• Journal of Biosystems Engineering
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• 제41권4호
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• pp.328-336
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• 2016

Purpose: The heat culture areas of greenhouses have been continuously increasing. In the face of international oil price fluctuations, development of energy saving technologies is becoming essential. To save energy, auxiliary heat source and thermal insulation technologies are being developed, but they lack cost-efficiency. The present study was conducted to save energy by developing a conceptually new semi-basement type greenhouse. Methods: A semi-basement type greenhouse, was designed and constructed in the form of a three quarter greenhouse as a basic structure, which is an advantageous structure to inflow sunlight. To evaluate the performance of the developed greenhouse, a similar structured general greenhouse was installed as a control plot, and heating tests were conducted under the same crop growth conditions. Results: Although shadows appeared during the winter in the semi-basement type greenhouse due to the underground drop, the results of crop growth tests indicated that there were no differences in crop growth and development between the semi-basement type greenhouse and the control greenhouse, indicating that the shadows did not affect the crop up to the height of the crop growing point. The amount of fuel used for heating from January to March was almost the same between the two greenhouses for tests. The heating load coefficients of the experimental greenhouses were calculated as $3.1kcal/m^2{\cdot}^{\circ}C{\cdot}h$ for the semi-basement type greenhouse and $2.9kcal/m^2{\cdot}^{\circ}C{\cdot}h$ for the control greenhouse. Since the value is lower than the double layer PE (polyethylene) film greenhouse value of $3.5kcal/m^2{\cdot}^{\circ}C{\cdot}h$ from a previous study, Tthe semi-basement type greenhouse seemed to have energy saving effects. Conclusions: The semi-basement type greenhouse could be operated with the same fuel consumption as general greenhouses, even though its underground portion resulted in a larger volume, indicating positive effects on energy saving and space utilization. It was identified that the heat losses could be reduced by installing a thermal curtain of multi-layered materials for heat insulation inside the greenhouse for the cultivation of horticultural products by installing thermal curtain of multi-layered materials for heat insulation inside the greenhouse, it was identified that the heat losses could be reduced.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.90-95
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• 2008

An SHGC(Solar Heat Gain Coefficient) is a determinant of total flux of solar radiation coming indoor and a critical factor in evaluating heating and cooling load. U-value represents heat loss while SHGC denominates heat gain. Recently, windows with high solar gain, mid solar gain or low solar gain are being produced with the development of Low-E coating technology. This study evaluated changes in energy consumption for heating and cooling according to changes in SHGC when using double-layered Low-E glass and triple layered Low-E glass in relation to double layered clear glass as base glass. An Office was chosen for the evaluation. For deriving optical properties of each window, WINDOW 5 by LBNL, an U.S. based company. and the results were analyzed to evaluate performance of heat and cooling energy on anannual basis using ESP-r, an energy interpretation program. Compared to the energy consumption of the double layered clear glass, the double layered Low-E glass with high solar gain consumed $69.5kWh/m^2,yr$, 9% more than the double layered clear glass in cooling energy. The one with mid solar gain consumed $63.1kWh/m^2,yr$, 1% less than the base glass while the one with low solar gain consumed $57.6kWh/m^2,yr$, 10% less than the base glass. When it comes to tripled layered glass, the ones with high solar showed 2% of increase respectively while the one with mid solar gain and low solar gain resulted 5% and 11% in decrease in energy consumption due to low acquisition of solar radiation. With respect to cooling energy. it was found that the lower the SHGC. the less energy consumption becomes.

• 생물환경조절학회지
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• 제20권2호
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• pp.72-77
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• 2011

본 연구는 국내 상업용 온실 피복재의 관류열전달계수를 산정히는데 필요한 기초자료를 제공하기 위하여 최근 국내에 많이 보급되어 사용되고 있는 플라스틱필름으로 피복된 온실에 대해 관류열량을 측정하고 관류열전달계수의 변화를 분석하였으며 그 결과를 요약하면 다음과 같다. 온실 내외부 온도차에 따른 관류열전달계수의 변화를 분석한 결과 피복의 층수에 따라 안정된 관류열전달계수를 나타내게 되는 온실 내외부 온도차의 값이 다르게 나타났기 때문에 온실 피복재에 대한 관류열전달계수를 결정할 때에는 피복층수별로 안정된 값을 나타내는 온실 내외부 온도차 범위에서의 관류열전달계수를 채택하여야할 것이다. 온도차이에 따른 관류열전달계수의 변화 경향은 기존의 연구결과와 잘 일치하였으나 안정된 값을 나타내는 온도차이의 구체적인 값은 다르게 나타났기 때문에 이에 대한 추가적인 연구가 필요할 것으로 판단된다. 풍속에 따른 관류열전달계수의 증가율은 연구자에 따라 많은 차이가 있음을 알 수 있었으며, 이중피복온실이나 커튼을 설치한 온실과 같이 보온성을 높인 온실은 일중피복온실에 비해 풍속에 따른 관류열 손실이 더 작다는 사실을 확인할 수 있었다. 관류열전달계수의 기존 연구결과들을 분석한 결과 연구자에 따라 값이 차이가 있었기 때문에 국내 온실의 정확한 난방부하량을 산정하는데 필요한 적절한 관류열전달계수를 제시하기 위해서는 우선 측정을 위한 표준화된 환경기준이 마련될 필요가 있으며, 또한 국내에서 실제로 사용되고 있는 주요 피복재별로 구체적인 관류열전달계수가 구해져야 할 것이다.

• 설비공학논문집
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• 제29권3호
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• pp.111-118
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• 2017

Performance factors such as the EER(Energy Efficiency Ratio) and the COP (Coefficient of Performance) are being replaced by seasonal energy efficiency factors, like the SEER (Seasonal EER) and the SCOP (Seasonal COP) to evaluate the performance of a heat pump by the time of the year. Seasonal performance factors, such as the CSPF (Cooling Seasonal Performance Factor) and the HSPF (Heating Seasonal Performance Factor) are used to describe the heat pump's performance during the cool and hot seasons. In this study, the optimization of all heat pump's operating parameters was experimentally conducted to enhance the SEER based on the EU standard (EN 14825). Moreover, the SEER was improved by the compressor frequency, as well as indoor and outdoor fan speeds. In addition, the performance characteristics of the heat pump were studied under partial load conditions. As a result, the SEER was enhanced by 17% when the compressor frequency was optimized. An additional 2% improvement was achievable with the optimization of indoor and outdoor fan speeds.

• 대한기계학회논문집B
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• 제36권8호
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• pp.797-802
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• 2012

본 연구에서는 두 대의 히트펌프를 이용하여 $60^{\circ}C$의 난방 공급을 하는 경우에 대하여, 병렬운전을 할 경우의 성능과 직렬운전을 할 경우의 성능을 서로 비교함으로써, 직렬운전에 의한 성능 향상 가능성을 연구하였다. 두 경우의 성능을 공정하게 비교하기 위하여, 히트펌프를 구성하는 열교환기의 전열면적을 고정하였으며, 부하측 및 열원측의 입구 유량 및 온도 조건을 고정하였다. 또한, 보다 현실적인 결과를 위하여 열교환기 내 열전달 및 압력강하 특성을 고려하였다. 시뮬레이션 결과, 직렬운전 시스템의 난방성능계수가 병렬운전 시스템의 난방성능계수에 비해 본 연구의 시뮬레이션 조건 하에서 약 5% 향상 될 수 있음을 관찰하였다.

• 열처리공학회지
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• 제29권6호
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• pp.284-291
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• 2016

High temperature alloy steel such as Ni-Cr-Mo-V material has excellent properties of high strength and high heating resistance. It has been used for several military weapon components such as gun barrel of a warship, turbine rotor and turbine disk for nuclear power plant. Being curious about this material required excellent wear resistance and durability in extreme environmental conditions. A dry wear test at the ambient air and Ar gas conditions in the room temperature were performed in this study. What's more a lubricant wear test at different temperature was conducted. In addition that DLC was coated on Ni-Cr-Mo-V alloy steel substrate with a thickness of $3{\mu}m$, a property of it was compare with lubricant conditions. All the coefficient of friction and wear volume, comparing with DLC coated specimens. The test parameters were selected as follows: 10 N for normal load; 80 rpm for sliding wear speed; and 300 m for the sliding wear distance.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.645-650
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• 2006

The heat transfer performance and energy transport ability are relatively high due to higher specific heat. Therefore, it can be used in fields such as heating, ventilating, air-conditioning, refrigeration and heat exchangers. In this study, liquid-cooling heat exchangers were designed and tested by varying geometry and operating conditions. In addition, liquid-cooling heat exchangers were tested to provide performance data for MPCM slurry. The liquid-cooling heat exchangers had twelve rectangular channels with flow paths of 1, 2, 4 and 12. Silicon rubber heaters were used to control the heat load to the heat exchanger. Heat input ranged from 293 to 800 W, and inlet temperatures of working fluid varied from 15S to $27^{\circ}C$. The standard deviation of surface temperature was strongly affected by the coolant of MPCM Slurry, All MPCM-cooling heat exchangers showed higher cooling performance than the water-cooling heat exchanger except one path channel heat exchanger.

• 대한금속재료학회지
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• 제47권10호
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• pp.667-674
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• 2009

High temperature wear of STD 61 tool steels sliding against the Al-9%Si coated steels used for hot press forming has been studied in comparison with that of the tool steels sliding against the uncoated steels. Wear tests have been performed using a pin-on-disc configuration under an applied normal load of 50N for 20 min with heating the coated and uncoated steels up to 800$^{\circ}C$. It was found on the worn surface of the STD 61 tool steels sliding against the Al-9%Si coated steels that the formation of the glazed layers containing Al transferred from the coated tribopair may contribute to a reduction of the coefficient of friction, and detachment in part occur due to delamination wear, resulting in higher specific wear rate. On the other hand the Fe-oxide wear debris entrapped on the softer surface of the uncoated steels can act as a tribosurface, leading to decreased adhesive wear of the STD 61 tool steels, resulting in a lower specific wear rate.

• Journal of Advanced Marine Engineering and Technology
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• 제14권4호
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• pp.57-66
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• 1990

In the design of an electric power plant, the capacity to meet the peak load demand is one of the important factors to be considered. This peak load usually occurs when the most of the cooling air conditioning systems are being operated during daytime in summer season, which inevitably entails the construction of an additional electric power plant. This study is aimed to carry out a basic experiment for the development of a cooling air conditioning system using the ice energy by the surplus electric power during the night-time. The experimental apparatus consists of four major parts; (1) the heating section consisting of the air duct and I.D. fan, (2) the cold section with the ice chamber, (3) the bundle of heat pipes made in a form of the staggered arrangement with ${C_y}/{d_o}$=2.0 and ${C_x}/{d_o}$=1.73, (4) the refrigerator system to cool down the ice chamber. This study involves an intensive experiment concerning the convective heat transfer of the air flow surrounding the bundle of heat pipes. This major experimental parameters are the amount of working fluid, the velocity of air and the working temperature. The major findings of the present study are as follows; (1) The optimum amount of the working fluid necessary for the horizontal heat pipes is much more than that for the vertical type. (2) The convective heat transfer coefficients of the air are coincided with the empirical equations of Grimson and ${\breve{Z}ukauskas}$. (3) The equation of the mean heat transfer coefficient obtained in the present study is ${N_um}=0.32 {Re_max^{0.63}}$.

• 한국산학기술학회논문지
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• 제20권3호
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• pp.252-262
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• 2019

2016년 경주 지진에 이어 2017년 포항 지진까지 발생한 대한민국은 더 이상 지진에 대해 안전지대라고 할 수 없다. 이에 따라 재난환경에 적합한 피난시설의 필요성이 증대되고 있다. 본 연구에서는 경량 복합패널을 이용하여 기존 피난시설의 단점들을 보완할 수 있는 구호주거를 제작하고자 하였다. 이를 위해 경량 복합패널로 구성된 구호주거에 대한 구조 성능과 에너지성능을 평가하고자 하였다. 구호주거의 구조 성능을 평가하기 위해 경량 복합패널로 제작한 시스템에 대한 횡하중가력 실험을 진행하였다. 실험체는 접합 방식을 변수로 하여 2가지로 구성하였다. 또한 KBC 2016에 따라 실험체에 대한 지진하중과 풍하중을 산정하여 실험 결과와 비교하였다. 에너지성능은 냉난방 및 조명에너지 사용량을 최소화하기 위해 기준 패널을 활용한 남측창호 최적화기법을 활용하여 분석하였고, 창면적비, 창 총일사취득율 최적화를 진행하였다. 결과적으로 경량 복합패널로 제작된 실험체는 횡하중에 대해 충분히 안전한 성능을 보일 것으로 판단되며, 창면적비 0.38, 총일사취득율 0.5수준의 최적화 계획을 통한 저에너지 운용이 기대된다.