• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.192-199
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• 2009

This study was conducted to find proper structural reinforcement methods for the 4.5m-high (eaves height) 1-2W type plastic greenhouse. 3D finite element analysis was used to analyze the steel-tube structure. The 4.5m-high 1-2W type plastic greenhouse was modified by welding 1.5m-long steel-pipes into a 3.0m-tall columns of the standard 1-2W type plastic greenhouse. This remodeling method is widely used in Korea with farmer's discretion to increase the production when they grow paprika. But it is not based on the quantitative structural analysis. The proposed reinforcement methods were proved to stand against the design wind velocity of $40m{\cdot}s^{-1}$ and snow depth of 40cm. It strongly implies that the cross beam between side columns and wind resistance walls, and the lattice type cross beam should be good reinforcements to improve the structural safety of the elevated eaves height plastic greenhouse.

• Journal of Bio-Environment Control
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• v.23 no.2
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• pp.95-108
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• 2014

The objective of this study is to develop the plastic greenhouse models which are structurally safe under the weather condition of Seongju and have the dimensions suitable for oriental melon cultivation as well. To grasp the structural features of greenhouses in Seongju, the field survey was conducted on 406 farmhouses which included 2,068 greenhouses. The field survey showed that the roof shape of arch type accounted for the highest rate, but recently even span or peach type became more popular and the width and height of greenhouse tended to increase as the period of use was short. The relationship of the width, ridge height and eaves height were established based on field survey data. Using climate data of Gumi adjacent to Seongju, the regressions were determined for the design wind speed and design snow depth depending on recurrence period. To design the greenhouse models against weather disasters in Seongju, the optimal design loads are 23.7 cm of snow depth and $33.8m{\cdot}s^1$ of wind speed. As the design results, four models of single-span greenhouse, two models of double-span greenhouses including extension were developed.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.320-327
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• 2016

Allium hookeri is used for food and medical materials in Asia. This study was carried out to elucidate the effects of shading rates on growth and quality of A. hookeri cultivation in greenhouse. Treatments were given with 35%, 55%, 75% and 95% shading rates and non-shading (Control). Photosynthesis photon flux density (PPFD) of control, 35%, 55%, 75%, and 95% shading were 792, 515, 351, 182, and $78.2{\mu}mol{\cdot}m{\cdot}s^{-1}$ respectively. The emergence ratio was 98% under non-shading, 35% and 75% shading condition, and it was 100% under 55% and 95% shading condition on April 20, 2016. These results showed no correlation between emergence rate and shading treatment. When shading net was set up inside at greenhouse, fresh weights in control, 35%, 55%, 75%, and 95% shading treatments were 1,142, 3,511, 5,936, 6,408 and 3,779kg/10a, respectively. When shading net was set up outside at greenhouse, fresh weights in control, 55%, 75%, and 95% shading treatments were 1,372, 5,442, 6,238 and 3,595kg/10a, respectively. Dry weight, percentage of dry matter, number of leavesand branches, plant height and root length in 75% shading treatment were higher than other shading treatments. From these results, we suggested that the proper shading rate in a greenhouse is 75% for A. hookeri cultivation in middle area of Korea.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.402-410
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• 2017

The effect of the steel pipe member joint on the design performance of a plastic multi-span greenhouse was analysed through the comparing full-scale experiment and numerical analysis. The design performance of the greenhouse is generally evaluated through numerical analysis, but it is rare to consider the characteristics of the connections or joints of the members. In this study, the effect of the column-gutter beam-rafter-wind break wall joint on the design performance of the whole structure of a plastic multi-span greenhouse was analysed. The numerical results with assuming that the member joint are rigid condition were compared with the full-scale load test results using member joints used in the field. The stiffness of the entire structure was compared using the load-displacement relationship and the change of the load sharing ratio that the main members such as column, rafters, and wind break wall was analysed. The results of the load test were about 40% larger than the numerical result and the member stress was more than twice as large as those of the loaded columns. In order to increase the reliability of the design performance of the greenhouse, it is necessary to develop a numerical analysis model which can consider the characteristics of various joints.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.473-479
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• 2020

In this study, the structural experiment was conducted with two types of specimens to investigate the mechanical behavior of the column-rafter-purlin connection of an arch-type greenhouse under monotonic loading. Based on the experimental results, the flexural performance was analyzed for two types of connections, and connection classification was attempted. Type B showed 77% of flexural performance compared to Type A, and both types showed that the rigidity and flexural strength did not reach the level of the full rigid. The behavior of the column-rafter-purlin connection was dominated by local buckling due to deformation of the weld and fasteners. As a result of connection classification by AISC standard, both Type A and B connections showed a result that did not meet the rigid connection performance assumed during design, and were classified as simple connection. Therefore, the connection performance evaluation and classification results show that the greenhouse design should be made in consideration of connection performance and in order to design a reliable greenhouse structure, a study on establishing clear design standards for the greenhouse connection is necessary.

• Journal of Bio-Environment Control
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• v.14 no.3
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• pp.166-173
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• 2005

This study was carried out to evaluate the structural stability in a non-heating greenhouse with a single cover for Citrus cultivation which was built up in Jeju on the basis of the drawing designed by Jejudo Agricultural Research & Extension Services and also to make use of the data for developing a standardized non-heating greenhouse in Jeju. The analysis of a structural stability was conducted by using CFX-5.7 and ANSYS under the design condition of a maximum accumulated snow-depth of 19.1 cm as well as an instantaneous maximum wind velocity of $36.6\;m{\cdot}s^{-1}$ which was set up on the basis of meteorological statistics in Jeju. As a result, the maximum von-Mises stress applied on pipes under the wind velocity of $36.6\;m{\cdot}s^{-1}$ showed a value of $250\;N{\cdot}mm^{-2}$ which was greater than the allowable stress of the pipe with a value of $235.4\;N{\cdot}mm^{-2}$ (=$2,400\;kg{\cdot}cm^{-2}$) and also $53.8\;N{\cdot}mm^{-2}$ under the snow-depth of 19.1 cm, respectively. This result suggested that the greenhouse be unstable under the design condition of an instantaneous wind velocity of $36.6\;m{\cdot}s^{-1}$ so that it was necessary for the greenhouse to be reinforced to secure the structural stability.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.312-316
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• 2012

This study evaluated the effect of polyolefine greenhouse covering film on growth of lettuce and cucumber. The growth of lettuce and cucumber plants under conventional film (polyethylene plus ethylenevinyl acetate, PE + EVA) and polyolefine (PO) film were evaluated in a greenhouse. The physical qualities of PO film, such as tensile strength and tear strength, were stronger than conventional PE + EVA film. PO film showed 4% higher transmission performance in photosynthetic active radiation (PAR) than PE + EVA film. The average day and night temperature in greenhouse under PO film were $1.5^{\circ}C$ and $0.8^{\circ}C$ higher but there was no significant difference in relative humidity compared with conventional film. Chlorophyll content of lettuce and cucumber plants grown under PO film were higher than conventional film. Growth characteristics; plant height, leaf area, fresh weight and dry weight of cucumber was shown better for PO film. The yields of cucumber and lettuce was increased 14.0% and 13.6% respectively, when the crops were grown under PO covering film greenhouse.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.410-418
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• 2021

This study was conducted in 8.2m wide single-span greenhouse to investigate the effect of presence or absence of rafter steel pipe joint and foundation conditions on greenhouse structural performance. Structural performance was evaluated by static loading test using the structural performance evaluation system for single-span greenhouse. The measured displacement was compared with the predicted result by numerical analysis. The displacement of each measurement location showed a significant difference regardless of the conditions of the foundation and presence or absence of rafter steel pipe joint. Compared to the hinge conditions, the difference in structural performance of the greenhouse in the fixed conditions was seen to be relatively large. The difference in structural performance according to presence or absence of rafter steel pipe joints, the lateral stiffness of the joint was 8.1% greater.

• Journal of Bio-Environment Control
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• v.31 no.1
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• pp.52-59
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• 2022

Pest control treatment was carried out using an unmanned automatic pesticide spraying system that can spray pesticides on crops while moving autonomously to control pests in vegetable greenhouse. As a result of examining the control effect on tomato and strawberry on thrips (Frankliniella occidentalis) and greenhouse whitefly (Trialeurodes vaporariorum) pests, 85.6% of yellow flower thrips were found in tomatoes and 87.5% in strawberries, and 81.7% (tomato) and 80.6% (strawberry) of greenhouse whitefly. In addition, the control effect according to the pesticide treatment method showed a control effect of 81.7% of the chemical spraying treatment by manpower and 83.9% of the automatic moving pesticide spraying treatment (F=22.1, p < 0.001). When comparing the control effect between the two treatment sections, there was no significance, but the automatic transfer spraying treatment showed a 2.2% higher effect. On the other hand, as a result of comparing the spraying time of the drug, the automatic unmanned control sprayer had a spraying time of 5 min/10a, which took about 25 min less than the conventional manpower spraying time of 25-30 min/10a. Based on these results, it was judged that the automatic transfer spraying method could be usefully used for efficient pest control in the facility greenhouse during the peak period of development.

• Research in Plant Disease
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• v.29 no.1
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• pp.1-10
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• 2023

The establishment of a laboratory assay and a greenhouse assay was conducted for evaluating the pathogenicity of Macrophomina phaseolina causing soybean charcoal rot established. In the laboratory assay, microsclerotia and hyphae were used as inoculum. In the laboratory assays using microsclerotia as an inoculum, disease incidences of M. phaseolina NSW17-108 and HSM17-034 were higher at 35℃ than 25℃. Of the two isolates NSW17-108 and HSM17-034, the disease incidence of HSM17-034 isolated from diseased sesame is higher than that of NSW17-108 isolated from diseased soybean. When the mycelia of M. phaseolina were used as an inoculum, the disease incidence of NSW17-108 and HSM17-034 at 35℃ exceeded 80% even after only 5 days of inoculation. Even at 25℃, furthermore, that of HSM17-034 exceeded 80% 5 days later. In the pathogenicity assays at a greenhouse, toothpicks where microsclerotia were produced or microsclerotia harvested from potato dextrose agar medium were used as an inoculum. In all greenhouse assays, M. phaseolina NSW17-108 and HSM17-034 showed 40-60% of disease incidences 35-65 days after inoculation with the pathogen, depending on the inoculation method. Between the two isolates, the pathogenicity of HSM17-034 was stronger than that of NSW17-108, and this result was consistent with laboratory assay results. Since the laboratory and greenhouse test methods tested in this study have different advantages and disadvantages depending on each test method, it is thought that the test method that can meet the purpose of the study should be selected and used.