• Title/Summary/Keyword: impermeable

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[$Ca^{2+}-activated\;Cl^-$ Current in Gastric Antral Myocytes

  • Lee, Moo-Yeol;Bang, Hyo-Weon;Uhm, Dae-Yong;Rhee, Sang-Don
    • The Korean Journal of Physiology
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    • v.28 no.2
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    • pp.143-150
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    • 1994
  • The whole-cell mode of the patch clamp technique was used to study $Ca^{2+}-activated\;Cl^-\;current$ $(I_{Cl_{Ca}})$ in gastric antral myocytes. Extracellular application of caffeine evoked $Ca^{2+}-activated\;current$. In order to isolate the chloride current from background current, all known systems were blocked with specific blockers. The current-voltage relationship of caffeine-induced current showed outward rectification and it reversed at around $E_{Cl^-}$. The shift of reversal potential upon the alteration of external and internal chloride concentrations was well fitted with results which were calculated by the Nernst equation. Extracellular addition of N-phenylanthranilic acid and niflumic acid which are known anion channel blockers abolished the caffeine induced current. Intracellular application of a high concentration of EGTA also abolished this current. Application of c-AMP, c-GMP, heparin, or $AIF^-_4$ made no remarkable changes to this current. Sodium replacement with the impermeable cation N-methylglucamine or with $Cd^{2+}$ rarely affected this current. From the above results it is suggested that the caffeine induced current was a $Cl^-$ current and it was activated by intracellular $Ca^{2+}$.

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An Analysis on the Hydrologic Cycle Effect of Rodway Permeable Pavement in Rasidential Site (단지내 차도용 투수성 포장의 물순환 효과분석)

  • Lee, Jungmin;Hyun, Kyoung hak;Yuh, OkKyung
    • Journal of Korean Society on Water Environment
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    • v.26 no.4
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    • pp.691-699
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    • 2010
  • In recent years, increases in impervious areas with rapid urbanization and land use changes are causing numerous hydrologic cycle and environmental problems. Impermeable pavement have a various defect such as collection rainwater, decreasing of sliding resistance, and etc. In this study, the hydrologic cycle effect of permeable pavement were analyzed by the experiment and the numerical simulation. The numerical model used was a modified SWMM especially for considering the hydrologic cycle effect of permeable pavement. The parameters of modified SWMM were revised by the experimental results. Also, the effects of runoff quantity reduction are reviewed when permeable pavement is applied to Incheon Cheongna watershed. The hydrologic cycle analysis of Incheon Cheongna watershed, continuous simulations of urban runoff were performed. The analysis results of permeable pavement setup effect on runoff are follows: the surface runoff after permeable pavement setup decreases to 74.35% of the precipitation whereas the surface runoff before permeable pavement setup amounts to 81.38% of the precipitation; the infiltration after permeable pavement setup increases to 15.13% of the precipitation whereas the infiltration before permeable pavement setup amounts to 8.32% of the precipitation.

Numerical Analysis of Waves coming with Oblique Angle to Submerged Breakwater on the Porous Seabed (침투층 위의 잠제에 경사각을 가지고 입사하는 파랑의 수치해석)

  • Kim, Nam-Hyeong;Woo, Su-Min
    • Journal of Navigation and Port Research
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    • v.37 no.3
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    • pp.283-289
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    • 2013
  • Wave profiles coming with oblique angle to trapezoidal submerged breakwater on the porous seabed are computed numerically by using a boundary element method. The analysis method is based on the wave pressure function with the continuity in the analytical region including fluid and structure. When compared with the existing results on the oblique incident wave, the results of this study show good agreement. The fluctuation of wave profiles is increased in the rear of the submerged breakwater due to the increase of the transmission coefficient, as the incident angle increases. In addition, in the case of the wave profiles passing over the submerged breakwater on porous seabed, it is able to verify that the attenuation of wave height occurs more significantly due to the wave energy dissipation than that of passing over the submerged breakwater on the impermeable seabed. The results indicate that wave profile own high dependability regarding the change of oblique incident waves and porous seabed. Therefore, the results of this study are estimated to be applied as an accurate numerical analysis referring to oblique incident waves and porous seabed in real sea environment.

Impacts on water-cycle by land use change and effects of infiltration trenches in Asan New town (토지이용 변화가 물순환에 미치는 영향과 침투트렌치 설치 효과 분석 - A 신도시 지구를 중심으로 -)

  • Hyun, Kyoung-Hak;Lee, Jung-Min
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.6
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    • pp.691-701
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    • 2010
  • As the water-cycle is transformed by increasing of the impermeable area in process of urbanization, decentralized rainwater management facilities(infiltration, harvesting and retention facilities) as source control are considered to be a method of restoring water-cycle of urban and reducing runoff. SWMM model was used to analyse the change of water-cycle structure before and after development in A new town watershed. Modified SWMM code was developed to apply infiltration facilities. The modified SWMM was used to analyse the change of water-cycle before and after infiltration trench setup in AJ subcatchment. Changes of the impervious area by development and consequent increase in runoff were analyzed. These analyses were performed by a day rainfall during ten years from 1998 to 2007. According to the results, surface runoff increased from 51.85% to 65.25 %, and total infiltration volume decreased from 34.15 % to 21.08 % in A newtown watershed. If more than 80 infiltration trenches are constructed in AJ subcatchment, the low flow and the drought flow increases by around 47%, 44%, separately. The results of this study, infiltration trench is interpreted to be an effective infiltration facility to restore water-cycle in new town.

Numerical analysis of an offshore platform with large partial porous cylindrical members due to wave forces

  • Park, Min-Su;Kawano, Kenji;Nagata, Shuichi
    • Ocean Systems Engineering
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    • v.1 no.4
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    • pp.337-353
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    • 2011
  • In the present study, an offshore platform having large partial porous cylindrical members, which are composed of permeable and impermeable cylinders, is suggested. In order to calculate the wave force on large partial porous cylindrical members, the fluid domain is divided into three regions: a single exterior region, N inner regions and N beneath regions, and the scattering wave in each fluid region is expressed by an Eigen-function expansion method. Applying Darcy's law to the porous boundary condition, the effect of porosity is simplified. Wave excitation forces and wave run up on the structures are presented for various wave conditions. For the idealized three-dimensional platform having large partial porous cylindrical members, the dynamic response evaluations of the platform due to wave forces are carried out through the modal analysis. In order to examine the effects of soil-structure interaction, the substructure method is also applied. The displacement and bending stress at the selective nodal points of the structure are computed using various input parameters, such as the shear-wave velocity of soil, the wave height and the wave period. Applying the Monte Carlo Simulation (MCS) method, the reliability evaluations at critical structure members, which contained uncertainties caused by dynamic forces and structural properties, are examined by the reliability index with the results obtained from MCS.

Experimental Study on Rainfall Runoff Reduction Effects by Permeable Polymer Block Pavement (투수성 폴리머 블록 포장에 의한 우수 유출 저감 효과에 관한 실험적 연구)

  • Sung, Chan-Yong;Kim, Young-Ik
    • Journal of The Korean Society of Agricultural Engineers
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    • v.54 no.2
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    • pp.157-166
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    • 2012
  • Most of the roads are paved with impermeable materials such as asphalt concrete and cement concrete, and in the event of heavy rainfall, rainwater directly flows into river through a drainage hole on the pavement surface. This large quantity of rainwater directly spilled into the river frequently leads to the flooding of urban streams, damaging lowlands and the lower reaches of a river. In recent years there has been a great deal of ongoing research concerning water permeability and drainage in pavements. Accordingly, in this research, a porous polymer concrete was developed for permeable pavement by using unsaturated polyester resin as a binder, recycled aggregate as coarse aggregate, fly ash and blast furnace slag as filler, and its physical and mechanical properties were investigated. Also, 3 types of permeable polymer block by optimum mix design were developed and rainfall runoff reduction effects by permeability pavement using permeable polymer block were analyzed based on hydraulic experimental model. The infiltration volume, infiltration ratio, runoff initial time and runoff volume in permeability pavement with permeable polymer block of $300{\times}300{\times}80$ mm were evaluated for 50, 100 and 200mm/hr rainfall intensity.

Integrated Application of Stormwater Network Analysis Model and Surfacewater Inundation Analysis Model (우수관망 해석모형과 지표수 침수해석 모형의 연계 적용)

  • Shin, Eun Taek;Lee, Sangeun;Eum, Tae Soo;Song, Chang Geun
    • Journal of the Korean Society of Safety
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    • v.33 no.5
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    • pp.78-83
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    • 2018
  • Recently, due to the rapid industrialization and urbanization, a great number of infrastructure and population were concentrated in urban areas. These changes have resulted in unprecedent runoff characteristics in urban basins, and the increase in impermeable areas leads to the growth of the runoff and the peak flow rate. Although many cities have made a lot of efforts to check and expand the stormwater network, the flash flood or the local torrential rain caused a growing number of casualty and property damage. This study analyzed the stormwater passage rate in a target area using SWMM. By incorporating the flow quantity surpassing the storm sewer capacity, a 2D inland flooding analysis model was applied to route the inundated area and velocity.

Washoff Characteristics and Correlation of Nonpoint pollutants in a Bridge Storm Runoff (교량 강우유출수내 비점오염물질의 유출특성 및 상관성)

  • Wee, Seung-Kyung;Kim, Lee-Hyung;Jung, Yong-Jun;Gil, Kyung-Ikt
    • Journal of Korean Society on Water Environment
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    • v.24 no.3
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    • pp.378-382
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    • 2008
  • During the dry periods, many types of pollutants are being accumulated on the paved surface by vehicle activities and the accumulated various pollutants are inflowing into the near watershed areas for the rainfall periods. Particularly, bridges are the centralized region to be the surface runoff of the stromwater due to the high ratio of the impermeable area. Also, the metals, toxic chemicals and sediments originated from bridges could be strongly influenced to the watershed areas during the runoff. Therefore, the present study is achieved to provide washoff characteristics and correlation from the bridge during rainfall periods. The result shows that the EMC ranges for 95% confidence intervals in a bridge land use are 10.12~128.09 mg/L for TSS, 6.07~21.15 mg/L for BOD, 2.10~6.70 mg/L for TN and 0.06~0.85 mg/L for TP.

Heavy Metal Contamination of Roadside Gully-Pot Sediments, Seoul, Korea

  • Kim, Sung-Hwan;Lee, Pyeong-Koo;Yun, Seong-Taek;So, Chil-Sup
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2001.04a
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    • pp.222-225
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    • 2001
  • In urban environments, the surface land impermeability fundamentally related to urban growth emphasizes the environmental problems such as the storm water peak flow (so-called the urban flooding) and the pollution. The conventional urban drainage system provides a number of temporary reservoirs intercepting and retaining surface-derived pollutants following their introduction to and deposition upon the impermeable surface. Gully-pots are common features in urban drainage systems in Korea, which were installed for draining rainwater to prevent regurgitation in rainy season and retaining larger particles, hence minimizing pipe blockage problems. When the road runoff conveying sediment enters a gully-pot, the sediment mixes with the gully liquor causing direct pollution of receiving waters. The characteristics of local sediment contamination are usually related to the types of land use activities that take place or have taken place within the area., This study was undertaken to evaluate the spatial and temporal variations of the contamination of gully-pot sediments in Seoul with respect to heavy metals such as As, Cd, Co, Cr, Ni, Pb, Cu and Zn. The heavy metal data were examined according to the land use type. In this paper, sampling sites in Seoul were divided into six groups (commercial area, industrial area, residental area, motor way, rural area, and local pollution).

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Slug Test Analysis in Vertical Cutoff Walls with Consideration of Filter Cake (연직차수벽에서 필터케익을 고려한 순간 변위시험 해석방법)

  • Nguyen, The Bao;Lee, Chul-Ho;Choi, Hang-Seok
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.220-228
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    • 2008
  • In constructing a slurry trench cutoff wall, a thin but relatively impermeable layer called filter cake can be formed on the excavation surface. The filter cake significantly influences the result of slug test analysis in the cutoff wall. This study is to examine the effect of filter cake on evaluating in situ hydraulic conductivity of the vertical cutoff wall along with slug test analyses. The numerical program Slug_3D was modified to take filter cake into account in the slug test simulation. With consideration of filter cake, the type curve method and the modified line-fitting method were used to reanalyze the case study taken from a landfill site. The previous results achieved by Choi and Daniel (2006b) without consideration of filter cake have been compared with the results in this study. The considerable difference between the two results shows the necessity of considering the filter cake in practice.

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