• International Journal of Air-Conditioning and Refrigeration
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• 제15권3호
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• pp.85-100
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• 2007

This study presents a short overview of the researches in connection to the fin-and-tube heat exchangers with and without the influence of dehumidification. Contents of this review article include the data reduction method, performance data, updated correlations, and the influence of hydrophilic coating for various enhanced fin patterns. This study emphasizes on the experimental researches. Performance of both sensible cooling and dehumidifying conditions are reported in this review article.

• 한국세라믹학회지
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• 제48권1호
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• pp.52-56
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• 2011

Silicon carbide (SiC) is a candidate material for heat exchangers for VHTR (Very High Temperature Gas Cooled Reactor) due to its refractory nature and high thermal conductivity. This research has focused on demonstration of physical properties and mock-up fabrication for the future heat exchange applications. It was found that the SiC-based components can be applied for process heat exchanger (PHE) and intermediate heat exchanger (IHX), which are operated at $400{\sim}1000^{\circ}C$, based on our examination for the following aspects: optimum fabrication technologies (design, machining and bonding) for compact design, thermal conductivity, corrosion resistance in sulfuric acid environment at high temperature, and simulation results on heat transferring and thermal stress distribution of heat exchanger mock-up.

• 한국산업융합학회 논문집
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• 제25권1호
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• pp.101-110
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• 2022

For this purpose, the authors proposed and proved usefulness of the modified mean skin temperature which is integrated mean radiation temperature and the effect of floor contacted heat conduction. The mean radiation temperature is applied form factor between half cross-legged human body and surrounding wall of indoor. In addition the floor contacted heat conduction is applied heat transfer coefficient of half cross-legged human body. Eight Korean young men were targeted for the experiment. From the experiment the authors excerpted physiological reaction and psychological reaction in Ondol environment which is combined physiccal environmental factor of artificial climate chamber, air and floor temperature. As a result of the experiment it is confirmed that heat conduction has more impact than heat exchange from existing research for the heat exchange between half cross-legged human body and surrounding wall in Ondol thermal environment. Thereby, it is proved the effectiveness of the modified mean skin temperature which is added floor contacted temperature to the Ondol thermal environmental evaluation index.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2009년도 추계학술발표대회 논문집
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• pp.100-103
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• 2009

The impermeable area on the surface of city has been increased as buildings and artificial landcover have continually been increased. Urban development has gradually decreased the green zone in downtown and alienated the city from the natural environment on outskirt area devastating the natural eco system. There arise the environmental problems peculiar to city including urban heat island phenomenon, urban flood, air pollution and urban desertification. As one of urban plans to solve such problems, green roof system is attracting attentions. The purpose of this study was to investigate the heat reduction effect according to the development of green roof system and to quantify the heat reduction effect by analyzing through simulation the heat environment before and after green roof system. For thermal environment analysis, Thermo-Render 3.0 was used that was developed by Tokyo Industrial College to simulate. The simulation showed that the heat island index before and after the development of tree-planting on rooftop changed maximum $0.86^{\circ}C$ and the surface temperature changed about $20^{\circ}C$. Only with lawn planting, heat reduction effect was great and it means that the green roof system in low-management-light-weight type is enough to see effect. The simulation identified that only lawn planting for green rooftop brought such difference and could lower the heat island index at a narrow area. It is judged that application of green roof system to wider areas might relieve urban heat island phenomenon positively.

• Journal of Biosystems Engineering
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• 제12권2호
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• pp.16-27
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• 1987

Greenhouse farming was introduced to the Korean farmers in the middle of 1950's and its area has been increased annually. The plastic greenhouse, which is covered with polyethylene or polyvinyl chloride film, has been rapidly spread in greenhouse farming since 1970. The greenhouse farming greatly contributed to the increase of farm household income and the improvement of crop productivity per unit area. Since the greenhouse farming is generally practiced during winter, from November to March, the thermal environment in the plastic greenhouse should be controlled in order to maintain favorable condition for plant growing. Main factors that influence the thermal environment in the plastic greenhouse are solar radiation, convective and radiative heat transfer among the thermal component of the greenhouse, and the use of heat source. The objective of this study was to develop a simulation model for thermal environment of the plastic greenhouse in order to determine the characteristics of heat flow and effects of various ambient environmental conditions upon thermal environments within the plastic greenhouse. The results obtained are summarized as follows: 1. Simulation model for thermal environment of the plastic greenhouse was developed, resulting in a good agreement between the experimental and predicted data. 2. Solar radiation being absorbed in the plant and soil during the daytime was 75 percent of the total solar radiation and the remainder was absorbed in the plastic cover. 3. About 83 percent of the total heat loss was due to convective and radiative heat transfer through the plastic cover. Air ventilation heat loss was 5 to 6 percent of total heat loss during the daytime and 16 to 17 percent during the night. 4. The effectiveness of thermal curtain for the plastic greenhouse at night was significantly increased by the increase of the inside air temperature of the greenhouse due to the supplementary heat. 5. When the temperature difference between the inside and outside of the greenhouse was small, the variation of ambient wind velocity did not greatly affect on the inside air temperature. 6. The more solar radiation in the plastic greenhouse was, the higher the inside air temperature. Because of low heat storage capacity of the plant and soil inside the greenhouse and a relatively high convective heat loss through the plastic cover, the increase of solar radiation during the daytime could not reduce the supplymentary heat requirement for the greenhouse during the night.

• 한국공간구조학회논문집
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• 제7권3호
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• pp.97-107
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• 2007

본 연구에서는 대공간의 동계시 인체발열에 따른 실내온열환경의 변화를 실측하고 난방조건 및 외부환경과 관련하여 대공간에서 형성되는 실내온열환경의 특성을 파악하는 것을 목적으로 한다. 본 논문에서는 대공간의 실내수직 및 수평온도분포, 객석의 온도분포, 실내표면온도분포, 객석의 풍속분포, 실내온열쾌적성 등의 실내온열환경을 검토한다.

• 한국대기환경학회지
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• 제24권5호
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• pp.523-537
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• 2008

In Korea, the global warming leads to more frequent high temperature region. increasing the need for research into physical damage caused by high temperature. We therefore analyzed the differences of mortality, caused by extreme heat, among gender and age. We also examined the trend of mortality from high temperature-sensitive diseases. Women are more affected by exposure to high temperature than are men; People over 65 years old have higher mortality rate (1.5 times) than under 65. As for high temperature-related diseases, cerebrovascular disease was the number one cause of death, and chronic lower respiratory disease and cardiovascular disease followed.

• 한국축산시설환경학회지
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• 제1권1호
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• pp.39-45
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• 1995

Temperatures of blood and skin, respiratory rate and plasma cortisol concentration in sheep at a warm (average ambient temperature of $15.3^{\circ}C$) and a hot (average ambient temperature of $27.0^{\circ}C$ environment were measured to investigate the effect of hot environment on the physiological responses in ruminant. Temperatures of core, mean skin and mean body in sheep were tended to increase at day time and to decrease at night time at both warm and hot environment, while 24-hr average for those temperatures were significantly higher at hot environment than at warm environment (P<0.05). The calculated body heat content was higher in sheep at hot environment than at warm environment (P<0.05). Respiratory rate and plasma cortisol concentration had no significant differences between warm and hot environment, suggesting that sheep were not stress by the hot environment in this experiment. It is, therefore, suggested that sheep were well adopted to hot environment by increasing body heat content against heat stress.

• 터널과지하공간
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• 제24권2호
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• pp.166-175
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• 2014

본 연구에서는 현장실측을 통하여 강원도 태백에 위치한 대규모 석탄광산의 열환경을 평가하였다. 열환경 평가를 위하여 WBGT, HSI, ESI, KATA지수 및 유효온도 등 다양한 열적지표를 적용하였고, 상관분석을 실시하였다. 분석결과 대부분의 작업장에서 높은 열환경이 평가되었고, 특히 열적지표 중 인체의 생리학적 특성을 반영하는 HSI와 최대 땀증발열의 상관계수는 -0.834이고 이것은 HSI지표에 가장 큰 영향을 미치는 것으로 나타났다. 최대 땀증발열에 가장 큰 영향을 미치는 인자는 공기속도이다. 따라서 운영 중인 제 1수직갱의 연장 굴착 또는 공기 누기를 방지하기 위한 구조물을 설치함으로써 환기량 증대를 통해 작업장의 열환경을 개선시킬 수 있을 것으로 판단된다.

• 한국환경과학회지
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• 제25권7호
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• pp.951-961
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• 2016

To prevent increasing instances of heat-related illnesses due to heat waves generated by climate change, a customized thermal environment index should be developed for outdoor workers. In this study, we conducted sensitivity analysis of the Masan harbor during a heat wave period (August 9th to 15th, 2013) using the MENEX model with metabolic rate and clothing-insulation data, in order to obtain realistic information about the thermal environment. This study shows that accurate input data are essential to gather information for thermophysiological indices (PST, DhR, and OhR). PST is sensitive to clothing insulation as a function of clothing. OhR is more sensitive to clothing insulation during the day and to the metabolic rate at night. From these results, it appears that when exposed to high-temperature thermal environments in summer, wearing highly insulated clothing and getting enough rest (to lower the metabolic rate) can aid in preventing heat-related illnesses. Moreover, in the case of high-intensity harbor work, quantification of allowed working time (OhR) during heat waves is significant for human health sciences.