• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.3 no.2
• /
• pp.91-93
• /
• 1974

본(本) 논문(論文)은 유효온도차(有效溫度差)에 의(依)한 하기랭방부하계산법(夏期冷房負荷計算法)의 기초가 되는 서울에서의 상당외기온도(相當外氣溫度)를 구(求)한 것이다. 상당외기온도(相當外氣溫度)는 유효온도차(有效溫度差)를 구(求)하기 위한 것으로 이것의 산출(算出)은 서울의 외기온(外氣溫)을 T.A.C.(Technical Advisory Committee) 2.5% 위험율을 기준치(基準値)로 한 하기(夏期)의 설계용(設計用) 외기온도(外氣溫度)와 이론식(理論式)에 의한 전일사량(全日射量)에서 7월(月) 22일(日) 서울의 상당외기온도표(相當外氣溫度表)를 작성(作成)하였다.

• Proceedings of the Korean Society for Bio-Environment Control Conference
• /
• 2001.04b
• /
• pp.88-89
• /
• 2001

꿀벌의 실내월동에 이용되는 월동용 저온양봉사의 내부환경에 영향을 주는 요소에는 외기온, 저장봉군수, 환기량 등이 있다. 이러한 환경요인을 고려하여 설계 제작된 국내 월동용 저온양봉사의 성능 및 저장봉군수와 양봉사 내부온도의 관계를 분석하고자 경상북도의 7개 지역에 설치된 월동용 저온양봉사(내부크기 폭4.5m×길이3m×높이3m)에 대하여 2000. 11. 25부터 2001, 2. 15까지 실내월동 실험을 수행하였다. 실험대상 지역은 포항, 문경, 상주, 칠곡, 성주, 영양, 안동이며, 지역별 저장봉군수는 각각 14, 74, 85, 110, 163, 170, 260군이다(Table 1). 꿀벌의 월동기간 중 안동과 성주지역을 제외한 5개 지역의 실내 월동성적은 폐사율이 10％미만으로 대체적으로 우수한 것으로 조사되었으나, 월동기간중 지역별 외기온을 분석한 결과, 평균외기온 및 최저외기온이 가장 낮은 지역은 안동이었으며, 그 값이 각각 -3.1℃와 -9.4℃일 때 양봉사 내부의 평균온도와 최저온도는 5.2℃와 3.8℃로 나타났다. 반면에 평균외기온 및 최저외기온이 가장 높은 지역은 포항이었으며 그 값이 각각 1.3℃와 -4.1℃일 때 양봉사 내부의 평균온도와 최저온도는 각각 3.1℃와 1.2℃로 나타나 저온양봉사 내부의 온도환경 조절성능이 모두 우수한 것으로 판단되었다(Table 1). 또한 월동기간중 주.야간으로 양봉사 내.외부의 온도변화를 분석한 결과, 저장봉군수의 증가에 따라 주야간 모두 양봉사 내.외부 온도편차가 증가하는 경향을 나타내었으며 양봉사 내부의 주.야간 평균온도는 모두 꿀벌의 월동에 적정한 범위인 2℃-9℃를 유지하는 것으로 분석되었다(Table 2). 그리고, 월동기간중 외기온이 가장 낮은 시기(1월 13-19일)의 평균 외기온이 -8℃--9℃로 유사한 문경, 상주, 영양, 안동지역의 월동용 저온양봉사의 평균 내부온도는 각각 -2.0℃, -1.0℃, 0.2℃, 4.2℃로 나타나 저장봉군수가 증가함에 따라 월동용 저온양봉사의 내부온도가 증가하여 꿀벌의 월동에 적합한 온도범위를 유지함을 알 수 있었다. 실험기간동안 대부분의 저온양봉사 내부온도는 꿀벌이 월동하기에 적정한 온도범위(2℃-9℃)로 유지하였다(Fig. 1).

• Solar Energy
• /
• v.12 no.2
• /
• pp.1-8
• /
• 1992

Identifying characteristics of heating and cooling systems requires estimation of thermal load of specific time interval, especially in cases that its system is operated intermittently, by using thermal storage, of in a partial load condition. Estimating the thermal load, however, needs to forecast hourly weather data variation. Hence, this paper attempts to examine characteristics of hourly ourdoor temperature variation as a preliminary research for the mathematical modeling of the hourly weather variation. Speculating characteristics of daily minimum and maximum temperature occurances, hourly outdoor temperature variation, and daily temperature differences in the increasing range ($07h{\sim}15h$) and decreasing range($15h{\sim}07h$), we were able to analyze changing patterns of daily temperature differences in each range in terms of daily solar amount, cloud ratio, and other weather data. Results from the multiple regression analysis enables us to conclude that daily differences in the increasing range are strongly affected last night temperature itself while the other range's differences are influenced by many weather data, which are solar amount, the variation of cloud, and the maximum temperature of the previous day.

• Journal of Bio-Environment Control
• /
• v.27 no.3
• /
• pp.269-275
• /
• 2018

In order to establish the criterion for analyzing outdoor weather conditions in the greenhouse heating and cooling system design, we analyzed heating and cooling design outdoor temperatures by the annual percentile method and compared with design outdoor temperatures by the existing seasonal percentile method. In the annual percentile method, 0.4%, 1% and 2% of the total 8,760 hours per year are presented as cooling design outdoor temperatures and 99.6% and 99% as heating design outdoor temperatures. When the annual percentile method was adopted, heating design outdoor temperatures increased by 6.7 to 9.6% compared with the seasonal percentile method, and cooling design outdoor temperatures decreased by 0.6 to 1.1%. The maximum heating load in the same greenhouse condition decreased by 3.0 to 3.6% when the annual percentile method was adopted, but the effect on the maximum cooling load was insignificant. Therefore, it is necessary to consider the change of heating design outdoor temperatures to the annual percentile method, but it is not necessary to change the cooling design outdoor temperatures since there is little difference between the two methods.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.3
• /
• pp.137-145
• /
• 2015

In this study, the actual energy consumption of the secondary side of District Heating System (DHS) with different hot water supply temperature control methods are compared. Three methods are Set-point Control, Outdoor Temperature Reset Control and Outdoor Temperature Prediction Control. While Outdoor Temperature Reset Control has been widely used for energy savings of the secondary side of the system, the results show that Outdoor Temperature Prediction Control method saves more energy. In general, Outdoor Temperature Prediction Control method lowers the supply temperature of hot water, and it reduces standby losses and increases overall heat transfer value of heated spaces due to more flow into the space. During actual energy consumption monitoring, Outdoor Temperature Prediction Control method saves about 7.1% in comparison to Outdoor Temperature Reset Control method and about 15.7% in comparison to Set-point Control method. Also, it is found that at when partial load condition, such as daytime, the fluctuation of hot water supply temperature with Set-point Control is more severe than Outdoor Temperature Prediction Control. Therefore, it proves that Outdoor Temperature Prediction Control is more stable even at the partial load conditions.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.2 no.4
• /
• pp.204-208
• /
• 2000

Little information is available for the temporal variation in air temperature profile within rice canopies under development, while much works have been done for a fully developed canopy. Fine wire thermocouples of 0.003 mm diameter (chromel-constantan) were installed at 10 vertical heights by a 10 cm step in a paddy rice field to monitor the air temperatures over and within the developing rice canopy from one month after transplanting (June 29) to just before heading (August 24). According to a preliminary analysis of the data, we found neither the daytime temperature maximum nor the night time minimum at the active radiation surface (the canopy height with maximum leafages) during this period, which is a typical profile of a fully developed canopy. Air temperature within the canopy never exceeded that above the canopy at 1.5 m height during the daytime. Temporal march of the within-canopy profile seemed to be controlled mainly by the ambient temperature above the canopy and the water temperature beneath the canopy, and to some extent by the solar altitude, resulting in alternating isothermal and inversion structures.

• Horticultural Science & Technology
• /
• v.33 no.5
• /
• pp.647-657
• /
• 2015

To investigate a method for calculation of the heating load for environmental designs of horticultural facilities, measurements of total heating load, infiltration rate, and floor heat flux in a large-scale plastic greenhouse were analyzed comparatively with the calculation results. Effects of ground heat exchange and infiltration loss on the greenhouse heating load were examined. The ranges of the indoor and outdoor temperatures were $13.3{\pm}1.2^{\circ}C$ and $-9.4{\sim}+7.2^{\circ}C$ respectively during the experimental period. It was confirmed that the outdoor temperatures were valid in the range of the design temperatures for the greenhouse heating design in Korea. Average infiltration rate of the experimental greenhouse measured by a gas tracer method was $0.245h^{-1}$. Applying a constant ventilation heat transfer coefficient to the covering area of the greenhouse was found to have a methodological problem in the case of various sizes of greenhouses. Thus, it was considered that the method of using the volume and the infiltration rate of greenhouses was reasonable for the infiltration loss. Floor heat flux measured in the center of the greenhouse tended to increase toward negative slightly according to the differences between indoor and outdoor temperature. By contrast, floor heat flux measured at the side of the greenhouse tended to increase greatly into plus according to the temperature differences. Based on the measured results, a new calculation method for ground heat exchange was developed by adopting the concept of heat loss through the perimeter of greenhouses. The developed method coincided closely with the experimental result. Average transmission heat loss was shown to be directly proportional to the differences between indoor and outdoor temperature, but the average overall heat transfer coefficient tended to decrease. Thus, in calculating the transmission heat loss, the overall heat transfer coefficient must be selected based on design conditions. The overall heat transfer coefficient of the experimental greenhouse averaged $2.73W{\cdot}m^{-2}{\cdot}C^{-1}$, which represents a 60% heat savings rate compared with plastic greenhouses with a single covering. The total heating load included, transmission heat loss of 84.7~95.4%, infiltration loss of 4.4~9.5%, and ground heat exchange of -0.2~+6.3%. The transmission heat loss accounted for larger proportions in groups with low differences between indoor and outdoor temperature, whereas infiltration heat loss played the larger role in groups with high temperature differences. Ground heat exchange could either heighten or lessen the heating load, depending on the difference between indoor and outdoor temperature. Therefore, the selection of a reference temperature difference is important. Since infiltration loss takes on greater importance than ground heat exchange, measures for lessening the infiltration loss are required to conserve energy.

• Journal of Bio-Environment Control
• /
• v.9 no.2
• /
• pp.107-114
• /
• 2000

We constructed climagraphs for 16 regions of Korea by using the average monthly minimum air temperature, maximum air temperature and global radiation. We characterized the outside climate requirements corresponding to the climate requirements of crops in greenhouses. The climagraphs allow to decide the appropriate climate periods for greenhouse cultivation without heating and cooling equipment. These graphs may be used for analyzing climatic characteristic of a given area, selecting the suitable region and greenhouse and making a rational plan for greenhouse cropping in Korea. We found difficulty in deciding the beginning and end of greenhouse heating and cooling period due to insufficient references.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.43 no.12
• /
• pp.60-65
• /
• 2014

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2019.05a
• /
• pp.197-198
• /
• 2019

The aim of the research is evaluating the feasibility of inspection for early age frozen damage and for expansion of concrete under the various time periods of -20℃ temperature condition. When the concrete samples were exposed for 12 hours and 24 hours, the frozen depth of the concrete were 10 and 60 mm, respectively, under the wet conditions. From the experiment results of temperature and expansion, only surface area suffered frozen damage for 12 hours exposing conditions while entire area suffered frozen damage for 24 hours exposing conditions.