• Journal of Soil and Groundwater Environment
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• v.9 no.3
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• pp.1-11
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• 2004

To evaluate the applicability of dielectric constant measurement method on the geoenvironmental investigation of subsurface contaminated by landfill leachate, the analysis on dielectric characteristics of sand containing contaminated pore water by landfill leachate was performed. The separate real and imaginary parts of dielectric constant were investigated in the frequency range of 75kHz to 12MHz. The real part of dielectric constant increased at the lower frequency wherea the real part of dielectric constant decreased at the higher frequency as the concentration of leachate increased. These results can be explained by the frequency dependence of space charge polarization and orientation polarization. The imaginary part of dielectric constant on the contaminated sand with leachate increased with their concentration for whole frequency range. These results are caused by the increase of energy loss due to the enhancement of conduction in soil with leachate concentration. The results in this study indicate that the dielectric constant measurement method has potential in evaluating the contaminated soil and pore water by landfill leachate.

• Horticultural Science & Technology
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• v.19 no.2
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• pp.179-185
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• 2001

Throughout the world, physical and chemical analyses of horticultural substrates are carried out in many different ways at the different laboratories. In Europe, standardization in properties and analytical methods of horticultural substrates has been a topic over the last decades. As a result, the CEN methods as European standard methods for the physical and chemical analyses were introduced and the final draft was reported in 1999 by CEN(Committee for European Standardization). Dry matter and moisture content are analyzed after drying samples at $103^{\circ}C$. Laboratory compacted bulk density is analyzed by determining the weight of sample compacted in the test cylinder with constant volume. Dry bulk density, particle density, total pore space, water volume, air volume and volume shrinkage are determined by saturating, draining and drying the sample using double rings and a sand suction table. pH and EC are analyzed by 1:5(sample:distilled water) extraction method on the basis of volume. Organic matter and ash content are determined after drying and combusting the samples. Now, CEN methods are being regarded almost as European standard methods. Further study needs to be carried out for universal applicability of the CEN methods to all the substrates.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.99-104
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• 1996

Carbohydrate-free caseinomacropeptide (CMP) was isolated from the sweet whey powder by a precipitation method using 12% trichloroacetic acid. The yield of carbohydrate-free CMP was 2.7 g from 100 g sweet whey powder. The electrophoretic pattern and the amino acid analysis of CMP showed that isolated CMP was quite pure, indicating the precipitation with 12% trichloroacetic acid was very effective for isolating carbohydrate-free CMP from the sweet whey powder. Trypsin, covalently immobilized on pore glass beads by carbodiimide (EDC) method, was 20mg per 1g glass beads. CMP was almost completely hydrolyzed by soluble trypsin in 24hr, but not by immobilized trypsin. The tryptic hydrolysates were fractionated on a Bio-Gel P 4 column $(1.5{\times}120\;cm)$and separated peptides were tested for their capacities to inhibit platelet aggregation using a aggregometer. The hydrolysate obtained from CMP after 24hr digestion by immobilized trypsin showed the highest activity.

• Membrane and Water Treatment
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• v.1 no.4
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• pp.297-316
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• 2010

Membrane fouling is one of the major operational concerns of membrane processes which results in loss of productivity. This paper investigates the ultrafiltration (UF) results of synthetic oil-in-water (o/w) emulsion using flat sheets of polysulfone (PSf) membrane synthesized with four different compositions. The aim is to identify the mechanisms responsible for the observed permeate flux reduction with time for different PSf membranes. The experiments were carried out at four transmembrane pressures i.e., 68.9 kPa, 103.4 kPa, 137.9 kPa and 172.4 kPa. Three initial oil concentrations i.e., 75 $mgL^{-1}$, 100 $mgL^{-1}$ and 200 $mgL^{-1}$ were considered. The resistance-in-series (RIS) model was applied to interpret the data and on that basis, the individual resistances were evaluated. The significances of these resistances were studied in relation to parameters, namely, transmembrane pressure and initial oil concentration. The total resistance to permeate flow is found to increase with increase in both transmembrane pressure and initial oil concentration while for higher oil concentration, resistance due to concentration polarization is found to be the prevailing resistance. The applicability of the constant pressure filtration models to the experimental data was also tested to explain the blocking process. The study shows that intermediate pore blocking is the dominant mechanism at the initial period of UF while in the later period, the fouling process is found to approach cake filtration like mechanism. However, the duration of pore blocking mechanism is different for different membranes depending on their morphological and permeation properties.

• The Korean Journal of Physiology and Pharmacology
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• v.23 no.3
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• pp.191-201
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• 2019

The transient receptor potential canonical (TRPC) 5 channel, known as a nonselective cation channel, has a crucial role in calcium influx. TRPC5 has been reported to be activated by muscarinic receptor activation and extracellular pH change and inhibited by the protein kinase C pathway. Recent studies have also suggested that TRPC5 is extracellularly activated by englerin A (EA), but the mechanism remains unclear. The purpose of this study is to identify the EA-interaction sites in TRPC5 and thereby clarify the mechanism of TRPC5 activation. TRPC5 channels are over-expressed in human embryonic kidney (HEK293) cells. TRPC5 mutants were generated by site-directed mutagenesis. The whole-cell patch-clamp configuration was used to record TRPC5 currents. Western analysis was also performed to observe the expression of TRPC5 mutants. To identify the EA-interaction site in TRPC5, we first generated pore mutants. When screening the mutants with EA, we observed the EA-induced current increases of TRPC5 abolished in K554N, H594N, and E598Q mutants. The current increases of other mutants were reduced in different levels. We also examined the functional intactness of the mutants that had no effect by EA with TRPC5 agonists, such as carbachol or $GTP{\gamma}S$. Our results suggest that the three residues, Lys-554, His-594, and Glu-598, in TRPC5 might be responsible for direct interaction with EA, inducing the channel activation. We also suggest that although other pore residues are not critical, they could partly contribute to the EA-induced channel activation.

• Composites Research
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• v.34 no.1
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• pp.16-22
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• 2021

Polyurethane foam (PUF) can be manufactured in soft, semi-rigid, and hard forms, so it is used in various fields industrially. Among them, rigid PUF has excellent mechanical properties and low thermal conductivity, and is used as a thermal insulation material for buildings and as a cold insulation material in the natural gas transportation field. In this field, there is a steady demand on higher mechanical strength and lower thermal conductivity. In this study, a rigid PUF was manufactured, and the microstructure and physical properties were studied according to the impeller type (propeller, dispersed turbine) of the agitator. Through FE-SEM and Micro-CT analysis, it was confirmed that the average pore size of the foam manufactured with the dispersed turbine was 21.5% smaller than that of the pore made by the propeller. The compressive strength was improved by 15.4%, and the thermal conductivity decreased by 3.1% in the foam with small pores. This result can be utilized for fabricating PUF composites.

• Membrane Journal
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• v.31 no.1
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• pp.67-79
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• 2021

Mesoporous polystyrene (PS) and polyethersulfone (PES) membranes have been fabricated by reverse-thermally induced phase separation (RTIPS) process, using flash freezing. The mesoporous pores can be created by the nano-scaled phase separation induced by the formation and growth of solvent crystals in the dope solution in RTIPS process. RTIPS process has been characterized through analysis on the enthalpy change in the solvent of the dope solution, the morphology of the membrane fabricated with different polymer content, and the pore size distribution and its standard deviation of pore size of the membrane with polymer content via DSC, SEM, and BET, respectively. It is found that the kinetic aspect of the dope solution, i.e., the crystallization of solvent is a crucial factor to determine the structure of membrane fabricated in RTIPS rather than the thermodynamic aspect of the dope solution.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.91-96
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• 2021

This study was conducted to improve the operating conditions of an adsorption tower filled with potassium impregnated activated carbon for high hydrogen sulfide capture capacity. Heat treatment modified the surface properties of activated carbon, and ultimately determined its adsorption capacity. The activated carbon doped with potassium showed 57 times more adsorption at room temperature than that of using the raw adsorbent. It is believed that uniform pore formation and strong bonding of the potassium on the surface of carbon contributed to the chemical and physical absorption of hydrogen sulfide. The SEM analysis on the surface structure of various commercial carbons showed that the modification of surface properties through the heat treatment generated the destruction of pore structures resulted in the decrease of the absorption performance. The pressure drop across the activated carbon bed was closely related with the grain size and shape. The optimum size of irregularly shaped activated carbon granules was 2~4 mesh indicating economical feasibility.

• Geomechanics and Engineering
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• v.27 no.5
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• pp.433-445
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• 2021

Artificial ground freezing (AGF) is a commonly used geotechnical support technique that can be applied in any soil type and has low environmental impact. Experimental and numerical investigations have been conducted to optimize AGF for application in diverse scenarios. Precise simulation of groundwater flow is crucial to improving the reliability these investigations' results. Previous experimental research has mostly considered horizontal seepage flow, which does not allow accurate calculation of the groundwater flow velocity due to spatial variation of the piezometric head. This study adopted vertical seepage flow-which can maintain a constant cross-sectional area-to eliminate the limitations of using horizontal seepage flow. The closure time is a measure of the time taken for an impermeable layer to begin to form, this being the time for a frozen soil-ice wall to start forming adjacent to the freeze pipes; this is of great importance to applied AGF. This study reports verification of the reliability of our experimental apparatus and measurement system using only water, because temperature data could be measured while freezing was observed visually. Subsequent experimental AFG tests with saturated sandy soil were also performed. From the experimental results, a method of estimating closure time is proposed using the inflection point in the thermal conductivity difference between pore water and pore ice. It is expected that this estimation method will be highly applicable in the field. A further parametric study assessed factors influencing the closure time using a two-dimensional coupled thermo-hydraulic numerical analysis model that can simulate the AGF of saturated sandy soil considering groundwater flow. It shows that the closure time is affected by factors such as hydraulic gradient, unfrozen permeability, particle thermal conductivity, and freezing temperature. Among these factors, changes in the unfrozen permeability and particle thermal conductivity have less effect on the formation of frozen soil-ice walls when the freezing temperature is sufficiently low.

• The Korea Journal of Herbology
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• v.34 no.2
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• pp.33-39
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• 2019

Objectives : The pores are the openings of sebaceous glands or apocrine glands. They are enlarged by various factors such as sex, age, genetic influence, sebum secretion, acne and so on. When the pores are visually recognizable, they become aesthetically problematic. There are various methods of treating pores, but we have tried to develop a method to reduce pore size by using daily cleanser. Methods : Facial skin examination was performed on 104 students of A university. Among them, 10 persons with large pore size were selected. We surveyed 72 students to determine their subjective skin condition, lifestyle, and washing habits etc. We made herbal fermented soaps using Seosiokyongsan and distributed them to experiment participants. We let them wash their face in the morning and evening for 6 weeks using herbal fermented soap. Prior to the experiment, their skin condition was checked and assessed using A-ONE Smart One-Click Automatic Facial Diagnosis System three times at 3-week intervals. After the experiment, the changes of skin were measured and analyzed through facial analysis test. Results : In our experiment, the early 20s, 9.6% of the students had slightly larger pores. For students with large pores, there was a high likelihood of side effects from using facial products. Using the fermented soap made of Seosiokyongsan, the average size of the pores and the number of large-sized pores were significantly reduced. Conclusion : Seosiokyongsan fermented soap can effectively reduce especially the large size of pores.