• Journal of Bio-Environment Control
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• v.20 no.3
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• pp.176-181
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• 2011

The fan and pad evaporative cooling system is one of the main cooling methods in greenhouses. Its efficiency is very high, but it has some disadvantages as temperature gradient in greenhouse is large. This study was conducted to reduce the internal temperature gradients in the fan and pad cooling greenhouses. Experiments on cooling performance were carried out in a greenhouse equipped with air duct and integrated fan and pad system as an idea of this study. It showed that the cooling efficiency of an integrated fan and pad system was 75.7% in the first stage and 88.6% in the second stage. When this cooling system was operated for an unshaded and a shaded greenhouse, there were cooling effects of $5.7\sim7.6^{\circ}C$ and $7.4\sim9.7^{\circ}C$ to the control greenhouse, respectively. Maximum temperature differences in a cooling greenhouse, with a length of 18m, were $1.6\sim1.7^{\circ}C$ for shaded conditions and $2.3\sim2.7^{\circ}C$ for unshaded conditions. This greenhouse cooling method, with air duct and integrated fan and pad system, can reduce about 40~50% of the internal temperature gradients in the usual fan and pad cooling greenhouses.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.135-135
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• 2017

Greenhouse have been developed to provide the plants with good environmental conditions for cultivation crop, two major factors of which are the inside air temperature and humidity. The inside temperature are influenced by the heating systems, ventilators and for systems among others, which in turn are geverned by some type of controller. Likewise, humidity environment is the result of complex mass exchanges between the inside air and the several elements of the greenhouse and the outside boundaries. Most of the existing models are based on the energy balance method and heat balance equation for modelling the heat and mass fluxes and generating dynamic elements. However, greenhouse are classified as complex system, and need to make a sophisticated modeling. Furthermore, there is a difficulty in using classical control methods for complex process system due to the process are non linear and multi-output(MIMO) systems. In order to predict the time evolution of conditions in certain greenhouse as a function, we present here to use of recurrent neural networks(RNN) which has been used to implement the direct dynamics of the inside temperature and inside humidity of greenhouse. For the training, we used algorithm of a backpropagation Through Time (BPTT). Because the environmental parameters are shared by all time steps in the network, the gradient at each output depends not only on the calculations of the current time step, but also the previous time steps. The training data was emulated to 13 input variables during March 1 to 7, and the model was tested with database file of March 8. The RMSE of results of the temperature modeling was $0.976^{\circ}C$, and the RMSE of humidity simulation was 4.11%, which will be given to prove the performance of RNN in prediction of the greenhouse environment.

• Journal of computational fluids engineering
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• v.21 no.2
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• pp.32-39
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• 2016

The Gradient Biome is a unique and large greenhouse(length 200 m, width 50 m, height:40 m) in which the elements of the weather, such as temperature and humidity, are controlled and reproduced in such a way as to create a continuous gradient from the tropical to frigid zones along specified longitudinal or transvers lines on the earth. One of the main purposes of the Gradient Biome is to observe the possible responses of the ecosystems (mainly plants), which are to be corresponding to each test climate and be introduced in the Biome, to the expected global warming. As one of the expected responses is the shift of the ecosystem(s) toward the region of suitable environment, there should be no artificial obstacles, which can prevent the shift, inside the facility. However, it is important but not so easy to find the ways of how the temperature and humidity in the Biome could be reproduced since the environmental variables tends to be homogeneous. In this paper, numerical simulations were carried out to find the effective control methods for air temperature and humidity inside the real scale Biome. One of the contributed solvers of OpenFOAM, which is an open source physics simulation code, was modified and used for the simulations.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.2
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• pp.47-58
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• 2023

The quality and yield of crops produced using field cultivation are expected to decrease due to the recent global climate change caused by extreme weather. The plant reproductive stage associated with crop yields is a highly vulnerable period to global warming caused by high temperatures. This study analyzed the adzuki bean's yield properties, antioxidant contents, and pollen viability of adzuki bean (Vigna angularis L.) under high-temperature stress and growth periods in a temperature gradient greenhouse that forms 0 to 4℃ above the outside temperatures. As the main variety of red beans cultivated in Korean farms, the "Arari" red bean was grown in the rain shield greenhouse and the temperature gradient greenhouse from 2021 to 2022 in Milyang, Korea. Compared to 2022, it showed a 0 - 1.0℃ lower temperature during the whole growth period in 2021. However, its average temperatures were 0 - 3.7℃ higher in the vegetative stage and 0.4 - 2.4℃ higher in the anthesis stage in 2021. The lowest yield (6.8 ± 0.7 g) was at the highest temperature (T4: low, 23.6℃; average, 28.5℃; high, 35.8℃) during the anthesis stage in 2021. The temperatures of the mature stage were 1.7 - 3.9℃, which were higher in 2022 than in 2021, although the low temperatures of 2022 were lower than in 2021. The yields of the mature stage in 2022 increased more than in 2021 because of the high temperature of the mature stage. The growth and yield were good at 40.5℃ in the vegetative stage. However, growth was poor when the average temperature was 27.0℃ or higher, and yields decreased during the flowering period. Total polyphenol and flavonoid contents were increased, and the pollen viability was 40.75% in the whole growth period at high temperature (T4: low, 22.9℃; average, 28.8℃; high, 36.9℃). These results showed that the antioxidant levels increased when the antioxidant component was affected at higher temperatures than at normal. In contrast, the pollen viability-related yield decreased as the temperature increased. Our results are the basic data for field growers and the breeding of thermos-tolerance in adzuki beans to prepare for the changeable future climate.

• Journal of computational fluids engineering
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• v.18 no.1
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• pp.43-48
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• 2013

The feasibility of a unique greenhouse, named as Gradient Biome, is now being examined extensively in the University of Tokyo. It is a large chamber (length:200m, width:50m, height:40m) in which the weather, such as temperature and humidity, of the tropical zone through to that of the frigid zone on the earth is reproduced with continuous gradient. In the Gradient Biome, ecosystems (mainly plants) corresponding to each weather are introduced and the possible responses of this ecosystems to the expected global warming are to be observed. Since one of the expected responses is the shift of the ecosystem(s) toward the region of suitable environment, there should be no artificial obstacles, which can prevent the shift, inside the Biome. This requirement is not so easy to be satisfied since the environment tends to be homogeneous. This paper presents the results of the numerical studies conducted to find the ways of how the temperature and humidity in the Gradient Biome could be reproduced. One of the contributed solvers of OpenFOAM, which is an open source physics simulation code, was modified and used for the numerical simulations.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.581-584
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• 2019

Food consumption is growing worldwide every year owing to a growing population. Hence, the increasing population needs the production of sufficient and good quality food products. Strawberry is one of the world's most famous fruit. To obtain the highest strawberry output, we worked with three strawberry varieties supplied with three kinds of nutrient water in a greenhouse and with the outcome of the strawberry production, the highest yielding strawberry variety is detected. This Study uses the nutrient water consumed every day by the highest yielding strawberry variety. The atmospheric temperature, humidity and CO2 levels within the greenhouse are identified and used for the prediction, since the water consumption by any plant depends primarily on weather conditions. Machine learning techniques show successful outcomes in a multitude of issues including time series and regression issues. In this study, daily nutrient water consumption of strawberry plants is predicted using machine learning algorithms is proposed. Four Machine learning algorithms are used such as Linear Regression (LR), K nearest neighbour (KNN), Support Vector Machine with Radial Kernel (SVM) and Gradient Boosting Machine (GBM). Gradient Boosting System produces the best results.

• Korean Journal of Environmental Biology
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• v.32 no.2
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• pp.95-101
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• 2014

In order to investigate effects of elevated $CO_2$ concentration and temperature on the ecological niche of Quercus serrata in Korea. We divided experimental condition in the greenhouse that are control (ambient condition) and treatment with elevated $CO_2$ (approximately 1.6 above than control) and increased air temperature (approximately $2.2^{\circ}C$ above than control). We measured twenty kind characters of seedlings and calculated the ecological niche breadth. As a result, the ecological niche breadth, treatment was widened in the light gradient than the control, was narrowed in the moisture and nutrient gradient. This is may be predicted when the global warming progress, Q. serrata is increases resistance to light environment, and decrease resistance to moisture and nutrient environment. According to the principal component analysis (PCA), control and treatment were arranged based on factor 1 and 2 in each environment gradients. Ecological response is involved variety characters. Among them, indicating that Characters of production is involved in many a parts.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.150-150
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• 2022

Plant reproduction associated with crop yields is highly vulnerable to global climate change components such as high and cold temperatures. The objectives of this study were to determine the effects of season-high exposure to temperature treatments in pollen morphology on Adzuki bean (V. angularis) and Mung bean (V. radiate). V. angularis and V. radiata were treated at high temperatures in the high temperature gradient greenhouse designed to cause temperature deviation. The pollen shapes treated at high temperature were compared by an electron scanning microscope. As a result, it was confirmed that the number of abnormal pollens morphology at high temperature was the least in V. radiata, and V. angularis was vulnerable to high temperatures. Also, it was found that the number of abnormal pollen morphology atT4 (Con +5~6℃) varied according to the cultivars of V. angularis. Therefore, the differences in Vigna species or cultivars with thermo-tolerance in pollen morphology to high temperature are projected to occur in the changeable future climate.

• Journal of the Korean Geographical Society
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• v.43 no.1
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• pp.1-19
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• 2008

This study intends to clarify the characteristics and causes of current changes in wintertime precipitation in Korea and to predict the future directions based on surface observational $(1973/04\sim2006/07)$ and modeled (GFDL 2.1) climate data. Analyses of surface observation data demonstrate that without changes in the total amount of precipitation, snowfall in winter (November-April) has reduced by 4.3cm/decade over the $1973\sim2007$ period. Moreover, the frequency and intensity of snowfall have decreased; the duration of snow season has shortened; and the snow-to-rain day ratio (STDR) has decreased. These patterns indicate that the type of wintertime precipitation has changed from snow to rain in recent decades. The snow-to-rain change in winter is associated with the increases of air temperature (AT) over South Korea. Analyses of synoptic charts reveal that the warming pattern is associated with the formation of a positive pressure anomaly core over northeast Asia by a hemispheric positive winter Arctic Oscillation (AO) mode. Moreover, the differentiated warming of AT versus sea surface temperature (SST) under the high pressure anomaly core reduces the air-sea temperature gradient, and subsequently it increases the atmospheric stability above oceans, which is associated with less formation of snow cloud. Comparisons of modeled data between torrent $(1981\sim2000)$ and future $(2081\sim2100)$ periods suggest that the intensified warming with larger anthropogenic greenhouse gas emission in the $21^{st}$ century will amplify the magnitude of these changes. More reduction of snow impossible days as well as more abbreviation of snow seasons is predicted in the $21^{st}$ century.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.631-640
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• 2018

The application of an oxy-combustion circulating fluidized bed combustor (Oxy-CFBC) for low grade coals has recently developed in the world to meet the continuous increase of energy demand and to achieve the reduction of greenhouse gases. Since demo plants for Oxy-CFBC have been developed, the combustion properties of Oxy-CFBC in various operation conditions, such as gas flow rates, combustion temperature, fuel, and so on, should be investigated to develop design criteria for a commercial Oxy-CFBC. In this study, a computational simulation tool for Oxy-CFBC was developed on the basis of the IEA-CFBC (International Energy Agency Circulating Fluidized Bed Combustor) model. Simulation was performed under various conditions such as reaction temperature ($800^{\circ}C{\sim}900^{\circ}C$), oxygen contents (21%~41%), coal feeding rate, Ca/S mole ratio (1.5~4.0), and so on. Simulation results show that the combustion furnace temperature is higher in oxy 1 than air fired. However, the temperature gradient tended to decrease with increasing oxy mixing percent. In case of $SO_x$, the higher the Ca/S mole ratio and oxy mixing percent, the higher the desulfurization efficiency.