• Journal of Biosystems Engineering
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• v.37 no.1
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• pp.19-27
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• 2012

Purpose: Utilizing air thermal energy during over-heated time in the greenhouse is a necessary component to save greenhouse heating costs for nighttime. However, there is no practical way to implement the related principles. Methods: In this study, a heating and cooling system which utilizes the surplus air thermal energy in a greenhouse was developed. Available air thermal energy and heating load for this experimental glasshouse were estimated based on temperature conditions of the plant growth and weather data. Results: Estimated values were 400 MJ/day for maximum surplus air thermal energy and 340 MJ/day for maximum heating energy which were target values of the design as well. The system consists of a heat pump, fan-coil units and heat storage tanks which are divided into low and high temperature tanks. Moreover, a new control logic was developed for surplus air thermal energy utilization. Conclusions: This paper explains the details of conceptual design process of the system. Results of test operations showed that the developed system performed the recovery and supply of the thermal energy according to design purposes.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.1101-1116
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• 1996

It is desirable to use the renewable energy for the greenhouse heating in winter season, it makes possible not only to save fossil fuel and conserve green farm environment but also to promote the quality of agricultural products and reduce the agricultural production cost. In this study the heat pump system was developed to use the natural energy as thermal energy resource for the thermal environment control of the greenhouse.

• Journal of Bio-Environment Control
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• v.2 no.2
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• pp.99-109
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• 1993

Cooling of nutrient solution is essential to improve the growth environment of crops in hydroponic culture during summer season in Korea. This study was carried out to provide fundamental data for development of the cooling system satisfying the required cooling load of nutrient solution in hydroponic greenhouse. A numerical model for prediction of the cooling load of nutrient solution in hydroponic greenhouse was developed, and the results by the model showed good agreements with those by experiments. Main factors effecting on cooling load were solar radiation and air temperature in weather data, and conductivity of planting board and area ratio of bed to floor in greenhouse parameters. Using the model developed, the design cooling load of nutrient solution in hydroponic greenhouse of 1,000$m^2$(300pyong) was predicted to be 95,000 kJ/hr in Suwon and the vicinity.

• Journal of Biosystems Engineering
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• v.21 no.4
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• pp.422-428
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• 1996

This study was conducted to developed to develop a simple battery-powered autonomous vehicle for greenhouse works. A steering method using speed difference of two independent driving motors was adopted. DC motor driving circuit, speed control circuit and controller using one-chip microcomputer were constructed. The inputs of controller are rolling of the vehicle and current speed of driving motors. Using these signals, automatic guidance system along furrow was developed. A computer simulation program by the kenematic analysis was developed to find out optimal control algorithm. The results of this study are as follows. 1. Automatic guidance system along the furrow that adopted two independent driving motors and rolling of vehicle was developed. 2. The results of simulation showed that PID control was adequate to automatic guidance system along furrow. 3. Two commercial 12V battery serially connected were able to drive the vehicle on the soil ground for five hours in continuous operation and for four hours in intermittent operation without recharging the battery. 4. The speed range was 0-0.7m/s and the rolling of vehicle could be controlled within $pm5^{\circ}$ range. 5. From a series of tests, developed vehicle was found to be a useful tool for greenhouse works.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.6
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• pp.145-152
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• 2011

In order to heat greenhouse nearby river channel, riverbank filtration water source heat pump was developed for getting plenty of heat flux from geothermal energy. Recharging well, thermal storage tank with separating insulation plate and filtering tank for eliminating iron, manganese were mainly developed for making the coefficient of performance (COP) of heat pump higher. Heating system using riverbank filtration water source heat pump was installed at a paprika greenhouse in the Jinju region where a single fold of vinyl cover and 2 layers of horizontal thermal curtain were installed as a part of temperature keeping and heat insulation with a greenhouse area of 3,185 $m^2$. 320,000 kcal/h was supplied for performing a site application tests. A greenhouse heating test was performed from Feb. 1, 2011 to Apr. 30, 2011. As the result of that, COPh of the heat pump was measured in the range of 4.0~4.5, while COPS of the system was represented as 2.9~3.3. COP measured of the heat pump was very good and well responded to indoor heating temperature of the environment control system of a greenhouse.

• Journal of Service Research and Studies
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• v.11 no.2
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• pp.118-130
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• 2021

This study designs and validates a greenhouse complex environmental control algorithm with a multi-phase processing scheme that can combine and control actuators according to the degree of change in the greenhouse environment. The composite environmental control system is a system in which the complex environmental controller analyzes the information detected by sensors and operates appropriately actuators to maintain the crop growth environment. A composite environmental controller directs control devices driving actuators through a composite environmental control algorithm, which calculates the values necessary for the operation of the control devices. Most existing algorithms carry out control procedures on a single phase by iteration cycle, which can cause abnormal changes in the greenhouse environment due to errors in output. The proposed algorithm distributes control procedures over multiple phases: environmental control, environmental control, and device operation, and every iteration cycle, detects environmental changes in the environmental control phase first, and then combines control devices that can control the environment in the environmental control phase, and finally, performs the controls to derive the actuators in the device operation phase. The proposed algorithm is designed based on the analysis of the relationship between greenhouse environmental elements and control devices deriving actuators. According to verification analysis, the multi-phase processing scheme provides room to modify or supplement the setting value and enables the control devices to reflect changes in the associated environmental components.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1998.05a
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• pp.54-60
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• 1998

시설재배의 생육은 지상부의 온도에 주로 영향을 받지만, 토양이 저온일 경우에는 양분의 흡수가 불량하고, 토양미생물의 활동이 떨어진다. 특히 세근의 발달이 억제될 뿐만 아니라 코르크화가 촉진되고, 정식후 묘의 활착이 지연되어 토양수분의 흡수가 불량해지므로 생육이 저하된다. (중략)

• Journal of Bio-Environment Control
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• v.13 no.3
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• pp.162-166
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• 2004

Air temperature variation along the length of the air duct in an air-heated plastic greenhouse was large, 13 ～ 15$^{\circ}C$ between the front and the rear side of a greenhouse. To reduce this temperature variation, a new PE-film air duct having a small duct inside a large duct (double duct) was developed. This double duct was consisted of an inner duct with air outlets at a 0.15 m interval and an outer duct with air outlets at a 2.5 m interval. Diameters of the air outlet holes were 7, 15, and 35 cm from the front to the end of the inner duct film, while identical 10 cm holes were used on the outer duct film. As a result, air temperature was $46^{\circ}C$ at the beginning side and $47^{\circ}C$ at the ending side, while the conventional single duct had $53^{\circ}C$ at the beginning point and $38^{\circ}C$ at the ending point with a variation of $15^{\circ}C$. Height of a cucumber crop grown in a greenhouse with the new double air duct system was 65.5 cm, 14% increase as compared to that in a greenhouse with a conventional air duct system. Total fruit yield per l0a greenhouse in a greenhouse with the new double air duct system was 4,616 kg, which was 17% greater than that in a greenhouse with a conventional air duct system. Amount of heating oil consumption during March 3 to April 24, 2002 was 3,233 L per l0a greenhouse with the new double air duct system, which was 13% less than that with a conventional air duct system.

• Journal of Biosystems Engineering
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• v.24 no.1
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• pp.25-30
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• 1999

The effectiveness of many greenhouse environment control methodologies depends on the growth information of crops. Acquisition of the growth information of crops requires a non-invasive and continuous monitoring method. Crop growth monitoring system using digital imaging technique was developed to conduct non-destructive and intact plant growth analyses. The monitoring system automatically measures crop growth information sends an appropriate control signal to the nutrient solution supplying system. To develop the monitoring system, a linear model that explains the relationship between the fresh weight and the top projected leaf area of a lettuce plant was developed from an experiment. The monitoring system was evaluated buy successive lettuce growing experiments. Results of the experiments showed that the developed system could estimate the fresh weight of lettuce from a lettuce image by using the linear model and generate an EC control signal according to the lettuce growth stage.

• Journal of Bio-Environment Control
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• v.8 no.4
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• pp.232-241
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• 1999

The automatic irrigation system using the stem diameter monitoring and the transpiration model for the determination, respectively, of irrigation timing and amount was designed and evaluated for its applicability in pot and field culture of greenhouse tomato. In the pot culture condition, the yield and quality of greenhouse tomato were improved when irrigation was practiced based on the stem diameter monitoring and the transpiration model as compared to the irrigation practice based on soil moisture monitoring. However, the effects were not significant in the field culture condition.