• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.683-690
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• 2021

The ventilation system of the engine room of a ship is generally installed to supply the combustion air necessary for the internal combustion engine and to remove the heat source generated in the engine room, and it must satisfy the international standard (ISO 8861) for the design conditions and calculation standards for the ventilation of the ship engine room. The response delay of the ventilation system including the fire detector is affected by the airflow formed inside the area and the location of the fire detector. In this study, to improve the initial fire detection response speed of a fire detector installed on a fishing vessel and to maintain the sensitivity of the installed detector, the smoke behavior was simulated using the air flow field inside the engine room, the amount of combustion air in the internal combustion engine, and the internal pressure of the engine room as variables. Analysis of the simulation results showed that reducing the flow rate in the air flow field and increasing the vortex by reducing the internal pressure of the engine room and installing a smoke curtain would accelerate the rise of the ceiling of the smoke component and improve the smoke detector response speed and ventilation system.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.3
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• pp.137-146
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• 2007

CFD simulation is a very useful tool to predict the concentration of contaminant generated from the building materials in a single room. However, there is a limitation on analyzing air movement and contaminant concentration in a multi-room when the door of each room is closed. In this study, network based simulation was coupled with contaminant simulation for the multi-room condition, using an network simulation tool 'ESP-r'. The coupled simulation was first validated with experimental measurements which performed to define the characteristics of the analyzed space prior to the simulation, and indoor air flow and contaminant concentration between rooms were then analyzed when the door of each room was open and closed in the case of natural and forced ventilation.

• Journal of Mechanical Science and Technology
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• v.14 no.11
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• pp.1286-1295
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• 2000

The ventilation effectiveness is evaluated as a function of air exchange rate and supply / extract locations in a simplified model chamber using a tracer gas technique of CO$_2$ gas injected into a supply duct. Ventilation systems consist of supply and extract fans, a CO$_2$gas generator, a CO$_2$gas analyzer and a test chamber. The ventilation effectiveness is evaluated using a step-down method based on ASTM Standard E741-83. The room mean age of the model chamber is decreased with increasing air exchange rate fanged from 6to 10 air changes per hour. The ventilation effectiveness of the mechanical inlet/natural extract system is better than that of the mechanical extract system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.57-66
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• 2006

The experimental and the numerical study was performed on the comparison of thermal comfort(TC) and indoor air quality(IAQ) in the lecture room for cooling loads when the operating conditions are changed. PMV value and $CO_2$ concentration of the lecture room were measured and compared with the numerical results. The numerical results showed a good agreement with the experimental one and then the numerical tool was used to analyze thermal comfort and IAQ for a couple of operating conditions. As a result it was found that the increment of the discharge angle of system air-conditioner makes TC uniformity worse, but rarely affects IAQ. Also TC and IAQ were hardly affected by the variation of the discharge airflow. Finally it turned out that TC is merely affected by the increment of the ventilation airflow, but the average $CO_2$ concentration can be satisfied with Japanese IAQ standards of classrooms when the ventilation airflow is more than $800m^3/h$ in this study.

• Journal of The Korea Institute of Healthcare Architecture
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• v.14 no.4
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• pp.39-46
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• 2008

Construction and operation of Germ Free Pigs' facilities are very expensive because pigs' rooms and other major rooms of the facility require germfree environments. Especially, running the HVAC system of aseptic facilities requires a lot of expenses. However, proper location and efficient shape of outlets/inlets for the ventilation of the room can reduce the excessive running cost. In order to do that, this study proposes alternative location and shape of ventilation outlets/inlets to the existing design pattern in germfree pigs' room. The design condition of this study is the maintenance of adequate temperature(24$^{\circ}C$, $NH_3$concentration level(below 1.5 ppm), and air stream speed(below .25m/sec) in the pigs' room for the summer and the winter together. As the Software Program, FLUENT(Ver. 6.2) has been used for the analysis of proposed ventilation patterns. In conclusion, wall inlets and ceiling inlet/outlet are advisable in summer, wall inlets and ceiling outlets is advisable in winter. As far as the shape is concerned, diffuser type for the ceiling outlet is desirable.

• Journal of Environmental Science International
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• v.27 no.6
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• pp.359-369
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• 2018

A model has been developed to predict natural ventilation in a single zone building with large openings. This study first presents pressure-based equations on natural ventilation, that include the combined effect of wind and thermal buoyancy. Moreover, the concept of neutral pressure level(NPL) is introduced to consider the two-way flow through a large opening. The total pressure differences across the opening and the NPL are calculated, and nonlinear equations are solved to find the zonal pressure to satisfy mass conservation. For this analysis, an iterative technique of successively approximating the zonal pressure is used. The results of applying this study model to several simple cases are as follows. When there is no wind and only the stack effect is caused, a one-way flow occurs in both the top and bottom openings in the case of two openings of equal-area, and a one-way flow occurs in the top opening; however, a two-way flow occurs in the bottom opening in the case of two openings of unequal-area. When there is a wind effect, regardless of whether the outside air temperature is lower or higher than the indoor air temperature, air flows into the room through the bottom opening and out of the room through the top opening. As the wind velocity increases, the wind effect appears to be more influential than the stack effect owing to the temperature difference.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.411-416
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• 2006

In this paper, we performed the experimental and numerical study on the thermal comfort(TC) and indoor air quality(IAQ) in the lecture room with a different airflow rate of the ventilation system and heating system for heating season. Through the experimental results, we found out that there was considerably difference of the PMV but there was little difference of $CO_2$ concentration with a different heating system. From a numerical results, the best operating condition was that discharge airflow rate of SAC is 29 CMM and supply airflow rate of the ventilation system is 1,200 CMH from a viewpoint of TC and IAQ.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.375-380
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• 2006

Embedded Duct Ventilation System in Ondol is embedded supply duct in Ondol. This system allows heat up outside air to inside temperature with out using heat exchanger and electric heating coiling in winter season. In this research, we measured temperature of inside and surface of Ondol, supply duct, and supply air temperature incorporate embedded duct ventilation system in Ondol in model house($110m^2$) & one room($23m^2$)

• Fire Science and Engineering
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• v.31 no.4
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• pp.26-34
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• 2017

The purpose of this study is to identify and improve the performance of the adjacent room ventilation system in living room ventilation facilities, and compare and analyze the smoke control regulations of the NFPA code and the national fire safety standard (NFSC). The analysis method was fire dynamics simulation (FDS) and was used to analyze the, variations of the air supply amount, width of the boundary, change in indoor combustion and wind velocity of the incoming air. It was found to be advantageous to secure the clean layer when the amount of air supplied is less than the amount of discharged air in the fire room. However, in the supply room, it is more effective to secure the clean layer when the amount of supplied air is larger than the amount of discharged air, as a longer boundary width gives rise to better performance. In addition, it is necessary to consider the amount of air supplied and discharged as a function of the kind of flammable material. Moreover, decreasing the air inlet wind speed and amount of incoming air is advantageous for securing the clean layer of the fire room.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.576-584
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• 2007

A PIV(Particle Imaging Velocimetry) diagnostic technique for the evaluation of the flow characteristics in refrigerator is introduced. Smoke particles of which density is small enough to follow up the air flow are used for visualization of the air flows in the refrigerators. A rectangular room model is tested for the verifications of the dignostic technique. By evaluating the turbulent intensity and the deviation value of the turbulent intensity distribution that were obtained from PIV results, an optimal ventilating condition is suggested. The constructed technique is used for the diagnostics on the flow of an actual refrigerator. It has experimentally proved that the present technique is able to evaluate the ventilation conditions of refrigerators.