• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
• /
• pp.12-31
• /
• 2000

The permeability of converter slag, replacing material of sand mat on improving soft clay foundation, was evaluated in the laboratory. The effects of grain size, flow water time and aging were investigated using sea and fresh water. Converter slag being submerged with fresh water, the coefficients of permeability in A and B samples less than 10mm grain sizes were measured as 6.52${\times}$10$\^$-2/cm/sec and 5,99${\times}$10$\^$-1/cm/sec, while changed as 1,88${\times}$10$\^$-2/cm/sec, 3.86${\times}$10$\^$-1/cm/sec under sea water condition. Also, the condition of turbulent flow may exit and was experimentally identified from the relationship between hydraulic gradient and seepage velocity. After 180 days on using sea water, the coefficients of permeability of sample A and B samples decreased ten times smaller than those initial values. And after that time continually decreased as for till 360 days. The reduction of permeability coefficient was considered to influence filled with voids in high-calcium quicklime(CaO). However, in-situ coefficient of permeability was practically satisfactory.

• Nuclear Engineering and Technology
• /
• 제44권1호
• /
• pp.43-52
• /
• 2012

To compute a permeability coefficient along a rough fracture that takes into account the fracture geometry, this study performed detailed measurements of fracture roughness using a confocal laser scanning microscope, a quantitative analysis of roughness using a spectral analysis, and a homogenization analysis to calculate the permeability coefficient on the microand macro-scale. The homogenization analysis is a type of perturbation theory that characterizes the behavior of microscopically inhomogeneous material with a periodic boundary condition in the microstructure. Therefore, it is possible to analyze accurate permeability characteristics that are represented by the local effect of the facture geometry. The Cpermeability coefficients that are calculated using the homogenization analysis for each rough fracture model exhibit an irregular distribution and do not follow the relationship of the cubic law. This distribution suggests that the permeability characteristics strongly depend on the geometric conditions of the fractures, such as the roughness and the aperture variation. The homogenization analysis may allow us to produce more accurate results than are possible with the preexisting equations for calculating permeability.

• 한국산학기술학회논문지
• /
• 제10권10호
• /
• pp.2810-2818
• /
• 2009

본 연구는 화강풍화토로 구성된 절토사면에서 얕은파괴의 특성을 규명하고자 우리나라의 강우특성에 따른 한계투수계수를 산정하고, 국내에 분포하는 화강풍화토의 대표적 물성을 기준으로 절토사면의 파괴면까지의 수평거리, 사면의 경사각, 사면높이 그리고 강우로 인한 포화깊이 등에 따른 안정해석을 수행하여 그 결과를 분석하였다. 한계투수계수를 분석한 결과 국내의 지역별 강우특성을 고려한 최대 한계투수계수가 $7.16{\times}10^{-4}cm/sec$의 값으로 나타났다. 최대 한계투수계수 이하의 값을 갖는 국내의 화강풍화토로 구성된 절토사면에서 한계강우강도 이하의 강우가 최소 강우지속시간보다 오랫동안 지속될 때에는 포화깊이에 따른 얕은파괴의 검토가 고려되어져야 할 것으로 판단되었다. 또한, 가상파괴면이 발생하는 수평거리, 포화깊이, 강도정수 변화에 따른 사면안전율의 변화관계를 통해 절토사면의 얕은파괴 특성을 파악 할 수 있었다.

• 한국농공학회지
• /
• 제44권6호
• /
• pp.99-105
• /
• 2002

A series of physical properties and rigid wall permeability tests were performed on two clays to investigate changes in permeability characteristics of clays with various pH values. Results of the study are as follows. As pH values were increased, coefficients of permeability of S-clay(clay fraction 18%) and J-clay(clay fraction 30%) were decreased in 3 and 4 times, respectively. Variation of coefficient of permeability of J-clay was considerably related to clay fraction. It can be said that coefficient of permeability of clays tested was increased, as pH values were decreased. This was because of increase in effective voids caused by decrease in thickness of diffused double layer, that is, change in soil structures and effective grain sizes.

• 한국소음진동공학회논문집
• /
• 제17권4호
• /
• pp.342-349
• /
• 2007

Following the 2002 World-Cup held in Korea, studies have been actively conducted on plans to utilize all-weather stadiums of fine figures, where large-scale spaces are available for various utilizations. In Japan, dome-type stadiums have been built and are utilizing across the whole nation not only for sports events but also variety of other large-scale events. PTFE(poly tetra fluoro ethylene) is one of the membrane material mainly used for the outer ceiling surface of membrane structures. However, there has not been enough research on the acoustical properties of PTFE membrane material which has been widely used in the multi-purpose stadiums. In this study, air permeability values and sound absorption coefficient of PTFE membrane materials were measured and evaluated in the gymnasium. From the results of measurements of sound absorption coefficient and air permeability of inner membrane materials, it was found that the sound absorption coefficient was good in the air permeability range of $5{\sim}15\;cc/cm^2/s$. Also the relation ship between air permeability and sound absorption coefficient was very high and the sound absorption coefficient was the highest in the range of $6{\sim}9\;cc/cm^2/s$. Secondly, an analysis on the measurements sound absorption characteristics of inner membrane material reveals that the overall sound absorption coefficient was stabilized(higher than 0.5 throughout the whole frequency bands) when the air space behind the membrane material was deeper than 600 mm. When PTFE sound absorptive membrane material was installed in the ceiling of gymnasium, it was confirmed that sound absorptive membrane material can reduce reverberation and increase speech intelligibility in the gymnasium.

• Journal of Pharmaceutical Investigation
• /
• 제35권2호
• /
• pp.71-74
• /
• 2005

The aim of this study was to analyze characteristics of the barrier function of excised porcine buccal mucosa to the test compounds, estradiol, propranolol HCI, melatonin, and mannitol with a wide range of partition coefficient values. The permeability of melatonin was measured through frozen, stored, and fresh porcine buccal mucosa to examine the impact of storage conditions on the permeability of porcine buccal mucosa. The results demonstrated that the ex vivo permeability of the porcine buccal mucosa was greater for more lipophilic solutes, which was consistent with a series of molecules transported by passive transepithelial diffusion. The melatonin permeation profiles through frozen, stored, and fresh mucosa illustrated that damage was incurred by the freezing process of the mucosal tissue, leading to loss of the barrier function and thereby an increased permeation coefficient. It can be observed that the influence of compound lipophilicity on the association of the compounds with buccal mucosa was clear. The relationship between permeation coefficient and Log P values for the four compounds investigated demonstrated a proportional relationship, further confirming the importance of the lipophilicity of a compound to permeate the buccal mucosa. These results showed that the ex vivo porcine buccal mucosa model is a suitable tool to screen oral mucosal permeability.

• 한국농공학회논문집
• /
• 제65권2호
• /
• pp.47-57
• /
• 2023

The increase of impermeable area ratio is causing hydrologic cycle problems in urban areas and groundwater depletion in rural areas, permeable pavements are getting attention to expand permeable areas. The performance of the permeable concrete block pavement, which is part of the permeable pavement, is greatly affected by the porosity. In addition, the permeability coefficient is a major factor when designing permeable concrete block pavement. Existing porosity and permeability test methods have problems such as uneconomical or poor field applicability. The object of this study was to develop a methodology for evaluating porosity and permeability coefficient using a surface image of a permeable concrete block. Specimens are manufactured with various porosity ranges and porosity and permeability tests are performed. After surface image preprocessing, normalization and binarization methods were compared. Through this, the method with the highest correlation with the lab test result was determined. From the results, the PDR (pore determined ratio) was obtained. Simple linear regression analysis is performed with PDR and lab test results. The results showed a high correlation of R² more than 0.8, and the errors were also low.

• 한국농공학회논문집
• /
• 제47권4호
• /
• pp.35-41
• /
• 2005

In order to analyse the flow problems for an unsaturated soil, it is required to examine closely the characteristics of the coefficient of permeability which is changing with the matric suction. To this ends, a permeability test was conducted on the three samples;granular soil, cohesive soil and silty soil. The specimen was made by pressing the static pressure on the mold filled with soil and the void ratio was controled with the different compaction ratio. And the test was performed by using the modified apparatus of the steady state method which was proposed by flute (1972). The range of matric suction was 0-90 kPa. The measured results for the coefficients of permeability were analysed with the void ratio and the compaction ratio, and it was examined closely the characteristics of the permeability for an unsaturated soil.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
• /
• pp.363-368
• /
• 1997

In this study, permeable polymer concretes using unsaturated polyester (UP) resin with binder contents of 6, 7 and 8%, filler-binder ratios of 0, 0.5, 1.0%, and various sand and aggregate contents are prepared, and tested for compressive and flexural strengths, length change and water permeability. The effects of the mix proportioning factors on the strength properties, length change and coefficient of permeability of the permeable polymer concrete are discussed. From the test results, increase in the compressive strength and decrease in the coefficient of permeability of permeable polymer concrete are clearly observed with increasing filler-binder ratio. The permeable polymer concretes having a compressive strength of 9.4~28.3MPa and a coefficient of permeability of 0.12~1.93 cm/s can be produced in the consideration of the mix proportioning factors.

• Geomechanics and Engineering
• /
• 제21권2호
• /
• pp.165-170
• /
• 2020

The groundwater during tunnel excavation not only affects the stability of the tunnel and constructability but also causes the subsidence of the upper ground due to the lowering of groundwater. Generally, the cutoff grouting is applied as a countermeasure to reduce the groundwater inflow during tunnel excavation, and the cutoff grouting is often applied in the range of plastic zone around the tunnel. However, grouting in the plastic zone is only appropriate for ground reinforcement purposes, and guidelines for the application range of cutoff grouting and the targeted permeability coefficient of the grouting zone are required. In this study, the relationship between groundwater inflow into tunnel and application range of cutoff grouting and permeability coefficient is proposed and compared with numerical analysis results. It was found that grouting with tunnel radius thickness is appropriate to reduce the groundwater inflows effectively. More than 90% reduction in groundwater inflow can be achieved when the annular area of the tunnel radius thickness is grouted with a permeability reduction ratio of 1/50~1/200.