• Title/Summary/Keyword: horizontal barrier

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Numerical Study on the formation of an injectable barrier in the subsurface

  • 김미정;박주양
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2002.04a
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    • pp.98-101
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    • 2002
  • Numerical experiments were performed to investigate horizontal barrier formation in unsaturated soils by permeation grouting through multiple vertical injection pipes. The results were compared with the horizontal barrier formation achieved by using multiple horizontal injection pipes. It was observed that tile point injection of the vertical pipe system generates a gel barrier that has a less lateral area than the injection through the horizontal pipe.

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Experimental and numerical investigation of a surface-fixed horizontal porous wave barrier

  • Poguluri, Sunny Kumar;Kim, Jeongrok;George, Arun;Cho, I.H.
    • Ocean Systems Engineering
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    • v.11 no.1
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    • pp.1-16
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    • 2021
  • Experimental and numerical investigations were conducted to study the performance of a surface-fixed horizontal porous wave barrier in regular waves. The characteristics of the reflection and transmission coefficients, energy dissipation, and vertical wave force were examined versus different porosities of the barrier. Numerical simulations based on 3D Reynolds Averaged Navier-Stokes equations with standard low-Re k-ε turbulent closure and volume of fluid approach were accomplished and compared with the experimental results conducted in a 2D wave tank. Experimental measurements and numerical simulations were shown to be in satisfactory agreement. The qualitative wave behavior propagating over a horizontal porous barrier such as wave run-up, wave breaking, air entrapment, jet flow, and vortex generation was reproduced by CFD computation. Through the discrete harmonic decomposition of the vertical wave force on a wave barrier, the nonlinear characteristics were revealed quantitatively. It was concluded that the surface-fixed horizontal barrier is more effective in dissipating wave energy in the short wave period region and more energy conversion was observed from the first harmonic to higher harmonics with the increase of porosity. The present numerical approach will provide a predictive tool for an accurate and efficient design of the surface-fixed horizontal porous wave barrier.

An Experimental Study on the Application of Horizontal Barrier and In-Rack Sprinklers to Prevent Vertical Spread of Rack-type Warehouse Fires (랙크식 창고 화재의 수직 확산 방지를 위한 수평차단막과 In-Rack 스프링클러 적용에 관한 실험연구)

  • Park, Moon-Woo;Hong, Sung-Ho;Choi, Ki-Ok;Choi, Don-Mook;Kim, Soo-Jin
    • Journal of the Korean Society of Safety
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    • v.34 no.5
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    • pp.15-21
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    • 2019
  • A rack-type warehouse has the advantage of storing a large amount in a small area by loading goods vertically. But in terms of fire risk, the fire load is very high, which can cause massive damage in the event of a fire. In the United States, research has been actively conducted to minimize the spread of vertical fires, and relevant standards have been established and operated. In Korea, research and related standards are insufficient to prevent the vertical spread of rack-type warehouse fires. In this study, an experimental study was conducted to prevent the vertical spread of a rack-type warehouse fire using a horizontal barrier and in-rack sprinklers. As a result of the test, the horizontal barrier considering the continuous flame prevented the vertical spread of the flame for a certain time. However, the horizontal barrier with continuous flame did not show the effect of preventing continuous flame. The combination of the horizontal barrier and the in-rack sprinkler prevented the vertical spread of fire effectively. In addition, the heat collecting effect through the horizontal barrier was shown and helped the early operation of the in-rack sprinklers.

A Study of Wave Control by New Type Floating Breakwater (신형식 부방파제의 파랑제어에 관한 연구)

  • 김도삼;이광호;최낙훈;윤희면
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.16 no.1
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    • pp.1-9
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    • 2004
  • In this study, several new types of floating breakwater are proposed according to the geometry of the vertical barrier and the existence of horizontal plate, and are compared to the steel floating breakwater adopted in Won-Jun fishing port and the performance of wave control is numerically investigated by using Green function method. From the numerical results, model attached the horizontal barrier under the vertical barrier is more efficient for reflection and transmission coefficient than the steel floating breakwater in Won-Jun fishing port. It is confirmed that the transmitted waves can be controlled efficiently by optimizing the length and distance of a vertical and horizontal barriers.

Application of Horizontal Barrier on a Rack to Reduce Fire Spread (화재확산 저감을 위한 랙크 내 수평차단막 적용에 관한 연구)

  • Yeo, In-Hwan;Cho, Gyu-Hwan
    • Fire Science and Engineering
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    • v.31 no.4
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    • pp.71-79
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    • 2017
  • A rack warehouse with a vertically loading type and high loading density has severe risks and damage during its fire. In this regard, US and Japan strive to minimize the fire spread by applying in-rack sprinkler, horizontal barriers, etc. corresponding to their own rack warehouse but there is no study and policy in Korea. Therefore, a model scale fire test was carried out targeting the standard rack incorporating the national rack warehouse in order to check fire characteristics in ignition points and installation distances of horizontal barriers in this study. As a result of the test, vertical fire spread of about 30% was inhibited by narrowing its installation distance from 2-layer to 1-layer in an ignition condition of the flue space. In addition, as a result of the measurement of the temperature in the upper and lower parts of the horizontal barrier, the temperature distribution showed about 2~4 higher in a condition with an installation of the barrier than that in the condition without the barrier. Consequently, it is likely that the horizontal barrier will help the initial operation of in-rack sprinkler.

A CFD Study of Roadside Barrier Impact on the Dispersion of Road Air Pollution

  • Jeong, Sang Jin
    • Asian Journal of Atmospheric Environment
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    • v.9 no.1
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    • pp.22-30
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    • 2015
  • This study evaluated road shape and roadside barrier impact on near-road air pollution dispersion using FLUENT computational fluid dynamics (CFD) model. Simulated road shapes are three types, namely at-grade, depressed, and filled road. The realizable k-${\varepsilon}$ model in FLUENT CFD code was used to simulate the flow and dispersion around road. The selected concentration profile results were compared with the wind tunnel experiments. The overall concentration profile results show good agreement with the wind tunnel results. The results showed that noise barriers, which positioned around the at-grade road, decrease the horizontal impact distance (In this study, the impact distance was defined as the distance from road surface origin coordinate to the position whose mass fraction is 0.1.) lower 0.33~0.65 times and change the vertical air pollution impact distance larger 2.0~2.27 times than those of no barrier case. In case of filled road, noise barriers decrease the horizontal impact distance lower 0.24~0.65 times and change the vertical air pollution impact distance larger 3.33~3.55 times than those of no barrier case. The depressed road increase 1.53~1.68 times the vertical air pollution impact distance. It contributes the decrease of horizontal air pollution impact distance 0.32~0.60 times compare with no barrier case.

Innovative Method to Expand a Degree of Freedom of Observation in the Depth Direction without Losses of the Horizontal Number of Views in Autostereoscopic Multi-Views 3D Display System (시차장벽식 무안경 다시점 입체디스플레이 시스템에서 수평방향의 시점 수 저하 없이 깊이방향의 자유도를 증가시키기 위한 혁신적 방법)

  • Lee, Kwang-Hoon;Park, Min-Chul
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38C no.10
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    • pp.903-910
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    • 2013
  • An autostereoscopic multi-view 3D display system has the narrower degrees of freedom in the observational directions, such as the horizontal and perpendicular directions to the display plane, than the glasses-on type of 3D display. In this paper, we propose an innovative method to expand the width of the viewing zone formed in the depth direction while maintaining the number of views in the horizontal direction by using a triple segmented-slanted parallax barrier (TS-SPB) in the glasses-off type of 3D display. The validity of the proposal was verified by an optical simulation based on an environment similar to an actual case. The maximum number of views that can be displayed in the horizontal direction is 2n, and the width of the viewing zone with depth increased up to a factor of 3.36 compared to the existing one-layered parallax barrier system.

INTERACTIONS OF A HORIZONTAL FLEXIBLE MEMBRANE WITH OBLIQUE INCIDENT WAVES

  • I.H. Cho;S.W. Hong;Kim, M.H.
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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    • 1997.10a
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    • pp.135-138
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    • 1997
  • The interaction of oblique monochromatic incident waves with a horizontal flexible membrane is investigated in the context of two-dimensional linear hydro-elastic theory. First, analytic diffraction and radiation solutions for a submerged impermeable horizontal membrane are obtained. Second, the theoretical prediction was compared with a series of experiments conducted in a two-dimensional wave tank at Texas A&M University. The measured reflection and transmission coefficients reasonably follow the trend of predicted values. Using the developed computer program, the performance of surface-mounted or submerged horizontal membrane wave barriers is tested with various system parameters and wave characteristics. It is found that the properly designed horizontal flexible membrane can be an effective wave barrier and its efficiency can be further improved using a porous material.

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A Road Traffic Noise Management Using a Noise Mapping Simulation (소음지도 시뮬레이션을 이용한 도로교통소음 개선방안 연구)

  • Kim, Hyung-Chul;Jeong, Jea-Hun;Kwon, Woo-Taeg
    • The Journal of the Acoustical Society of Korea
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    • v.26 no.7
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    • pp.353-360
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    • 2007
  • Rapid urbanization and population increasing are making a high-rise residential building and high-density residential area. According to spacial concentration of population is occurred road traffic noise problem. Now we are popularly using almost only noise barrier installation, but it makes many disfunctions such as poor landscape, low noise barrier performance and crimes. The purpose of this research is to figure out which is best method one the traffic noise management. Alternative are composed to building layout type ($30^{\circ},\;90^{\circ},\;180^{\circ}$), separation between road and residential building, noise barrier types(noise barrier only, noise barrier and forests and etc). The noise barrier are shown to reduce barrier and building layout angle $30^{\circ}$ position is the best comparing with horizontal and vertical layouts. The gab distance is decreased approximately noise level 5dB(A). We figured out there are noise important method except noise barrier wall and it was analyzed how much decreased. This can be very useful before making a road planning and residential building design.