• 농업과학연구
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• 제38권3호
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• pp.505-512
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• 2011

Structural characteristics for standard models of single-span plastic greenhouse in Korea and high tunnels in North America were analyzed, and comparative analysis for greenhouse environments measuring in Korean farmhouse and Rutgers high tunnel was carried out to find structural and environmental improvements of single-span plastic greenhouses that occupy most of Korean greenhouse. Widths of high tunnels are similar to single-span plastic greenhouses but their heights are high comparatively and their side heights are fairly higher than single-span plastic greenhouses specially. Rafters, which are main frames, section sizes of high tunnels are bigger and their intervals are wider than single-span plastic greenhouses. Relative bending resistances compared with representative Korean greenhouse were analyzed by 0.92 to 1.42 in single-span plastic greenhouses, and 1.38 to 2.96 in high tunnels. Frame ratios of single-span plastic greenhouses were 6.8 to 8.6%, and those of high tunnels were 5.5 to 8.7%. We analyzed air temperatures and solar radiations measured in single-span plastic greenhouse and high tunnel on clear days in late March. There were outside temperatures in generally similar range, and judging by rise of indoor temperatures, ventilation performance of high tunnel is more excellent than single-span plastic greenhouse. Solar radiations of two areas were no big difference but light transmittance of high tunnel was a little bit higher than single-span plastic greenhouse. Single-span plastic greenhouses are disadvantageous in environmental managements such as ventilation performance and light transmittance because distance between greenhouses is too narrow and length of greenhouse is too long compared to high tunnels. To get the environmental improvement effects as well as to increase the structural resistance of single-span plastic greenhouses are achievable by widening the width of greenhouse in possible range, widening the space between rafters, and enlarging the section size of rafters. Also, we need to secure enough distance between greenhouses and to restrict the length of greenhouse by maximum 50 m in order to improve the ventilation performance and the light transmittance.

• 농업과학연구
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• 제40권4호
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• pp.317-323
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• 2013

This research was conducted to obtain the basic information for establishment of standard guidelines in the design and installation of roof ventilation system in single-span plastic greenhouse. To achieve this, the greenhouse structure & characteristics, cultivation status, and ventilation system were investigated for single-span greenhouse with roof ventilation system cultivating the Cucurbitaceae vegetables, watermelon, cucumber, and oriental melon. Most of single-span watermelon greenhouse in Haman and Buyeo area were a hoop-style and the ventilation system in those greenhouses mostly consisted of two different types of 'roof vent (circular or chimney type) + side vent (hole) + fan' and 'roof vent (circular type) + side vent (hole or roll-up type)'. The diameter of circular and chimney-type vent was mostly 60cm and the average number of vents was 10.5 per a bay with vent spacing of average 6.75m. The ratio of roof vent area to floor area and side vent area in the single-span watermelon greenhouse with ventilation fan were 0.46% and 7.6%, respectively. The single-span cucumber greenhouse in Haman and Changnyeong area were a gable roof type, such as even span, half span, three quarter and the 70.6% of total investigated single-span greenhouses was equipped with a roof ventilation fan while 58.8% had a circulation fan inside the greenhouse. The ratios of roof vent area to floor area in the single-span cucumber greenhouse ranged from 0.61 to 0.96% and in the case of the square roof vent, were higher than that of the circular type vent. On average, the roof ventilation fan in single-span cucumber greenhouse was equipped with the power input of 210W and maximum air volume of $85.0m^3/min$, and the number of fans was 9.75 per a bay. The number of roof vent of single-span oriental melon greenhouse with only roll-up type side vent ranged from 8 to 21 (average 14.8), which was higher than that of other Cucurbitaceae vegetables while the vent number of the greenhouse with a roof ventilation fan was average 7 per a bay.

• Current Research on Agriculture and Life Sciences
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• 제31권4호
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• pp.280-285
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• 2013

국내에 설치되어 있는 원예시설 중 가장 많은 면적을 차지하고 있는 단동비닐하우스의 기상재해로 인한 피해를 경감시킬 수 있는 모델 개발에 필요한 기초자료를 제공하고자 재배작물별로 대표적인 온실규격를 선정하여 안전풍속과 적설심을 구한 후 재현기간 8년에 해당하는 지역의 설계풍속 및 적설심과 비교하여 온실의 구조 안전성을 분석한 결과를 요약하면 다음과 같다. 1. 재배작물별 대표온실에 단위풍하중을 적용한 결과, 최대 단면력은 과채류, 근채류, 엽채류 온실 순으로 크게 나타났으며 재배작물별 서까래 간격을 고려한 안전풍속은 엽채류 온실이 17.7 m/s, 과채류 온실이 20.2 m/s, 근채류 온실이 22.3 m/s로 나타나 지역별 8년 빈도의 설계풍하중과 비교하였을 때 홍천, 이천, 성주지역을 제외하고는 대부분의 지역에 있어서 불안전한 것으로 나타났다. 2. 재배작물별 대표온실에 단위 적설하중을 적용한 결과, 근채류 온실의 최대 단면력이 가장 크게 나타났으나 재배작물별 서까래 간격을 고려한 안전적설심은 엽채류 온실이 8.8 cm, 과채류 온실이 9.4 cm, 근채류 온실이 11.8 cm인 것으로 나타났다. 이러한 결과를 지역별 8년 빈도의 적설하중과 비교하였을 때 경남지역 일부를 제외하고는 대부분의 지역에 있어서 불안전한 것으로 분석되었다. 3. 재배작물별 대표 온실의 안전풍속과 적설심에 대하여 구조물에 발생하는 최대 인발력은 12.7~15.1 kgf/개소, 최대 연직하중은 20.6~21.7 kgf/개소로 나타나 기초는 안전한 것으로 분석되었으나 안전풍속과 안전적설심이 매우 작기 때문에 폭설이나 강풍에 대비한 보강이 필요한 것으로 나타났다. 4. 재배작물별 대표온실의 안전풍속과 적설심을 증가시키기 위해서는 서까래 간격을 감소시키거나 부재의 단면 치수를 증가시키는 등의 보강대책이 필요한 것으로 나타났다.

• Journal of Biosystems Engineering
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• 제36권3호
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• pp.217-222
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• 2011

This study was carried out in order to reduce the amount of underground water which is used in the double layered single span plastic greenhouse for retaining heat. For this research, two plastic green houses of the double layered single span plastic greenhouse were installed. There 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 50 cm in diameter filled with subsurface water. The surplus solar energy in the greenhouse was stored in the water in the PVC duct. Four FCUs (Fan Coil Unit), which has the capacity of 8,000 kcal per hour, were installed in the middle of the house, and a circulation motor in heat storage water tank was operated from 10:30 a.m. to 16:00 p.m. in order to circulate water between the water tank and the FCUs. 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 lower 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. To prevent the water freezing, mixing antifreezing liquid in the water or operating FCU continuously was needed. 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. Considering the amount of water used in the house with water-curtain-heating system is 150~200 ton per day, using the system mentioned in this research showed that reducing the underground water more than 80% in order to maintain the internal temperature as the level of 5 degree celsius at the extreme temperature of minus 5 degrees celsius.

• 한국생물환경조절학회:학술대회논문집
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• 한국생물환경조절학회 2000년도 학술발표논문집 ProceedingofBio-Environment control
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• pp.22-25
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• 2000

• 한국농공학회논문집
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• 제66권1호
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• pp.39-48
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• 2024

Plastic greenhouses are simple structures consisting of lightweight materials such as steel pipes and polyvinyl chloride. However, serious damage occurs due to heavy winds and typhoon every year. To prevent a collapse of structural members, the Ministry of Agriculture and Rural Development has distributed plans and specifications for disaster-resistant standards. Despite these efforts, more than 50% of greenhouses still do not satisfy the disaster-resistant standards. Among the greenhouses that do not meet these standards, 85% are single-span greenhouses proposed 20 years ago. Consequently, there is a need to evaluate the safety of wind loads for the single-span greenhouse. Unfortunately, there are no design specifications for the greenhouses under wind loads. Therefore, a Korean design standard (KDS) has been utilized. KDS is defined with reference to wind speeds occurring once every 500 years, raising concerns about potential overdesign when considering the durability of plastic greenhouses. To address this, the modified wind load, considering the durability of the plastic greenhouse, was calculated, and a safety evaluation was conducted for sigle G-type plastic greenhouse. It was observed that the moment acting on the windward surface was substantial, and there was a risk of the foundation being pulled out if the basic wind speed exceeded 32 m/s. In terms of the combination strength ratio, it was less than 1.0 only on the leeward side when the basic wind speed was 24 m/s and 26 m/s. However, in all other cases, it exceeded 1.0, indicating an unsafe condition and highlighting the necessity for reinforcement.

• 생물환경조절학회지
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• 제20권2호
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• pp.78-82
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• 2011

온실의 환기설계 기준 설정 및 단동 플라스틱 온실의 원형 천창 설치 가이드라인 제정을 위한 기초자료를 제공할 목적으로 천창이 설치된 토마토 재배 단동 온실에서 환기실험을 통하여 자연환기 성능을 분석하고, 열평형 모델을 이용하여 온실 재배 토마토의 증발 추정하였다. 직경 60cm의 원형 천창을 지붕의 중앙에 8m 간격으로 설치한 단동온실의 자연환기 성능을 실험한 결과 환기회수는 분당 0.02~0.32회(평균 0.17회 $min^{-1}$)의 범위를 보여 상당히 낮은 것으로 나타났다. 그러나 상업용 온실의 권장환기율과 비교하면 6m 간격으로 설치할 경우에는 봄이나 가을철에 필요한 환기량을 충족할 수 있을 것으로 판단되며, 여름철 권장환기를 위해서는 2m 정도의 간격으로 설치한 해야만 가능할 것으로 판단되므로 광투과를 저해하지 않으면서 지붕의 개구면적을 확대할 수 있는 방안을 찾아야 할 것으로 생각된다. 실험에 사용한 단동 온실은 인접 동 간격이 1.2m에 불과한 밀집된 단지 내에 위치하고 있어서 측창 주변의 외부 풍속이 최대 $0.9m{\cdot}s^{-1}$(평균 $0.4m{\cdot}s^{-1}$에 불과하고 풍력에 의한 환기효과를 기대하기가 어려웠다. 환기량과 풍속 및 실내외 온도차와의 관계를 비교 분석해 본 결과 중력환기가 우세함을 확인 할 수 있었다. 본 환기실험 자료를 온실의 환기설계를 위한 열평형모델에 적용하여 증발산계수를 추정해 본 결과 0.39~0.85의 범위(평균 0.62)를 보였고, 다른 연구자들이 제시하는 일반적인 온실의 설계 권장 값과 유사한 경향을 나타냈다. 따라서 토마토 재배 단동 플라스틱 온실의 환기설계에서 증발산계수는 0.6 정도를 사용하면 적당할 것으로 판단된다.

• 태양에너지
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• 제9권3호
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• pp.13-24
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• 1989

Direct and diffuse components of solar radiation were measured inside and outside a single-span plastic greenhouse. To analyze the direct solar radiation inside the plastic greenhouse, the cross-section of the greenhouse was assumed to be circular. Then the direct solar radiation transmitted into the greenhouse was calculated theoretically, and compared with the experimental measurements. The results are summarized as follows: (1) The transmissivities of total solar radiation were about 65% on cloudy days and 50% on clear days. For cloudy days, the transmissivity of the total solar radiation was regarded as the transmissivity of sky diffuse radiation. (2) The ratio of the inside effective scattered component of direct solar radiation to the diffuse radiation was 60-65%. (3) It appeared that the seasonal variation of the transmissivity of total solar radiation was adversely affected by the transmissivity of direct solar radiation and the effective scattered coefficient. But the effect of the transmissivity of direct solar radiation was dominant factor. (4) Computer simulation showed that the inside direct solar radiation was decreased as the floor of the plastic greenhouse was higher. (5) The predicted value of the inside direct solar radiation was 3.3% to 29.0% higher than the measured value.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2004년도 학술발표논문집
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• pp.40-40
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• 2004

• 생물환경조절학회지
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• 제19권2호
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• pp.63-69
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• 2010

2007년 4월 이전까지 10~15년 동안 규격시설로 운영되어 오던 농가지도형 단동하우스에서의 보강지주 설치효과를 분석하였다. 이전의 연구로 적설하중에 대한 수식 계산을 통해 보강지주 설치 단동하우스의 추가적설심이 제시된 바 있으나 모델이 농가지도형 단동하우스 규격과 상이해 연구 결과를 농가지도형 단동하우스에 그대로 적용하기에 무리가 따랐다. 본 연구에서는 농가지도형 단동하우스를 3차원 강뼈대 구조물로 모델링 하여 보강지주 설치 효과를 분석하였으며 재하시험을 통해 해석결과를 검증하였다. 구조해석 결과, 단동하우스에 보강지주 설치 시 안전적설심은 오히려 줄어드는 것으로 나타났는데 파이프 체결 부에서의 집중 하중으로 지붕도리에 큰 응력이 걸리기 때문으로 보강지주 설치 시에는 지붕도리의 규격도 함께 강화되어야 할 것으로 판단되었다. 지붕도리를 강화하고 보강지주를 3~4m 간격으로 설치할 경우, 안전적설심은 기본모델에서 보다 2배 이상 높아지는 것으로 나타났다. 보강지주 규격별 농가지도형 단동하우스 5종의 안전적설심을 제시하였다.