• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.103-110
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• 2018

This study was conducted to investigate the optimum irrigation method for propagation of cutting strawberry ($Fragaria{\times}ananassa$ Duch. cv. Maehyang) plantlet in summer season. The cutting strawberry plantlets were planted in 24-cell tray ($60{\times}34{\times}10cm$) filled with commercial mixed medium (Tosilee) and placed in semi closed-type small plastic tunnel. Each semi closed-type small plastic tunnel was treated as follows; control (non-treatment), over head irrigation (twice a day), capillary mats irrigation (twice a day), or fog irrigation (30 minutes turn on and 10 minutes off from 8:00 to 18:00). The strawberry plantlets were rooted during 8 days in the semi closed-type small plastic tunnel, and then plastic film was removed. Growth parameters, such as plant height, root length, number of primary roots, petiole length, leaf length, leaf width, crown diameter, SPAD, leaf area, fresh and dry weights of the shoot and root, were measured at 61 days after cutting. Relative humidity in tunnel was high in the order by fog irrigation, over head irrigation, capillary mats, and the control as 72.5, 56.3, 45.8, and 29% on average, respectively. However, the air temperature was similar in all treatments. On the 4 and 8 days, the rooting rate of strawberry plantlet was significantly higher in the over head irrigation and fog irrigation treatments. Plant height, petiole length, crown diameter, and leaf area were highest in the over head irrigation and fog irrigation treatments. In addition, fresh and dry weights of shoot were greater in over head irrigation and fog irrigation treatments than the others. Dry weight of root was differed significantly heaviest in the fog irrigation treatment. However, root length, no. of primary roots, SPAD value, and fresh weight of root were not significantly different in all treatments. These results indicated that growth and rooting for propagation of cutting strawberry plantlet 'Maehyang' were best achievement in the over head irrigation and fog irrigation treatments.

• Journal of Bio-Environment Control
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• v.25 no.2
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• pp.83-88
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• 2016

In this study, previously reported surplus solar energy-related study result and current status of fan coil unit (FCU) for cooling and heating installed in the current sites were briefly examined and then a method to determine the number of FCUs required to recover surplus solar energy was schematically proposed to provide basic data for researchers and technical engineers in this field. The maximum, mean, and minimum outside temperatures during the experiment period were about $28.2^{\circ}C$, $4.4^{\circ}C$, and $-11.5^{\circ}C$, respectively. The horizontal surface solar radiation level outside the greenhouse was in a range of $0.8-20.5MJ{\cdot}m^{-2}$ and mean and total solar radiation were $10.8MJ{\cdot}m^{-2}$ and $1,187.5MJ{\cdot}m^{-2}$. The mean temperature and relative humidity in the greenhouse during the daytime were in a range of 18.8-45.5 and 53.5-77.5%. The total surplus solar energy recovered from the greenhouse during the experiment period was approximately 6,613.4MJ, which could supplement about 6.7% of the total heating energy 98,600.2 MJ. In addition, the number of FCUs installed for heating varies case to case, although similar FCUs are used. Thus, it is necessary to study the installation height, orientation and installation distance as well as the appropriate number of FCUs from the efficient and economical viewpoints. The required numbers of FCUs for surplus solar energy recovery were 8.4-10.9units and 6.1-8.0units based on air mass and circular flow rate that passed through the FCUs. Considering calculation methods and the risks such as efficiency and use environments of FCUs, it was found that about nine units (one unit per $24m^3$ approximately) needed to be installed. The required number of FCUs for surplus solar energy recovery was around one unit per $24m^3$ approximately.

• Journal of Bio-Environment Control
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• v.29 no.1
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• pp.20-27
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• 2020

The study was performed to calculate canopy temperatures and crop water stress index (CWSI) of 2-year-old 'Yumi' peach trees using thermal infrared imaging under different soil water conditions, and to evaluate availability for water stress determination. Canopy temperatures showed similar daily variations to air temperatures and they were higher during the daytime than air temperatures. Canopy temperatures for 24 h were correlated highly to air temperatures (r² =0.95), solar radiations (r² =0.74), and relative humidity (r² =-0.88). In addition, soil water potential showed a highly negative correlation to canopy temperatures (r² =-0.57), temperature differences between leaf and air (TD) (r² =-0.71), and CWSI (r² =-0.72) during the daytime (11 to 16 h). CWSI for 24 h was highly related to canopy temperatures (r² =0.90) and TD (r² =0.92), whereas CWSI was not correlated to soil water potential (r² =-0.27) for 24 h but related highly to water potential (r² =-0.72) during the daytime (11 to 16 h). Correlation coefficients between CWSI (y) and soil water potential (x) were highest from 11 to 12 h and a regression equation was deduced as y = -0.0087x + 0.14. CWSI was calculated as 0.575 at -50 kPa, which soil water stress generally occurs. Thus our result suggests that this regression equation using thermal infrared imaging is useful to evaluate soil water stress of peach trees.

• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.80-85
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• 2018

This study was carried out to clarify the effect of CHO-CO and PO film on air temperature in greenhouse and Korean melon fruit characteristics and yield. On January 8 in 2017, the maximum, minimum and average air temperature in greenhouse covered with CHO-CO film were $38.9^{\circ}C$, $13.4^{\circ}C$ and $20.1^{\circ}C$, respectively. At the same date, the maximum, minimum and average air temperature in greenhouse covered with PO film were $40.0^{\circ}C$, $14.9^{\circ}C$ and $20.3^{\circ}C$, respectively. On August 7 in 2017, the maximum, minimum and average air temperature in greenhouse covered with CHO-CO film were $47.2^{\circ}C$, $23.1^{\circ}C$ and $32.4^{\circ}C$, respectively, and the maximum, minimum and average air temperature in greenhouse covered with PO film were $50.3^{\circ}C$, $23.6^{\circ}C$ and $34.0^{\circ}C$, respectively. The results of investigation of qualities and yields of Korean melons from May 26 to August 15 in 2017 were as follows. The fruit weight of Korean melon harvested in CHO-CO film's greenhouse was 371.6g which was 22.2g less than that of PO film greenhouse. The sugar contents of Korean melon harvested in CHO-CO film greenhouse was $14.5^{\circ}brix$ which was $1.4^{\circ}brix$ greater than that of the fruits harvested in PO film greenhouse. The chromaticity (a-value) of fruit skin of Korean melon harvested in CHO-CO film greenhouse was 12.3 which was 1.5 greater than that of the fruits harvested in PO film greenhouse. The marketable yield rate of Korean melon harvested in CHO-CO film's greenhouse was 89.4% which was 8.0% higher than the fruits harvested in PO film greenhouse. The yield of Korean melon harvested in CHO-CO film's greenhouse was 2694kg per 10 a which was 26% more than that harvested in PO film greenhouse. In conclusion, the CHO-CO film could be effective to produce Korean melon in high temperature season.

• Journal of Bio-Environment Control
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• v.14 no.1
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• pp.22-28
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• 2005

The use of blankets to preserve heat in oriental melon cultivation is a common practise without artificial heating and warming systems. Efficiency of blanket decreased with annually usage. This experiment was conducted to investigate the effect of double layer nonwoven fabrics on heat conservation, plant growth, fruit quality and yield of oriental melon in greenhouse. The results were compared among the non-woven fabrics of 9+3, 6+6, 6+3 and 12 ounce from transplanting to April 20, 2001, 2002. Night temperature within tunnel was high at 9+3, 6+6, 6+3 and 12 ounce in order. In plant growth, stem length, leaf numbers and exudate, under double layer nonwoven fabrics were better than single layer blanket of 12 ounce especially, 9+3 double layer blanket was the best. Fruit weight, flesh thickness, soluble solid and marketable yield rate remained same in all treatments. Fermented fruit rate was the highest in 12 ounce as $32.9\%,\;19.6\%\;under\;9+3,\;17.1\%\;under\;6+6,\;16.6\%$ under 6+3 double layer nonwoven fabric, respectively. Compared to 2,260kg yield per 10a of 12 ounce single layer nonwoven fabrics, $7\%$ was increased under 9+3 but $3\%\;and\;13\%$ were decreased under 6+6 and 6+3 double layer nonwoven fabrics, respectively. Compared to income, 4,499-thousand-won per 10a, of 12 ounce single layer blanket, $13\%\;and\;3$ were increased under 9+3 and 6+6 double layer nonwoven fabrics, respectively. Whereas, $10\%$ decreased under 6+3 double layer nonwoven fabrics. From this results it is evident that 9+3 double layer nonwoven fabrics was the best for thermokeeping, fruit quality, and was most economic under non heating system.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.296-305
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• 2006

The heterogeneity of crop transpiration is important to clearly understand the microclimate mechanisms and to efficiently handle the water resource in greenhouses. A computational fluid dynamic program (Fluent CFD version 6.2) was developed to study the internal climate and crop transpiration distributions of greenhouses. Additionally, the global solar radiation model and a crop heat exchange model were programmed together. Those models programmed using $C^{++}$ software were connected to the CFD main module using the user define function (UDF) technology. For the developed CFD validity, a field experiment was conducted at a $17{\times}6 m^2$ plastic-covered mechanically ventilated single-span greenhouse located at Pusan in Korea. The CFD internal distributions of air temperature, relative humidity, and air velocity at 1m height were validated against the experimental results. The CFD computed results were in close agreement with the measured distributions of the air temperature, relative humidity, and air velocity along the greenhouse. The averaged errors of their CFD computed results were 2.2%,2.1%, and 7.7%, respectively.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.306-316
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• 2006

In this study, the effect of the shade level, water flow rate applied to the shades and the temperature of water on the greenhouse cooling was investigated depending on the shade level of 0, 35, 55, 75%, and water flow rate and water temperature by the test on the small wooden frames to find out the low cost cooling method. With increasing of the dry bulb temperature of outside air, the dry bulb temperature in the wooden frames increased. For the frames with the shade and water, inside temperatures of the frames were lower of -0.2$\sim$-1.2$^{\circ}C$ than the temperature of the outside air and higher than the water temperature. For the frames without water, inside temperatures of the frames were higher of 1.7$\sim$4$^{\circ}C$ than the outside and not affected by the shade level very much. The water flow rate and the temperature of the water were not the important factors to decrease the inside temperatures in the frames. The black globe temperature became lower with increasing of shade level. The shade frames with water curtain showed the best cooling effect because of reducing thermal radiation and cooling the plastic film cover. The surface temperatures of the plastic film cover for the water supplied modules became lower with increasing of the shade level. The relative humidity was decreased with the dry bulb temperature in the frame increasing and not affected by the dry bulb temperature of the outside air for the frames with the shade and water.

• Journal of Bio-Environment Control
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• v.23 no.2
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• pp.83-87
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• 2014

The objective of this study was to examine the changes in carbon dioxide ($CO_2$) concentration due to application of solid $CO_2$ generator (Tansansol) in plastic greenhouses during winter cultivation of Korean melon. The experimental treatments consisted of four levels, namely, 0 (control) 10, 20 and 30bags with solid $CO_2$ generator per $600m^2$ of plastic greenhouse. $CO_2$ concentration in plots with solid gas generators was higher by 3.0-3.2% compared to control. Fruit weight, sugar content and color parameter were also enhanced due to application of solid $CO_2$ generator. The fraction of fermentated and unmarketable fruits were decreased by 2.9-3.9% and 5.4-7.3%, respectively, in plots where solid $CO_2$ generators were applied. The marketable yield increased by 10.3, 14.8 and 16.2% in plots with 10, 20 and 30bags with $CO_2$ generators, respectively. As a result, $CO_2$ concentration within the greenhouses was increased by applying $CO_2$ generators and it is positively affected the rate of photosynthesis.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.324-332
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• 2017

The comparative experiments were conducted for single span greenhouses where cucumbers were cultivated to analyze the effect of heating between a carbon fiber electric heating element heater and an oil hot air heater in terms of the inside climate, energy consumption and plant growth. In order to analyze the effect of heating capacity, 6, 9, and 16 kW of electric powers were supplied to the electric heating element for same setting temperature of 15?. As a result, as the heating capacity increased, the number of ON-OFF cycles of the electric heating element and the temperature inside the greenhouse increased proportionally. In the comparison of two heaters, it was shown that the temperature and relative humidity distributions of the electric heating element installed greenhouse was much uniform than those of the oil hot air heater installed greenhouse. The heating energy consumptions during the heating period of 79 days were 867L for the oil hot air heater and 8,959 kWh for the electric heating element heater, and the heating costs were 607 and 403 thousand won respectively. In the electric heating element installed greenhouse, the cucumber growth was slightly better and the yield was 4.3% higher than those of the oil hot air heater installed greenhouse, but there were no statically significant difference in the cucumber growth and yield between greenhouses.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.386-392
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• 2017

This study was conducted to examine the growth and phytochemical contents of spinach (Spinacia Oleracea L. 'Sushiro') as affected by different fluorescent lamps in a closed-type plant production system. Seeds were sown in a 128-cell plug tray filled in rockwool. The seedlings were transplanted into a DFT (deep floating technique) system with recycling nutrient solution (EC $1.5dS{\cdot}m^{-1}$ and pH 6.5) in a closed-type plant production system. The seedlings were grown under 3 types of fluorescent lamp, #S (NBFHF 32S8EX-D, CH LIGHTING Co. Ltd., China), #O (FHF32SSEX-D, Osram Co. Ltd., Germany), and #P (FLR32SS EX-D, Philips Co. Ltd., The Netherlands) at $150{\mu}mol{\cdot}m-2{\cdot}s^{-1}\;PPFD$ with a photoperiod of 14/10 (light/dark) hours. Plants were cultured under condition of $25{\pm}1^{\circ}C$ temperature and $60{\pm}10%$ relative humidity after transplanting. Thirty plants per each treatment were cultivated for $6^{th}$ week after transplanting. And growth and phytochemical contents were measured at $3^{rd}$ and $6^{th}$ week. At the $3^{rd}$ week after transplanting, the parameter values of plant height and leaf width were higher in the #O than the others. However, fresh and dry weights of root were the greatest in the #P. In addition, total phenolic concentration was the greatest in the #P. At $6^{th}$ week after transplanting, the #O had the greatest growth of spinach in the plant height and fresh and dry weights of shoot. The total phenolic contents significantly increased in the #O and showed significantly difference. However, there was no significant difference all treatments in antioxidant activity. Therefore, these results suggest that the #O was suitable for the growth and phytochemical accumulation of spinach in a closed-type plant production system.