• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.655-668
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• 2012

Foliar diseases are major constraints to profitable organic tomato production. Especially, powdery mildew, leaf mold and gray mold of tomato occur severely on organic cultured tomatoes in Korea. This study was conducted to develop organic tomato cultivation technology using environmental-friendly disease control methods (resistance cultivar planting, air circulation fan installation, oil-egg yolk mixtures, and microbial agents). When tomatoes were cultivated in plastic film house installed with air circulation fan, daily range of temperature was decreased by $2{\sim}7^{\circ}C$, average relative humidity was decreased by 1~5% compared to those in plastic house without air circulation fan. Consequently, incidence of tomato leaf mold and tomato gray mold was reduced by 55.0% and 24.4%, respectively. Control effect of microbial agents and oil-egg yolk mixtures against major tomato diseases was examined in plastic house. As a result, the control value of microbial agents against tomato gray mold and tomato leaf mold showed at the range of 49.0~55.9 %(gray mold) and 39.2~58.2%(leaf mold), respectively. The control value of oilegg yolk mixtures against tomato powdery mildew showed 97.6%. Fifteen tomato cultivars were evaluated for disease resistance against leaf mold and powdery mildew in organically cultivated tomato field. Among 15 tomato cultivars, seven cultivars including 'Super-top' were found to be high resistant to tomato leaf mold. Also 'Powerking', one of fifteen tomato cultivars, showed to be high resistant to tomato powdery mildew.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.250-254
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• 1998

This paper shows how the environmental parameters(temperature, humidity) in the greenhouse are influenced by air movement produced by air circulation fans. When the fans were used, they could make indoor temperature and humidity homogenious, but there was no significant difference in the location and number of fans. When the fans were not used during the night time, there was no significant difference in the temperature and humidity, but the standard deviation was reduced by using the fans.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.31-32
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• 2005

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.24-32
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• 2015

The global success of PSY's Gangnam Style was mediated through combination of YouTube and SNS. PSY's success led into some communication scholars' consideration of new international circulation of Korean pop culture (Korean Trend 2.0). In terms of global circulation of pop culture, it is noticeable how users appropriate YouTube channel beyond mere watching music videos and mere international circulation of Korean pop culture. The mode of fan's activity and appropriation contributes to the expansion of the width and amplification of the volume of Korean popular culture as well. The circulation of pop culture was considered in the level of exchange of tangible commodities such as CD, DVD, and so on until the adoption of digital media and Internet. YouTube has brought new mode in which the international circulation of pop culture is mediated without exchange of tangible commodities but was amplified with the diffusion of network. This study grasps how the mode of users' appropriation contributes to international circulation of pop culture through case studies of some K-pop music videos and international K-pop fans' tribute activities. In terms of theoretical perspective, fandom studies will be examined. In terms of research method, the researcher adopts netnography, a participatory observation on network, to find the feature of fandom and its contribution to the international circulation of pop cultures.

• Journal of Biosystems Engineering
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• v.37 no.2
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• pp.75-81
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• 2012

Oyster mushroom farm which could not meet optimum temperature range yields non-uniform sized, low quality products. Thus, this study, utilizing STAR CCM+, one of the computational fluid dynamics (CFD) programs, analyzed the impact of air circulation and temperature distribution. Methods: After we visited numerous mushroom farms, we measured the temperature at the discharge ports of heaters, fan capacity, and the locations of the air circulators in the farms. According to the data, most mushroom growers installed the heaters near the entrance and discharge ports of the heaters at the third growing bed on the same height as the heaters in the entrance. The temperature at the discharge port of heater was $1,26^{\circ}C$, and the fan capacity was 4,500 $m^3$/hr. The air circulator was placed in the center of the mushroom farm 50cm above the ground, and its capacity of inlet port was 1,100 $m^3$/hr and discharge port 1,600 $m^3$/hr. The mushroom farm was insulated. Results: According to the analysis of the temperature distribution in the vertical plane of the entrance side, no air circulation causes the high temperature zone of 296~299K at the discharge port of the heater to take up 34% of area while the operation of air circulators causes it to occupy only 9%. This means that not using air circulators leads to a concentration of high temperature at the discharge port near the entrance. In addition, with the results of the analysis of the temperature distribution in the vertical planes of the center, no air circulation causes the temperature zone of 295~298K at the discharge port of the heater to take up 48% of area while the operation of air circulators causes it to occupy 80%. This shows that the high outlet port temperature disseminated to the center. Conclusions: After ninety minute operation of both heater and air circulator, the interior temperature became stabilized in the mushroom farm. Air circulation made the high temperature at the discharge port disseminate to the center and exit in the farm and equalize the temperature distribution.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.4
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• pp.167-173
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• 2018

We propose an air purification system that utilizes aerial plant parts and root zone of indoor plants where light is insufficient and air circulation is bad. In order to maximize the air purification effect of the plant, the aerial plant parts illuminates mixed light combining blue and green LED and CRI(Color Rendering Index) LEDs close to natural light, respectively. And the root zone was forcibly circulated by the fan to use the soil as a filter. The indoor air purification system combined with the light source and the fan removed most polluted air in the shortest. In the case of mixed light and CRI LEDs of indoor air purification system, fine dust decreased by 14%, 14.2%, and TVOC(Total volatile organic compounds) decreased by 7.5% and 9.4%, respectively. In the experiment in which the fan was operated for 15 minutes, the TVOC decreased to 97.8%. The photosynthesis of the plant and the use of soil as a filter were able to purify polluted air in a short time. And the fan's temporary operation gave the similar effect of continuous operation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.743-750
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• 2017

It is important to ensure a uniform temperature distribution in greenhouses for the mushroom cultivation. The air temperature of the mushroom cultivation greenhouse is made uniform by supplying a constant air temperature with the underground air. The mushroom cultivation array in a greenhouse in seven columns and four rows can make smooth air flows between the rows and prevent air differences between the top and bottom. The buoyancy effect in the entering air of 0.5m/s based on following density difference depending on initial internal temperature needs to be considered. The locations of the Fan Coil Unit (FCU) and fan were defined through flow analysis in a greenhouse to distribute the optimal uniform temperature. In this study, the air conditioning system of a greenhouse with a sandwich heat insulting panel shape which is composed of a FCU and fan was designed by flow analysis. A relatively uniform temperature distribution can be formed because the circulation path of air becomes longer in the different locations of the FCU (inlet) and fan (outlet) through the internal temperature and flow analysis. The cultivation and quality uniformity of the mushrooms could be promoted through these environmental improvements.

• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.325-331
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• 2016

A bathtub vortex above the outlet of a rotating barrel is simulated. By analyzing the Ekman layer theory, it can be found that the main flow circulation is inversely proportional to the thickness of Ekman layer. The thicker the Ekman boundary layer, the weaker the rotational strength and the shorter of the length of gas core is. According to this law, models of barriers with rods of different heights are established. The reduction of air-core length in this air entrainment vortex and weakening the strength of rotation field were achieved.

• Journal of Internet Computing and Services
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• v.16 no.1
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• pp.57-65
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• 2015

As information technology fusion is accelerated, the researches to improve the quality and productivity of crops inside a plant factory actively progress. Advanced growth environment management technology that can provide thermal environment and air flow suited to the growth of crops and considering the characteristics inside a facility is necessary to maximize productivity inside a plant factory. Currently running plant factories are designed to rely on experience or personal judgment; hence, design and operation technology specific to plant factories are not established, inherently producing problems such as uneven crop production due to the deviation of temperature and air flow and additional increases in energy consumption after prolonged cultivation. The optimization process has to be set up in advance for the arrangement of air flow devices and operation technology using computational fluid dynamics (CFD) during the design stage of a facility for plant factories to resolve the problems. In this study, the optimum arrangement and air flow of air circulation fans were investigated to save energy while minimizing temperature deviation at each point inside a plant factory using CFD. The condition for simulation was categorized into a total of 12 types according to installation location, quantity, and air flow changes in air circulation fans. Also, the variables of boundary conditions for simulation were set in the same level. The analysis results for each case showed that an average temperature of 296.33K matching with a set temperature and average air flow velocity of 0.51m/s suiting plant growth were well-maintained under Case 4 condition wherein two sets of air circulation fans were installed at the upper part of plant cultivation beds. Further, control of air circulation fan set under Case D yielded the most excellent results from Case D-3 conditions wherein air velocity at the outlet was adjusted to 2.9m/s.

• Korean Journal of Agricultural Science
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• v.40 no.4
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• pp.317-323
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• 2013

This research was conducted to obtain the basic information for establishment of standard guidelines in the design and installation of roof ventilation system in single-span plastic greenhouse. To achieve this, the greenhouse structure & characteristics, cultivation status, and ventilation system were investigated for single-span greenhouse with roof ventilation system cultivating the Cucurbitaceae vegetables, watermelon, cucumber, and oriental melon. Most of single-span watermelon greenhouse in Haman and Buyeo area were a hoop-style and the ventilation system in those greenhouses mostly consisted of two different types of 'roof vent (circular or chimney type) + side vent (hole) + fan' and 'roof vent (circular type) + side vent (hole or roll-up type)'. The diameter of circular and chimney-type vent was mostly 60cm and the average number of vents was 10.5 per a bay with vent spacing of average 6.75m. The ratio of roof vent area to floor area and side vent area in the single-span watermelon greenhouse with ventilation fan were 0.46% and 7.6%, respectively. The single-span cucumber greenhouse in Haman and Changnyeong area were a gable roof type, such as even span, half span, three quarter and the 70.6% of total investigated single-span greenhouses was equipped with a roof ventilation fan while 58.8% had a circulation fan inside the greenhouse. The ratios of roof vent area to floor area in the single-span cucumber greenhouse ranged from 0.61 to 0.96% and in the case of the square roof vent, were higher than that of the circular type vent. On average, the roof ventilation fan in single-span cucumber greenhouse was equipped with the power input of 210W and maximum air volume of $85.0m^3/min$, and the number of fans was 9.75 per a bay. The number of roof vent of single-span oriental melon greenhouse with only roll-up type side vent ranged from 8 to 21 (average 14.8), which was higher than that of other Cucurbitaceae vegetables while the vent number of the greenhouse with a roof ventilation fan was average 7 per a bay.