• 한국태양에너지학회 논문집
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• 제28권5호
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• pp.49-55
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• 2008

The radiant cooling(RC) effects are studied during the winter night. The plate was viewing the nighttime sky. The data were collected at the rooftop of the Engineering building at the Dongguk University in Seoul, Korea. As observed during the summer night, the plate temperature was lower than ambient temperature under the RC favorable conditions. The parameters under study are the wind velocity, cloud index, and visibility for given system size and surface condition. The results follow the same tendency with these parameters as observed from the previous study for the summer night. As long as the wind velocity is less than around 2 m/s, the radiant cooling was observed with the system under study. In some cases, the radiant cooling temperature differences (RCTD) are higher than those for the summer night. The larger the RCTD as the wind velocity decreases and as the sky becomes clear.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1300-1305
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• 2004

The purpose of this experiment is to study the radiant cooling effects by a plate directly viewing the nighttime sky. The measurements are performed at a rooftop of the Engineering building at the Dongguk University in Seoul during the month of August in 2004. The radiant cooling effects are compared using three different types of plate surfaces such as galvanized Iron, black painted, and aluminum film coated galvanized iron plate. Among these plates, the black painted surface show the lowest temperature that is lower than its ambient temperature. The maximum radiant cooling temperature difference, that is ambient temperature minus plate temperature, observed is about 5K..

• 설비공학논문집
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• 제17권6호
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• pp.605-610
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• 2005

The purpose of this experiment is to study the radiant cooling effects by a plate directly viewing the nighttime sky. The measurements are performed on a rooftop of the Engineering building at the Dongguk University in Seoul during the month of August in 2004. The radiant cooling effects are compared using three different types of plate sufaces, namely, galvanized iron, black painted, and aluminum film coated galvanized iron plate. Among these plates, the black Painted surface showed the lowest temperature that is lower than the ambient temperature. The maximum radiant cooling temperature difference, which is ambient temperature minus plate temperature, observed is about 5 K.

• 한국태양에너지학회 논문집
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• 제29권6호
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• pp.32-38
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• 2009

The effects of surface radiative properties on the radiant cooling of opaque surfaces under clear sky condition are studied. Two types of surfaces, one gray and the other selective, are compared. For the nighttime cooling, black surface gives the lowest plate temperature and on the other hand the ideal selective surface gives the highest temperature. The reverse is true when there is an insolation. Equivalent radiative heat transfer coefficient of radiant cooling without convection is about $1{\sim}7\;W/m^2-K$ for the range of values studied. The surface with black within the $6{\sim}13\;{\mu}m$ band else zero emissivity could be regarded as a black surface for the nighttime radiant cooling purposes. However, lower band limit of $4\;{\mu}m$ is preferred to $6\;{\mu}m$ for small insolation situations.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.11-17
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• 2007

The purpose of this study is to check whether the plate temperature could be lower than the surrounding air by using the radiant cooling during the day time in summer at Seoul. Without an insolation shield as this experiment was performed, a few cases were found. The temperatures of the black painted plate are lower than those of the aluminium film coated plate if the following condition exist; no or small insolation over the plate, the wind velocity less than around 2 m/s, and clear sky However if there are insolation over the plate, the temperatures of the aluminium coated plate are lower than the black painted plate. Also, as the wind velocity increases, the plate temperature decreases faster. The temperature response of the small system is much faster than the large system.

• 한국태양에너지학회 논문집
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• 제21권4호
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• pp.1-11
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• 2001

The authors carried out a study on the cooling effect of radiant cooling system using the metallic lightweight radiator for cooling energy saying in building. The radiant cooling performance was examined, analyzed, and presented through the case study. In this study, the cooling effect of various factors was analyzed, especially in a thin plate above the roof. These numerical results can be used as the basic design data for application of radiant cooling system. As a result of these researches, the system was verified to be an available cooling energy sources for improvement of indoor environment in summer. Finally, to complete the system can be suitable for Korean climate conditions, experimental study should be performed on the basis of these results.

• 토지주택연구
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• 제12권1호
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• pp.129-137
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• 2021

외부 차양장치는 대표적인 여름철 일사조절 장치이다. 특히 냉방부하가 높은 업무용 건물에 적합한 기술로 인식되어왔다. 그러나 본 연구에서는 차양장치의 냉방부하 저감뿐만 아니라 난방부하 저감 효과를 검증하기 위한 실험을 수행하였다. 이를 위해 겨울철 야간 천공복사냉각에 따른 영향을 중심으로 일반 창호, 롤 블라인드, 외부 차양장치를 대상으로 실험을 수행하였으며, 그 결과는 다음과 같다. 외부 차양장치가 적용된 경우 유리 내·외표면 온도차는 평균 11.8℃로 차양장치가 없는 경우의 14.6℃ 보다 평균 2.8℃ 낮은 온도차를 나타냈으며, 이는 천공복사에 의한 열교환으로 차양 표면온도가 외기온도보다 낮은 시간때에 발생한다. 한편, 롤 블라인드는 내부 중공층의 평균온도보다 0.8℃ 낮은 온도를 나타냈으며 이 또한 투과체를 통과한 천공복사가 롤 블라인드 표면과 열교환이 이뤄졌기 때문이다. 유리 외부 표면온도만을 고려하면 약 3℃ 이상의 온도 상승이 예상된다. 그리고 차양장치가 없는 경우 일반적인 온도구배를 나타내고 있었다. 한편 남동향과 남서향에 외부 차양장치가 설치되었을 때 남서향의 외측 유리 표면온도가 더 낮게 나타나는 특징이 있다. 이 결과는 천공복사에 의한 냉방 저감 효과를 정량화할 수는 없지만 적어도 타당성은 확인할 수 있었다. 향후 연구에서는 천공복사 냉각과 에너지 소비 사이의 상관관계를 조사하고 외부 차양장치의 난방에너지 절감 효과에 대한 독립 챔버 실험을 진행할 계획이다.