• Journal of Korean Society for Atmospheric Environment
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• v.9 no.3
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• pp.236-241
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• 1993

Recently, with the ourdoor air pollution, the indoor air pollution devided into living environment and working environment are raised as the problem of indoor space. Also, the more time lived in indoor space, the larger the influence of indoor air pollution. Therefore in this study, the spatial variation of ventilation efficiency was estimated through the experiment using a physical model. The experiment using a physical model. The experiment was conducted in two category; the central zone of ventilated air flow and the corner zone. As the result of experiment, high ventilation efficiency (90$\sim$108%) was shown in the central zone of ventilated air flow. Whereas low ventilation efficiency (46$\sim$77%) was shown in the corner zone. In conclusion, when the designing of ventilation was planned, the zone showed low ventilation efficiency should be considered.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.676-682
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• 2002

The laminar convective heat transfer in ventilated space with various horizontal partitions was studied numerically and experimentally For the numerical study, the governing equations were solved by using a finite volume method for various numbers Re, Gr, Pr and partition numbers. The experimental study was conducted by using a holographic interferometer. The isotherms and velocity vectors have been presented for various parameters. As the number and length of partition increased, convective heat transfer decreased. Based on the numerical data, correlation equations were obtained for the mean Nusselt number in term of Gr/Re$^2$. In the region of Gr/Re$^2$$\leq$ 1, the mean Nusselt number was small, but in the region of Gr/Re$^2$> 1, the mean Nusselt number was constant.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.300-306
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• 2016

The gas ventilated by supercavitation splits into smaller bubbles and follows the water passage of the cavitation tunnel. The bubbles quickly return to the test section by rather high speed flow, and interrupt the observation of the supercavitation. To secure clear observation in the test section, the bubble collecting section(settling chamber) of large volume is prepared to collect bubbles in the water passage ahead of the test section. The bubble collecting section should provide enough buoyancy effect to the bubbles for proper bubble collecting. However, rather high-speed oncoming flow produces non-uniform velocity distribution and deteriorates buoyancy effect in the bubble collecting section. In the present study, the bubble collecting space and three porous plates are designed and analyzed through numerical methods, and the bubble collecting function is experimentally validated by 1/10-scaled model in terms of the formation of uniformly low velocity distribution in the bubble collecting section.

• Fire Science and Engineering
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• v.27 no.3
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• pp.20-29
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• 2013

To investigate numerically the effects of geometry and location of vertical opening on the thermal and chemical fire characteristics in full-scale under-ventilated compartment fires, the ventilation factor ($A\sqrt{h}$) to estimate a theoretical maximum inflow of ambient air and the mass loss rate in a heptane pool fire were fixed for all cases. It was shown that variations in door geometry affected significantly the change in thermal and chemical characteristics inside the compartment. Variations in window location resulted in the complex change in additional fire characteristics including the fire duration time and recirculating flow structure. These results were analyzed in details by the multi-dimensional flow and fire characteristics including the vent flow and fuel/air mixing phenomena.

• Korean Journal of Human Ecology
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• v.20 no.5
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• pp.1059-1074
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• 2011

The purpose of this study is to provide a practical guide for planning the private and shared space of student housing for one person household by analyzing their satisfaction and preference. The data was collected through a questionnaire-survey from the students of the university in the city of Cheongju, Chungbuk. 191 samples were collected and analyzed by using SPSS-PC. The results are as follows: (1) this survey showed that most students are dissatisfied with private and shared spaces to narrow size, an unpleasant indoor environment, and incomplete facilities. (2) The most preferred housing type is an officetel in one room style because of its convenience. The majority of students preferred a bedroom, bathroom, kitchen and dining room in personal preferential order with a wide room, well-ventilated environment, and reasonable space zoning for planning the private space. Broad personal spaces with shared spaces such as a study room, cafeteria and health zone are in demand for unit planning. Therefore, to provide privacy for personal living and to develop community spirit, there needs to be a movement to better for community living by arranging optional shared spaces.

• Wind and Structures
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• v.19 no.2
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• pp.185-197
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• 2014

Ventilation and fire safety design in road tunnels are one of the most complex issues that need to be carefully considered and analysed in the designing stage of any potential upgrade of ventilation and other fire safety systems in tunnels. Placement road tunnels space has an important influence on fire safety, especially when considering the effect of adverse wind conditions that significantly influence ventilation characteristics. The appropriate analysis of fire and smoke control is almost impossible without the use of modern simulation tools (e.g., CFD) due to a large number of influential parameters and consequently extensive data. The impact of the strong wind is briefly presented in this paper in the case of a longitudinally ventilated road tunnel Kastelec, which is exposed to various severe wind conditions that significantly influence its fire safety. The possibility of using CFD simulations in the analysis of the tunnel placement in space terms negative effect of wind influence on the tunnel ventilation is clearly indicated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.12
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• pp.1230-1235
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• 2001

The laminar convection heat transfer in a ventilated space with various horizontal partitions was studied numerically and experimentally. The experimental results by holographic interferometer showed good agreements with the numerical results. For the numerical study, the governing equations were solved by using a finite volume method for $46.6\leqRe\leq1332,\;1460\leqGr\leql1585$, Pr=0.71 and the variations of partition lengths. The isotherms and velocity vectors have been represented for various parameters. As the length of partition increases, the convection heat transfer decreases. Based on the numerical data, a correlation was obtained for the dimensionless mean Nusselt number in terms of $Gr/Re^2$. In the region of $Gr/Re^2$<1, the mean Nusselt number was very small, but in the region of $Gr/Re^2\geq1$, the mean Nusselt number was constant.

• Journal of Preventive Medicine and Public Health
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• v.14 no.1
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• pp.23-31
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• 1981

This study was conducted to investigate the effects of passive inhalation of cigarette smoke and the correlation between change of flicker value and active or passive smoking in poorly ventilated room. Forty five male students were tested by divided into four experimental groups composed of active and passive smokers and three control groups. Each four experimental groups were exposed to smoke for Two hours in enclosed room. Vital capacities, flicker values, blood carboxyhemoglobin levels and carbon monoxide concentration in room air were estimated before, during and after the exposure, and amounts of smoking or smoke exposure during two hours were also noted. The results obtained were as follows; 1. Concentration of carbon monoxide in air and increase of blood carboxyhemoglobin level (% COHb) were positively correlated with smoking amount. 2. Increase of blood carboxyhemoglobin in passive smokeres, in average, were about seventy six percent of that in smokers, as 2.2% vs. 2.9%. 3. Comparison with published data showed that Peterson's equation gave most similar result to this study in estimation of increase of blood carboxyhemoglobin level. 4. During the exposure, flicker values fell steadily in both experimental groups and control groups as time passed. Flicker values were, however, elevated again in experimental groups after exposure, despite the fact that values still fell in control groups. 5. Blood carboxyhemoglobin and flicker value were negatively correlated and this correlationship was stronger in passive smoker than in active smoker. 6. Multiple regression equation between flicker value and exposure time and blood carboxyhemoglobin level was expressed as: Flicker value=41.6-0.2 COHb%-0.9Hour, 7. In general, it is suggested that biological criteria would be more preferrable than chemical criteria in establishment of statutory limitation of smoking in enclosed spaces.

• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.29-37
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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 standard k-${\epsilon}$ model was carried out. In the present study, the marine engine room is separated to two floors with porus horizontal partition and considered as a closed space with a heat source and forced ventilation ducts. The porosity of horizontal partition is found to be important. For the engine room with 2 supply ports & 2 exhaust ports, the increasing of the porosity of horizontal partition is effective to reduce the recirculation flow zone in the second floor. When the engine room is ventilated with three supply air ports & one exhaust port, the increasing of the porosity of horizontal partition is effective to reduce the recirculating flow zone in the exhaust air area, but there is a possibility of local extreme heating at the lower side of engine near bottom.

• International Journal of High-Rise Buildings
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• v.2 no.4
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• pp.293-314
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• 2013

Double-Skin Façade (DSF), which is a kind of passive indoor environmental control technique, is effective way to control environmental loads while maintaining the transparency especially in perimeter zone and hence the adoption example of DSF keep increasing recently. The objective of this study was to perform a field survey of air quality environment with natural ventilation through DSF and thermal environment within office building with six stories during a mild climate period in Japan. Moreover, to understand the comprehensive environmental performance of the target building, questionnaire survey was conducted to subjectively evaluate the productivity and satisfaction with the environmental factors in office space. In this field measurement, there was a positive correlation between the DSF internal ventilation flow and the amount of solar radiation on the DSF normal surface; the primary driving force for ventilation in the DSF was considered to be the buoyancy force caused by solar radiation. The results of questionnaire survey with regard to productivity level indicated the need for improvement in the thermal (temperature) and spatial environment (room size and furniture placement).