• 한국안전학회지
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• 제18권2호
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• pp.40-45
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• 2003

To evaluate the smoke control systems, the large eddy simulation turbulence model based Fire Dynamics Simulate was applied to a 2m $\times$ 2m $\times$ 2.4m room with an opening. The smoke removal rate was investigated for three different smoke control systems: ventilation, extraction and pressurization. When the opening was closed, the smoke removal rates of the smoke control systems were almost the same as expected. The pressurization system showed a lower smoke removal rate compared with the other two smoke control systems for the room with the opening, and hence the pressurization system might not be efficient for a place with large openings. It was shown that the lower extraction flowrate is, the longer time the ventilation system requires to remove smoke. From these results, the ventilation system is recommended for subway stations where several large openings exist.

• Journal of Advanced Marine Engineering and Technology
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• 제22권1호
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• pp.100-107
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• 1998

Ventilation of the marine engine room is very important for the health of the workers as well as the nomal 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 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 downword angle depresses recirculation flow, causing a strong steam 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 engine when supply and exhaust ports of air are in bilateral symmetry. The effect of the increase of exhaust port area on ventilation decreases as the number of supply port increases.

• 설비공학논문집
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• 제16권9호
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• pp.838-844
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• 2004

In a long road tunnel, a tunnel ventilation system may be used in order to reduce the pollution below the required level. To develop control algorithms for a tunnel ventilation system, a dynamic simulation program may be used to predict the pollution level in a tunnel. Research was carried out to develop better pollution models for a tunnel ventilation control system. A neural network structure was adopted and compared by using actual poilution data. Simulation results showed that the dynamic model developed by a neural network may be effective for the development of tunnel ventilation control algorithms.

• 한국태양에너지학회 논문집
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• 제22권4호
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• pp.68-76
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• 2002

This paper discusses thermal and ventilation performance which might be caused by the adoption of one of specific building facade techniques, Double Skin System(DSS). One building with a prototypical DSS was selected and systematically investigated through field monitoring and computer simulation techniques. A network model of ventilation was successfully made using COMIS to evaluate ventilation performance of the system which can hardly be done by field measurements. Various operating conditions of air conditioning on/off and window opening were implemented in this type of building. Through the appropriate operation of the DSS in summer, simulation-based and experimental results implicate that it can lead to cooling energy savings.

• 한국환경보건학회지
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• 제46권6호
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• pp.627-635
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• 2020

Objectives: Indoor air quality has become more important aspeople spend most of their times indoors. Since students spend most of their times at home or at school, they are more likely to be exposed to indoor air pollutants. Ventilation in school classrooms can affect health and learning performance. In this study, ventilation deficiency was evaluated in school classrooms using Monte Carlo simulation. Methods: This study used sensor-based monitoring for six months to measure carbon dioxide (CO2) concentrations in classrooms in elementary, middle, and high schools. The volume of the classroom and the number of students were investigated, and the students' body surface area was used to calculate the CO2 emission rate. The distribution of ventilation rates was estimated by measured CO2 concentration and a mass-balance model using Monte Carlo simulation. Results: In the elementary, middle, and high schools, the average CO2 concentrations exceeded 1000 ppm, indicating that the ventilation rates were insufficient. The ventilation rates were deficient from July to August and in December, but showed relatively high ventilation rates in October. Forty-three percent of elementary schools, 56% of middle schools, and 62% of high schools showed insufficient ventilation rates. Conclusions: The ventilation rates calculated in elementary, middle and high schools were found to be quite insufficient. Therefore, proper management is needed to overcome the lack of ventilation and improve air quality.

• 설비공학논문집
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• 제23권1호
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• pp.8-15
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• 2011

Cooling load reduction was analysed of a ventilation system adopting a regenerative evaporative cooler. The regenerative evaporative cooler is a kind of indirect evaporative cooler which cools the air down to its inlet dewpoint temperature in principle without change in the humidity ratio. The regenerative evaporative cooler was found able to cool the ventilation air to $18{\sim}21^{\circ}C$ when the outdoor condition ranges $25{\sim}35^{\circ}C$ and 0.01~0.02 kg/kg. When the outdoor humidity ratio is lower than 0.018 kg/kg, the regenerative evaporative cooler was found to provide cooling performance enough to compensate the ventilation load completely and to supply additional cooling as well. Energy simulation during the summer was carried out for a typical office building with the ventilation system using the regenerative evaporative cooler. The results showed that the seasonal cooling load can be reduced by about 40% by applying the regenerative evaporative cooler as a ventilation conditioner. The reduction was found to increase as the outdoor temperature increases and the outdoor humidity ratio decreases.

• 한국안전학회지
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• 제27권3호
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• pp.89-95
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• 2012

The concentrations of Volatile Organic Compounds(VOCs) and Formaldehyde(HCHO) for interior materials of new vehicles are estimated and recognized by using the simulation program known as IAQx. The concentrations of contaminants are estimated and evaluated by the ventilation rates of new domestic vehicles and the required ventilation rates for new vehicles are estimated through the given contaminant data. This study is conducted to compare the ventilation rates for the contaminants between the discontinuously ventilated new vehicles and the continuously ventilated new vehicles using the simulation program. The equation of ventilation rate of new vehicles is acquired to be able to lower initial concentrations below the standard level under different conditions for both business and personal commuting.

• KIEAE Journal
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• 제10권5호
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• pp.87-93
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• 2010

The objective of this study is to verify the safety in case of fire and change of residential environment for different wall construction approaches in a stairways apartment house. In order to confirm that case_1, which is current case that most of wall is opened and the case 2, which upper part of wall is limitedly opened are compared and analyzed based on simulations of fire, escape and natural ventilation performance. The analysis reveals that possible escape time for case 1 was more than 600 seconds and for case 2 was 195 seconds. Since the escape times for both cases were over 128 seconds, it would be reasonable to assume that every resident would escape. The simulation results on natural ventilation performance shows the air change per hour of case 1 and case 2 were .19n/h and .16n/h and there was 1.2 times difference. However, the difference was too insignificant and it could be seen as that different approaches on wall construction would not significantly influence on natural ventilation performance.

• 대한기계학회논문집B
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• 제25권3호
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• pp.347-355
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• 2001

A heat transfer analysis in a ventilation chamber of Plasma Display Panel(PDP) has been conducted. The process requirement is to precisely follow prescribed temperature trajectory while maintaining temperature uniformity for each panel. Firstly, experiment in a test chamber has been carried out and the results are compared with the unsteady 3D numerical data. Reasonable agreement was found, which suggested that the employed numerical model had its credibility in actual PDP ventilation processes. On this ground, a tact-type heating/cooling system was analyzed. The panel temperature in the 40$^{\circ}C$ tact-type system was more uniform than that in the 80$^{\circ}C$ one. For improving the uniformity of panel temperature, relocation of ventilation head to the rear part and inlet flow control are required. Comparison of full simulation of a cart and simplified simulation of one panel indicates the optimized panel pitch can also be predicted.

• 한국가스학회지
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• 제15권3호
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• pp.31-38
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• 2011

본 연구에서는 미국 NIST의 Fire Dynamics Simulator (FDS) ver. 5.4.8을 이용하여 지하철 터널 안의 지하철에서 화재가 발생한 경우에 터널에 설치된 환기팬의 제연효과를 검증하였다. 시뮬레이션을 위해 서울 지하철의 실측 자료를 활용하여 지하터널과 지하철을 모델링 하였다. 이를 바탕으로 환기용량을 2.0~3.0 m/s 범위에서 변화시키면서 CO와 $CO_2$의 제거 효율을 예측한 결과, 0.5 m/s의 용량 증가에 의해 평균 35 % 이상의 제거효과가 있음을 확인하였다. 또한 FDS의 결과값이 전체 그리드 개수와 크기에 영향을 받는 점을 고려하여 정확한 결과값을 얻기 위해 FDS의 그리드 민감성을 검토하였다. 그리고 그리드 크기를 변화시켜 CO와 $CO_2$ 농도 산출값과 계산에 걸리는 시간을 비교한 결과를 바탕으로 최적의 그리드를 선정하여 시뮬레이션에 적용하였다.