• Korean Journal of Agricultural Science
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• v.38 no.3
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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.

• Korean Journal of Agricultural Science
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• v.40 no.4
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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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• v.31 no.4
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• pp.280-285
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• 2013

This study supplies basic data to develop a greenhouse model for reducing the damage to single-span greenhouses caused by strong winds and heavy snow. Single-span plastic greenhouses are predominantly used for growing crops in Korea. Thus, the safety wind speeds for single-span greenhouses were calculated and compared with the actual wind speeds and snow depths over a period of 8 years in different regions to analyze the structural safety of single-span greenhouses. The unit wind load and unit snow load were applied to different designs of single-span greenhouse according to the cultivated crop to achieve a structural analysis. As a result, the maximum section force for the wind and snow load was greatest for leaf and root vegetables, where the safety wind speeds for single-span greenhouses according to the cultivated crop were 17.7 m/s(leaf vegetables), 20.2 m/s (fruit vegetables), and 22.3 m/s (root vegetables). Thus, the single-span greenhouses were not found to be safe for the wind load in most regions, except for Hongcheon, Icheon and Sungju. Plus, the safety snow depths for single-span greenhouses according to the crop were 8.8 cm (leaf vegetables), 9.4 cm (fruit vegetables), and 11.8cm (root vegetables). Thus, when comparing the safety snow depths with the actual snow depths, the single-span greenhouses were not found to be safe. Therefore, to improve the safety of single-span greenhouses, the structures need reinforcement by reducing the interval between rafters or increasing the size of the pipes. However, additional research is needed.

• Journal of IKEEE
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• v.23 no.4
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• pp.1448-1456
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• 2019

In this study, when applying LED light sources within a single-span glass greenhouse for growing crops, the illumination simulation was performed on the ceiling and side of the glass greenhouse to determine the selective placement and effective light transmission of Si series solar cells and dye-sensitive solar cells (DSSC) for supplying LED power source. In addition, energy saving effects of glass greenhouses were analyzed for optimum lighting control when both daylight and LED light sources are considered in glass greenhouses.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.428-439
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• 2020

This study was carried out to investigate the effect of PO film on the increase of crop yield and energy saving through PO and PE film greenhouse application and comparison test. As a experimental greenhouse, two single span greenhouses (1-1 W) and two double span greenhouses (1-2 W) were used. During winter season, PO film (0.15 mm outer layer, 0.10mm inner layer) was used as a covering material of greenhouse in double layers for double-span (B15) and single-span(B21), and PE film used for double-span (B15), and single-span (B23) as a control. The experimental vegetable was tomato(Solanum lycopersicum L.) cultivated in soil and the cultivar of that was 'Happiness'. That was cultivated from December 3, 2019 to April 30, 2020. The temperature at night inside the greenhouse was maintained at 15℃, and the side and roof windows were opened to maintain 23 ~ 24℃ during the day. As a result, this study showed that the yield in single-span greenhouse(B21) covered with a PO film increased 20% and that in double-span greenhouse (B16) increased by 9% compared to the greenhouse covered with a PE film (B23, B15). Fuel consumption of the single-span greenhouse (B21) with the cover of PO film was reduced by 12.4% and that of double-span greenhouse was done by 11.5% compared to that of the PE film greenhouse (B23, B15) without any difference between them in growing state.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.267-270
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• 2001

It is difficult to install a ventilation window on the roof of single span greenhouse of arch shape. Investigation on the roof ventilation structure for those greenhouses was conducted. The effect of roof ventilation was evaluated by comparative experiments between greenhouse installing roof vent and having controlled side vent only. And ventilation efficiency was analyzed by experiments on the opening and closing operation of the roof and side vent.

• Journal of Environmental Science International
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• v.30 no.11
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• pp.907-914
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• 2021

In this study, strawberry cultivation environment in a greenhouse located in Jeonju was monitored and internal environmental parameters were analyzed. Temperature, humidity, RAD, and PPF sensors were installed to monitor environmental conditions in the test greenhouse. Data were collected every 10 minutes during four winter months from sensors placed across the greenhouse to assess its permeability and environmental uniformity. Temperature and humidity inside the greenhouse were relatively uniform with negligible deviations among the center, south, and north; however, it was judged that further analysis of gradients of these parameters from the east to the west of the greenhouse would be needed. Both RAD (Total solar radiation) and PPF (Photosynthetic photon flux) had high values on the south and were low on the north and the reduction rate of these parameters was 54% and 61%, respectively, indicating that a significant amount of light could not be transmitted. This implied a significant decrease in the amount of light entering the greenhouse during winter. Therefore, it is concluded that environmental control devices and auxiliary lighting are needed to achieve uniform greenhouse environment for efficient strawberry cultivation.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.315-320
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• 2000

An investigation and structural safety analysis was conducted to get the basic data for establishing maintenance strategy of pipe framed greenhouses. The number of greenhouses investigated was 108 in total. Most multi-span greenhouses had narrower width and lower height than the standard 1-2W greenhouse, and most of single-span greenhouses were tunnel type. In multi-span greenhouses, the size and interval of frameworks such as rafter, purline, column, and cross beam were mostly suitable, but frameworks of single-span greenhouses were mostly insufficient.

• Journal of Bio-Environment Control
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• v.4 no.1
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• pp.1-8
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• 1995

One of the most destructive forces around greenhouses is wind. Wind loads can be obtained by multiplying velocity pressure by dimensionless wind force coefficient. Generally, wind force coefficients can be determined by wind tunnel experiments. The wind force coefficient distribution on a single - span arched greenhouse was estimated using experimental data and compared with reported values from various countries. The results obtained are as follows : 1. The coefficients obtained from this study agree with the values proposed by G. L. Nelson except about 0.5 of difference in the middle region of roof section. This discrepancy is mainly attributed to the dissimilarity of experimental conditions (or wind tunnel test such as Reynolds number, type of terrain, surface roughness of model, location of the lapping and measuring methods. 2. Considering that the wind force coefficients are varied along the height of a wall at wind direction perpendicular to wall, structural analysis using subdivided wind force coefficient distribution is more resonable for wall. 3. It is recommendable that wind force coefficient distribution on a roof should take more subdivision than the existing four equal divisions for more accurate structural design. 4. Structural design using wind forces close to real values is more advantageous in safety and expense.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.29-35
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• 2015

The optimal greenhouse scales for controlled tomato should be studied because the increase of oil price and labor costs following the shortage of workforce makes greenhouse cultivation hard to gain profits. The purpose of this study is to estimate optimal production scales by greenhouse types for controlled tomato. The translog cost function is estimated based on the production cost survey data. The results can be summarized as follows: First, the average production cost of controlled tomato per kg decreases as the production scale increases. Second, according to the tomatoes farm of standard farming income data of RDA, the minimum production scale is 23 ton. Third, the estimated output of single-span greenhouse considering production scale with minimum average cost is 345 ton and production cost per kg is 1,476 won. The corresponding figures of multi-span greenhouse are 415 ton and 936 won, respectively. The study results can be used as basic materials for efficient decision making of tomato farmhouses and novice farmers. Also, the study shows that multi-span greenhouse should be encouraged to be built, since it requires lower marginal cost than single greenhouse. The results of this paper will help increase the income of farmhouses and cut expenses for the coming years.