• Title/Summary/Keyword: impermeable

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A Study on the Ground Reinforcement and Impermeable Effect by McG (McG(맥) 주입공법에 의한 지반보강 및 차수효과에 관한 연구)

  • Chun, Byung-Sik;Jung, Jong-Ju;Chung, Chang-Hee;Do, Kyung-Yang;Do, Jong-Nam
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.352-361
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    • 2006
  • The grouting method is widely used in construction to reduce permeability and reinforce the ground. If the cement and grout material are not mixed well in the injection tip equipment, an opposite flow and Interception state of the chemical grouting can occur. McG method installs a special grouting device to allow better mixing of the grouting material and prevent backward flow. The block of nozzle also diversify powder rate of cement. YSS that lowers $Na_2O$ and thereby increases durability is developed by gel-forming reaction material. In this study, the seepage state and unconfined compressive strength of the injection material using the special injection tip equipment is tested. The results of laboratory and field tests clearly demonstrate that the strength increases and permeability decreases using the McG method.

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A Study on the Application of Permeable Preactive Barriers in Landfill (매립지에서 반응성 투수벽체의 적용성에 관한 연구)

  • Chun, Byung-Sik;Park, Jae-Woo;Do, Jong-Nam;Park, Joong-Sub;Park, Chan-Su
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.1126-1131
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    • 2006
  • This study is part of the project that develops the permeable preactive barrier to be applied in a landfill. The geotechnical applicability of the permeable preactive barrier that filters the leachate from the landfill was evaluated. Dry specimens were made using a mixture of sand, loess and bentonite. A series of experiments are performed to determine the unconfined compressive strength and permeability of various mixing ratio of bentonite, loess, and sand. The laboratory test indicate that the optimum-mixing ratio that satisfied the regulation of unconfined compressive strength(490kPa) and coefficient of permeability$(10^{-3}\sim10^{-4}cm/s)$ of the landfill was when the ratio of sand and loess was 8:2 with bentonite content of 2%. The permeable preactive barrier is different from an impermeable barrier in that it permits a limited diffusion of the leachate, which will be directly purified biologically and chemically in the landfill.

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The Watershed Imperviousness Impact for the characteristic of stormwater runoff (유역의 불투수성에 따른 강우유출특성 비교)

  • Ham, Kwang-Jun;Kim, Joon-Hyun;Huh, Beom-Nyung;Choi, Ji-Yong;Kim, Yeong-Jin
    • Journal of Environmental Impact Assessment
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    • v.15 no.2
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    • pp.157-163
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    • 2006
  • The purpose of this study is to understand imperviousness impact for the characteristics of stormwater runoff and water temperature. The land-use map was used to estimate the watershed imperviousness(percent of impermeable area) and the RMS(Remote Monitoring System) was used to evaluate the stormwater runoff of watershed. This study was investigated for two streams(Jiam and Gongji) in Chunchon City. The detailed results of these studies are as follows; The imperviousness(%) of two watersheds(Jiam and Gongji) estimated by spatial analysis which is main function of GIS were 0.24% and 24.16%. So, Gongji watershed as urban area was about 100 times than jiam watershed as forest area. In case of rainfall of low intensity, stormwater runoff flowrate in higher imperviousness area(Gongji) was more than it in forest area(jiam). Also, The time to peak flowrate(Tp) was short in Gongji stream and the water temperature difference between Gongji and Jiam stream was about $4.4^{\circ}C$ in summer.

Wave Control by an Array of Porous Dual Cylindrical Structures (투과성 이중 원통구조물 배열에 의한 파랑제어)

  • CHO IL-HYOUNG
    • Journal of Ocean Engineering and Technology
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    • v.18 no.5
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    • pp.7-14
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    • 2004
  • The interaction of incident manochromatic waves with an array of N surface-piercing porous dual cylindrical structures is investigated in the frame of three-dimensional linear potential theory. The dual cylindrical structure is camposed of concentric two cylinders. The exterior cylinder is porous and the interior cylinder is impermeable. The fluid domain is divided into N+1 regions i.e. a single exterior region and N interior regions. The diffraction potentials in each region representing the scattering of incident waves by an array of porous cylindrical structures are expressed by the Fourier Bessel series. The unknown coefficients in each region are determined by applying the porous boundary condition and continuity of mass flux at the matching boundary. It is found that an array of porous cylindrical structures reduces both the wave forces and the wave run-up, and shows the excellent performance of wave blocking. The results show that various types of breakwater exchanging seawater are prospective by controlling the porosity and the configuration of cylindrical structures.

Prediction of Permeability for Braided Preform (브레이드 프리폼의 투과율 계수 예측)

  • Youngseok Song;Youn, Jae-Roun
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2003.04a
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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.

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Double-Diffusive Convection Due to Heating from Below in a Rotating Cylindrical Cavity (회전하는 원통형밀폐용기내의 아랫면가열에 의한 이중확산대류에 관한 실험적 연구)

  • 강신형;이태홍;이진호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.7
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    • pp.1731-1740
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    • 1995
  • Experimental investigations have been made to study the double-diffusive nature of convection of an initially stratified salt-water solution due to heating from below in a rotating cylindrical cavity. The objective is to examine the flow phenomena and the heat transfer characteristics according to the changes in temperature gradient, concentration gradient and rotating velocity of cavity. Thermal and solutal boundary conditions at side wall are adiabatic and impermeable, respectively. The top and bottom plate are maintained each at constant temperature and concentration. The cavity is put into a state of solid body rotation. Like the stationary case, the types of initially-formed flow pattern are classified into three regimes depending on the effective Rayleigh number and Taylor number; stagnant flow regime, single mixed-layer flow regime and successively formed multi-mixed layer flow regime. At the same effective Rayleigh number, the number of initially-formed mixed layer and its growth rate decrease as the effect of rotation increases. The temperature and concentration profiles are both uniform in each layer due to convective mixing in the layered-flow regime, but look both liner in stagnant flow regime and single mixed-layer flow regime. At the interface between adjacent layers, the temperature changes smoothly but the concentration changes rapidly.

Inclined Edge Crack in a Piezoelectric Material Under Antiplane Loads (압전재료에 대한 면외하중하의 모서리 경사 균열)

  • Choi, Sung Ryul;Sah, Jong Youb;Jeong, Jae Tack
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.6
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    • pp.589-596
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    • 2015
  • The occurrence of an inclined edge crack in transversely piezoelectric material is analyzed. Concentrated antiplane mechanical and inplane electrical loads are applied at the boundary and crack surface, respectively. The crack surfaces are assumed to be impermeable to the electric field. Using the Mellin transform with the introduction of a generalized displacement vector, the problem is formulated, and the Wiener-Hopf equation is derived. By solving the equation, the solution is obtained in a closed form. The intensity factors of the stress, the electric displacement, and the energy release rate are obtained for any crack length and inclination angle. These solutions can be used as fundamental solutions and can be superimposed to represent any arbitrary electromechanical loading.

A study on the Effective Operation of Pump Stations (빗물펌프장 운영합리화 방안 연구)

  • 한국원자력연구소
    • Journal of Korea Water Resources Association
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    • v.31 no.2
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    • pp.133-144
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    • 1998
  • Recent development booms in urban watersheds have increased impermeable areas and brought about an increase of peak flood. Eventually, some people living in the lower area of an urban watershed, very often and seriously, have suffered form inundation. In this study, for minimization of inundation in urban watersheds, the operational criteria for pump stations are suggested. At first, ILLUDAS has been selected as a runoff model which can explain the past precipitations. Secondly the operational criteria for pump stations could be suggested by working out an operational criteria for pump stations could be suggested by working out an operation program from the relationship between pumping capacity and accumulative hydrographs, and from the Intensity-Duration-Frequency relationship.

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Hydrologic Cycle Simulation of Urban river for Rehabilitation of Water Environment (I) - Anyangcheon Basin - (물 환경 건전화를 위한 도시하천의 물 순환 모의 (I) - 안양천 유역 -)

  • Lee, Jung-Min;Lee, Sang-Ho;Lee, Kil-Seong
    • Journal of Korean Society on Water Environment
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    • v.22 no.2
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    • pp.349-357
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    • 2006
  • Nowadays, the discharges of urban streams during dry season are depleted because the hydrologic cycle in the watershed has been destroyed due to the expansion of the impermeable area, the excessive groundwater pumping, climate change, and so forth. The streamflow depletion may bring out severe water quality problems. This research are to investigate the hydrologic characteristics and to develop a technology to restore sound hydrologic cycle of Anyangcheon watershed. For the hydrological cycle analysis of the Anyangcheon watershed, continuous simulations of urban runoff were performed for the upstream basin of Gocheok bridge whose basin area covered 4/5 of the whole catchment area. The increase of impervious area by urbanization was analysed and its effect on urban runoff was evaluated. The SWMM 5 (Storm Water Management Model 5) was used for the continuous simulation of urban runoff. The analysis results of urbanization effect on runoff are as follows: the surface runoff in 2000 increases to 65% of the whole precipitation whereas the surface runoff in 1975 amounts to 50% of the precipitation; the groundwater runoff in 2000 amounts to 7% and shows 6% decrease during the period from 1975 to 2000.

Measurements of velocity distributions between the impermeable spur dikes (불투과 횡수제에서 유속 분포의 측정)

  • Hwang, Seung-Yong;Kim, Sung Jung;Lyu, Siwan;Yeo, Hong Koo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2004.05b
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    • pp.932-936
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    • 2004
  • 수제는 하천에서의 흐름 방향과 유속을 제어하여 하안 또는 제방을 유수에 의한 침식작용으로부터 보호하기 위해 호안 또는 하안 전면부에 설치하는 구조물이다. 수제를 설치하는 목적은 하안 및 제방의 보호, 유로의 제어, 그리고 수환경의 개선 등을 들 수 있다. 국내에는 해방 이후 수제의 시공 사례가 거의 없었으나, 최근 들어 자연형 하천파 하천생태계 복원에 대한 관심이 점증하면서 수제에 대한 관심이 커지고 있다. 그러나 현재 국내에는 수제설계에 대한 실증적인 지침이 미비하고 국외의 기준을 검증 없이 소개하는 수준이어서 현장의 설계단계에서 수제공의 채택을 망설이게 하는 원인이 되고 있다. 이 연구에서는 국내${\cdot}$외 수제의 현황과 기술 동향을 파악하여 수제의 기하학적 특성인 수제길이, 수제길이, 그리고 설치각도의 3가지 설계인자를 조합하여 실험을 실시하였다. LSPIV 기법을 적용하여 측정한 유속자료를 분석한 결과 수제역 내 평균유속이 유입부 유속에 비해 $40\%$ 이하로 감소하는 것을 관찰할 수 있었다. 유속성분을 통하여 수제역 내 와도 및 사분면 검토를 실시한 결과 수제역 내에서는 비교적 안정적인 수치를 보이고 있어 호안침식방지에 유리한 것으로 보인다. 수제의 길이가 하폭의 $15\%$ 이하인 경우 상향 또는 하향수제가, $20\%$ 이상인 경우 직각수제가 유리한 것으로 나타났다.

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