• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.238-244
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• 2008

This study investigates on the improvement of inhalation effect of hood which attached new device named as "gas-guide-device" in local exhaust ventilation system for the effective elimination of harmful material and dust in manufacturing factory. The gas-guide-device having a diamond shape is composed of width (b) and two sides of a device (X, Y) and its size is selected the industrial hood under application in manufacturing factory after due consideration. In order to investigate the effect of gas-guide-device, numerical and experimental study is performed that the flow velocity is calculated and is measured by a commercial program "COMSOL $Multiphysics^{TM}$" and a hot wire type of anemometer, respectively. The numerical and experimental results are revealed is a similar pattern and flow velocity has improved to hood attached gas-guide-device. Also, the numerical method and result is also verified the dependance. Moreover, the optimum shape and size of gas-guide-device is revealed that the width (b) and the ratio of two sides of gas-guide-device (X, Y) has 125mm and 4 to 6.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.1
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• pp.36-44
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• 2005

A push pull hood system is frequently applied to control contaminants evaporated from an open surface tank in recent years. Efficiency of push pull hood system is affected by various parameters, such as cross draft, vessel shapes, size of tanks surface, liquid temperature, and so on. Among these, velocity of cross draft might be one of the most influencing factor for determining the ventilation efficiency. To take account of the effect of cross draft velocities over 0.38m/s, a flow adjustment of ${\pm}$20% should be considered into the push and +20% into the pull flow system Although there are many studies about the efficiency evaluation of push pull hood system based on CFDs(Computational Fluid Dynamics) and experiments, there have been no reports regarding the influence of velocities and direction of cross-draft on push-pull hood efficiency. This study was conducted to investigate the influence of cross draft direction and velocities on the capture efficiency of the push-pull ventilation system. Smoke visualization method was used along with mock-up of push-pull hood systems to verify the ventilation efficiency by experiments. When the cross-draft blew from the same origins of the push flows, the efficiency of the system was in it's high value, but it was decreased significantly when the cross-draft came from the opposite side of push flows Moreover, the efficiency of the system dramatically decreased when the cross-draft of open surface tank was faster than 0.4m/s.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.594-599
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• 2007

This study represents numerical analysis on the fluid flow and concentration characteristics by scattering fume at push-pull ventilation system. And the principal point is making optimum on improve an existing ventilation system. This phenomenon simulated about local ventilation system by using commercial CFD tool and base on these fact has find improvements. Advanced model shows most low different pressure and velocity which are suction capability at inlet surface of pull hood has most uniformity. When compared with existing model, Improved model has more good ventilation performance.

• Journal of the Korean Professional Engineers Association
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• v.45 no.6
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• pp.44-51
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• 2012

Local functional, closed the hood and exhaust are classified as open-style hood. Around the closed hood contaminants prevent the spread of contaminants. Surrounded Some pollutants (open-style hood is used in cases where the odor, vapor diffusion, and inferior) of indoor allowed to Hood expressions, which are used for kitchen, laboratory, factory canopy is typical. Contamination that occurs during cooking, kitchen ventilation barrier materials are the biggest problem, its solution by introducing fresh outside air in the kitchen troubleshoot and. Study on the kitchen exhaust airflow for my kitchen, and perform a number of each Institute and at the University of hydrodynamic analysis is investigated.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.35-47
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• 2024

Objectives: Many cases of lung cancer have been reported by school kitchen workers as occupational cancer. Twenty-eight schools in Gyeongsangnam-do Province were selected to evaluate the effect of improved kitchen ventilation systems. Ventilation characteristics before and after renovation were compared and design techniques were identified. Methods: In the design stage for kitchen ventilation systems, expert intervention was used to improve the designs. Ventilation characteristics and air quality were evaluated before and after the renovations. Hood face velocity and fan flow rate were measured and the smoke visualization technique was used to evaluate the capability of protecting worker's breathing zone. The concentrations of PM_0.3 were measured at points not adjacent to cooking equipment because these concentrations fluctuate greatly. Results: Mean hood face velocity increased from 0.29 m/s before renovation to 0.7m/s after renovation. The concentrations of PM_0.3 showed a roughly 95% reduction. Concentrations of CO showed more than a 75% reduction. Smoke visualization showed greater protection of workers' breathing zone. Conclusions: Advanced design techniques for school kitchen ventilation systems were applied to renovate old kitchen ventilation systems. The performance of the new kitchen ventilation systems was nearly excellent. Further improvement of design techniques is still needed, however.

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.372-378
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• 2005

To enhance educational effect for exhaust ventilation system, more instructive educational engineering such as experimental system should be needed. This study was performed to 1) manufacture the basic experimental system for local exhaust ventilation, 2) experiment with this system and 3) develop methodology of exhaust ventilation education. With this system, three pressures (static pressure(SP), velocity pressure(VP) and total pressure(TP)) were measured and illustrated and the graphic shapes agreed to theoretical ones relatively. Entry loss factor ($F_h$) of each hood was found to be different with hood shape, duct velocity and flow rate. This result implies that precise $F_h$ should be determined case by case and a industrial hygienist should not be dependent on the existing values. Pressure loss using velocity pressure method and characteristics of air movement near hoods using fume were grasped with this system. But larger system should be recommended to produce more precise experimental results.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.2
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• pp.204-212
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• 1993

This study was conducted to evaluate ventilation efficiency of 4-stage slot hood by variation of slot width, flow rate, hood size and baffle size. The slot velocity, control velocity and plenum velocity were related to slot width and the distance between source of contamination and hood. The results obtained from laboratory experiment for local exhaust ventilation systems were as follows ; 1. When slot widths were constant(equally changed) and the velocity was 6-10 m/s, the slot velocity from 1st slot to 4th slot gradually decreased. As the slot width-to-slot length ratio(WLR) decreased, the slot velocity of each stage increased. But if WLR value was less than 0.04, the slot velocity decreased. 2. When slot velocity exceeded 10 m/s with constant slot widths, the slot velocity of each stage was uniform. 3. When the slot velocity was uniform within 10 m/s and the first slot width was 14-20 mm, the slot width ratio between 1st slot and each of three other slots were 1, 1.25, 1.5 and 3.0, respectively. 4. The slot and plenum velocity were uniform when exhaust flow rate changed from 14 to $19m^3/min$ and there were no hood splitter vanes. 5. When the slot velocity at each stage was uniform, the control velocity at site 30 cm away from hood No.2 increased from 0.15-0.30 to 0.25-0.45 m/s and the control distance from 20 to 30 cm(about 1.5 times).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.2
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• pp.208-216
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• 2019

Objective: The aim of this study is to control residual chemicals or by-products generated in chambers during preventive maintenance (PM) in the semiconductor manufacturing industry. We designed local exhaust ventilation using computational fluid dynamics (CFD). Methods: The air flow characteristics and capture efficiency between rectangular and slot hoods were compared numerically. The software Fluent 18.1 was used to estimate uniform velocity distribution and capture efficiency for contaminants. A metal from group 15 in the periodic table was released at the bottom of the chamber to simulate emissions. Results: The slot hood had a higher capture efficiency than a rectangular hood under the same conditions because the slot hood provided uniform air flow and higher face velocity. Also, there was no rotating swirl in the plenum for slot, that is why slot had better efficiency than rectangular even though they had similar face velocity. With less than 10 slots, the capture efficiencies for contaminants were nearly 95%. The optimum conditions for a hood to achieve high efficiency was 8 to 10 slots and a face velocity over 1 m/s. Conclusions: Well-designed ventilation systems must consider both efficiency and convenience. For this study, a slot hood that had high capture efficiency and no work disturbance was designed. This will contribute to protection of the worker's health in a PM area and other areas as well. Also, this study confirms the possibility of the application CFD in the semiconductor fabrication industry.

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.215-215
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• 2007

• Journal of the Korean housing association
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• v.15 no.3
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• pp.101-108
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• 2004

To find more efficient exhaust effect, air curtain of upward or downward trend in gas table and left or right side of range hood were made. As result that film vapor from range hood lower part by digital camera, the air current change by moving existence and nonexistence of exhaust fan and direction of air curtain were known. Under all experiment condition, upward air curtain superior exhaust performance.