• Title/Summary/Keyword: urban temperature

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An Analysis of Rational Green Area Ratio by Land Use Types for Mitigating Heat-Island Effects (도시열섬완화를 위한 토지 이용 유형별 합리적 녹지율 분석)

  • SONG, Bong-Geun;PARK, Kyung-Hun
    • Journal of the Korean Association of Geographic Information Studies
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    • v.18 no.2
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    • pp.59-74
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    • 2015
  • The purpose of this study is to analyze reasonable green area ratios for mitigating urban heat island considering various land use types. Land uses of 5 types such as single residential, multi residential, commercial area, public facility, and industrial area were considered. Green areas were extracted from the tree attribution of land cover. Effect of urban heat island was analysed by the surface temperature of ASTER thermal infrared radiance scanned daytime and nighttime. Mitigation effect of green area at daytime was higher than nighttime. Surface temperature of green area was low in single residential at daytime. But the difference of surface temperature by each land use type was small. The effect of surface temperature mitigation of green area was lower in industrial area. The results of reasonable green area ratios for mitigating urban heat island indicate that surface temperature was the lowest with green area ratio of 40~50% in single residential, multi residential, and commercial area at daytime. Surface temperature of nighttime was not changed much by green area ratios. Therefore, the results of this study will be suggested in urban development planning to construct effectively green area for mitigating urban heat island.

A Study on Land Surface Temperature Changes in Redevelopment Area Using Landsat Satellite Images : Focusing on Godeok-dong and Dunchon-dong in Gangdong-gu, Seoul (Landsat 위성영상을 활용한 재건축 지역의 지표 온도 변화에 관한 연구 : 서울특별시 강동구의 고덕동과 둔촌동을 중심으로)

  • Jihoon HAN;Chul SON
    • Journal of the Korean Association of Geographic Information Studies
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    • v.26 no.2
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    • pp.42-54
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    • 2023
  • The population is concentrated in the metropolitan areas in Korea, and low-density residential areas are transforming into high density residential areas through redevelopment to meet this demand. However, large-scale redevelopment in a short period of time has a negative impact on the urban climate, such as generating a heat island effect due to the reduction of urban green areas. In this study, the change in surface temperature from 2013 to 2022 in the redevelpment areas of Godeok-dong and Dunchon-dong, Gangdong-gu, Seoul, was analyzed using Landsat 8 satellite images. In the Godeok-dong area, the difference in surface temperature was analyzed for the target redevelopment area, forest area, mixed forest and urban area, and low density residential area. In the Dunchon-dong area, the difference in surface temperature was analyzed for the target redevelopment area, forest area, and low density residential area. The difference in surface temperature was analyzed through multiple regression analysis conducted yearly over the three different stages in redevelopment period. The results from the multiple regression analysis show that in both areas, the land surface temperature of target redevelopment area was higher than that of the forest area and lower than low density residential area. It can be seen that these results occurred because the low-density residential area in Godeok-dong and Dunchon-dong had a lower green area ratio and a higher building-to-land ratio than the target redevelopment area. The results of this study suggest that even if low-density residential areas are transforming into high-density areas, adjusting the management of green areas and building-to-land ratio can contribute to lessen urban heat island effect.

Effects of Building-roof Cooling on Scalar Dispersion in Urban Street Canyons (도시 협곡에서 건물 지붕 냉각이 스칼라 물질 확산에 미치는 영향)

  • Park, Soo-Jin;Kim, Jae-Jin
    • Atmosphere
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    • v.24 no.3
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    • pp.331-341
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    • 2014
  • In this study, the effects of building-roof cooling on scalar dispersion in three-dimensional street canyons are investigated using a computational fluid dynamics (CFD) model. For this, surface temperature of building roof is systematically changed and non-reactive pollutants are released from street bottom in urban street canyons with the aspect ratio of 1. The characteristics of flow, air temperature, and non-reactive pollutant dispersion in the control experiment are analyzed first. Then, the effects of building-roof cooling are investigated by comparing the results with those in the control experiment. In the control experiment, a portal vortex which is a secondary flow induced by ambient air flow is formed in each street canyon. Averaged air temperature is higher inside the street canyon than in both sides of the street canyon, because warmer air is coming into the street canyon from the roof level. However, air temperature near the street bottom is lower inside the street canyon due to the inflow of cooler air from both sides of the street canyon. As building-roof temperature decreases, wind speed at the roof level increases and portal vortex becomes intensified (that is, downdraft, reverse flow, and updraft becomes stronger). Building-roof cooling contributes to the reduction of average concentration of the non-reactive pollutants and average air temperature in the street canyon. The results imply that building-roof cooling has positive effects on improvement of thermal environment and air quality in urban areas.

Exploring Relationships between Urban Tree Plantings and Microclimate Amelioration (도시 수목식재와 미기후 개선의 상관성 구명)

  • Jo, Hyun-Kil;Ahn, Tae-Won
    • Journal of the Korean Institute of Landscape Architecture
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    • v.34 no.5 s.118
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    • pp.70-75
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    • 2006
  • The purpose of this study is to explore the effects of difference in urban tree plantings on microclimate amelioration, and to suggest essential information for quantifying urban energy budgets and energy savings. This study was focused on measuring and analyzing air temperature and relative humidity in summer. Daytime air temperatures at places with 8%, 24%, 44%, 79%, and 100% cover of woody plants were, respectively, 0.6C,1.3C,2.4C,3.5C,and4.8C cooler, compared to a place with 0% cover. A 10% increase of woody plant cover was estimated to reduce the temperature by approximately 0.55C. The temperature reduction effects were relatively greater between places with lower cover of woody plants than between those with higher cover. Woody plant cover and crown volume were the appropriate indicators which quantified the effects of tree plantings on air temperatures, based on the correlation analysis. Regression equations to estimate temperature change (Y:C) using woody plant cover (X1:) or crown volume (X2:m3) as independent variables are as follows: 1nY=3.32330.0018X1(r2=0.99,p<0.0001)Y=27.52970.0019X2(r2=0.96,p=0.0007)

Analysis of the Characteristics of Thermal Environment Change Due to Urban Stream Restoration (도심 하천 복원에 따른 주변지역 열환경 변화 특성 분석)

  • Do, Woo-Gon;Jung, Woo-Sik
    • Journal of Environmental Science International
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    • v.28 no.2
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    • pp.235-248
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    • 2019
  • The purpose of this study is to quantitatively analyze the effects of a restoration project on the decrease in the temperature in the surrounding areas. The thermal environment characteristics of the investigation area were analyzed using the meteorological data from the Busanjin Automatic Weather System which is closest to the target area. The terrain data of the modeling domain was constructed using a digital map and the urban spatial information data, and the numerical simulation of the meteorological changes before and after the restoration of the stream was performed using the Envi-met model. The average temperature of the target area in 2016 was 15.2C and was higher than that of the suburbs. The monthly mean temperature difference was the highest at 1.1C in November and the lowest in June, indicating that the temperatures in the urban areas were high in spring and winter. From the Envi-met modeling results, reductions in temperature due to stream restoration were up to 1.7C in winter, and decreased to 3.5C in summer. The effect of temperature reduction was seen in the entire region where streams are being restored.

Evaluation of Temperature and Humidity Maintenance Performance with Vegetation Blocks Incorporating Waste Glass Beads Using Arduino Sensor (아두이노 센서를 활용한 폐유리 발포비드 혼입 식생블록의 온습도 유지성능 평가)

  • Gil, Min-Woo;Kim, Gyu-Yong;Pyeon, Su-Jeong;Choi, Byung-Cheol;Kim, Moon-Kyu;Nam, Jeong-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.125-126
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    • 2023
  • Recently, heat island and dry island phenomena occur frequently due to land surface development and excessive energy consumption in urban areas. As a result, the surface temperature of the building and the entire temperature of its surroundings are increased, and as a result, the durability of the building is rapidly deteriorated. In order to suppress these causes, a method of maintaining the temperature of road heating wires was implemented as a temporary measure, but this did not predict climate change. Therefore, this study is a method to measure the compressive strength, density, and thermal conductivity of lightweight concrete using waste glass foam beads. After fabricating a simple chamber, the temperature and humidity of the inside and outside were measured with an Arduino device in consideration of external factors. Therefore, if waste glass foam beads made through proper mixing are constructed in the urban center, the quality of the urban can be improved.

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Temperature and humidity characteristics of waste glass aggregate-based vegetation blocks using smart environmental sensor (스마트 환경 센서를 활용한 폐유리 골재 기반 식생블록의 온/습도 특성)

  • Gil, Min-Woo;Kim, Gyu-Yong;Pyeon, Su-Jeong;Choi, Youn-Sung;Park, Jong-Yeop;Nam, Jeong-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.11a
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    • pp.51-52
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    • 2023
  • Recently, heat island and dry island phenomena occur frequently due to land surface development and excessive energy consumption in urban areas. As a result, the surface temperature of the building and the entire temperature of its surroundings are increased, and as a result, the durability of the building is rapidly deteriorated. In order to suppress these causes, a method of maintaining the temperature of road heating wires was implemented as a temporary measure, but this did not predict climate change. Therefore, this study is a method to measure the compressive strength, density, and thermal conductivity of light weight concrete using waste glass foam beads. After fabricating a simple chamber, the temperature and humidity of the inside and outside were measured with an Arduino device in consideration of external factors. Therefore, if waste glass foam beads made through proper mixing are constructed in the urban center, the quality of the urban can be improved.

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Manufacturing lightweight aggregate uses high content of sewage sludge for non-structural concrete

  • Phung Trong-Quyen;Kim, Duck-Mo;Mun, Kyoung-Ju;Soh, Yang-Seob
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.124-127
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    • 2003
  • Sewage sludge and clay used as raw materials in the study. Green aggregates contain different contents by dried weight of the sewage sludge, up to 80 percent is manufactured and burning conditions of soak temperature, soak time and rate of temperature increase. influence of burning condition and mixing ratio on specific gravity of burned aggregate are discussed. The appropriate burning condition to all aggregates is evaluated. Aggregates result form the thermal treatment get specific gravity under 0.8, water absorption fewer than 7.5 percent, and aggregate crushing value from 28 to 53. As the result, aggregates can be available as the lightweight aggregate for non-structural concrete.

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Implementation of Prediction Program for Deterioration Judgment on Substation Power Systems in Urban Railway (도시철도 전력설비의 노후화 판단을 위한 예측 프로그램 구현)

  • Jung, Ho-Sung;Park, Young;Kang, Hyun-Il
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.6
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    • pp.881-885
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    • 2013
  • In this paper, we present a deterioration judgment model of urban rail power equipment using driving history, the frequency and number of failures. In addition, we have developed a deterioration judgment program based on the derived failure rate. A deterioration judgment model of power equipments on metro system was designed to establish how much environmental factors, such as thermal cycling, humidity, overvoltage and partial discharge. The deterioration rate of the transformers followed the Arrhenius log life versus reciprocal Kelvin temperature (hotspot temperature) relation. The deterioration judgment program is linked to the online condition monitoring system of urban railway system. The deterioration judgment program is based on the user interface it is possible to apply immediately to the urban rail power equipment.

Impact of Urban Thermal Environment Improvement by Street Trees and Pavement Surface Albedo (가로수와 바닥 포장 표면 알베도의 도시 열 환경 개선 효과)

  • Na-youn Kim;Eun-sub Kim;Seok-hwan Yun;Zheng-gang Piao;Sang-hyuck Kim;Sang-jun Nam;Hwa-Jun Jea;Dong-kun Lee
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.26 no.1
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    • pp.47-59
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    • 2023
  • Due to climate change and urbanization, abnormally high temperatures and heat waves are expected to increase in urban and deteriorate thermal comfort. Planting of street trees and changing the albedo of urban surfaces are the strategies for mitigating the thermal environment of urban, and both of these strategies affect the exposure and blocking of radiative fluxes to pedestrians. After measuring the shortwave and longwave radiation according to the ground surface with different albedo and the presence of street trees using the CNR4 net radiometer, this study analyzed the relationship between this two strategies in terms of thermal environment mitigation by calculating the MRT(Mean Radiant Temperature) of each environment. As a result of comparing the difference between the downward shortwave radiation measured under the right tree and at the control, the shortwave radiation blocking effect of the tree increased as the downward shortwave radiation increased. During daytime hours (from 11 am to 3 pm), the MRT difference caused by the albedo difference(The albedo of the surfaces are 0.479 and 0.131, respectively.) on surfaces with no tree is approximately 3.58℃. When tree is present, the MRT difference caused by the albedo difference is approximately 0.49℃. In addition, in the case of the light-colored ground surface with high albedo, the surface temperature was low and the range of temperature change was lower than the surrounding surface with low albedo. This result shows that the urban thermal environment can be midigate through the planting of street trees, and that the ground surface with high albedo can be considered for short pedestrians. These results can be utilized in planning street and open space in urban by choosing surfaces with high albedo along with the shading effect of vegetation, considering the use by various users.