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PTV velocity field measurements of flow around a triangular prism located behind a porous fence (다공성 방풍벽 뒤에 놓인 삼각 프리즘 주위 유동의 PTV 속도장 측정)

  • Kim, Hyeong-Beom;Lee, Sang-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.5
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    • pp.708-715
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    • 1998
  • The shelter effect of a porous wind fence on a triangular prism was experimentally investigated in a circulating water channel. A porous fence of porosity .epsilon.=38.5% was installed in front of the prism model. The fence and prism model were embedded in a turbulent boundary layer. The instantaneous velocity fields around the fence and prism model were measured by using the instantaneous velocity fields around the fence and prism model were measured by using the 2-frame PTV(Particle Tracking Velocimetry) system. By installing the fence in front of the prism, the recirculation flow region decreases compared with that of no fence case. The porous fence also decreases the mean velocity, turbulent intensity and turbulent kinetic energy around the prism. Especially, at the top of the prism, the turbulent kinetic energy is about half of that without the fence.

Effect of fence porosity on the velocity field of wake flow past porous wind fences (다공성 방풍벽의 다공도가 펜스후류 속도장에 미치는 영향에 관한 연구)

  • Kim, Hyeong-Beom;Lee, Sang-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.7
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    • pp.915-926
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    • 1998
  • Velocity fields of near turbulent was behind a porous wind fence were measured using the 2-frame PTV method in a circulating water channel. The fences used in this study had different geometric porosity(.epsilon.) of 0, 20, 40 and 65%. The fence was embedded in a thin laminar boundary layer, i.e., .delta./H ~ = 0.1. Reynolds number based on the fence height H and free stream velocity(U$\_$o/) was about 8,400. As a result, a recirculating flow region was formed behind the fence for the .epsilon.=0% and 20% wind fence. For the wind fences having porosity larger than .epsilon.=40%, it was difficult to see separation bubbles behind the fence. The .epsilon.=20% porous fence reveals the maximum velocity reduction, however, the turbulent intensity and Reynolds shear stress are much greater than those of .epsilon.=40% fence. Among the wind fence tested in this study, the porous wind fence of .epsilon.=40% porosity is the most effective for abating wind erosion.

Experiment of the Shelter Effect of Porous Wind Fences base on the Wind Tunnel Test (풍동실험을 이용한 다공성 방풍팬스의 방풍성능실험)

  • You, Jang-Youl;Jeon, Jong-Gil;Kim, Young-Moon
    • Proceeding of KASS Symposium
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    • pp.91-101
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    • 2006
  • We have conducted the study about the shelter effect against the wind by using the wind fence with various porosities and the measured distance from the wind fence, in three different types of it ; (Circle wind fence, Vertical wind fence, Horizontal wind fence) The shelter effect and turbulence characteristics of the selected wind barrier is throughly investigated by wind tunnel test. flow characteristics of velocities and turbulences behind wind fence were measured using hot-wire anemometer. we characterize the turbulence behind the wind fence by varying the porosity of 0 %, 20 %, 40%, and 60%, and the distances from the wind fence from 1 H to 9 H with maintaining the uniform flow velocity of 6 m/s. In addition, we investigated the overall characterization of the wind fence by measuring total of twenty eight points on the wind fence, which forms the lattice structure on it with seven points in lateral direction and four points in vertical direction. The results of analysis from the circle wind fence indicate that the degree of the turbulence is lowered and the velocity of the wind is decreased when the porosity of 40 % are used at the distance from 3 H to 9 H. On the other hand, the vertical, horizontal wind fence with the porosity of 20% is more advantageous at the distance of 2 H to 9 H. For the effectiveness of the wind fence depending on the position, the center part is the greatest and it decreases at the edges with 10 % to 30 % less than that of at the center.

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Wind Engineering Study on the Surface-Pressure Characteristic of a Triangular Prism Located Behind a Porous Fence (다공성 방풍펜스 후방에 놓인 삼각프리즘의 표면압력특성에 관한 풍공학적 연구)

  • Park, Cheol-U;Lee, Sang-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.11
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    • pp.1496-1508
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    • 1997
  • The effects of porous wind fence on the pressure characteristics around a 2-dimensional prism model of triangular cross-section were investigated experimentally. The fence and prism model were embedded in a neutral atmospheric surface boundary layer over the city suburb. In this study, various fences of different porosity, back fence, inclination angle of prism and location of additional back prisms were tested to investigate their effects on the pressure and wall shear stress of the prism surface. The fence and prism had the same height of 40 mm and Reynolds number based on the model height was Re=3.9*10$^{4}$. The porous fence with porosity 40% was found to be the best wind fence for decreasing the mean and pressure fluctuations on the prism surface. By installing the fence of porosity 40%, the wall shear stress on the windward surface of prism was largely decreased up to 1/3 of that without the fence. This indicates that the porous fence is most effective to abate the wind erosion. Pressure fluctuations on the model surface were decreased more than half when a back fence was located behind the prism in addition to the front fence. With locating several back prisms and decreasing the inclination angle of triangular prism, the pressure fluctuations on the model surface were increased on the contrary.

A Study on the Nature of the Expression of Construction Fence Screens to enhance the Images of Cities - Focus on the fence screens of Seoul - (도시이미지 향상을 위한 공사 가림막 표현특성에 관한 연구 - 서울시 공사 가림막을 중심으로 -)

  • Oh, Sang-Min;Han, Young-Ho
    • Korean Institute of Interior Design Journal
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    • v.20 no.3
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    • pp.259-266
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    • 2011
  • Today, construction fence screens which were understood simply as structures of separating people from the dangers of construction sites have evolved into landmarks to enhance the images of Cities. Now, construction fence screens should have the function as landmarks stimulating people's sensibility through providing aesthetic values as well as the function of protecting people from the dangers of fields of construction. For this reason, this study tried 1) to show the relationships among these 4 classifications. is 4 realms of Human Beings - Cultural - Ecological - Digital in the expression methods of the construction fence screens of Seoul and 2) to simplify the characteristic elements of construction fence screens by way of extracting with Ecology, Installation Art, Symbolic, Commercial Expression. This study examined whether or not the construction fence screens of Seoul were playing the role as landmarks stimulating people's sensibility with sustainable improvement to the environment of Seoul as public design structures, by investigating some of the construction fence screens of Seoul. Also through analyzing the diversity of expression methods of the construction fence screens of other local governments as well as those of Seoul, we hope that they will be the public structures for enhancing the images of Cities.

Effect of tip configuration of an oil fence on wake structure behind the fence (오일펜스의 tip 형상이 후류유동에 미치는 영향에 관한 연구)

  • Koh, Min-Seok;Lee, Sang-Joon;Lee, Choung-Mook;Chung, Sang-Kook
    • Proceedings of the KSME Conference
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    • pp.772-776
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    • 2001
  • The flow structures of turbulent shear layer behind oil fences with different tip configurations were investigated experimentally using flow visualization and PIV velocity field measurement. An oil fence was installed in a circulating water channel and the flow structure around the fence tip was mainly analyzed in this experiment. The four tip configurations tested in this experiment are knife edge; semi-circle edge, circular edge and rectangular edge. The 300 instantaneous velocity fields were measured using the single-frame PIV system and they were ensemble averaged to give the mean velocity field and spatial distribution of turbulent statistics. Free stream velocity was fixed at 10ms/sec and the corresponding Reynolds number based on the fence height was Re=4000. As a result, for the oil fence with rectangular edge, the streamwise velocity component was decreased. On the other hand it was increased for the oil fence with circular edge. For all four fences tested in this study, general flow pattern of the lower shear layer is analogous but the upper layer shows difference depending on the tip configurations. The oil fence with circular edge has more diffusive upper shear layer than that of the others. The shear layer of the oil fence with rectangular edge has relatively thin thickness. The oil fence with circular edge was found to be proper shape for tandem fence.

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Porous Fence Effects on Surface-Pressure of a Triangular Prism in Atmospheric Boundary Layer (다공성 방풍펜스가 대기경계층내에 놓인 삼각프리즘 표면압력에 미치는 영향에 관한 연구)

  • Park, Cheol-U;Seong, Seung-Hak
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.8
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    • pp.2670-2680
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    • 1996
  • Effeccs of porous wind fence on surface-pressure around 2-dimensional prism model of triangular cross-section were investigated experimentally. The pressure data were obtained at a Reynolds number based on the model height of Re=2.1*10$^{5}$ . Flow visualization also carried out to investigate the flow structure qualitatively. The mean velocity and turbulent intensity profiles measured at fence location were well fitted to the neutral atmospheric surface boundary layer over the open terrain. Various fences with different porosity and height were tested to investigate their effects on the surface pressure acting on a prism model at different locations. As the results, porous fence with porosity 40 ~ 50% is most effective for abating wind erosion. With decreasing porosity of the fence, pressure fluctuations on the model surface are increased. The mean pressure coefficients are decreased only when the fence height is greater than the model height. The effect of distance between wind fence and triangular prism was not significant, compared to that of the fence porosity and height.

A Survey Study on the Consciousness of the School Fence Removal -focused on the consciousness of the five schools on fence removal, in Wonju city- (학교담장허물기에 관한 의식조사 연구 -원주지역 5개 학교담장에 관한 의식조사를 중심으로-)

  • Lee, Eun-Hee;Seo, Deok-Suk;Choi, Jae-Suk
    • The Journal of Sustainable Design and Educational Environment Research
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    • v.9 no.1
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    • pp.11-22
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    • 2010
  • Recently, the necessity of open spaces is increased greatly in the city. But in many reasons, open spaces are diminishing gradually in the existing cities. It is more difficult to keep that space because of expensive land price, and the interests between the neighbors. To solve this problem, the local governments tries to change the street system more convenient to the pedestrian by adapting no vechile street system during some specific time. In this point of view, the street which include fence of school, house, and apartment can be the open space. Especially, removal of the school fence can be a useful solution providing open spaces to small cities suffering from lack of open spaces. In this researching background, several schools in Wonju were selected in this research, some has already been opened, and others yet. Opinions of students, presidents of these schools, and citizens are surveyed about removal of fence. In the basis of this result, we deduce problems followed by removing the fence, and reflect it in the plan of opening the fence to present the guidance to cross over the functional limitation of the fence and use it as a open space.

Development and Performance Evaluation of the Expanded Metal Rockfall Protection Fence

  • Hwang, Young-Cheol;Kim, Bum-Joo;Noh, Heung-Jae
    • Journal of the Korean GEO-environmental Society
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    • v.6 no.3
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    • pp.35-45
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    • 2005
  • The rockfall protection fence is one of the most common rockfall protection methods in Korea. The typical rockfall protection fence consists mainly of three parts ; H-beam supports, wire meshes, and wire ropes. The design of the rockfall protection fence is made such that the total energy absorbing capacity of the fence. Therefore, resulting from the combined energy absorbing capacity of the three parts is larger than the falling energy of rocks. In present study, a new rockfall protection fence, constructed using expanded metals instead of the existing wire rope and wire mesh for the typical type of rockfall protection fence, was evaluated on its performance by conducting both laboratory and field tests. Also, for a comparison, the same tests were performed on the typical rockfall protection fence. The test results revealed that the expanded material is an economic alternative to the existing protection materials and the expanded metal rockfall protection fence exhibits the higher energy absorbing capacity compared to that of the typical rockfall protection fence.

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A Study on the Construction Method of Traditional Fence in the Late Joseun Dynasty in the 『Imwon Gyeongjeji』 (임원경제지에 나타난 조선후기 전통 담장의 시공법 연구)

  • Lee, Eun-Jung;Cheon, Deuk-Youm;Yoo, Uoo-San
    • Journal of architectural history
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    • v.28 no.5
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    • pp.7-18
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    • 2019
  • The "Imwon Gyeongjeji(林園經濟志)", the largest encyclopedia of the Late Joseon Dynasty covers the details of the materials and construction methods related to everyday life's facilities. It is very useful to examine the "Imwon Gyeongjeji" for studying the materials and construction methods of the fences in traditional dwellings. Therefore, we tried to find the characteristics of the traditional fences exhibited in the "Imwon Gyeongjeji" by examining the construction methods shown in the book by structure of the fence. The results are as follow. First, the nine types of fence were listed in the "Imwon Gyeongjeji". Second, we could figure out the construction methods according to the structure of fences. The fence is divided into three parts: foundation, body, and roof. The body of the fence is a characteristic part distinguishing the types of fence. The foundation and the roof are related to the durability of the fence, regardless of the type of fence. The "Imwon Gyeongjeji" showed a robust manner in building fences than known today. Third, we found that the introductions and transformations of certain fence types. Fences such as Chuibyong(翠屛), Jeon Doldam(甎墻) and Bunjang were originated from China, yet has developed unique Korean styles in Joseon. It could also be seen that Kajo Zhang(哥窯墻) and Yonglong Zhang(玲瓏墻) were special fence types imported from China. It is not certain that the fences depicted in the "Imwon Gyeongjeji", represent the whole features of Joseon fences, but it is certainly an important literature to understand the structure and design of traditional fences of the Late Joseon Dynasty.