• 생물환경조절학회지
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• 제24권3호
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• pp.147-152
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• 2015

온실의 냉방부하 산정방법 개발을 위하여 열수지 방법에 기초한 냉방부하 산정식을 구성하고, 포그냉방 온실에서 냉방부하를 실측하여 검증하였다. 포그냉방 온실의 냉각열량은 포그분사에 의한 증발수량에 물의 증발잠열을 곱하여 구할 수 있다. 여기서, 증발수량은 포그 분사량에 증발효율을 곱하면 구할 수 있으며, 즉 분무수량을 계측하고 포그시스템의 증발효율을 알면 온실의 냉방부하를 실측할 수 있다. 따라서 온실의 냉방부하 실측을 위하여 실험온실에서 포그시스템의 증발효율을 실험하고, 실험온실의 열환경 계측과 더불어 포그 분사량을 계측하여 냉방부하 산정방법을 검토하였다. 먼저 냉방부하 산정식의 환기전열량을 검토하기 위하여 냉방을 실시하지 않은 상태에서 환기량 실측 실험을 통해 비교한 결과 열수지식을 이용한 환기전열량 예측은 비교적 양호한 결과를 보이는 것으로 나타났다. 이류체 포그시스템의 증발효율은 0.3~0.94의 범위를 보였으며 평균 0.67로 나타났고, 환기율이 증가함에 따라 커지는 것으로 나타났다. 포그냉방을 실시하면서 온실의 환경을 계측하여 열수지식으로 냉방부하를 계산하고, 분무량 실측치로부터 증발 냉각열량을 구하여 비교한 결과 냉방부하 계산치와 실측치는 대체로 유사한 경향을 보이는 것으로 나타났다. 냉방부하가 낮은 경우에는 실측치에 비하여 약간 크게 예측되었고, 냉방부하가 높은 경우에는 실측치보다 작게 예측되었다. 온실의 냉방시스템 설계 시에는 최대냉방부하를 이용하여 냉방설비의 용량을 결정하게 된다. 따라서 냉방부하가 큰 쪽에서 실측치보다 작게 예측되는 부분은 검토가 필요하지만 설비용량 산정시의 안전계수를 고려하면 본 연구에서 제시한 냉방부하 산정방법은 온실의 환경설계에 적용할 수 있는 것으로 판단된다.

• KIEAE Journal
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• 제14권6호
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• pp.105-110
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• 2014

The basic factors determining the amount of energy used in hospital buildings are weather conditions and building factors. But the real energy consumer is central plant equipment such as boilers and chillers that produce thermal energy for heating and cooling. Inaccurate decision of the primary equipment's size can cause a high initial-cost, an excessive equipment space, a wasted energy by low operation-efficiency and shortening of the machine's life. In this reason, the decision of optimal size for central plant equipment is very important. There are several factors for the decision such as an operation factor, a factor (equipment factor), piping losses and a simultaneous usage factor applied in the sizing process except a basic cooling load. But there is no standard method for applying those factors. Usually, factors are applied individually by an experience or custom of each engineer. In this study, the authors emphasize the meaning and the problem of those factors, examine them by analyzing factors which were applied to actual practices, and propose the recommendation value of safety, load, operation factors and application methods.

• 전자공학회논문지 IE
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• 제49권2호
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• pp.40-45
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• 2012

본 논문은 전력용 변압기의 최적화된 온도제어를 위하여 부하율을 이용하여 권선최고점온도를 예측하고 냉각장치를 제어하는 방법을 제안하였다. 전력용 변압기의 최적화된 온도제어를 위하여, 하중함수를 사용하여 부하전류에 따른 부하율과 권선온도, 외기온도, 오일온도 등을 바탕으로 권선최고점온도를 예측하는 상관관계식을 제시한다. 또한, 이를 전력용변압기에 적용하여 제어한 결과를 제시한다.

• 전기학회논문지P
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• 제63권2호
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• pp.107-112
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• 2014

To cope with the ever increasing electric power demands in metropolitan areas, a greater underground cable transmission capacity is required. In general, it must be determined whether the temperature in the tunnel maintains the maximum allowable temperature. In order to improve this point, it is used to the loss factor. But, for economic cooling, it is problem to use such loss factor in this country. In this study, based on the load factor in this country, technique for calculating the loss factor has been presents. The suggested method has been tested in a sample section using the computer and the results have shown the usefullness of the suggested method.

• 설비공학논문집
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• 제28권4호
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• pp.137-144
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• 2016

Commercial buildings account for a significant proportion of the total building energy use in Korea, and cooling energy, in turn, accounts for the largest proportion of total energy consumption in commercial buildings. Under this circumstance, chiller staging is considered to be a reasonable and practical solution for cooling energy saving. In this study, the part-load ratio and the operating characteristics of a vapor compression chiller were analysed within an office building. In addition, energy consumption among different chiller staging schemes was comparatively analysed. As a result, significant proportions of total operating hours, cooling load and energy consumption turned out to be in the part load ratio range from 0% through 50%, and thus energy consumption was significantly affected by the chiller COP at low part-load conditions, indicating that the chiller operation at the part-load is an important factor in commercial buildings. In addition, utilizing a sequential chiller staging scheme can reduce the annual cooling energy usage by more than 10.3% compared to operating a single chiller.

• Structural Engineering and Mechanics
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• 제7권2호
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• pp.217-224
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• 1999

A semi-stochastic process model of reliability was established for hyperbolic cooling towers subjected to combined loadings of wind force, self-weight, temperature loading. Effect of the soil-structure interaction on reliability was evaluated. By involving the gust factor, an equivalent static scheme was employed to convert the dynamic model to static model. The TR combination rule was used to consider relations between load responses. An analysis example was made on the 90M cooling tower of Maoming, Guangdong of China. Numerical results show that the design not including interaction turns to be conservative.

• 설비공학논문집
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• 제11권5호
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• pp.684-691
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• 1999

A load calculation program based on TFM(Transfer function method) has been proposed in this study. The validity of the current method has been verified by comparing heat gain calculation by TRF(Thermal response factor) with that by CTF(Conduction transfer function) adopted in ASHRAE. In addition, it seems that the CTF coefficients given in ASHRAE tables have somewhat ambiguity The load calculation program developed in the current study has been employed to calculate cooling load from the exterior walls and roof of example 6 in the ASHRAE. The results are found in good agreement.

• 동력기계공학회지
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• 제10권3호
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• pp.67-72
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• 2006

The effect of manufacturing parameters on wear and improve cooling of motorcycle break system was studied using a disk-on-pad type friction tester. Such parameters conditions have an effect on the wear and improve cooling factor such as applied load, sliding speed, frictional time and number of ventilated disk hole. However, it is difficult to know the mutual relation of these factor. In this study, the wear and cooling characteristics using design of experiment containing 4 elements were investigated for an optimal condition for the best motorcycle disk break system employing Taguchi robust experimental design. From this study, the result was shown that vents have an effect on convection area improving more cooling ability and reduced wear of the disk.

• Architectural research
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• 제14권1호
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• pp.11-18
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• 2012

College of Architecture, Georgia Institute of Technology, Atlanta, GA, US Abstract The intermittent heating and cooling energy need calculation of the ISO 13790 monthly method was examined. The current ISO 13790 method applies a reduction factor to the continuous heating and cooling need calculation result to derive the intermittent heating and cooling for each month. This paper proposes a method for the intermittent energy need calculation based on the internal mean temperature calculation. The internal temperature calculation procedure was introduced considering the heat-balance taking into account of heat gain, heat loss, and thermal inertia for reduced heating and cooling period. Then, the calculated internal mean temperature was used for the intermittent heating and cooling energy need calculation. The calculation results from the proposed method were compared to the current ISO 13790 method and validated with a dynamic simulation using EnergyPlus. The study indicates that the intermittent heating and cooling energy need calculation method using the proposed model improves transparency of the current ISO 13790 method and draws more rational outcomes in the monthly heating and cooling energy need calculation.

• 한국태양에너지학회 논문집
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• 제31권6호
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• pp.95-102
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• 2011

The purpose of study is to estimate heating, cooling load performance and economic efficiency in office building with applied the functional paint. this paint can reduced SHGC(Solar Heat Gain Coefficient) on the glazing surface by coating. In this study, estimated to compared with double glazing, low-e glazing, IP(Insulation Paint) and IPu(Insulation UV-Cut Paint) coating glazing. As a result of this study, 1)heating & cooling load Analysis, SHGC value and U-factor of double glazing is about 0.70 and 3.29($W/m^2K$). low-E glazing is about 0.65 and 2.70($W/m^2K$). Two-side it is about 0.27 and 3.25($W/m^2K$). When compared to double glazing, annual heating & cooling load of low-E glazing, Two-side IPu and IP paint coating glazing is 3,012MWh($124kWh/m^2$), 2,910MWh($120kWh/m^2$), 2,867MWh($118.4kWh/m^2$) and 2,867MWh($118.4kWh/m^2$). It i sreduced to 2.0%, 5.2%, 6.7%, and 6.7% respectively. 2)the estimation of economic efficiency, low-e glazing installed in office building can not recover the investment within a lifetime 40years. but IPu and IP paint, two-side coating in glazing, have a payback period of 13 years respectively.