• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.19-29
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• 2010

In South Korea, as the living standard has been getting higher, meat consumption is steadily increasing. To meet the country's demand, livestock houses become larger and wider with increased raising density. In larger livestock houses, pollutants such as flake of pig skin, excrement, odor, various dusts and noxious gas like ammonia are excessively accumulated inside the facility. These will cause weak immunity for the pigs, diminution of productivity and degeneration of working condition. These problems can be solved through the ventilation performance of the facility. In the winter time, ventilation must be controlled to minimum to maintain a suitable thermal condition. However, this affects the other internal environmental condition because of the minimum ventilation. The installation of "wet air cleaner" especially in the winter time can be an alternative solution. For efficient application of this machine, there is a need to understand the existing ventilation condition and analyze the interaction of existing ventilation system with the wet air cleaner considering its appropriate location. In this study, the existing ventilation system as well as the internal environmental condition negatively inside the facility with the wet air cleaner has been studied using CFD technology. The CFD simulation model was validated from the study conducted by Seo et al. (2008). Results show that the elimination rate of ammonia was 39.4 % and stability could be improved to 35.1 % (Comparing case 5 to 1 where wet air cleaner machine was not used). It can therefore be concluded that case 5 shows the optimum location of a wet air cleaner in the livestock house.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.2
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• pp.113-126
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• 2009

In the recent years, health effect of dimethylformamide(DMF) has been one of critical industrial hygiene issues. There might be many factors to increase the exposure level of DMF. Among those factors, industrial ventilation would be one of the main factors. In this study, industrial ventilation systems of printing processes in synthetic leather factories were thoroughly surveyed and the improved ventilation systems were proposed. 7 synthetic leather factories were selected for this study. After the ventilation systems were visually inspected, each component of the system was tested by using the appropriate instruments. Hood face velocities, fan exhaust flow rates, fan static pressures, fan rotation rates, etc were measured. In addition, flow visualization techniques were used to observe flow patten around hoods and inside the factory buildings. After gathering all qualitative and quantitative information, the test results were analysed to see if any improvement might be necessary. For the system to be improved, the re-design plans were made by using computational fluid dynamics softwares. The softwares used in this study were AIRPAK and STAR-CD. The effectiveness of the several improvement options were tested, then the best cost effective option was selected. Finally, the standard ventilation systems were proposed to minimize the exposure levels of DMF.

• Proceedings of the SAREK Conference
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• 2006.11a
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• pp.67-67
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• 2006

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.865-870
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• 2000

The flow and the moisture contamination of the dry room in the manufacturing process of lithium ion battery are analyzed numerically by finite volume method. Standard ${\kappa}-{\varepsilon}$ turbulent model widely applied in predicting turbulent flow is adopted in this study. Moisture contamination and distribution are studied by assumption of two cases; one-point generation and uniform generation throughout the room. To evaluate ventilation efficiency on moisture contamination, scales of ventilation efficiency are introduced. From these analyses, moisture contamination is strongly dependent on the flow field and the radius of moisture contamination can be reduced by closing a part of outlets in a dry room.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.110-126
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• 1993

Worker exposures to total chromium, hexavalent chromium (VI), sulfuric acid and alkaline dust at electroplating operations and worker exposures to trichloroethylene (TCE) and methyl chloroform (MCM) at degreasing operations in eleven small industrial plants were evaluated. Appropriate local exhaust ventilation systems for both operations were designed and recommended. Results of the study are summarized as follows ; 1. Out of 134 measurements for airborne hexavalent chromium concentrations, seven were exceeding the Korean occupational health standard of $50{\mu}g/m^3$ and 45 were exceeding the NIOSH standard of $1{\mu}g/m^3$. With an exception of one measurement, concentrations of total chromium were below the Korean standard of $500{\mu}g/m^3$. 2. Worker exposures to chromium were closely related to the existing control methods at the electroplating operations. Local exhaust systems, partial coverage of the tank surface, and antifoaming agents on liquid surface were adopted as control methods. 3. With an exception of one sample, airborne concentrations of sulfuric acid and alkaline dusts were below the applicable occupational heatlth standards. 4. Three plants indicated that airborne concentrations of TCE and MCM were exceeding the Korean standards. Other plants showed lower concentrations than the standards. It should be noted that generally, the activities and workloads on the day of surveys were less than normal. 5. Since the most existing ventilation systems did not satisfy the ACGIH criteria, the ventilation systems should be improved. Some examples for designing appropriate ventilation systems are presented.

• 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 Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3307-3314
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• 2012

The annual energy demand of the standard rural house models was analyzed using the DesignBuilder. Indoor temperature set-point, U-value of outer wall, type of window, and degree of ventilation were selected as simulation parameters. In all the simulation cases, heating energy demand was higher than cooling energy demand regardless of the building size. When the lower U-value of the outer wall was applied to account for the thicker insulation layer, heating energy demand was decreased while cooling energy demand was increased. However, it is better to reduce the area of outer wall which is directly exposed to outdoor air because reducing the U-value of the outer wall is not effective in decreasing heating energy demand. Among the four different window types, the double skin window is most favorable because heating energy demand is the lowest. For a fixed infiltration rate, higher ventilation rate resulted in an increased heating energy demand and had minor impact on cooling energy demand. As long as the indoor air quality is acceptable, lower ventilation rate is favorable to reduce the annual energy demand.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.3
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• pp.291-303
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• 2016

Recently, various forms of diverging sections in tunnels have been designed as the demand for underground passageway in urban areas increases. Therefore, the complexity of the ventilation system in tunnels with diverging sections requires a ventilation analysis method different from the conventional method for the straight tunnels. None of the domestic and foreign tunnel ventilation design standards specifies the method for the ventilation network analysis, and the numerical analysis methods have been most widely used. This paper aims at reviewing the ventilation network analytical method applicable as the design standard. The proposed method is based on the characteristic equations rather than the numerical analysis. Thanks to the advantages of easy application, the Hardy-Cross method has been widely applied in the fields of mine ventilation and tunnel ventilation. However, limitations with the cutting errors in the Taylor series expansion and the convergence problem mainly caused by the mesh selection algorithm have been reported. Therefore, this paper examines the applicability of the ventilation analysis method for network-type tunnels with the gradient method that can analyze flow rate and pressure simultaneously without the configuration of mesh. A simple ventilation analysis method for network-type tunnels is proposed.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.179-184
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• 2007

In this paper, the ventilation characteristics of an underground parking lot with 17 buses has been investigated for two cases by computational fluid dynamics. It has been found that the average concentration of CO and $NO_x$ gas in the parking lot were 1.3 and 0.3 ppm respectively, when four buses operated. When the fifteen vehicles stopped in the parking lot, the average concentration of CO and $NO_x$ gas was 2.9 and 0.8 ppm respectively. The average concentration of two pollutants$(CO,\;NO_x)$ are lower than the standard values. Therefore the facilities and its location is proper to ventilation.