• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.552-558
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• 1999

Ventilation of the marine engine room is very important for the health of the workers as well as the normal operation of machines. To find proper ventilation conditions of this engine room numerical simulation with a standard k-$\varepsilon$model was carried out. In the present study the marine engine room is considered as a closed space with a heat source and forced ventilation ducts. The injection angle of air supply is found to be important. Injection with a downward angle depresses recirculation flow causing a strong stream in the wider space of the room Ventilation and removal of the released heat are promoted with this pattern, There is a possibility of local extreme heating at the upper surface of the engine when supply and exhaust ports of air are in bilateral symmetry.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.25-33
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• 2019

PURPOSE: This study examined the effective impact of self and resistive and ultrasound-biofeedback diaphragm breathing on the pulmonary function and diaphragm thickening ratio of young adults. METHODS: Thirty normal adults were assigned randomly to three experimental groups (self- diaphragm breathing (n=9), resistive-diaphragm breathing (n=11), ultrasound-biofeedback diaphragm breathing (n=10)). Each group participated for 15 minutes for times with a two minute rest between two sets. The subjects were assessed using the pre- and post- diaphragm thickening ratio and the pulmonary function (forced vital capacity, forced expiratory volume at one second, maximal voluntary ventilation, and respiratory rate) on the thirty subjects. A paired t-test was to determine the difference between before and after the experiment in each group of diaphragm breathing before and after the exercises. One-way ANOVA was used to determine the differences between the groups. RESULTS: The forced vital capacity and maximal voluntary ventilation measurements revealed a significant difference in the resistive-diaphragm breathing group than the other two groups. On the other hand, there was no significant difference between the self-diaphragm breathing and ultrasound-biofeedback breathing groups. CONCLUSION: The resistive-diaphragm breathing group showed greater improvement in the pulmonary function than the other two groups. Therefore, resistive-diaphragm breathing will improve the pulmonary function on normal young adults.

• Journal of Environmental Impact Assessment
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• v.31 no.5
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• pp.334-342
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• 2022

The stringent air environment conservation act forced to build an indoor dome for coal storage. However, it causes some problems due to accumulation of fly ash and harmful substances inside. To solve this problem, this study analyzed the pattern of internal airflow and the amount of ventilation for an indoor coal yard. Overall, the airflow inside the indoor coal yard tended to move to the southwest facing the mountain. In addition, sea-breeze was blowing from the northern louver window facing the sea, where airflow was flowing in. The total flow rate flowing into the indoor coal yard was 918,691 m³/h, and the number of natural ventilation per hour was 0.6 times. Therefore, it is proposed to install a forced ventilation device at the location where internal air flow is concentrated.

• Journal of Bio-Environment Control
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• v.10 no.1
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• pp.23-29
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• 2001

This experiment was conducted to investigate to investigate the effect of air circulation and forced ventilation of greenhouse on the development of fermented fruits in an oriental melon. An air circulation system and a forced ventilation system were operated during 09:30~17:00 at a 15 min. interval from Apr. 6, 5 days after fruit setting, to Jun. 29, everyday except rainy days. Wind velocities in the greenhouse were 0.06~0.08, 0.24~0.32, and 0.60~0.72m.s$^{-1}$ in the naturally ventilated (control), in the air circulated, and including leaf length and width, were observed between treatments. However, the amount of xylem exudate increased in the air circulated treatment as compared to the control. Percent of fermented fruits significantly decreased in the air circulated treatment as compared to the control. The forced ventilation treatment showed no significant difference in percent of fermented fruits as compared to the control or to the air circulated treatment.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.540-545
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• 2008

An atrium has great potential in natural ventilation aided by buoyance effect. Architectural design of an atrium is very critical to maximize the effect. However, it is not easy of an atrium to have optimum shape for natural ventilation, from the aesthetic and economic point of view. Admitting this condition, we suggested a strategy to promote natural ventilation, which can be adopted only with small design change. At first, we installed BIPV on the top of an atrium to strengthen buoyancy effect, and combine forced ventilation by low pressure fan. To evaluate the performance of the measure, CFD simulation and Energy-Airflow analysis were achieved.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.7
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• pp.541-548
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• 2006

A hybrid ventilation system was introduced to predict the ventilation performance of the apartments. This ventilation system was composed of the natural supply-air inlet and the forced exhaust-air outlet. Analysis was conducted by CFD technique and was performed on three ventilating flow rates; 30, 60, $120m^3/h$. As the results, residents feel comfortable thermally for $60m^3/h$. In the case of $120m^3/h$, however, residents feel uncomfortable both thermally and in air currents. In this study the energy saving for space heating is also an important factor. In the case of whole region with $180m^3/h$, residents feel comfortable at each region of the model apartment. It is shown that this hybrid ventilation system is possible method for the apartment house.

• Journal of Distribution Science
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• v.17 no.7
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• pp.65-76
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• 2019

Purpose - The purpose of this study is to investigate economical ventilation effectiveness to reduce hazardous materials exposure and damage of workers by analyzing exposure amount of noxious substances under various ventilation conditions of nail salon for indoor environments. Research design, data, and methodology - This study was carried out with cooperation of Nail shop located in SeongNam city to involve an analysis of the environmental impact indoor air quality, pollutant exposure and economical cost-effectiveness in the nail workplace. The hazardous substances were PM-10(Particulate Matter-10㎛), VOCs(Volatile Organic Compounds) and Formaldehyde, which are the major materials of nail workplace. Results - PM-10 is reduced by about 60% with air cleaner, forced artificial ventilation by 32%, and natural ventilation by about 12%. TVOCs and Formaldehyde showed similar efficiency (80~100%) after natural ventilation and ventilation after 60 minutes. The removal efficiencies of VOCs and formaldehyde were similar to those of natural ventilation and mechanical ventilation system. However, in case of dust, natural ventilation was reduced by artificial ventilation system due to inflow of external dust during natural ventilation. Conclusions - If the pollution degree of outdoor air is not high, air volume is high, and natural ventilation is performed when the air conditioning and heating system is not operated. Even at the end of the work, it keeps operating for 60 minutes to remove the pollutants generated. Results of this analysis demonstrated that the worker environment can be improved by adopting institutional legislation and guidelines for ventilation.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1970-1974
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• 2010

This paper is how to improve contaminated air by the pollutant from vehicles through ventilators and entrance at the underground station. We are looking for the environment management to take care of customers. There is two ventilation systems. One is natural ventilation system, the other is forced ventilation system. Usually, subway ventilators were installed low on the sidewalk. There are lots of craps on the ventilators, so these things interrupt influx of outside air. But the gas from the vehicles comes into the station through entrance. There is lots of noise while ventilations run. So we install the supply air vents away from the road for the customers. If it's difficult, we cover around the ventilator with clear plastic plates more than 2M heights. We also install silencer on the ventilators. We install the air curtains on the entrances to prevent dust from outside. Seoul Metropolitan has a plan to make 60M deep underground road. To improve underground road air quality, ventilators should be installed that consider the above information.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1427-1435
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• 2001

Air movement in wokplaces, whether resulting from a forced ventilation system or naturally occurring airflow, has a significant impact on occupational health. In a huge shipbuilding factory building, typical harmful factors such as fume or vaporized gas from welding and cutting of steel plates, and dusts from grinding give unpleasant feeling. From field data survey, the yearly dominant, wind directions for the shipbuilding factory building tested were northwest, northeast and southeast Among the three wind directions, the ventilation improvement was the worst for the northeastern wind. This study was focused on location of the opening vents in order to utilize the natural ventilation effectively. Instantaneous velocity fields inside the 1/1000 scale-down factory building model were measured using a 2-frame PIV system. The factory building model was embedded in an atmospheric boundary layer simulated in a wind tunnel. The modified vents improve the internal Ventilation flow with increasing the flow speed more than two times, compared with that of present vents.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.33-38
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• 2005

A hybrid ventilation system was introduced to predict the ventilation performance of the apartments. This ventilation system was composed of the natural supply-air inlet and the forced exhaust-air outlet. Analysis was conducted by CFD technique and was performed on three ventilating flow rates; 30, 60, 120 $m^3/h$. As the results, residents feel comfortable thermally and in air flow conditions for 60 $m^3/h$. But the case of 30 $m^3/h$ shows 1100ppm of $CO_2$ concentration due to the deficient of air flow rate. In the case of 120 $m^3/h$, however, residents feel uncomfortable thermally and in air currents. In this study the energy saving for space heating is also an important factor. A detailed prediction for more complicated whole apartment space will be investigated in the future.