• Title/Summary/Keyword: impermeable

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Variation Profiles of Temperature by Green Area of Apartments in Gangnam, Seoul (서울 강남지역 아파트단지의 녹지면적에 따른 온도변화 모형)

  • 홍석환;이경재
    • Korean Journal of Environment and Ecology
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    • v.18 no.1
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    • pp.53-60
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    • 2004
  • This study was carried out to investigate the effect of green area in apartment complexes to variation of temperature. The inside temperature of each site was estimated by analyzing Landsat ETM+ image data. The factors on variation of temperature were landcover type, building density, and Normalised Difference Vegetation Index(NDVI). The results of correlation between inside temperature of apartment complex and land cover type showed that the green area ratio had negative(-) correlation and impermeable pavement ratio had positive(+) correlation. Building-to-land ratio was not significant with inside temperature. A coefficient of correlation between the temperature value and the value of permeable pavement ratio added up green area ratio was higher than a coefficient of correlation between the temperature value and the value of permeable pavement ratio added up impermeable pavement ratio. Thus we may define that permeable pavement area decrease urban temperature with green area in apartment complex. Floor area ratio had no significant correlation with inside temperature. Inside temperature was decreased as the NDVI was increased. To establish the temperature distribution model in a development apartment complex, As the result of regression analysis between inside temperature as dependent variable and permeable pave ratio+green area ratio, green area ratio, building-to-land ratio and NDIT as independent variables, only permeable pavement ratio added up green area ratio of the independent variables was accepted fur regression equation in both two seasons and adjusted coefficient of determination was 41.4 on September, 2000 and 40.4 on June,2001.

Control of Short-period and Solitary Waves Using Two-rowed Impermeable Rectangular Submerged Dike (2열 불투과성 사각형 잠제를 이용한 단주기파랑 및 고립파의 제어)

  • Lee, Kwang-Ho;Jung, Sung-Ho;Ha, Sun-Wook;Kim, Do-Sam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.4
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    • pp.203-214
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    • 2010
  • This study numerically investigates the wave control of 2-rowed Impermeable Rectangular Submerged Dike(IRSD) with an object of how to control short-period and solitary waves simultaneously based on the Bragg resonance phenomenon that elevates the wave control performance. The boundary integral method using Green formula and the 3-D one-field Model for immiscible TWO-Phase flows (TWOPM-3D) by 3-D numerical wave flume have been used for the numerical predictions for short-period and solitary waves, respectively. These numerical models were verified through the comparisons with the previously published numerical results by other researchers. Through the parametric tests of numerical experiments for short-period waves, an optimum model of 2-rowed IRSD of a lowest transmission coefficient has been found. Furthermore, the performances of 3-D wave control for solitary waves were evaluated for the various free board, crown widths and gap distance between dikes, and have been compared with those of a single-rowed IRSD. Numerical results show that a 2-rowed IRSD with a less cross sectional area than 1-rowed one improves the wave attenuation performances when it is compared to that of single-rowed IRSD. Within the test frequency ranges of the numerical simulations conducted in this study, 2-rowed IRSD with an optimum gap distance shows an outstanding improvement of the wave attenuation up to 58% compared to that of single-rowed IRSD.

FALKNER-SKAN EQUATION FOR FLOW PAST A MOVING WEDGE WITH SUCTION OR INJECTION

  • Ishak, Anuar;Nazar, Roslinda;Pop, Ioan
    • Journal of applied mathematics & informatics
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    • v.25 no.1_2
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    • pp.67-83
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    • 2007
  • The characteristics of steady two-dimensional laminar boundary layer flow of a viscous and incompressible fluid past a moving wedge with suction or injection are theoretically investigated. The transformed boundary layer equations are solved numerically using an implicit finite-difference scheme known as the Keller-box method. The effects of Falkner-Skan power-law parameter (m), suction/injection parameter ($f_0$) and the ratio of free stream velocity to boundary velocity parameter (${\lambda}$) are discussed in detail. The numerical results for velocity distribution and skin friction coefficient are given for several values of these parameters. Comparisons with the existing results obtained by other researchers under certain conditions are made. The critical values of $f_0$, m and ${\lambda}$ are obtained numerically and their significance on the skin friction and velocity profiles is discussed. The numerical evidence would seem to indicate the onset of reverse flow as it has been found by Riley and Weidman in 1989 for the Falkner-Skan equation for flow past an impermeable stretching boundary.

The Development of the Hydrophobic - Low Viscosity Filling Material for the Surface Treatment for Pavement Preventive Maintenance (예방적 유지보수를 위한 소수성 저점도 AP 표면처리재 개발)

  • Choi, Jun Seong;Kim, Jo Sun
    • International Journal of Highway Engineering
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    • v.16 no.2
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    • pp.35-41
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    • 2014
  • PURPOSES : Surface treatment is a favorable method in the pavement preventive maintenance. This study (Part I) aimed to develop the low viscosity filling material for waterproof characteristics and high penetrable and weather resistance, and a series of companion study (Part II) presents the coating characteristics and performance analysis using field and lab tests. METHODS : Hydrophobic characteristics of the advanced surface treatment material are observed and measured the filling depth and the permeability for sand and asphalt pavement specimen using the water absorption test and permeability test, X-RAY CT test. Color difference for the weather resistance using ultraviolet ray accelerated weathering test is compared with asphalt pavement specimens. RESULTS : The developed material shows the decreased water absorption and increased impermeable effect because of the hydrophobic characteristics. It is found that the filling depth is about 6mm and weather resistance is better than asphalt pavement specimen. CONCLUSIONS : The advanced hydrophobic - low viscosity filling treatment material is developed in this study (Part I) to improve the waterproof characteristics and high filling capacity and weather resistance for the pavement preventive maintenance.

Seepage-Advection-Dispersion Numerical Analysis of Barrier System of Offshore Rubble Mound Revetment Landfill Under Steady Flow (정상류 조건에서 경사식호안 해상폐기물매립장의 차수에 대한 침투이류 분산해석)

  • Hwang, Woong-Ki;Kim, Hyang-Eun;Kim, Tae-Hyung
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.4
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    • pp.97-106
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    • 2019
  • This study was conducted to propose a reasonable requirement regulation of barrier system of rubble mound revetment offshore landfill for preventing contaminant leakage. The barrier is composed with bottom layer and side barrier. The bottom layer was assumed as impermeable clay layer and side barrier was composed with HDPE sheet (primary element) and mid-protection layer (supplementary element). Seepage-advection-dispersion numerical analysis has been conducted using SEEP/W and CTRAN/W programs under steady flow. As the results, the minimum required barrier regulations for hydraulic conductivity and thickness of the bottom layer were suggested. For side barrier, the extended length of HDPE sheet and the hydraulic conductivity of mid-protection layer were also suggested.

Physiological functions of the TRPM4 channels via protein interactions

  • Cho, Chang-Hoon;Lee, Young-Sun;Kim, Eunju;Hwang, Eun Mi;Park, Jae-Yong
    • BMB Reports
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    • v.48 no.1
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    • pp.1-5
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    • 2015
  • Transient Receptor Potential, Melastatin-related, member 4 (TRPM4) channels are $Ca^{2+}$-activated $Ca^{2+}$-impermeable cation channels. These channels are expressed in various types of mammalian tissues including the brain and are implicated in many diverse physiological and pathophysiological conditions. In the past several years, the trafficking processes and regulatory mechanism of these channels and their interacting proteins have been uncovered. Here in this minireview, we summarize the current understanding of the trafficking mechanism of TRPM4 channels on the plasma membrane as well as heteromeric complex formation via protein interactions. We also describe physiological implications of protein-TRPM4 interactions and suggest TRPM4 channels as therapeutic targets in many related diseases.

A Study on Monitoring to Investigate Dynamic Temperature Model by Sensible Heat Flux of Green Roof System (옥상녹화시스템의 현열유동에 따른 동적온도모형 검증을 위한 모니터링 연구)

  • Park, Eun-hee;Kim, Tae-han;Park, Sang-yeon;Jang, Seong-wan
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.18 no.6
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    • pp.15-25
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    • 2015
  • The growth of impermeable layers in the city center due to today's urban development is emerging as a major cause of urban heat island effects as well as recurring inland flood damages. In order to cope with such disasters caused by climatic changes, an artificial ground afforestation system is suggested as a fundamental solution that addresses both water environment and heat environment. For the afforestation system to replace the current disaster prevention facilities, quantitative performance verification through related numerical analysis models and actual survey monitoring is necessary. Therefore, this study seeks to propose the performance predication method for the heat environment of the afforestation system by looking into correlations between measurements by physical vegetation indicators such as LAI and FVC and forecasts from FASST, a vegetation canopy model used by US Corps of Engineers.

Thermal Analysis of a Film Cooling System with Normal Injection Holes Using Experimental Data

  • Kim, Kyung-Min;Lee, Dong-Hyun;Cho, Hyung-Hee;Kim, Moon-Young
    • International Journal of Fluid Machinery and Systems
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    • v.2 no.1
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    • pp.55-60
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    • 2009
  • The present study investigated temperature and thermal stress distributions in a film cooling system with normal injection cooling flow. 3D-numerical simulations using the FEM commercial code ANSYS were conducted to calculate distributions of temperature and thermal stresses. In the simulations, the surface boundary conditions used the surface heat transfer coefficients and adiabatic wall temperature which were converted from the Sherwood numbers and impermeable wall effectiveness obtained from previous mass transfer experiments. As a result, the temperature gradients, in contrast to the adiabatic wall temperature, were generated by conduction between the hot and cold regions in the film cooling system. The gradient magnitudes were about 10~20K in the y-axis (spanwise) direction and about 50~60K in the x-axis (streamwise) direction. The high thermal stresses resulting from this temperature distribution appeared in the side regions of holes. These locations were similar to those of thermal cracks in actual gas turbines. Thus, this thermal analysis can apply to a thermal design of film cooling holes to prevent or reduce thermal stresses.

The Fluid Loss and Sealing Mechanisms in Slurry Trench Condition (I) : A Large Scale Test and Design Procedure (Slurry wall 공법에서 안정액의 역할 (I) : 대형모형실험과 설계절차)

  • Kim, Hak-Moon
    • Journal of the Korean Geotechnical Society
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    • v.18 no.4
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    • pp.239-248
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    • 2002
  • Bentonite slurries in a slurry wall construction must fulfill a stabilizing function by forming impermeable membrane (surface cake and penetrated cake) on the excavated soil faces. Thus problems are occurring in practice for the construction of diaphram walls and cut-off walls with a low permeability for wastes disposal areas in some deep excavations or different grounds. In this paper, the fundamental mechanics of fluid loss and filter cake formation in various soil beds are investigated using large scale laboratory apparatus. The sealing efficiency of filter cake from the large scale tests and the significance of fluid loss in a slurry trench are utilized for practical situation as a recommended design procedure.

Hydrogen Transport through Palladium Foil Placed in Nafion Electrolyte of H2/O2 Fuel Cellsorption

  • Song, Seong-Min;Koo, Il-Gyo;Lee, Woong-Moo
    • Journal of Hydrogen and New Energy
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    • v.12 no.4
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    • pp.257-265
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    • 2001
  • Placing a hydrogen conducting, methanol impermeable metallic barrier like palladium (Pd) is a well-known method for preventing methanol crossover through solid polymer electrolyte for direct methanol fuel cells (DMFC). Applying a bias potential between the anode and the barrier can further develop this concept so that the hydrogen transfer rate is enhanced. Since hydrogen diffuses in Pd as atomic form while it moves through nafion electrolyte as ion, it has to be reduced or oxidized whenever it passes the interface formed by Pd and the electrolyte. We performed experiments to measure the hydrogen transport through the Pd membrane placed in Nafion electrolyte of hydrogen/oxygen fuel cell (PEMFC). Applying a bias potential between the hydrogen electrode of the cell and the Pd membrane facilitated the hydrogen passage through the Pd membrane. The results show that the cell current measured with the Pd membrane placed reached almost 40 % the value measured with the cell without Pd membrane. It was found that the current flown through the bias path is only a few percent of the cell current.

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