• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.64-70
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• 2018

In this study, eleven major coastal areas were selected and the climate environment and the greenhouse direction were analyzed. This research investigates the greenhouse heat loss according to the wind environment at target areas. The target areas were selected based on heated greenhouse cultivation area and wind environment standard. Temperature, wind speed, and wind direction among weather data for 30 years were collected and analyzed. The data were divided into the minimum, average, and maximum temperatures and the Meteorological Agency criteria applied to the weather and wind direction criteria. Data were collected in the range of $0{\sim}180^{\circ}$ considering the symmetry of the shape of the greenhouse. In addition, the wind direction is different for each region and the applied wind direction can be different when referring to the longitudinal direction of the greenhouse and the data are collected in the range of $0{\sim}90^{\circ}$. The results of this study are expected to be used to calculate the heating load of greenhouse installed in places wind speed high.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.269-280
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• 2014

To cope with increasing of vegetables and flowers consumptions, horticulture facilities have been modernized. Korea government recently announced construction plan of new greenhouse complex at reclaimed land. However wind characteristics of reclaimed land is totally different from those of inland, wind pressure on greenhouse built in reclaimed land should be carefully evaluated to secure structural safety on the greenhouse. In this study, as a first step, wind pressure coefficient and local wind pressure coefficient on even-span greenhouse were measured using wind tunnel test. ESDU was adopted to realize wind characteristics of reclaimed land such as wind and turbulence profiles. From the wind tunnel test, when wind direction was 0 degree, it was concluded that KBC2009 standard underestimated scale of wind pressure coefficients at roof area of greenhouse whereas NEN-EN2002 standard underestimated those at every surface of greenhouse. When wind direction was 90 degree, both standards did not well reflect the characteristics of wind pressure distribution. From the analysis of local wind pressure coefficients according to wind direction conditions, design of covering, glazing bar of greenhouse where large effects of the local wind pressure were estimated should be well established. Wind pressure coefficients and local wind pressure coefficients according to parts of the greenhouse were finally suggested and these results could be practically used for suggesting new design standards of greenhouse.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.2
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• pp.145-151
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• 1996

Wind force coefficients of multi-span arched greenhouses with respect to wind direction of $0^{\circ}$ and $30^{\circ}$ were estimated to give more reasonable coefficient. The conventional and subdivided division types of wind force coefficient distribution diagrams were constructed by using the wind tunnel experimental data. Bending moments on the greenhouses were determined through structural analysis using obtained wind force coefficients, and were analyzed. Because actual wind pressure values on a face of greenhouse varied with locations, the more divisions of wind force coefficient distribution were subdivided, the better distribution type was coincided with actual state. In order to calculate the more accurate section force occurred on the arched greenhouse by the wind loads, it was recommendable that the wind force coefficient distribution should take more subdivision type. The maximum bending moment at the multi-span greenhouse frame at wind direction of $30^{\circ}$ was greater than that at O。, therefore the wind force coefficient at inclined wind direction to the wall was needed to be considered for the multi-span greenhouse structural design.

• Journal of Biosystems Engineering
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• v.36 no.6
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• pp.444-452
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• 2011

In this study the characteristics of natural ventilation of Venlo-type greenhouse with continuous roof vents were analyzed using commercial computational fluid dynamics (CFD) code. Developed CFD simulation model was verified by comparison with experimental data. Simulation errors were 1.9-46.0% for air velocity and 1.7-11.2% for air temperature at each measurement point. CFD simulations were conducted to estimate the effect of roof vents opening direction, opening angle, outside wind velocity and wind directions on ventilation rate and climate condition in greenhouse. The results of this study showed that ventilation rate of the present greenhouse was increased linearly in proportion to the increase of roof vent opening angle and outside wind velocity over 2.0 m/s. According to the analysis on the effects of different roof vent opening direction, simultaneous opening of wind and leeward vents showed the highest ventilation rate and lowest mean temperature in greenhouse.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.3
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• pp.9-19
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• 2015

Internal air temperature of greenhouse is an important variable that can be influenced by the complex interaction between outside weather and greenhouse inside climate. This paper focuses on a data-based model approach to predict internal air temperature of the greenhouse. External air temperature, solar radiation, wind speed and wind direction were measured next to an experimental greenhouse supported by the Electronics and Telecommunications Research Institute and used as input variables for the model. Internal air temperature was measured at the center of three sections of the greenhouse and used as an output variable. The proposed model consisted of a transfer function including the four input variables and tested the prediction accuracy according to the sampling interval of the input variables, the orders of model polynomials and the time delay variable. As a result, a second-order model was suitable to predict the internal air temperature having the predictable time of 20-30 minutes and average errors of less than ${\pm}1K$. Afterwards mechanistic interpretation was conducted based on the energy balance equation, and it was found that the resulting model was considered physically acceptable and satisfied the physical reality of the heat transfer phenomena in a greenhouse. The proposed data-based model approach is applicable to any input variables and is expected to be useful for predicting complex greenhouse microclimate involving environmental control systems.

• Journal of Environmental Science International
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• v.18 no.2
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• pp.197-203
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• 2009

The aim of this study is to calculate process emission of GHGs(greenhouse gases) in nonferrous-metal industry, such as Zn, Pb, Cu and Ni. In addition, variation and emission of GHGs generated from these company were defined. And then, GHGs algorithm and calculation formular which were considered as production process in each part of nonferrous-metal industry were developed to develop calculation program of GHGs emission. These algorithm and calculation formular would present fundamental direction about other nonferrous-metal industry in the future.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.126-129
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• 1999

Natural ventilation is achieved by air exchanges through multiple openings due to natural pressure variations inside and outside the greenhouse. Wind is the primary driving force making natural ventilation systems very difficult to design properly because of variations in wind velocity and direction. The optimization of these systems for acceptable climate control requires a thorough knowledge of the airflow rates and patterns as related to weather conditions and greenhouse structural details. (omitted)

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.3
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• pp.75-81
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• 2014

Fossil energy is needed for a whole year greenhouse cropping due to climate in South Korea. Because the most of the fossil energy resources is imported, it is necessary to develop technology to be able to reduce the energy cost in order to manage greenhouse profitably. The greenhouse commonly consume less amount of energy as compared to other industrial sectors. Replacement of fossil fuel with solar thermal storage, therefore, can be an economical as well as environmentally sustainable option for greenhouse heating. The fluid flow, heat storage and radiation characteristic of the gravel bed model were analyzed to provide basic data for design of the experimental solar heated greenhouse with underground thermal storage using gravel. The air flow velocity in the gravel storage bed was proven to be affected from the capacity of circulation fan and the circulation method and the positive pressure method was proven to be the best among the different air circulation methods. The initial air temperature of the thermal storage bed of 1.2 m $wide{\times}9$ m $long{\times}0.9$ m deep was $10^{\circ}C$. After the thermal storage bed is heated by air of the mean temperature $4^{\circ}C$ during 9 hours, the temperature has increased about $20.3^{\circ}C$ and the storage of heat was about 33,000 kcal. The important factors should be taken into consideration for design of the solar heated greenhouse with underground thermal storage using gravel are insulation of rock storage, amount of storing heat, inflow rate and direction of inlet and outlet duct.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2005.05a
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• pp.94-94
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• 2005

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.4
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• pp.99-106
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• 2002

This research was performed to study the actual behavior of 1-2W type pipe greenhouse under the influence of typhoon by measuring the various strains in structural materials. These results can eventually be utilized in the design criteria as well as in the modification of conventional equation for calculating more realistic wind loads. The first data under the influence of Typhoon Olga arrived in Jinju on Aug. 1999 were obtained by strain gage with 10 sensor points. According to the data obtained, the typical variation of strain depending on wind pattern could be observed. The strains in structural frame were fluctuated very sensitively depending on the direction and magnitude of wind velocity. But some of the data were lost or missed by system's failure. A kind of inherent vibration pattern of greenhouse pipe frame was observed from the plotted data, but this phenomenon is not so clear as to be separated from the overall fluctuation so far. This experimental research is expected to be continued as a long term project to measure and analyze the strain pattern of structural frame depending on the various locations and section characteristics by way of adopting more efficient instrument with sufficient number of measuring points and accuracy.