• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.146-150
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• 2017

This research investigated the effect of photo/dark period and relative humidity during dark period on the growth and quality of water dropwort in a closed-type plant factory system. At 30 days after planting, the shoot fresh weight of water dropwort under relative humidity of 60/90%(light/dark) treatment significantly higher than that under relative humidity of 60/60% treatment. The shoot fresh weight of water dropwort increased by extending light period under relative humidity of 60/60% treatment, but 16/8h photo/dark period showed the best shoot fresh weight, followed by 20/4h and 22/2h under relative humidity of 60/90% treatment. In the relative humidity of 60/90% treatment, the tipburn occurrence was reduced under 16/8h photo/dark period condition as 1.4%, whereas it was significantly increased under 20/4h and 22/2h of relatively long light time duration as 15.5% and 30.3%, respectively. In the relative humidity of 60/60% treatment, the tipburn occurrence was 15.5% under 16/8h photo/dark period condition and those under 20/4h and 22/2h photo/dark period condition were higher than 25%. The stem hardness of water dropwort was lowest in relative humidity of 60/90% and 16/8h photo/dark period treatment. The mineral contents of leaves were decreased by extending light period, but the contents of Ca were not different significantly among the treatments except the 60/60% and 22/2h treatment.

• Journal of the Korean Solar Energy Society
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• v.36 no.5
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• pp.31-50
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• 2016

To develope a greenhouse fog cooling system to control the temperature and relative humidity simultaneously to the target value, a theoretical analysis and experiments were done. The control process includes the measuring of environmental variables, setting and coding of the water and heat balance equations to maintain the target temperature and relative humidity in greenhouse, calculating of the open level of the greenhouse roof window that governs the natural ventilation and spray water quantity, and operating of the motor to open/close the roof window and pump to spray for water. The study results were shown to be very good because the average air temperature in the greenhouse was kept to be about $28.2^{\circ}C$ with the standard deviation of about $0.37^{\circ}C$ compared to the target temperature of $28^{\circ}C$ and the average relative humidity was about 75.2% compared to the target relative humidity was 75% during the experiments. The average outside relative humidity was about 41.0% and the average outside temperature was $27.2^{\circ}C$ with the standard deviation of about $0.54^{\circ}C$. The average solar intensity in the greenhouse was 712.9 W. The wind velocity of outside greenhouse was 0.558 m/s with the standard deviation of 0.46 m/s.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.2
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• pp.34-38
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• 2002

This studies were performed to determine the effects of indoor relative humidity conditions on the growth of Arachniodes aristata and Pyrrosia lingua in native fern and investigate an applicable possibility of indoor plants. The response of Arachniodes aristata and Pyrrosia lingua was evaluated in growth chamber (KG-8407-87) to 3 relative humidity and 3 soils. Relative humidity was applied to 25%, 50%, 90%; soils were prepared based on soil mixture(SM), top field soil(TF), masa soil(MS). Results of experiments are as follows ; 1. Under a low humidity condition, such as 25%, Water contents, chlorophyll content, ornamental value of Arachniodes aristata and Pyrrosia lingua decreased much more a 50-90%. 2. The growth of Arachniodes aristata were best in pots under a soil mixture(SM) but Pyrrosia lingua were field top soil(FT) under 25%. It seemed that Pyrrosia lingua due to tolerance of desiccation more than Arachniodes aristata. Though these studies, coefficient of relative humidity and soil was plays an important role in Arachniodes aristata and Pyrrosia lingua growth in indoor environments.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.11 no.2
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• pp.91-96
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• 2005

Determination of safety factor of corrugated fiberboard boxes used for agricultural products is very complicated process due to nature of living products. Moisture content is one of the most critical factors to determine overall physical strength of paper, so its influences on strength properties of corrugated board made from different raw materials must be quantified. The results obtained from the study were summarized as follows; 1. Results show a detrimental effect on bursting strength and compressive strength of liners with increasing relative humidity of environment and moisture content of liners. 2. The relevance of equilibrium moisture content at varying relative humidity levels was proved and its relationship was used as an important factor to estimate box compression strength. 3. Test results was statistically used for establish the relationship between relative humidity and moisture content of liners. Estimated compression strength of boxes at varying moisture content was similar to results of theoretical equations such as Kellicutt's. Further study could be carried out in order to determine a optimum safety factors of various corrugated board boxes for agricultural products.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.7 no.2
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• pp.43-51
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• 2001

This study was carried out to analyze changes of the physical properties of corrugated fiberboard boxes for fruits packaging by various moisture and temperature changes. There were significant decrease in burst strength with increased relative humidity. And also compressive strength(ring crush test) of corrugated fiberboard and box were reduced with moisture content. The decreasing amounts of single wall(SW) corrugated fiberboard was bigger than that of double wall(DW). The physical properties reductions of corrugated fiberboard and box were mainly affected by relative humidity. Therefore, it is suggested that development of the water-resistant corrugated fiberboard and box be useful under the condition of low temperature and high relative humidity such as the cold chain system.

• Journal of the Korean Society of Tobacco Science
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• v.26 no.1
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• pp.43-49
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• 2004

This study was carried out to investigate moisture sorption and desorption characteristics followed by tobacco type. Experiments were performed at various temperature(5, 15, 25, 40 $^{\circ}C$) and relative humidity range (11～84 %) controlled by saturated salt solution. Regression equation was obtained to predict equilibrium moisture according to various relative humidity, temperature and tobacco types. The obtained regression equation showed high $R^2$(above 0.95) and predicted accurate equilibrium moisture. Equilibrium moisture contents declines in the following order when a relative humidity is 50 % or above: expanded stem, flue-cured, expanded tobacco, reconstituted tobacco, USA flue-cured, orient, burley. To maintain 13 % moisture of each tobacco type in the range of 5～40 $^{\circ}C$ it is recommendable to control relative humidity 49～56 % for expanded stem, 50～57 % for flue-cured, 54～61 % for USA flue-cured, 56～60 % for reconstituted tobacco, 57～62 % for expanded tobacco, 58～64 % for orient and 58～65 % for burley, respectively. It means that the relative humidity of each tobacco type should be differently controlled to maintain the same moisture under the same temperature. In the range of 5～25 $^{\circ}C$, the lower temperature showed the higher equilibrium moisture content.

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.110-113
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• 2005

Relative humidity of air In the greenhouse has to be maintained at 70 to 80 percents to provide a better growth condition of crops. To control relative humidity of air in the greenhouse, a dehumidifier functioning by refrigeration cycle was designed and manufactured in this study. And, results of its performance test in the greenhouse site were reported. The developed dehumidifier has separated condenser and evaporator in the heat exchanger part in order to increase dehumidifying capacity at a low temperature condition. When the conditions of incoming air into the dehumidifier were temperature of $15\~25^{\circ}C$ and relative humidity of $0\~95\%$, quantity of condensed water per hour, ie, dehumidification rate was $4.7\~7.0\;kg/hr$. Relative humidity difference was not greater than 5 percents at various locations in the greenhouse due to proper distributing of dehumidified air through vinyl duct. Thermal energy output from the developed dehumidifier was about 8,5000 kcal/hr that was 7 percents of maximum greenhouse heating load of 10 a.

• The Korean Journal of Food And Nutrition
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• v.11 no.2
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• pp.221-227
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• 1998

This study was investigate correlation of moisture content, relative humidity, pH, color difference, myoglobin(Myo), oxymyoglobin(Oxy) and metmyoglobin(Met). The moisture content, relative humidity of loin and shank were not changed uniformly during storage, the pH was raised according to storage period. The L value was raised at the closing stage of the storage period, the surface of the b value was higher than interior. Between Myo and Met were positive correlation in common with loin and shank. The surface and interior of loin were negative correlation between Oxy and Met, the surface and interior shank were positive correlation between Myo and L value and were negative correlation between Myo and Oxy. The moisture content, relative humidity, pH and color was not correlation uniformly.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.108-112
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• 1984

The sorption characteristics of red pepper powder stored at various relative humidity and temperature were studied. At low relative humidity below RH 57%, the sorption equilibrium was easily attained, whereas at higher relative humidity above RH 75%, the powder was browned by higher equilibrium moisture content. The moisture content of monolayer value for the powder was ranging from 11.32% to 12.13% with temperature. First order regression equation of equilibrium moisture content for relative humidity was determined.

• Journal of Biosystems Engineering
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• v.19 no.4
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• pp.358-368
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• 1994

Major factors in reducing the stacking strength of corrugated fiberboard boxes in cold storage or transport conditions are high relative humidity, causing elevated moisture absorption by the boxes. The bottom boxes in a stack will deform to the critical deflection causing agricultural products damage there, and eventually additional deflection will cause box collapse and finally toppling of the stack. The study was conducted to determine the water absorption characteristics and the compressive strength of the corrugated fiberboard boxes being widely used in packaging agricultural products in Korea. The sample boxes for the study were selected from the regular slotted containers (RSC) types, and one was the box used in apple packaging (Box A), another one was the box used in pear packaging (Box B). The corrugated shipping containers were made from a large portion of recycled fibers in Korea, and comparing with Box B, Box A was fabricated from fiberboard which contained more percentage of old corrugated containers (OCC) imported from foreign countries than domestic waste paper. The results obtained from the study were summarized as follows ; 1. Equilibrium moisture content (EMC) of the sample boxes was established after about 20 hours, and the EMC by absorption was lower than that by desorption. The EMC increased with the increasing of relative humidity and with the decreasing of temperature, and the rate of increasing was much higher above the relative humidity of 50%. 2. The maximum compressive strength of Box A was about 100 kgf greater than that of Box B on the same enviromental conditions. The strength of the sample boxes decreased rapidly with the increasing of relative humidity. The effect of relative humidity on the strength was a little higher than that of temperature. 3. As the applied load was progressively increased and a level was reached, the vertical side panels ($L{\times}D$) deflected laterally inwards or outwards. The panels deflected laterally inwards at higher relative humidity. 4. The maximum compressive deflection ratio and the critical deflection ratio of the sample boxes were increased linearly with the increasing of relative hunidity, but trends for its ratios showed inconsistant response to temperature.