• Journal of the Korean Solar Energy Society
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• v.25 no.2
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• pp.71-79
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• 2005

In this study, the ventilation performance of mechanical ventilation system in apartment House was analyzed through model test according to characteristics of air-vent. Then adequate interval of air-vent was suggested using computer simulation which will create comfort environment through improvement of ventilation performance in apartment house. The result of experiment with separation plate to prevent mixture of contaminated exhaust air with fresh supply air, the ventilation efficiency improved about 10%. The result of simulation with horizontal location of exterior air-vent, contaminated exhaust air is mixed regardless of interval variation. Consequently, mixture of the exhaust air can be prevented through locating the supply air vent on the top side and exhaust air vent on the lower side.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.845-856
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• 2017

In the long railway tunnel, in order to secure safety in case of fire, it is required a emergency station. However, there is no standard or research results on smoke exhaust method and exhaust flow rate in emergency station, so it is necessary to study the smoke exhaust system for emergency station. In this study, we are created a numerical analysis model for emergency station where the evacuation cross passage connected to the service tunnel or the relative tunnel was installed at regular intervals (40 m intervals). And the fire analysis are carried out by varying the fire intensity (15, 30MW), the smoke exhaust method (only air supply, forced air supply and exhaust, forced air exhaust only), and the air flow rate (7, 14, $40m^3/s$). From the results of fire analysis, temperature and CO concentration are analyzed and ASET based on the limit temperature are compared at various condition. As a result, in the case with fire intensity of 15 MW, it is shown that a sufficiently safe evacuation environment can be ensured by applying forced air supply and exhaust method or forced air exhaust only method when the air flow rate is $7m^3/s$ above. In case of fire intensity of 30 MW, it is impossible to maintain the safety evacuation environment for more than 900 seconds when the exhaust air volume is below $14m^3/s$. And when the air flow rate is $40m^3/s$, the exhaust port is disposed at the side portion of the upper duct, which is most advantageous for securing the temperature-based safety.

• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.4
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• pp.12-18
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• 1995

To improve the performance of diesel automobile engine, we designed new fuel supply system named ultrasonic fuel supply system. The performance test of diesel automobile engine carried out to examine possibility of practical use of ultrasonic fuel supply system to test engine. This paper deals with the comparative results of performance test of diesel automobile engine in terms of smoke, HC, SFC, PS, thermal, efficiency, torque. Following are obtained result. 1) In naturally aspirated diesel engine, when we use ultrasonic fuel supply system output, fuel consumptions are improved and exhaust gas reduced significantly. 2) In turbo-charging diesel engine both using of ultrasonic fuel supply system and using of conventional injector, engine performance and exhaust gas temperature are almost constant. 3) In turbo-charging diesel engine, when we use ultrasonic fuel supply system, NOx are emitted approximately 3.5% higher than total average. 4) In turbo-charging diesel engine, when we use ultrasonic fuel supply system, smoke and CO are 17% and 11.8% improved respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.411-415
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• 2008

This paper presents on design factor considered in an altitude test cell facility to determine the best sizing to optimize exhaust diffuser pressure recovery and the exact cooling load required to be supplied under transient operation. Engine simulation was performed to analyse the exhaust gas temperature, exit mass flow rate, specific fuel consumption and exhaust velocity helpful in determining secondary mass air flow and the mixed air temperature entering the ejector. based on this, the amount of cooling load was deduced. It was found that improved pressure recovery reduces operational cost(air supply facility, cooling water).

• Fire Science and Engineering
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• v.30 no.2
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• pp.68-74
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• 2016

In semi-transverse ventilation system applied for road tunnel, adjustment of the port opening ratio is an essential part for uniform airflow rate per unit length over the entire tunnel. However, it has not been considered decently throughout the design process and operating of the tunnel. Therefore, in this study, we developed a program for the calculation of the opening size ratio of supply or exhaust port in transverse ventilation system and carried out the research to present a management plan for the port. In supply duct system, the opening size of the port had a tendency to increase and then decrease later when it gradually becomes closer toward the bulkhead at the beginning of the duct the minimum opening degree is to appeared as 56%. In the exhaust system, port size is the smallest at the beginning of duct as 15%, has shown a tendency to increase towards the bulk head. As results of estimating the air flow rate for 300 m intervals, the exhaust flow rate in the center of tunnel appeared to be extremely low as 8.1% and 12.5% when port size is constant and is adjusted supply type. Thus, even if the normal ventilation efficiency is declines, yet it is highly recommend adjusting the port size in order to obtain a uniform flow rate at fire accidents.

• Journal of Urban Science
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• v.9 no.2
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• pp.13-20
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• 2020

The Recently, several countries have been affected by respiratory diseases, resulting in renewed research interest in their prevention and control. One such example was the 2015 outbreak of Middle East Respiratory Syndrome (MERS) in South Korea and COVID-19. In this study, we performed experiments and simulations based on concentration decay using CO2 as the tracer gas to elucidate the pollutant-removal efficiency for different inlet and exhaust locations and outdoor air-supply ratios. The wall inlet exhibited a higher pollutant-removal efficiency, owing to the upward movement of the air from the lower zone to the upper one. In conclusion, it is recommended that a total air-conditioning plan for isolation rooms be established as well as efficient system operation for pollutant removal and air-flow control to prevent the transmission of infections from the patients to others.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1091-1096
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• 2004

It is necessary to consider the stability, economic environmental-friendly problems by the development of the road, supply of the automobile, environmental problem as designing the exhaust system. To reduce the noise and the vibration of the automobile. The need for stricter regulation limits emission and demand for lower fuel comsumption. According to motor vehicle company develop variable type muffler, dual muffler and active intelligence exhaust system unit. Improvement in engine performance and fuel consumption for demand information of pressure fraction and heat characteristics. To be able to determine these factor for we experiment on each case of exhaust system unit. In this study, in order to establish the optimized conditions design factors which are taking many performance as the variable valve, it shows how the standard performance and the additional element of the exhaust system effects on the engine performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.12
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• pp.1691-1698
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• 2003

In this paper, the combination effects of oxygen component in fuel and exhaust gas recirculation on the exhaust emissions have been investigated for a direct injection diesel engine. It is a kind of effective oxygenated fuel of diether group that the smoke emission of DGM(diethylene glycol dimethyl ether) blended fuel is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in diesel engine. But, NOx emission of oxygenated fuel was increased compared with commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel(DGM 5vol-%) and cooled EGR method(10∼15%).

• Journal of Aerospace System Engineering
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• v.14 no.6
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• pp.85-90
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• 2020

The infrared signature that is associated with an aircraft is mainly caused by heat released from the engine and the exhaust plume. In this study, a test-system was designed to observe the overall infrared signature characteristics of a turbofan engine during operation under ground running conditions and the infrared reduction features that result from different exhaust nozzle configurations. A test stand was designed for the 1400 lbf class turbofan engine that included a bell-mouth type intake, fuel supply system, a measurement system, and a data acquisition/control system. The design and verification of the test system were conducted so that the basic nozzle and various 2D nozzles could be applied to study the infrared signature produced by a turbofan engine exhaust.