• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.459-465
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• 2012

This study analyzed the effect of semi-rigid rafter-purlin cross-linking connection and driven steel pipe base on the static behavior of plastic greenhouse (PG). To promote the time and cost efficiency of the assembly process, each cross-linking connections of space arch type grid that consists of rafter and purlin is linked with steel-wire buckles, and each end of the rafters was driven directly to the ground to support the PG structure. However, in the design process, cross-linking connections and bases are idealized by being categorized as fully rigid or frictionless pinned, which does not appropriately reflect actual conditions. This study takes a full-scale loading test of PG and analyzes the effect of member cross-linking connections and driven steel pipe base on the behavior of a structure. The analysis provided a basis for determining the rigidity factor of member cross-linking nodes needed for finite element analysis, and the reliability of the result regarding the static behavior of PG.

• Journal of Bio-Environment Control
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• v.31 no.1
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• pp.43-51
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• 2022

This study was conducted to investigate the effect of ventilation at high temperature on the control of powdery mildew, silverleaf whitefly two-spotted spider mite occurred at Korean melon cultivation greenhouse, and on leaf rolling and flowering of the plant in summer season. 'Alchanggul' grafted onto 'Hidden Power' rootstock was planted on soil bed with the distance of 40 cm. Three ventilation temperatures of 45℃, 40℃, and 35℃ as set points were compared. Ventilation treatment was done by control of side window operation from 18th June to 13th July when silverleaf whitefly, mite, and powdery mildew were occurred in all greenhouses. The temperature inside greenhouse was increased up to the set temperature point on sunny days and maintained for about 9 hours with high relative humidity at 45℃ condition. The differences of day maximum air temperature and day minimum RH were the highest at 45℃ treatment. After 11 days of treatments, the damage by powdery mildew and two-spotted spider mite was almost recovered at 45℃ treatment but not at 40 and 35℃. The population of silverleaf whitefly and two-spotted spider mite were significantly decreased at 45℃ treatment at 14 days after treatment, while powdery mildew symptom was not significantly decreased. Leaf rolling was observed at high temperature but not severe at 45℃ treatment. After 26 days of treatments, female flowers did not bloom at all at 45℃ treatment, and the number of male flowers was 1.2 among 15 nodes of newly grown shoots. As the result, it indicates that ventilation at the high temperature of 45℃ for about 2 to 3 weeks can be an applicable method to control above mentioned pests and disease, and to recover the vegetative growth of Korean melon by reducing flowering of the plant.

• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.306-312
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• 2020

This study was conducted to investigate cucumber plants response to greenhouse environments by solar shading in greenhouse in the summer. In order to estimate heat stress reduction of cucumber plants by solar shading in greenhouse, we measured and analyzed physiological conditions of cucumber plants, such as leaf temperature, leaf-air temperature, rubisco maximum carboxylation rate, maximum electron transport rate, thermal breakdown, light leaf respiration, etc. Shading levels were 90% mobile shading of full sunlight, 40% mobile shading of full sunlight and no shading(full sunlight). The 90% shading screen was operated when the external solar radiation is greater than 650 W·m^-2. Air temperature, solar radiation, leaf temperature, leaf-air temperature and light leaf respiration in the 90% shading of full sunlight was lower than those of 40% shading and no shading. Rubisco maximum carboxylation rate, arrhenius function value and light leaf respiration of the 90% shading were significantly lower than those of 40% shading and no shading. The thermal breakdown, high temperature inhibition, of 90% shading was significantly higher than that of 40% shading and no shading. Therefore, these results suggest that 90% mobile shading made a less stressful growth environment for cucumber crops.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.224-235
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• 2019

The increase in the amount of energy used in the agricultural sector due to the expansion of agricultural machinery and greenhouse horticulture has caused a range of problems, such as an increase in the cost of input, such as heating costs and greenhouse gas emission. To overcome these problems, this study examined the current status of energy use in greenhouse horticulture as well as the change patterns of non-taxable oil and agricultural electricity, and reviewed the current status of the supply of renewable energy and energy saving facilities for agriculture. This study investigated the area of advanced and renewable energy and energy saving facilities implemented, applied the energy saving ratio of advanced and renewable energy and energy saving facilities, and determined the effects of renewable energy in the agricultural sector, such as increase in production, decrease in heating cost, reduction in Government financial expenditure, reduction in greenhouse gas emission, and oil substitution effect.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.501-508
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• 2012

Reducing carbon dioxide ($CO_2$) exhaust has become a major issue for society in the last few years, especially since the initial release of the Kyoto Protocol in 1997 that strictly limited the emissions of greenhouse gas for each country. One of the primary sectors affecting the levels of atmospheric greenhouse gases is agriculture where $CO_2$ is not only consumed by plants but also produced from various types of soil and agricultural ecosystems including greenhouses. In greenhouse cultivation, $CO_2$ concentration plays an essential role in the photosynthesis process of crops. Optimum control of greenhouse $CO_2$ enrichment based on accurate monitoring of the added $CO_2$ can improve profitability through efficient crop production and reduce environmental impact, compared to traditional management practices. In this study, a sensor-based control system that could estimate the required $CO_2$ concentration considering emission from soil for cucumber greenhouses was developed and evaluated. The relative profitability index (RPI) was defined by the ratio of growth rate to supplied $CO_2$. RPI for a greenhouse controlled at lower set point of $CO_2$ concentration (500 ${\mu}mol{\cdot}mol^{-1}$) was greater than that of greenhouse at higher set point (800 ${\mu}mol{\cdot}mol^{-1}$). Evaluation tests to optimize $CO_2$ enrichment concluded that the developed control system would be applicable not only to minimize over-exhaust of $CO_2$ but also to maintain the crop profitability.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.193-200
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• 2015

Purpose: The purpose of this study was to investigate the energy saving effects and characteristics of plant growth in a greenhouse with an aluminum multi-layer curtain compared to a greenhouse with non-woven fabric. Method: The dimensions of both greenhouses $43m{\times}3.6m{\times}8m(L{\times}H{\times}W)$, and both used hot air heater systems for maintaining a constant temperature $15^{\circ}C$. Heating characteristics such as solar intensity, inside and ambient temperatures, and fuel consumption were measured and analyzed. Results: The changes of average temperature of both greenhouses during a 15-days (December 06 - 20) showed approximately $26^{\circ}C$ at around 2 pm when the ambient temperature was highest. The greenhouses were set by the heater to keep a temperature of $15^{\circ}C$ from 4 pm to 8 am the following day. The average heat loss (for 15 days) from the greenhouse with an aluminum multi-layer curtain was $161.2-268.4kJ/m^2{\cdot}h$ during the daytime and $152.3-198.1kJ/m^2{\cdot}h$ during the nighttime. The average heat loss (for 15 days) from the greenhouse with non-woven fabric was $155.7-258.9kJ/m^2{\cdot}h$ during the daytime and $144.9-207.0kJ/m^2{\cdot}h$ during the nighttime. The total heat loss (for one day) from the non-woven fabric system was $7,960kJ/m^2$($2,876kJ/m^2$ during the daytime, $5,084kJ/m^2$ during the nighttime). The heat supply over 36 days for the non-woven fabric system was higher than the aluminum multi-layer curtain system by $616.3-65,079.4kJ/m^2$. Conclusions: These results suggest that a greenhouse with an aluminum multi-layer curtain could save energy usage by 35% over a greenhouse with non-woven fabric.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.287-294
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• 2013

Purpose: Greenhouses for a protected horticulture covered with a plastic or glass are easy to have weakness in a heat loss by deterioration, damage, poor construction, and so on. To grasp the vulnerable points of heat loss of the greenhouses is important for heating energy saving. In this study, an on-site heat loss audit and energy consulting system were developed for an efficient energy usage of a greenhouse. Method: Developed system was mounted with infrared thermal and visual cameras to grasp the heat loss from the greenhouse quickly and exactly, and a trial calculation program of heating load of greenhouse to provide farmers with the information of heating energy usage. Results: Developed system could print out the reports about the locations and causes of the heat losses and improvement methods made up by an operator. The mounted trial calculation program could print out the information of the period heating load and fuel cost according to the conditions of greenhouse and cultivation. The program also mounted the databases of the information on the 13 horticultural energy saving technologies developed by the Korea Rural Development Administration and simple economic analysis sub-program to predict the payback period of the technologies. Conclusion: The developed system was expected to be used as the basic equipment for an instructors of district Agricultural Technology and Extension Centers to conduct the energy consulting service for the farmers within the jurisdiction.

• Journal of Plant Biotechnology
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• v.5 no.3
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• pp.169-172
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• 2003

Somatic embryogenesis was initiated from in vitro grown leaf explants of rose following an induction period of four weeks on MS basal medium supplemented with auxin and several subcultures on MS medium with cytokinin. '4th of July' showed the highest regeneration frequencies on 1 mg/L NAA followed by culture on medium with 4 mg/L zeatin. The embryogenic callus was propagated on MS medium with NAA, zeatin and $GA_3$. Germination of somatic embryos was achieved on MS medium with 1 mg/L BA. Somatic embryo derived plantlets were hardened and successfully transferred to the greenhouse.

• Journal of Bio-Environment Control
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• v.1 no.1
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• pp.61-71
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• 1992

This study is performed to develop an automatic irrigation control of system for effective water management in greenhouse. The automatic irrigation control system is composed of an IR-RED optical sensor in tensiometer and an One-chip micro controller. The following results are obtained : 1. A practical IR-RED optical sensor in tensiometer, which shows the starting point of irrigation, was developed. 2. The automatic irrigation system with the optical sensor and One-chip micro controller was developed and also designed to be able to combine with the control system for temperature, curtain opening, etc. 3. A multiple irrigation control system for several greenhouses were suggested. 4. The results of the system test with the driving program for automatic water management were excellent.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.1-8
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• 2006

The objective of this research is to study on the analysis of long-term performance characteristics of various solar thermal system for heating protected horticulture system for reducing heating cost, increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Long term field test for the demonstration was carried out in horticulture complex in Jeju Island. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Optimum operating condition and its characteristics were closely investigated by changing the control condition based on the temperature difference which is the most important operating parameter. However, it is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.