• Title/Summary/Keyword: Urban vertical structure

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A Study on the Occurrence Pattern of Vacant Spaces as the Decline Index in Old Hillside Residential Area (노후 경사주거지 쇠퇴지표로서의 유휴공간 발생패턴 연구)

  • Jung, In-A;Woo, Shin-Koo
    • Journal of the Architectural Institute of Korea Planning & Design
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    • v.34 no.3
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    • pp.93-104
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    • 2018
  • This study is about occurrence pattern of vacant spaces as a urban decline indicator to consider a decline of old hillside residential area from spatial structure perspective. For investigation based upon vacant space and the street structure, this study selects Ami Chojang-dong in Seo-gu, Busan, of which 79.7% of total area is over a gradient of $10^{\circ}$. Focused on relationship between occurrence pattern of vacant spaces and 'vertical alleys(link)' serving as main movement path of local residents in hillside residential area, the length, numbers, slopes, and use characteristic of vertical alleys were analyzed using Arc GIS 9.3 program to classify characteristic zone types of spacial structure in hillside residential area. After the occurrence pattern of vacant space are interpreted in relation with building density, vertical alleys' number length slope, the social and economic issues have been considered as well. After analyzing the occurrence pattern of vacant space, this study argues that the occurrence pattern of vacant space in old hillside residential area is rather affected by street structure system consisting of vertical alleys than the impacts of social economical issues.

A Modified Digital Elevation Modeling for Stormwater Management Planning in Segmentalized Micro-catchment Areas

  • Lee, Eun-seok
    • Journal of People, Plants, and Environment
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    • v.24 no.1
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    • pp.39-51
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    • 2021
  • Background and objective: Urban topology can be characterized as impervious, which changes the hydrologic features of an area, increasing surface water flow during local heavy rain events. The pluvial flooding is also influenced by the vertical structures of the urban area. This study suggested a modified digital elevation model (DEM) to identify changes in urban hydrological conditions and segmentalized urban micro catchment areas using a geographical information system (GIS). Methods: This study suggests using a modified DEM creation process based on Rolling Ball Method concepts along with a GIS program. This method proposes adding realized urban vertical data to normal DEM data and simulating hydrological analyses based on RBM concepts. The most important aspect is the combination of the DEM with polygon data, which includes urban vertical data in three datasets: the contour polyline, the locations of buildings and roads, and the elevation point data from the DEM. DEM without vertical data (DCA) were compared with the DEM including vertical data (VCA) to analyze catchment areas in Shin-wol district, Seoul, Korea. Results: The DCA had 136 catchments, and the area of each catchment ranged from 3,406 m2 to 423,449 m2. The VCA had 2,963 catchments, with the area of each ranging from 50 m2 to 16,209 m2. The most important finding is that in the overlapped VCA; the boundary of areas directly affected by flooding and the direction of surface water flow could be identified. Flooding data from September 21, 2010 and July 27, 2011 in the Shin-wol district were applied as ground reference data. The finding is that in the overlapped VCA; the boundary of areas directly affected by flooding and the direction of surface water flow could be identified. Conclusion: The analysis of the area vulnerable to surface water flooding (SWF) was more accurately determined using the VCA than using the DCA.

Diffusion Simulation Using Envi-Met. in Urban Planetary Boundary Layer (Envi-Met.을 이용한 도심 대기경계층 내 확산장 변화 수치 모의)

  • Choi, Hyun-Jeong
    • Journal of Climate Change Research
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    • v.7 no.3
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    • pp.357-371
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    • 2016
  • Buildings in the city acts as a cause of distorted wind direction, wind speed, causing the stagnation of the air flow. In the recent trend of climate change can not but consider the temperature rise of the urbanization. This study was aimed to analyze the thermal comfort of planetary boundary layer in different artificial constructions areas which has a direct impact on urban climate, and estimating the warming phenomena. Envi-met model was used to consider the urban structure associated with urban growth in order to precisely determine the impact of the building on the city weather condition. The analyzed values of thermal comfort index were temperature, wind speed, horizontal and vertical turbulent diffusivity. In particular, analysis of the PPD(Predicted Percentage of Dissatisfied) represents the human thermal comfort. In this study, by adjusting the arrangement and proportion of the top floor building in the urban it was found that the inflow of the fresh air and cooling can be derived low PPD. Vertical heat flux amount of the city caused by climate change was a factor to form a high potential temperature in the city and the accumulation of cold air does not appear near the surface. Based on this, to make the city effectively respond to climate change may require a long-term restructuring of urban spatial structure and density management.

Study on mechanical behaviors of column foot joint in traditional timber structure

  • Wang, Juan;He, Jun-Xiao;Yang, Qing-Shan;Yang, Na
    • Structural Engineering and Mechanics
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    • v.66 no.1
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    • pp.1-14
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    • 2018
  • Column is usually floating on the stone base directly with or without positioning tenon in traditional Chinese timber structure. Vertical load originated by the heavy upper structure would induce large friction force and compression force between interfaces of column foot and stone base. This study focused on the mechanical behaviors of column foot joint with consideration of the influence of vertical load. Mechanism of column rocking and stress state of column foot has been explored by theoretical analysis. A nonlinear finite element model of column foot joint has been built and verified using the full-scale test. The verified model is then used to investigate the mechanical behaviors of the joint subjected to cyclic loading with different static vertical loads. Column rocking mechanism and stress distributions of column foot were studied in detail, showing good agreement with the theoretical analysis. Mechanical behaviors of column foot joint and the effects of the vertical load on the seismic behavior of column foot were studied. Result showed that compression stress, restoring moment and stiffness increased with the increase of vertical load. An appropriate vertical load originated by the heavy upper structure would produce certain restoring moment and reset the rocking columns, ensuring the stability of the whole frame.

Research on Characteristics of Vegetation Subsequent to Crossing Structure of the Urban Streams - Centering on the Cases of Dorimcheon, Banghakcheon, Seongnaecheon and Yangjaecheon in Seoul - (도시하천의 횡단구조에 따른 식생분포특성 연구 -서울시 도림천, 방학천, 성내천, 양재천을 사례로-)

  • Bae, Jung-Hee;Lee, Kyong-Jae;Han, Bong-Ho
    • Korean Journal of Environment and Ecology
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    • v.22 no.3
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    • pp.268-279
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    • 2008
  • This study is aimed at typifying the crossing structure and inquiring into the characteristics of vegetation distribution by type targeting Dorimcheon(stream), Banghakcheon(stream), Seongnaecheon(stream) and some sections of Yangjaecheon(stream) in Seoul through the establishment of basic data for restoring vegetation in urban stream. This research classified the crossing structure into 56 slope types and 31 vertical types in combination with the three items, such as bank slope(vertical style, slope style) of bank, absence or presence of waterside, and revetment structure. This research derived nine slope types including SB1 (revetment of low water level-revetment with vegetation, and revetment of high water level-nature riverside) including SG5(revetment of low water-concrete, and revetment of high water level-riprap work), and three vertical types, such as VH4(bank revetment-wet masonry), and VH7(bank revetment - concrete )from the target survey areas. Among these, both revetment of low water level and high water level were found to be distributed on the longest section as the type of SG7 and VG7 structured in concrete. As a result of inquiry and analysis of micro topography structure and vegetation structure of eight major types, this research could find out the influence of crossing structure on plant vegetation according to the characteristic by typified item, but there appeared no distinct characteristic of vegetation distribution by crossing structure.

The Effects of Street Tree's Vertical Structures on Thermal Comfort (열쾌적성에 대한 가로수 수직적 구조의 영향 분석)

  • Lee, Su-Been;Choe, Hye-Yeong;Jo, Hyun-Kil;Yun, Young-Jo;Kil, Sung-Ho
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.24 no.4
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    • pp.15-29
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    • 2021
  • Urban green spaces offer a variety of benefits to living things and humans. However, existing green spaces have been reduced and fragmented due to urbanization, and there is a limit to creating new large green spaces in densely developed cities. Street trees have fewer restrictions on land use, which can be a measure to secure green areas in cities. In Korea, excessive pruning is being done on some street trees for reasons such as blocking of building signboards, contact with electric wires, and restrictions on sidewalk widths. Therefore, it is necessary to quantitatively understand the relationship between the benefits provided by street trees and their structures to come up with an efficient and systematic planning and management plan for urban street trees. In this study, we quantitatively analyzed the relationship between the thermal comfort improvement by the shades of street trees and the vertical structure, planting environment, and types of street trees. To calculate the thermal comfort felt by human body, we calculated UTCI (Universal Thermal Climate Index) of each street tree. For the vertical structure of street trees, we used Terrestrial LiDAR and the point clouds of street tree's crown was sliced vertically at 1m intervals. We conducted a multiple regression analysis on the thermal comfort improvement using the variables we obtained from fields. As a result, in the case of a street tree's vertical structure, the lager the volume of tree's crown located 3-4m (β=0.298, p<.05) and 6-7m (β=0.568, p<.001) above clear length, the better the cooling effect. In addition, the thermal comfort improvement was assessed to decrease as the DBH increased (β=-0.435, p<.001). In general, the crown diameter and DBH are positively correlated, with a cooling effect occurring as crown diameter increases. In this study, the opposite result was obtained due to the small number of trees measured, so additional research is needed by increasing the number of tree samples. In the case of the planting environment, the effect of improving thermal comfort was higher in the shaded area of trees planted to the south (β=-0.541, p<.001). Since unsystematic management of street trees can deteriorate the function of them, quantitative evaluations of the vertical structure of street trees are required, which can provide specific measures for planning and management of urban street trees with thermal comfort effect.

A Simple Mlodel for Dispersion in the Stable Boundary Layer

  • Sung-Dae Kang;Fuj
    • Journal of Environmental Science International
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    • v.1 no.1
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    • pp.35-43
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    • 1992
  • Handling the emergency problems such as Chemobyl accident require real time prediction of pollutants dispersion. One-point real time sounding at pollutant source and simple model including turbulent-radiation process are very important to predict dispersion at real time. The stability categories obtained by one-dimensional numerical model (including PBL dynamics and radiative process) are good agreement with observational data (Golder, 1972). Therefore, the meteorological parameters (thermal, moisture and momentum fluxes; sensible and latent heat; Monin-Obukhov length and bulk Richardson number; vertical diffusion coefficient and TKE; mixing height) calculated by this model will be useful to understand the structure of stable boundary layer and to handling the emergency problems such as dangerous gasses accident. Especially, this simple model has strong merit for practical dispersion models which require turbulence process but does not takes long time to real predictions. According to the results of this model, the urban area has stronger vertical dispersion and weaker horizontal dispersion than rural area during daytime in summer season. The maximum stability class of urban area and rural area are "A" and "B" at 14 LST, respectively. After 20 LST, both urban and rural area have weak vertical dispersion, but they have strong horizontal dispersion. Generally, the urban area have larger radius of horizontal dispersion than rural area. Considering the resolution and time consuming problems of three dimensional grid model, one-dimensional model with one-point real sounding have strong merit for practical dispersion model.al dispersion model.

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Mapping Vegetation Volume in Urban Environments by Fusing LiDAR and Multispectral Data

  • Jung, Jinha;Pijanowski, Bryan
    • Korean Journal of Remote Sensing
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    • v.28 no.6
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    • pp.661-670
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    • 2012
  • Urban forests provide great ecosystem services to population in metropolitan areas even though they occupy little green space in a huge gray landscape. Unfortunately, urbanization inherently results in threatening the green infrastructure, and the recent urbanization trends drew great attention of scientists and policy makers on how to preserve or restore green infrastructure in metropolitan area. For this reason, mapping the spatial distribution of the green infrastructure is important in urban environments since the resulting map helps us identify hot green spots and set up long term plan on how to preserve or restore green infrastructure in urban environments. As a preliminary step for mapping green infrastructure utilizing multi-source remote sensing data in urban environments, the objective of this study is to map vegetation volume by fusing LiDAR and multispectral data in urban environments. Multispectral imageries are used to identify the two dimensional distribution of green infrastructure, while LiDAR data are utilized to characterize the vertical structure of the identified green structure. Vegetation volume was calculated over the metropolitan Chicago city area, and the vegetation volume was summarized over 16 NLCD classes. The experimental results indicated that vegetation volume varies greatly even in the same land cover class, and traditional land cover map based above ground biomass estimation approach may introduce bias in the estimation results.

Improvement of the Planting Method to Increase the Carbon Reduction Capacity of Urban Street Trees

  • Kim, Jin-Young;Jo, Hyun-Kil;Park, Hye-Mi
    • Journal of People, Plants, and Environment
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    • v.24 no.2
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    • pp.219-227
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    • 2021
  • Background and objective: Urban street trees play an important role in carbon reduction in cities where greenspace is scarce. There are ongoing studies on carbon reduction by street trees. However, information on the carbon reduction capacity of street trees based on field surveys is still limited. This study aimed to quantify carbon uptake and storage by urban street trees and suggest a method to improve planting of trees in order to increase their carbon reduction capacity. Methods: The cities selected were Sejong, Chungju, and Jeonju among cities without research on carbon reduction, considering the regional distribution in Korea. In the cities, 155 sample sites were selected using systematic sampling to conduct a field survey on street environments and planting structures. The surveyed data included tree species, diameter at breast height (DBH), diameter at root collar (DRC), height, crown width, and vertical structures. The carbon uptake and storage per tree were calculated using the quantification models developed for the urban trees of each species. Results: The average carbon uptake and storage of street trees were approximately 7.2 ± 0.6 kg/tree/yr and 87.1 ± 10.2 kg/tree, respectively. The key factors determining carbon uptake and storage were tree size, vertical structure, the composition of tree species, and growth conditions. The annual total carbon uptake and storage were approximately 1,135.8 tons and 22,737.8 tons, respectively. The total carbon uptake was about the same amount as carbon emitted by 2,272 vehicles a year. Conclusion: This study has significance in providing the basic unit to quantify carbon uptake and storage of street trees based on field surveys. To improve the carbon reduction capacity of street trees, it is necessary to consider planning strategies such as securing and extending available grounds and spaces for high-density street trees with a multi-layered structure.

Vertical Shortening Considerations in the 1 km Tall Jeddah Tower

  • Peronto, John;Sinn, Robert;Huizinga, Matthew
    • International Journal of High-Rise Buildings
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    • v.6 no.1
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    • pp.21-31
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    • 2017
  • Jeddah Tower will be the first man-made structure to reach a kilometer in height upon its completion in 2019. From conception, it was clear that an all-concrete superstructure would present many advantages for a building of such unprecedented height and slenderness. An all-concrete structure, however, did present many challenges that needed to be addressed in the system arrangement and through comprehensive analysis and design, among them vertical shortening effects due to the time-dependent creep and shrinkage of concrete. This paper outlines and presents the engineering solutions developed by the authors regarding this complex concrete material phenomenon, while addressing the construction and regional challenges associated with realizing a concrete tower of this unprecedented scale.