• 한국환경과학회지
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• 제25권2호
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• pp.259-265
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• 2016

We analyzed diurnal variations in the surface air temperature using the high density urban climate observation network of Daegu in summer, 2013. We compared the time elements, which are characterized by the diurnal variation of surface air temperature. The warming and cooling rates in rural areas are faster than in urban areas. It is mainly due to the difference of surface heat capacity. In addition, local wind circulation also affects the discrepancy of thermal spatiotemporal distribution in Daegu. Namely, the valley and mountain breezes affect diurnal variation of horizontal distribution of air temperature. During daytimes, the air(valley breeze) flows up from urban located at lowlands to higher altitudes of rural areas. The temperature of valley breeze rises gradually as it flows from lowland to upland. Hence the difference of air temperature decreases between urban and rural areas. At nighttime, the mountains cool more rapidly than do low-lying areas, so the air(mountain breeze) becomes denser and sinks toward the valleys(lowlands). As the result, the air temperature becomes lower in rural areas than in urban areas.

• 한국대기환경학회지
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• 제28권2호
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• pp.119-130
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• 2012

Heat island phenomena in Chuncheon (Korea) were investigated using air temperature measured by automatic weather stations and temperature dataloggers located at rural and urban sites. Numerical simulation of the phenomena was performed using Weather Research and Forecasting Urban Canopy Model (WRF-UCM) and results were compared with the observation. The model was initialized with NCEP/FNL data. The horizontal resolution of the fine domain is 0.33 km. The results of observational analyses show that the intensity of heat island was significantly higher during the nighttime than during the daytime. The highest measured temperature difference between rural and urban site is $3.49^{\circ}C$ and average temperature difference varies between 1.4 and $1.9^{\circ}C$. Good agreement was found between the simulated and observed temperatures. However, significantly overestimated wind speed was found at the urban sites. The linear regression analysis between observed and simulated temperature shows high correlation coefficient 0.96 for urban and 0.94 for rural sites while for wind speed, a very low correlation coefficient was found, 0.30 and 0.55 respectively.

• 한국태양에너지학회 논문집
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• 제32권spc3호
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• pp.185-193
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• 2012

Recently rapid urbanization facilitates development of high-rise building complex including apartment and office building in urban area. Many problems related with high -rise building are reported. Especially, unpleasant strong winds in pedestrian area are frequently encountered around the high-rise building. CFD simulation methods are used to analyze the wind environment of pedestrian level in high-rise building block. However, the results show differences between CFD and measurement. This difference is attributed to improper use of CFD. Conventional CFD simulation for wind environment around high-rise building does not describe the effect of trees, shrubs and plants near ground which affect the wind environment of pedestrian level. Canopy model can be used to reproduce the aerodynamic effects of trees, shrubs and plants near ground. In this paper, CFD simulation methods coupled with the tree canopy model to predict wind environment of pedestrian level in high-rise residential building block were suggested and the validity was analyzed by comparison between measurement and CFD results.

• Wind and Structures
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• 제12권3호
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• pp.281-283
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• 2009

Marquardt method is used to estimate the aerodynamic parameters in urban area of Beijing City, China, including displacement length (d), roughness length ($z_0$) and friction velocity (u*) and drag coefficient. The surface drag coefficient defined as the ratio between friction velocity and mean wind speed is 0.125 in our research, which is close to typical urban area value. The averaged d and $z_0$ are 1.2 m and 7.6 m. d and $z_0$ change with direction because of the surface heterogeneity over urban surface and reach their maximum values at S-SW sector, this tendency agrees with the surface rough element distribution around the observation tower.

• 한국대기환경학회지
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• 제5권2호
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• pp.97-105
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• 1989

Recently, many studies on air quality prediction models have been performed to develope new ones. The purpose of the study is to obtain a method to predict $SO_2$ concentration simply in urban area using hour-to-hour meteorological data such as the wind speed, the incoming solar radiation, and the cloud coverages. The relationships between with speed and $SO_2$ concentrations are plotted in flgures. Predicted concentration curves are obtained for equation C=b/(1+au).

• 대기
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• 제33권4호
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• pp.413-422
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• 2023

Urban Air Mobility (UAM) is promising, sustainable and efficient air transportation in a metropolitan area. Korean government has recently announced operation demonstration plans as a step toward commercialization of UAM. However, there is lack of understanding on the potential impact of weather on UAM operation. We collected weather observations from Gimpo International Airport and 5 automatic weather stations (AWS) along UAM corridor of the Han-River to assess weather barriers such as low visibility, wind gust and wind shear. The results show the frequency of low visibility near the corridor fluctuated significantly from year to year depending on the concentration of fine particulate matter (PM_2.5) in Seoul. The frequency of high wind speed-shift calculated using 1-minute wind observations was increased not only during the spring season (March, April, and May) but also the beginning of rainy season (Jun). In addition, a chance of high wind shear from 1-minute wind observations varied by the stations, suggesting that the condition is largely affected by topography including a river and high-rise buildings. These basic weather properties suggest that there are substantial weather barriers to UAM operations along the Han-River Corridor, while they cannot properly surveil micro-scale weather conditions in detail such as wind gust and wind shear over the corridor. Thus, this study suggests that potential barriers related to adverse weather need to be evaluated, building high-density weather observations infrastructure prior to UAM demonstration and commercialization.

• 국제초고층학회논문집
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• 제11권4호
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• pp.321-329
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• 2022

High-rise buildings constructed adjacent to low-rise structures experience frequent damage caused by the associated strong wind. This study aimed to implement a standard evaluation of the wind environment and airflow characteristics around high-rise apartment blocks using wind tunnel tests (WTT) and computational fluid dynamics (CFD) simulations. The correlation coefficient between the CFD and wind tunnel results ranged between 0.6-0.8. Correlations below 0.8 were due to differences in the wake flow area range generated behind the target building according to wind direction angle and the effect of the surrounding buildings. In addition, a difference was observed between the average velocity ratio of the wake flow wind measured by the WTT and by the CFD analysis. The wind velocity values of the CFD analysis were therefore compensated, and, consequently, the correlations for most wind angles increased.

• 한국조경학회지
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• 제30권4호
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• pp.37-46
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• 2002

The main purpose of this research is to discuss the urban heat island which will be caused by urbanization, especially by the construction of new town on a wide green zone. Over the last ten years, five new towns have been developed around the Seoul metropolitan area. However these new towns become bedroom communities and create traffic problems between Seoul and its surrounding areas because of an increase in population and a lack of roads and other infrastructures. The construction of another such new town is under consideration in the Pan-gyo area. But it is important that Pan-gyo remains a wide green zone. Many studies show that green space can play an important role in improving urban eco-meteorological, ameliorative capability and air hygiene. The objective of this study is to analyze the urban heat islands of Bund-Dang Si which was constructed in 1996 and of the Pan-Gyo area planned as new town. To investigate the local thermal environment and its negative effects caused by change of the land use type and urbanization we used LANDSAT TM images for extraction of urban surface temperature according to change of land use over 15 years. These data were analyzed together with digital land use and topographic data. As a study result, we found that the thermal island of this area from 1985 to 1999 rapidly increased with a difference of mean temperature of more than 12'E. Before construction of Bun-Dang Si the temperature of this area was the same as the forest, but during the new town construction in 1991, an urban heat island developed. The temperature of forest with a size of over 50% of the investigation area was lowest, which leads us to conclude that the forest cools the urban and its surroundings. The mean temperature of the residential and commercial area is more than +4.5$^{\circ}C$ higher then forest, so this method of land use is the main factor increasing the urban heat island. Urban heat islands and green space play an important role in urban wind systems, i.e. Thermal Induced Air Exchange and Structural Wind Circulation, because of their special properties with regard to energy balance between constructed urban and land. The skill to allocate land use types in urban areas is a very important planning device to reduce air pollution and induce the fresh cold air from green space. An urban climatic experiment featuring a numerical wind simulation study to show the air corridor will be published in a following research paper.

• 한국주거학회논문집
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• 제20권3호
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• pp.85-95
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• 2009

One of the most important elements in creating the pleasant residential environment is the wind. For the pleasant residential environment, it is important that the air pollutants are not stagnant but appropriately and swiftly diffused and removed by winds. Especially, the river becomes a main route of wind in the urban core. So, it is necessary to secure the space to circulate the sufficient cool air to this area. But, recently many high-rise apartment complexes have been built along the rivers that have the fine view and pleasant environment. As a result, the cool and fresh air coming from mountains hardly diffuses into the urban core but just flows along the river. Considering the facts above, this study selected types of building layout and kind of land cover as complex or architectural design factors that have an influence on wind environment. Based on the factors, it analyzed change in wind environment according to apartment complex development aiming at the Sinchun area which is Daegu Metropolitan City's main wind corridor. Therefore, when apartment complex development is planned in the future, it can offer basic data for establishing plans for more pleasant complexes. As a result of the analysis, it was shown that the layout type of housing and the building height plan in consideration of wind corridor around the river were pretty effective in increasing the wind speed and circulating the air in the apartment complex. Therefore, if wind corridor is considered when apartment complex development is planed in the future, this study can offer useful information contributing to improve comfort in residential environment in the level of complex building as well as city planning.

• 한국지리정보학회지
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• 제16권2호
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• pp.16-29
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• 2013

본 연구는 경상남도 창원시를 대상으로 MetPhoMod 모델링의 야간시간대 바람패턴결과를 이용하여 공기순환성 평가를 실시하였다. 공기순환성 평가는 바람의 지속성과 교란성의 평가지수를 이용하여 분석하였으며, 바람의 지속성은 바람패턴의 풍속, 바람의 교란성은 풍향의 다양성 결과를 활용하였다. 분석결과 도시지역 중 공기순환성이 취약한 지역은 봉림동, 용지동, 반송동 등으로 나타났으며, 특히 용지동과 상남동, 사파동의 고층아파트 및 상업지역, 단독주거지역에서 바람정체현상이 발생하는 것으로 확인되었다. 따라서 이러한 공기순환성이 취약하여 바람정체현상이 발생하는 지역에 대해 공간개선을 함으로써 바람의 유동이 원활할 수 있도록 조성되어야 할 것이며, 도시외곽에서 생성되는 바람이 지속적으로 유입될 수 있도록 개발계획차원에서 바람길 조성방안이 마련되어야 할 것으로 판단된다.