• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.173-179
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• 2002

본 연구는 시설재배지의 장기재배를 위하여 연작장해를 극복하는 데 필요한 벼재배를 위하여 일손이 부족한 농번기에 생력적인 단동비닐하우스 골조파이프의 설치 및 철거장치 개발을 위한 연구로 수행하였다. 농업용 로더용의 차체와 차륜을 사용하는 전용기로서 단동비닐하우스 골조파이프를 적재하고 1본씩 이송 가능한 4스크류방식의 피딩장치와 타설위치에서 매설깊이를 일정하게 관입할 수 있는 롤러 방식의 그리퍼 및 타설장치로 구성하였다. 이상의 연구 결과를 요약하면 다음과 같다. 1. 단동비닐하우스 골조파이프를 기계적으로 설치 철거하는 장치를 개발하였으며, 1동 분량의 골조파이프를 적재하여 1본 이송, 피딩, 관입 등이 자동으로 가능하며, 주행하면서 철거가 가능한 장치로 구성하였다. 2. 수작업의 골조파이프 타설작업 시간대비 10배 정도의 노동력 절감효과가 있으며, 농번기와 중노동의 회피, 연작장해 스트레스 경감 등 시설재배농가의 현장애로 해결에 많은 도움이 예상된다. 3. 단동비닐하우스 골조파이프의 설치 및 철거장치를 활용함으로서 연작장해 회피를 위한 수도작의 재배 등 시설재배농가의 안정적인 장기 재배가 가능하여 생산성 향상과 고품질 농산물의 안정적인 공급에도 기여할 것으로 판단된다.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2003.10a
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• pp.209-212
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• 2003

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.200.2-200.2
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• 2010

This study was carried out in order to reduce the amount of underground water which is used in the water curtain system for retaining heat. To proceed to the research, two plastic green houses of water curtain system were installed. One was equipped of internal small tunnel for keeping warm air in the interior of the house. Then the internal small tunnel for keeping warm air was fitted with PVC duct of 50cm in diameter filled with subsurface water. Storing surplus solar energy in the water filled in PVC duct was the method used to this house. Another was installed with FCU in the middle of the house, and was fitted a circulation motor in water tank for heat storage which was operated from 10 a.m. to 4 p.m. in order to interchange heat with FCU. The latter was installed with four FCUs which has a capacity of 8000kcal per hour. Consequently about 5 degrees celsius could be maintained in the interior of the internal small tunnel for keeping warm air with the external temperature of more than minus 5 degrees celsius. It appeared that the alteration of an internal temperature of the house was flexible depending on the sunlight during daytime. It happened that to prevent the water from freezing, mixing antifreezing liquid in the flowing water of FCU or changing the operating method of FCU was a suitable measure. Also, in order to use the surplus solar thermal energy on plastic green house of water curtain system efficiently, storing the surplus heat during daytime simultaneously finding a method of using water curtain systematic underground water happened to be important. As a result of this research, when the house's interior temperature is below zero the operation of FCU appeared to be impossible. Therefore when supposed that the amount of water used in the house is 150~200ton for stable operation of FCU, using the system mentioned in the above research happened to be appropriate of reducing the amount of subsurface water from 80% to 100% when maintaining the interior of internal small tunnel's temperature for keeping warm air of 5 degrees celsius at the extreme temperature of minus 5 degrees celsius.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.225-233
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• 2019

In the summer season, natural ventilation is commonly used to reduce the inside air temperature of greenhouse when it rises above the optimal level. The greenhouse shape, vent design, and position play a critical role in the effectiveness of natural ventilation. In this study, computational fluid dynamics (CFD) was employed to investigate the effect of different roof vent designs along with side vents on the buoyancy-driven natural ventilation. The boussinesq hypothesis was used to simulate the buoyancy effect to the whole computational domain. RNG K-epsilon turbulence model was utilized, and a discrete originates (DO) radiation model was used with solar ray tracing to simulate the effect of solar radiation. The CFD model was validated using the experimentally obtained greenhouse internal temperature, and the experimental and computed results agreed well. Furthermore, this model was adopted to compare the internal greenhouse air temperature and ventilation rate for seven different roof vent designs. The results revealed that the inside-to-outside air temperature differences of the greenhouse varied from 3.2 to $9.6^{\circ}C$ depending on the different studied roof vent types. Moreover, the ventilation rate was within the range from 0.33 to $0.49min^{-1}$. Our findings show that the conical type roof ventilation has minimum inside-to-outside air temperature difference of $3.2^{\circ}C$ and a maximum ventilation rate of $0.49min^{-1}$.

• Current Research on Agriculture and Life Sciences
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• v.30 no.1
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• pp.27-33
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• 2012

This study was conducted to provide data necessary for clearing up the way to be able to improve covering and management method of covering material in commercial plastic greenhouse. The photosynthetic photon flux(PPF) in representative 4 different commercial tomato greenhouses was measured and analyzed. The variation trend of daily integral PPF was in agreement with that of the duration of sunshine. Each of daily integral PPF for 4 different experimental greenhouses was quite dissimilar, and was less than the amount of PPF necessary to grow tomato. October to November of beginning of winter was a good season to replace covering material in order to secure more PPF during insufficient winter season in greenhouse. The main inside factors to interrupt PPF incidence were thermal screen, inside covering material, condensation receiver in greenhouse. The single wide span greenhouse covered with PO film was superior to the other experimental greenhouses in the aspect of PPF transmittance.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.215-224
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• 2009

A survey on the actual state of heating, cooling, ventilation, and air-flow and experimental measurement of temperature and humidity distribution in tomato greenhouse were performed to provide fundamental data required in the development of air-flow control technology. In single-span plastic houses, which account for most of 136 tomato greenhouses surveyed, roof windows, ventilation and air-flow fans were installed in a low rate, and installation specs of those facilities showed a very large deviation. There were no farms installed greenhouse cooling facilities. In the hot air heating system, which account for most of heating type, installation specs of hot air duct showed also a large deviation. The exhaust air temperature and wind speed in hot air duct also were measured to have a big difference depending on the distance from the heater. We are using the maximum difference as indicator to determine whether temperature distribution is uniform. However if the temperature slope is not identical in greenhouse, it can't represent the uniformity. We analyzed relation between the maximum difference and the uniformity of temperature and humidity distribution. The uniformity was calculated using the mean and standard deviation of data from 12 measuring points. They showed high correlation but were represented differently by linear in the daytime and quadratic in the nighttime. It could see that the uniformity of temperature and humidity distribution was much different according to greenhouse type and heating method. The installation guidelines for ventilation and air-flow fan, the spread of greenhouse cooling technology for year-round stable production, and improvement of air duct and heating system, etc. are needed.

• Korean Journal of Agricultural Science
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• v.36 no.1
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• pp.73-85
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• 2009

An investigation was conducted to get the basic data for establishing structural safety and environmental management of tomato greenhouses in Chungnam region. The contents of the investigation consisted of actual state of greenhouse structures and environmental control facilities. Most of greenhouses were arch type single-span plastic houses and they had too low height for growing tomatoes. Frameworks of multi-span greenhouses were suitable, but those of single-span were mostly insufficient. Every greenhouse had thermal curtain movable or covering fixed inside the greenhouse for energy saving, and heating facilities were mostly warm air heater. Irrigation facilities were mostly drip tube and controlled by manual operation or timer. Almost all of the greenhouses didn't install high level of environmental control facilities such as ventilator, air circulation fan, $CO_2$ fertilizer, insect screen, supplemental light, and cooling device.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.143-151
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• 2022

This study was carried out to investigate quantitative characteristics of the cooling effect in a single-span arch greenhouse with roll-up side vents depending on operation of circulation and exhaust fans during ventilation, in order to suggest a practical strategy regarding installation or operation of forced ventilation systems. The examination was conducted under 3 different ventilation conditions (side vents only, side vents + circulation fans, and side vents + circulation fans + exhaust fans). In each condition, variations of internal and external air temperatures and exogenous environmental factors were recorded during ventilation, and the cooling effects were investigated by comparing the normalized temperature difference (NTD) of each ventilation condition. In the morning time (11:00-12:00), a temporary peak in the temperature difference was observed at the beginning of ventilation regardless of ventilation methods. The time taken to the maximum NTD was decreased from 340 s to 110s, and the NTD was dropped from 1.158 to 1.037 as the more forced ventilation systems were operated. The more operations caused the passing time over specific NTD values reduced by 60% as the time was reduced from 1,030 s to 550 s at NTD = 0.8, 1,610 s to 915 s at NTD = 0.6, and 2,315 s to 1,360 s at NTD = 0.4. The temporary peak in NTD was not observed in the afternoon time (14:00-15:00) but it was dropped as quickly as the ventilation started. Also the more operations resulted in the passing time over specific NTD values reduced by 70% as the time was reduced from 560 s to 345 s at NTD = 0.8, from 825 s to 540 s at NTD = 0.6, and from 1,145 s to 810 s at NTD = 0.4. Conclusively, the intervention of the forced ventilation system is recommended in the morning time or in high thermal conditions to achieve more effective and economical ventilation.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.296-305
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• 2006

The heterogeneity of crop transpiration is important to clearly understand the microclimate mechanisms and to efficiently handle the water resource in greenhouses. A computational fluid dynamic program (Fluent CFD version 6.2) was developed to study the internal climate and crop transpiration distributions of greenhouses. Additionally, the global solar radiation model and a crop heat exchange model were programmed together. Those models programmed using $C^{++}$ software were connected to the CFD main module using the user define function (UDF) technology. For the developed CFD validity, a field experiment was conducted at a $17{\times}6 m^2$ plastic-covered mechanically ventilated single-span greenhouse located at Pusan in Korea. The CFD internal distributions of air temperature, relative humidity, and air velocity at 1m height were validated against the experimental results. The CFD computed results were in close agreement with the measured distributions of the air temperature, relative humidity, and air velocity along the greenhouse. The averaged errors of their CFD computed results were 2.2%,2.1%, and 7.7%, respectively.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.334-342
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• 2016

In order to evaluate the modified installation methods of roof ventilation devices, derived from the previous experiment ('investigation into the optimum capacity of roof ventilation devices and their deployment'), the conventional and modified (improved) roof ventilation systems were installed in the single-span plastic greenhouse for growing oriental melons. The roof vents ($60{\varphi}$) and roof fans (maximum air capacity of $38m^3/min$) were installed in the spacing of 15m (FT, modified 'side vent+roof fan' ventilation) and 6m (TT, modified 'side vent+roof vent' ventilation) respectively on the roof of greenhouses for the modified roof ventilation treatments, and 20m (FC, conventional 'side vent+roof fan' ventilation) and 8m (TC, conventional 'side vent+roof vent' ventilation) for the conventional ones. The stem diameter, leaf blade lengh, petiole length, and leaf width were lower in the FT and TT treatments than those in the conventional treatments, FC and TC. Although the fruit weight and total yields were slightly lower in the FT and TT treatments, the marketable fruit ratio (%) were higher, as a result of increased fruiting ratio (%) in these treatments, than those of FC and TC. The marketable yields (kg/10a) in the FT and TT treatments were 8,391 kg/10a and 7,283 kg/10a, which were respectively 661 kg/10a and 487 kg/10a higher than those in the treatments of FC and TC. The modified installation methods of roof fan resulted in production of more female flowers and lower fruit drop ratio (%) compared to conventional meathods. In the treatment of the conventional ventilation with roof vent, the fruit weight, fruit length & width, and flesh thickness were higher than in other treatments, but there were no significant differences in the fruit width and flesh thickness among the treatments.