• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.685-692
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• 2000

Vertical drain used improvement soft clay is made of not only decreasing construction time but also increasing the ground strength during some decades. As, it is applied to improvement soft clay with vertical drain, it is designed by the result that is caused by oedemeter test ignored anisotropic of the ground related to consolidation conditions. When we are expected consolidation conditions, the most important factors is soil of compaction and water permeability. Above all, anisotropic of the ground permeability show the results which differ between vertical and radial drainage. Recently, We study for radial consolidation coefficient and permeability coefficient that utilized Rowe Cell Consolidation and permeability tester but, it dont use well because of not only a supply lack also difficulty of test. The paper experimented with searching anisotropic of the ground so there are Rowe Cell test, standard consolidation tester and modified standard consolidation test that have pohang's soft clay ground. Therefore, we find anisotropic of the ground and a tester of easy use more than before. We made a comparison test result between the devised tester and Rowe Cell tester, Also, we learned average degree of consolidation for partial penetrating vertical drains. We were found relations as effective stress-void and effective stress-permeability coefficient through those tests.

• 한국잡초학회지
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• 제5권1호
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• pp.85-88
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• 1985

본(本) 실험(實驗)은 신종(新種) 제초제(除草劑)인 CGA 82725와 DOWCO 453의 살초기구중(殺草機構中) 하나의 기작(機作)으로 사료(思料)되는 세포막투과성(細胞膜透過性)에 미치는 영향(影響)을 조사(調査)하였다. 1. CGA 82725는 $10{-3}M$ 농도(濃度)에서 세포막투과성(細胞膜透過性)으 증가(增加)시켰다. 2. DOWCD 453은 $10^{-2}M$ 농도(濃度)에서 세포막투과성(細胞膜透過性)을 증가(增加)시켰다. 3. Paraquat와 Dinoseb은 $10^{-5}M$과 $10^{-4}M$에서 세포막투과성(細胞膜透過性)을 증가(增加)시켰다. 4. 세포막투과성(細胞膜透過性) 증가(增加)와 잎에 나타나는 necrosis 현상(現象)과는 항상 일치(一致)하지는 않는다.

• 한국표면공학회지
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• 제32권3호
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• pp.423-427
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• 1999

Electroplating of 80%Ni permalloy thin plate for magnetic core materials. was studied The convected flow of electrolyte was used for stirring methode. The current density could be increased up to 250mA/$\textrm{cm}^2$ by flow cell. The composition of electroplated layer with vespect to current density and flow rate was investigated and experimental equation to predict the composition was made. How cell yielded more uniform thickness distribution than paddle cell did. The composition distribution was also studied. The thickness was the most important factor to the permeability. The permeability of 5$\mu\textrm{m}$plated permalloy was over 2000 at 1 MHz.

• 한국주조공학회지
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• 제21권4호
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• pp.253-259
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• 2001

There are many methods to produce metal foams, which can be classified into three groups according to the state of the starting metal i.e. liquid or powder or solid. Three types of defects such as cell closing, cell deformation or breakdown and cell misrun are thought to be occurred when we make the open cell aluminum foams by precision casting. Filling ability of the mold slurry between preform is related with cell closing, mold collapsibility is related with cell deformation or breakdown, mold temperature and pouring pressure are related with cell misrun. These factors can be evaluated by measuring slurry fluidity, burnout strength and permeability of the mold. Properties of the plaster mold were evaluated to find optimum mold conditions for high quality open cell aluminum foam in this study. Permeability was almost zero independent of burnout conditions, however, crack initiation was found on the surface of all specimens one or two minutes after taking out from the furnace. Crack has grown and disappeared with time. This crack may facilitate the mold filling when molten metal is poured, because of the improved mold permeability. It was considered that crack initiation and disappearance was closely related with temperature difference between the surface and inner part. Knocking-out the mold is a difficult problem due to the small cell size, because continuous mesh structure of the metal foam is not strong. It is not easy to remove molding material after pouring. We can expect that water quenching can facilitate the knocking-out the mold after solidification without damaging cell structures. Collapsed particles after water quenching became bigger with the increase in time.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.184-187
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• 2003

Complete prediction of second order permeability tensor for three dimensional circular braided preform is critical to understand the resin transfer molding process of composites. The permeability can be predicted by considering resin flow through the multi-axial fiber structure. In this study, permeability tensor for a 3-D circular braided preform is calculated by solving a boundary problem of a periodic unit cell. Flow field through the unit cell is obtained by using a 3-D finite volume method (FVM) and Darcy's law is utilized to obtain permeability tensor. Flow analysis for two cases that a fiber tow is regarded as impermeable solid and permeable porous medium is carried out respectively. It is found that the flow within the intra-tow region of the braided preform is negligible if inter-tow porosity is relatively high but the flow through the tow must be considered when the porosity is low. To avoid checkerboard pressure field and improve the efficiency of numerical computation, a new interpolation function for velocity variation is proposed on the basis of analytic solutions. Permeability of the braided preform is measured through a radial flow experiment and compared with the permeability predicted numerically.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3114-3119
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• 2008

Relatively high convective flow exists in the under-rib regions of a gas diffusion layer (GDL) when serpentine flow fields are employed in a PEMFC. This under-rib convection is believed to be favorable for the performance of PEMFCs, by enabling more effective use of catalysts in the under-rib regions. From the fact that the under-rib convection in a GDL is directly proportional to the permeability of the GDL, computational fluid dynamics (CFD) simulations were performed to discover the relationship between the GDL permeability and the PEMFC performance. Single-, triple-, and quintuple-path parallel serpentine flow fields for $9\;cm^2$ active cell area were considered while changing the GDL permeability from $1{\times}10^{-12}$ to $5{\times}10^{-11}m^2$. The results showed that higher GDL permeability generally resulted in better performance of PEMFCs, but the degree of performance enhancement became smaller as the parallel path number increased. The effects of the permeability on the local variables were also discussed.

• Journal of Applied Biological Chemistry
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• 제63권1호
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• pp.35-41
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• 2020

(-)-epigallocatechin-3-gallate (EGGG), a flavonoid found in green tea, is known to have low bioavailability. In this study, we determine whether piperine, a natural bioenhancer, can increase the absorption rate of EGCG. Using a Caco-2 cell monolayer, permeability experiments were performed in Hanks' balanced salt solution (HBSS) and EGCG stability was adjusted to pH 6.5 and pH 5.5 by ascorbic acid treatment. When HBSS was adjusted to pH 6.5, EGCG remained at 94.78% for up to 2 h and remained at 86.04% after 4 h and the net efflux decreased compared to the control. As a result, uptake was significantly increased in the piperine co-administered group compared to the EGCG-alone group, showing that piperine increased the permeability of EGCG in the Caco-2 cell monolayer. These results suggest that piperine inhibits EGCG glucuronidation and efflux, allowing for greater absorption of EGCG.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1635-1643
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• 2009

The aim of this study was to provide new insight into the mechanism whereby the housekeeping enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) locates to cell walls of Lactobacillus plantarum 299v. After purification, cytosolic and cell wall GAPDH (cw-GAPDH) forms were characterized and shown to be identical homotetrameric active enzymes. GAPDH concentration on cell walls was growth-time dependent. Free GAPDH was not observed on the culture supernatant at any time during growth, and provoked cell lysis was not concomitant with any reassociation of GAPDH onto the cell surface. Hence, with the possibility of cw-GAPDH resulting from autolysis being unlikely, entrapment of intracellular GAPDH on the cell wall after a passive efflux through altered plasma membrane was investigated. Flow cytometry was used to assess L. plantarum 299v membrane permeabilization after labeling with propidium iodide (PI). By combining PI uptake and cw-GAPDH activity measurements, we demonstrate here that the increase in cw-GAPDH concentration from the early exponential phase to the late stationary phase is closely related to an increase in plasma membrane permeability during growth. Moreover, we observed that increases in both plasma membrane permeability and cw-GAPDH activity were delayed when glucose was added during L. plantarum 299v growth. Using a double labeling of L. plantarum 299v cells with anti-GAPDH antibodies and propidium iodide, we established unambiguously that cells with impaired membrane manifest five times more cw-GAPDH than unaltered cells. Our results show that plasma membrane permeability appears to be closely related to the efflux of GAPDH on the bacterial cell surface, offering new insight into the understanding of the cell wall location of this enzyme.

• Journal of Pharmaceutical Investigation
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• 제35권2호
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• pp.111-116
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• 2005

The unstirred water layer (UWL), which has been known to exist in the boundary of the intestinal lumen and intestinal wall, often behaves as an absorption barrier especially for lipophilic drugs. The intestinal absorption of drugs is often characterized using Caco-2 cell monolayers grown on Transwell polycarbonate membranes. The permeability $(P_{app})$ of drugs across the cell monolayer might be influenced by the agitation of the donor compartment, since the width of UWL on the surface of the cell monolayer would be reduced by the agitation. In this study, the effect of agitation of the donor compartment with 60 rpm on the permeability was measured for 12 drugs with a wide range of lipophilicity and permeability. The $P_{app}$ of mannitol, tributylmethyl ammonium, cimetidine, ranitidine, hydrocortisone, benzylpenicillin and loxoprofen was not influenced by the agitation, while the $P_{app}$ of theophylline, propranolol, YH439, phenylpropanolamine and testosterone was increased by the agitation. There was a significant correlation between the increase of $P_{app}$ by agitation and the lipophilicity for the compounds having $P_{app}>2{\times}10^{-5}$ cm/sec. No correlation was observed for the difference in $P_{app}$ by agitation and the molecular weight, or lipophilicity of the drugs. Therefore, the agitation rate of the donor compartment in the Caco-2 cell monolayer study should be carefully controlled in order to estimate $P_{app}$ reproducibly especially for lipophilic drugs.

• 한국식품영양과학회지
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• 제41권7호
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• pp.881-887
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• 2012

유산균과 금은화, 발효 금은화는 장누수 증후군과 연관된 장 상피세포 점막 투과성 감소에 대하여 유의한 효과를 나타내었다. 따라서 유산균을 단독으로 사용하는 방법과 유산균을 이용해 발효시킨 금은화를 증가된 장 투과성 및 장내미생물 불균형으로 인한 장누수 증후군과 관련된 일련의 증상들을 치료하고 면역관련 질환 및 만성 염증성 질환에도 응용할 수 있을 것으로 예상되며 이에 대한 앞으로의 추가 연구가 필요할 것으로 사료된다.