• Wind and Structures
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• 제11권6호
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• pp.455-478
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• 2008

The present study aims to estimate the wind ventilation performance for pedestrian level domains from the air quality point of view. Three typical models of a dense urban area were considered and numerically simulated in order to examine the effects of the geometry of such models on wind flow characteristics, which in turn affect the air quality, within the pedestrian domain of a street canyon located within this area. The calculated flow fields were employed to estimate the exceedance probabilities within the study domain using a new approach: air exchange rate within the domain. The study has been applied to nine cities in Japan: Tokyo, Osaka, Sapporo, Niigata, Fukuoka, Nagoya, Sendai, Yokohama, and Kyoto, based on their mean wind velocity data. The results demonstrated that the exceedance probability analysis of the pedestrian wind environment could be a valuable tool during the design stage of inhabited areas for the evaluation of pollutant-removal efficiency by the applied wind. Also, the calculated probabilities demonstrated substantial dependence on both the geometry of building arrays and the wind conditions of the nine cities.

• 한국농림기상학회지
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• 제3권2호
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• pp.114-120
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• 2001

대기오염 농도가 높은 종로, 잠실, 그리고 남산지역과 대조구로 태능지역의 가로수로 식재된 은행나무 (Ginkgo biloba L)를 대상으로 대기오염에 노출되었을 때의 생육상황을 조사한 결과는 다음과 같다. 1. 서울에서 생육하고 있는 가로수 은행나무의 대기오염에 의한 엽록소 함량은 태능 48.77, 남산 47.90, 종로 46.88, 그리고 잠실 40.92로 태능지역이 가장 높게 나타났다. 각 지역별 흉고직경은 남산 23.8 cm, 종로 23.4cm, 태능 23.3cm,잠실 21.6cm로 조사지역간 흉고직경의 차이는 잠실지역 이외에는 별로 없다. 2. 대조구인 태능지역 보다 조사된 남산과 종로지역의 은행나무 엽록소 함량이 낮았다. 3. 잠실지역의 낮은 흉고직경은 도심지 가로수의 생육상황이 대기오염물질보다는 다른 외부인자에 의해서 영향 받을 수 있음을 나타낸다. 4. 분석에 사용된 Got-2, Pgi-2, Pgm, Acon, Mnr, Mdh, Skdh,및 6Pgd의 8개 동위효소에서 정색반응이 확인되었으며, 8개의 유전자좌 중 Pgi-2와 Mdh가 대립유전자에선 Pgi-2와 Pgm에서 각각 통계적인 유의성(P＜0.01)이 인정되었다. 5. T(tolerant), S(sensitive) 두 group으로 나누어 분석된 동위효소분석은 유전자당 대립유전자수(A/L)는 T가 2.63, S가 2.5로 나타났다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.113-122
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• 2000

Dynamic structures of unsteady $CH_4$/Air jet diffusion flames with flame-vortex interaction were numerically investigated. A time-dependent, axisymmetric computational model was adopted for this calculation. Two step global reaction mechanism which considers 6 species, was used to calculate the reaction rates. The predicted results including gravitational effect show that the large outer vortices and the small inner vortex street can be well simulated without any additional disturbances in the downstream of nozzle tip. It was found that the temperature and species concentrations had various values for the same mixture fraction in flame-vortex interaction region. This unsteady jet flame configuration accompanying flame-vortex interaction is expected to give good implications for the structure of turbulent flames.

• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.471-476
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• 2010

This paper has studied dissymmetrical light distribution design using the secondary optics in the simulation. fundamental Lambertian radiation distribution based on LED has been cut off by the secondary optics, and the first surface slope of lens and second surface slope of total reflection area have been calculated through formula. PMMA (the index of refraction: 1.49361) which is material of lens has been selected. critical angle($42.02993^{\circ}$) between Air and PMMA has been calulated by snell's law, and total reflection angle slope has been selected about $16.67^{\circ}$ to occur the total reflection. when the first surface slope and the second surface slope has been set up, Rays of all total reflection area have generated the total reflection. finally, designed LED Module has been estimated by Korean Industrial Standards for LED safety street lighting. dissymmetrical light distribution have been analyzed with reached effect of road illuminance, and average road illuminance which are each 70.6 lx, 40.35 lx, and 25.88 lx have been satisfied with Korean Industrial Standards for LED safety street lighting.

• 한국환경보건학회지
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• 제48권6호
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• pp.291-297
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• 2022

Background: PM_2.5 and black carbon (BC) can be generated from cooking and from vehicle operation. Street vendors may be exposed to PM_2.5 and BC due to their proximity both to roads and to cooking activities. Objectives: The objectives of this study were to evaluate the PM_2.5 and BC concentrations in cooking stalls and to determine the effects of cooking activity and of types of cooking. Methods: Indoor and outdoor PM_2.5 and BC concentrations, temperature, and relative humidity were measured in 32 stalls in April and May 2022. Behavioral factors such as the presence of cooking activity and types of cooking were observed. Student's T-test was performed using the difference of indoor and outdoor PM_2.5 and BC concentrations to compare the effects of cooking activity and to compare types of cooking. Results: One-hour averages of the difference in indoor and outdoor PM_2.5 concentrations for cooking stalls and non-cooking stalls were 9.7±15.7 ㎍/m³ (n=22) and -0.5±0.4 ㎍/m³ (n=10), respectively. The difference in indoor and outdoor PM_2.5 concentrations in cooking stalls was significantly higher than in non-cooking stalls (p<0.05). The indoor PM_2.5 concentration for stalls for Chinese pancakes and teokbokki exceeded the standards for indoor air quality in South Korea (50 ㎍/m³ ). The indoor PM_2.5 concentration for Korean pancake stalls exceeded the standards for outdoor air quality in South Korea (35 ㎍/m³ for 24 hours). Conclusions: The PM_2.5 concentrations in stalls with cooking activity was significantly higher than those in stalls without cooking activity. Some stalls with certain types of foods exceeded standards for indoor and outdoor air quality in South Korea. Better management of indoor air quality in stalls with cooking activities is necessary.

• 한국환경과학회지
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• 제18권9호
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• pp.941-952
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• 2009

The urban microscale wind field around the air quality monitoring station was investigated in order to check how a building complex influences it. For this study as the high density areas Jwa-dong and Yeonsan-dong monitoring sites in Busan were chosen. As the direction of inflow which is perpendicular to the building of the monitoring station was expected to cause the considerable variation of the wind field, that direction was selected. The model Envi-met was used as the diagnostic numerical model for this study. It is suitable for this investigation because Envi-met has the microscale resolution. After simulating it, on the leeward side around a building complex the decrease of flow velocity and some of vortexes or circulation area were discovered. In addition, on the edge of the top at the building and at the back of the building the upward flow was developed. If the sampling hole of monitoring site were located in this upward flow, it would be under the influence of upward flow from the near street.

• 한국조경학회지
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• 제45권5호
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• pp.105-112
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• 2017

가로수가 여름철 인간 열환경지수(열쾌적성)에 미치는 영향을 분석하기 위해, 낙엽활엽교목 2종과 상록활엽교목 3종 총 5종의 가로수를 대상으로 수목 하부의 음지와 그 옆의 양지에서 미기후 자료를 측정하여 비교 분석하였다. 그 결과, 기온, 상대습도, 풍속의 차이는 각각 평균 $0.2{\sim}1.5^{\circ}C$, 0.9~5.3%, $0.1{\sim}0.5ms^{-1}$로 미비하였으나, 평균복사온도는 평균 $27.1^{\circ}C$의 매우 큰 차이를 보여 주었다. 인간 열환경지수인 PET와 UTCI 결과에서는 수목 하부의 음지가 양지에 비해 PET에서는 평균 21.2~31.3%의 저감 비율을 보여 1.5~2.5단계의 열지각 개선 효과를 나타내었으며, UTCI에서는 평균 12.7~20.0%의 저감 비율을 보여 1~1.5단계의 heat stress 저감 효과를 보이는 것으로 나타났다. 또한, 상록활엽교목이 낙엽활엽교목에 비해 PET에서 평균 5% 더 높은 저감 비율을 나타냈지만, 낙엽활엽교목에 속하는 느티나무는 지엽의 밀도가 높아 상록활엽교목 만큼의 열환경지수(열쾌적성) 개선 효과를 나타내었다. 이에 따라, 가로수의 여름철 열 저감 효과에서 지엽의 밀도와 평균복사온도가 주요 영향임을 알 수 있었다.

• 한국조경학회지
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• 제41권3호
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• pp.22-30
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• 2013

본 연구는 서울시 도심보행공간에서가로수녹음이보행자열쾌적성에미치는영향을WBGT(Wet Bulb Globe Temperature-습구흑구온도) 분석을 통하여 밝히고자 하였다. 일사 영향을 많이 받아 열쾌적성이 저하되는 여름철(8월)에 측정하였으며, 보행공간 WBGT 지수는 한국표준협회 "KS A ISO 7243: 고온환경 WBGT 지수에 의한 열 스트레스 추정"과 일본국립환경연구소의 작업환경, 일상생활 및 운동 WBGT 지침을 활용하여 결과를 해석하였다. 강남구 테헤란로 4개 구간에 대해 측정한 결과, 가로수에 의해 일사가 차단된 녹음(shade)지점 WBGT 지수는 최저 $27.40^{\circ}C$~최고 $30.60^{\circ}C$로 나타났으며, 일사(sun)지점은 최저 $28.45^{\circ}C$~최고 $34.2^{\circ}C$로 나타났다. 모든 녹음 지점에서 보행환경에 적합한 열쾌적성을 보였으며, 구간 최고값을 비교해 보았을 때 녹음(shade)지점이 일사(sun)지점에 비해 $4^{\circ}C$ 낮은 WBGT 지수를 나타내 가로수 녹음의 열쾌적성 개선 효과가 크다는 것을 알 수 있었다. 보행자를 대상으로 실시한 설문 및 행태조사 결과, 대부분 보행자는 일사를 피해 수목 하부 그늘 쪽 보행공간을 이용하는 것으로 나타났으며, 그늘을 이용하는 보행자의 75% 이상 녹음의 쾌적함을 보통 이상 쾌적하다고 평가하였다. 본 연구를 통해 가로수 녹음의 열쾌적성 향상 효과를 확인하였으며, 향후 가로수 식재시 열환경을 고려하여 연속적인 녹음이 형성될 수 있도록 정책적 변화가 필요하다.

• 한국조경학회지
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• 제30권3호
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• pp.25-34
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• 2002

The purpose of this paper is to discuss the function of microclimate amelioration of urban trees regarding the environmental benefits of street trees in summer, focusing on the heat pollution-urban heat island, tropical climate day's phenomenon and air pollution. We measured the diurnal variation of air/ground temperatures and humidity within the vegetation canopy with the meteorological tower observation system. Summertime air temperatures within the vegetation canopy layer were 1-2$^{\circ}C$ cooler than in places with no vegetation. Due to lack of evaporation, the ground surface temperatures of footpaths were, at a midafternoon maximum, 8$^{\circ}C$ hotter than those under trees. This means that heat flows from a place with no vegetation to a vegetation canopy layer during the daytime. The heat is consumed as a evaporation latent heat. These results suggest that the extension of vegetation canopy bring about a more pleasant urban climate. Diurnal variation of air/ground temperatures and humidity within the vegetation canopy were measured with the meteorological tower observation system. According to the findings, summertime air temperatures under a vegetation canopy layer were 1-2$^{\circ}C$ cooler than places with no vegetation. Due mainly to lack of evaporation the ground surface temperature of footpaths were up to 8$^{\circ}C$ hotter than under trees during mid-afternoon. This means that heat flows from a place where there is no vegetation to another place where there is a vegetation canopy layer during the daytime. Through the energy redistribution analysis, we ascertain that the major part of solar radiation reaching the vegetation cover is consumed as a evaporation latent heat. This result suggests that the expansion of vegetation cover creates a more pleasant urban climate through the cooling effect in summer. Vegetation plays an important role because of its special properties with energy balance. Depended on their evapotranspiration, vegetation cover and water surfaces diminish the peaks of temperature during the day. The skill to make the best use of the vegetation effect in urban areas is a very important planning device to optimize urban climate. Numerical simulation study to examine the vegetation effects on urban climate will be published in our next research paper.

• 한국의류학회지
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• 제33권11호
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• pp.1806-1816
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• 2009

This study analyzes the efficiency of a solar cell attached to an air circulation jacket. A commercially available silicon solar panel was selected and attached at four spots where the body angle was $40-60^{\circ}$ and voltage ($V_{oc}$, V), current ($I_{sc}$, A), and output power (P, W) were measured to determine the efficiency. The solar panel was applied to the outer jacket that operates with two fans to increase the convection that lowers the body temperature. The heavy work of standing, walking, and sweeping of a street sweeper was simulated in the field test. The microclimate within the jacket (with or without a fan) was measured and the subjective thermal, humidity, and comfort sensations were surveyed. SPSS 12.0 statistical package was used for a t-test and Wilcoxon signed-rank test. The results show that the highest efficiency of the solar cell was at the incident angle of $60^{\circ}$ in terms of voltage, current and output power distribution. The microclimate temperature of the air circulation jacket decreased significantly with the high power of the fan and subjects felt cooler than the jacket with a fan at the incident angle of $60^{\circ}$. Air circulation jackets operated by a silicon solar panel showed a significant cooling effect on the wearers.