated the fault displacement in shear direction and the range of reactivated zone, which was attributed to the progressive shear failures along the fault at high injection pressure. In the field experiment results, however, fracture tensile opening seems the dominant mechanism affecting the hydraulic aperture increase.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.17-21
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• 2019

The redox flow battery (RFB) is a large-capacity energy storage equipment, and the vanadium redox flow cell is a typical RFB, but VRFB is expensive. Iron-chrome RFBs are economical because they use low-cost active materials, but their low performance is an urgent problem. One of the reasons for the low performance is the crossover of the active materials. In this study, the sulfonated Poly (ether ether ketone) (sPEEK) membrane, which is a hydrocarbon membrane, was used instead of the fluorine membrane to reduce the crossover of the active materials. The chromium ion permeability of the sPEEK membrane was $1.8{\times}10^{-6}cm^2/min$, which was about 1/33 of that of the Nafion membrane. Thus, it was shown that the use of the sPEEK membrane instead of the fluorine membrane could solve the high active material crossover problem. The activation energy of iron diffusion through the sPEEK membrane was 24.9 kJ/mol, which was about 66% of Nafion membrane. And that the e-PTFE support in the polymer membrane reduces the active material crossover through Iron-Chrome Redox Flow Battery (ICRFB).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.2
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• pp.173-183
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• 2021

Objectives: This study evaluated the skin permeability of lawsone in henna hair dyes to understand the exposure characteristics of henna hair dyes in the human body. It examined the protective effects of protectants by applying protectants A, B, and C to test skin. Methods: Skin absorption tests were conducted using Franz diffusion cells according to OECD test guideline 428. After applying one kind of natural henna hair dye and chemical henna hair dye, respectively, to a standardized pig skin model, samples of receptor fluid were collected at 1h, 3h, 6h, and 24h. The skin permeation of lawsone was determined using HPLC. After the skin absorption experiment, the skin to which hair dye was applied was analyzed to determine the residual amount of lawsone in the skin. Results: The cumulative permeation of both natural and chemical henna hair dyes increased over time, and the natural henna hair dye had a flux value (t=3.194, p<.05) high both in the K_p value (t=3.207, p<.05) and the residual amount (t=22.701, p<.001). For skin treated with a protectant, the cumulative permeation of natural henna hair dye 24h control and the cumulative permeation of protectant A, B, and C increased over time. Flux and K_p values were in the order control > protectant A > protectant C > protectant B. The residual amount (F=4.469, p<.05) was in the order of protectant C > protectant A > protectant B > control. At 3h, the dye application time of natural henna hair dye, the lawsone flux value (F=4.454, p<.05) and K_p value (F=4.455, p<.05) were higher in the control group than in the protectant groups. The 24h cumulative permeation of the chemical henna hair dye increased with time in both the control and the protectant groups, and the flux and K_p values were in the order of protectant A > protectant C > protectant B > control. The residual amount (F=7.901, p<.01) was in the order of protectant B > protectant A> protectant C > control. Conclusions: Within the normal dyeing time for henna hair dye (three hours for natural henna hair dyes and 30 minutes for chemical henna hair dyes) lawsone skin penetration was not observed even when no protective agent was applied. After that time, however, evidence of skin penetration and retention of lawsone and the protective effect of protective agents were observed.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.138-143
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• 2011

To investigate the electromagnetic interference shielding efficiency (EMI SE) property based on heat treatment effects of carbon fibers in various temperatures, the polyacrilonitrle-based carbon fibers were prepared by electrospinning method and treated at 1073, 1323, 1873 and 2573 K. The surface morphology of carbon fibers was investigated by using FE-SEM and the carbon crystallization was studied by Raman spectroscopy based on effects of reaction temperatures. The electrical conductivity was obtained by measuring the surface resistance with four probe method on carbon crystallization. The permittivity, permeability and EMI SE were investigated by using S-parameter in the range of 800~4500 MHz. In case of carbon fibers treated at 2573 K, the improved carbon crystallization was confirmed by Raman spectrum and the enhanced electrical conductivity showing 54.7 S/cm was also observed. The permittivity was dramatically improved by factor of 4 based on effect of high reaction temperature. Eventually, the highly improved EMI SE value was obtained showing around 41.7 dB.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.9-19
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• 2021

This paper deals with the reinforcement performance of acrylate for reinforcing the settled railway roadbed. Concrete tracks have the advantage of reducing track maintenance costs and high resistance to track destruction. However, roadbed settlement is occurring in some construction sections, and the safety of railways is a serious concern because of difficulties in maintenance. Currently, maintenance through the track restoration method is being carried out in Korea as a way of roadbed settlement in concrete tracks, but continuous re-settlement can occur because the roadbed itself cannot be reinforced, and there are very few cases of reinforcement of railway roadbeds and field application. So the development of reinforcement materials and construction methods to reinforce railway roadbeds is required. Therefore, in this paper, acrylate was selected as reinforcement material for railway roadbed, and the reinforcement performance of acrylate was analyzed through experiment. As a result, it was analyzed that the acrylate can penetrate into a permeability coefficient of 1×10^-4 cm/sec, and secure uniaxial compression strength of 0.5 MPa/30min or more and stiffness of 80 MPa or more.

• Membrane Journal
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• v.31 no.6
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• pp.434-442
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• 2021

Poly(vinylidene fluoride) (PVDF) membrane has a good membrane durability because of its high mechanical resistance, thermal and chemical stability. However, the strong hydrophobic property of PVDF membrane can induce a low water permeability and easy fouling by proteins and organic matters. In order to improve the anti-fouling properties of PVDF membrane, the PVDF mixed matrix asymmetric membranes impregnated with biofunctional material 𝛽-cyclodextrin (𝛽-CD) in the membrane structure were prepared by phase inversion method. The membrane filtration experiments of pure water and BSA solution were performed using the PVDF/𝛽-CD mixed matrix asymmetric membranes prepared according to the 𝛽-CD contents. The experiments showed that the introduction of 𝛽-CD into the PVDF polymer matrix contributed to increase in the hydrophilic property of the PVDF membranes, and this led to the reduction of contact angles and improvement of anti-fouling properties. The PVDF/𝛽-CD membrane which was prepared using the dope solution with a 2 wt% 𝛽-CD content represented 64 L/m²·h of pure water flux, 95% of BSA rejection and maximum 80% of flux enhancements compared to flux results of the pristine PVDF membrane.

• Journal of the Korean GEO-environmental Society
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• v.23 no.2
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• pp.25-36
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• 2022

In this study, seepage control effect of relief well was evaluated quantitatively on embankment of small fill dam and levee. Seepage analysis of dam and levee were carried out according to the permeability of fill material and foundation and to analyze behaviour characteristics of seepage. The up-lift pressure at toe of embankment was analyzed which is generated by seepage according to relief well installation condition. The relief well could reduce pore water pressure which is to cause piping or up-lift pressure at foundation ground of embankment and it does not be influenced on geometric condition such as dam height and slope incline. In case of relative low permeable ground, the pore water pressure reduction effect of relief well was decreased compare with high permeable ground but it shows pore water pressure reduction effect compare with no relief well condition. The reduction effect of relief well shows relative gap according to diameter and penetration length of relief well and the installation length of relief well is the most effective factor for seepage control.