• Geosystem Engineering
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• 제21권6호
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• pp.344-351
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• 2018

It is reported that the flooding rate in low permeability sandstones is low and the oil recovery is hard to increase after water breakthrough. Understanding characteristics of waterflood is hence important for the recovery improvement. In this work, flooding tests on low permeability sandstones were conducted. The corresponding flooding characteristics were investigated by means of CT scanning and Nuclear Magnetic Resonance. Effects of irreducible water and different rates were also discussed in detail. Experimental results reveal a piston-like displacement at a low rate in low permeability samples. The saturation profile is steep and almost vertical to the forward direction. The results at a low rate confirm that once water broke through, increasing the flooding rate or flooding time can hardly reduce the remaining oil inside the sample. It is probably due to the high pore-throat ratio proven by rate-controlled mercury. Results also confirm that the presence of initial water enhanced sweep efficiency substantially. On one hand, because water had previously occupied the small pores, the subsequent oil can only invade relatively large pores and became more movable. On the other hand, stable collars can not form due to the steep front, which may suppress the snap-off.

• 한국식품저장유통학회지
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• 제17권6호
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• pp.793-799
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• 2010

김치를 기체 투과도가 조절된 플라스틱 용기, 시유옹기, 유리병을 사용하여 각각 발효하였을 때, 그 품질특성이 어떻게 변화하는지를 $5^{\circ}C$에서 8주간 발효하면서 관찰하였다. 다른 용기에 보관한 김치에 비해, 투과도 조절 플라스틱 용기에 보관한 김치의 pH 감소가 적었으며, 산도 역시 8주 후에 0.99로 나타나 증가율이 가장 적게 나타났다. 미생물수의 변화를 보면 투과도 조절 플라스틱 용기에 보관한 김치가 총균수의 증가는 적고, 유산균의 증가는 높게 나타나 김치의 발효가 바람직한 방향으로 진행되었다. 김치 조직의 탄성은 역시 투과도 조절 플라스틱 용기에 보관한 김치에서 그 감소폭이 가장 적었으며, 적숙기인 3-4주차 때에는 투과도 조절 플라스틱 용기와 유리병에 보관한 김치간의 탄성 차이가 10%정도로 매우 크게 나타났다. 관능평가 결과에서도 투과도 조절 플라스틱 용기에서 발효한 김치가 높은 점수를 나타내었으며, 질감 및 외관과 종합적인 기호도에서 점수가 높았다. 투과도 조절 플라스틱 용기에 보관한 김치의 항산화 효과는 다른 용기에 보관한 김치에 비해 우수하였으며, 용기별 기체투과도에 있어서도, 시유옹기에서 $O_2$, $CO_2$ 투과력이 각각 $10\;mmol\;h^{-1}\;m^{-2}\;atm^{-1}$, $13.7\;mmol\;h^{-1}\;m^{-2}\;atm^{-1}$,이었는데 비해 투과도 조절 플라스틱 용기가 $458\;mmol\;h^{-1}\;m^{-2}\;atm^{-1}$, $357\;mmol\;h^{-1}\;m^{-2}\;atm^{-1}$, 로 더 높은 결과를 나타내었다. 이는 전통적으로 김치발효 용기로 사용된 옹기와 유사한 결과이며, 따라서 투과도 조절 플라스틱 용기는 김치 발효에 적합한 용기이며, 앞으로 김치의 보관 및 발효에 있어서 산업적으로 유용하게 사용될 것으로 기대된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1203-1206
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• 2001

The main intent of this research is to determine the feasibility of utilizing bottom ash as CLSM(Controlled Low-strength Materials). The durability tests including permeability, repeated wetting and drying, freezing and thawing for bottom ash CLSM were conducted. Laboratory test results indicated that CLSM using bottom ash has acceptable durability performance.

• 산업기술연구
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• 제27권A호
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• pp.111-120
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• 2007

This paper is results of experimental research on the effect of application of similarity related to permeability of soil on the consolidation behavior as centrifuge modeling of consolidation is performed with the centrifuge model facility. In this research, the permeability of soil was controlled by changing the viscosity of porewater as the mixed water with glycerin was used during the centrifuge model experiments. The effect of drainage path on consolidation was investigated by installing the vertical drains. A serise of centrifuge model tests with conditions of single vertical and radial horizontal drainage were carried out. Kaolinite and Jumunjin standard sand were used as soft clay and surcharges respectively during tests. For testing condition of single vertical drainage considering similarity of permeability, it was found that consolidation with mixed porewater with glycerin was delayed in comparisons sons with test results with water only. For conditions of horizontal drainage with vertical drains, a low permeability by changing the viscosity of pore water resulted in delayed degree of consolidation at an initial stage of consolidation. But, it predicted not much differences in settlement as long as the consolidation time was sufficiently long enough to finish consolidation. Consequently, it was found that similarity in permeability should be considered to be critical for the case of centrifuge model experiments related to consolidation with long drainage path.

• Coupled systems mechanics
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• 제11권2호
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• pp.93-106
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• 2022

The total embankment settlement consists of three stages: the initial settlement, the primary consolidation settlement, and the secondary consolidation settlement. The total embankment settlement is largely controlled by the primary consolidation settlement, which is usually computed with numerical models that implement Biot's theory of consolidation. The key parameter that affects the primary consolidation time is the coefficient of permeability. Due to the complex stress and strain states in the foundation soil under the embankment, to be able to predict the consolidation time more precisely, aside from porosity-dependency, the strain-dependency of the coefficient of permeability should be also taken into account in numerical analyses. In this paper, we propose a two-dimensional plane strain numerical model of embankment primary consolidation, which implements Biot's theory of consolidation with both porosity-dependent and strain-dependent coefficient of permeability. We perform several numerical simulations. First, we demonstrate the influence of the strain-dependent coefficient of permeability on the computed results. Next, we validate our numerical model by comparing computed results against in-situ measurements for two road embankments: one near the city of Saga, and the other near the city of Boston. Finally, we give our concluding remarks.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 봄 학술발표회 논문집
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• pp.13-18
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• 1992

Moisture movement which is controlled by water potential and permeability of concrete is a very important phenomenon which affects the shrinkage of concrete. Thermocouple psychrometer were used to measure the moisture potentials in concrete. Based on the measured moisture potentials, three method have been proposed to calculate hycraulic conductivity and diffusivity. And also the hystresis of sorption isotherm due to drying and wetting cycle has been crawn.

• Archives of Pharmacal Research
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• 제10권2호
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• pp.88-93
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• 1987

Chitosan ($\beta$-D-glucosaminan) is chemically prepared from chitin (N-acetyl-$\beta$- D-glucosaminan) which is an unutilized natural resource. We now report on the suitability of the chitosan matrix for use as vehicles for the controlled release of drugs. Salicylic acid and aspirin were used as model drugs in this study. The permeation of salicylic acid in the chitosan membranes was determined in a glass diffusion cell with two compartments of equal volume. Drug release studies on the devices were conducted in a beaker containing 5% sodium hydroxide solution. Partition coefficient (Kd) value for acetate membrane (472) is much greater than that for fluoro-perchlorate chitosan membrane (282). Higher Kd value for acetate chitosan membrane appears to be inconsisstent with the bulk salicylic acid concentration. The permeability constants of fluoro-perchlorate and acetate chisotan membranes for salicylic acid were 3.139 ${\times}10^{-7}cm^2$ min up to 60 min and that of 30% aspirin in the devices was 4.739${\times}10^{-7}cm^2$sec upto 60 min. As the loading dose of aspirin in a chitosan device increased, water up-take of chitosan device increased, but in case of salicylic acid it decreased. The release rate increased with increase in the molecular volume of the drugs. Thses result suggest that the release mechanism may be controlled mainly by diffusion through pores.

• The Plant Pathology Journal
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• 제19권4호
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• pp.189-194
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• 2003

The effects of prochloraz on membrane permeability and germination of uredospores of Puccinia recondita were investigated to determine its potential mode of action on wheat leaf rust control activity. Disease control activity of ergosterol biosynthesis inhibitors (EBIs) and their activities on uredospore membrane permeability and germination were examined with wheat leaf rust pathogen, both in vitro and in vivo. While wheat leaf rust was not controlled by prochloraz, electrolytic leakage and spore germination of P. recondita uredospore was the highest with the use of prochloraz among the eight fungicides tested. Prochloraz stimulated uredospore of P. recondita to germinate at a higher ratio. Although certain EBIs, such as hexaconazole, showed excellent control activity, their effects on uredospore membrane permeability and germination was much inferior to prochloraz. Therefore, results of this study suggest that effects of EBIs on membrane permeability and germination of uredospore are not always correlated with their disease control activity.

• 한국지반환경공학회 논문집
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• 제17권9호
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• pp.29-35
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• 2016

Being mostly made up of highly permeable basalt and volcanic ash soil, Jeju Island's lithosphere characterizes its streams to be dry, flowing only when precipitation is happening. Under this condition, this research was motivated to identify the need of conservation of underground water, which is taking up most of (84% of) Jeju's water usage, and made an attempt to reduce the permeability of stream beds so that it can replace underground water and be used instead. To this end, this study suggested a simple method to make dry streams to carry water all-year-round by reducing permeability of stream floor. The experiment of permeability was performed on the porous basalt and compared it with that of same basalt with volcanic ash soil and Jumunjin sand layer added on top. The results showed a dramatic decrease in permeability of water when both volcanic ash soil and Jumunjin sand is were layered on top of porous basalt. Despite being gained in a controlled environment with a simple test, this result may provide a realistic and effective method of preserving Jeju Island's underground water which ultimately is a method of resolving water related issues.

• 한국세라믹학회지
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• 제53권5호
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• pp.548-556
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• 2016

Recently, porous alumina-based ceramics have been extensively applied in the semi-conductor and display industries, because of their high mechanical strength, high chemical resistance, and high thermal resistance. However, the high electrical resistance of alumina-based ceramics has a negative effect in many applications due to the generation of static electricity. The low electrical resistance and high air permeability are key aspects in using porous alumina-based ceramics as vacuum chucks in the semi-conductor industry. In this study, we tailored the pore structure of porous alumina-based ceramics by adjusting the mixing ratio of the starting alumina, which has different particle sizes. And the electrical resistance was controlled by using chemical additives. The characteristics of the specimens were studied using scanning electron microscopy, mercury porosimetry, capillary flow porosimetry, a universal testing machine, X-ray diffraction, and a high-resistance meter.