• Fire Science and Engineering
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• v.23 no.5
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• pp.117-124
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• 2009

The objective of this research is to analyze the ventilation performance of mechanical ventilation systems to enhance removal efficiency of indoor hamful gases. The ventilation performance is evaluated using a step-down method based on ASTM Standard E741-83. The ventilation performance is evaluated as a function of the ventilation rate and supply/extract locations using a tracer gas ($CO_2$) technique. As a result, the $CO_2$ concentration as a function of time is decayed exponentially and the ventilation performance is found to increase with increased the ventilation rate. The ventilation performance of the second type ventilation system is better than that of the first type or the third type. The ventilation performance without human occupancy increases up to 55% and the ventilation performance with one person increases up to 25% at the supply air of 570Lpm comparing with a natural reduction after one hour in the test chamber. The ventilation performance is better than 15% comparing with natural decay at the supply of 570Lpm in an office room.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.111-116
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• 2008

The objective of this paper was to show the possibility of demand-controlled ventilation (DCV) using the current Korean ventilation standard for multi-purposed facilites. Two attractive DCV approaches; $CO_2$-DCV and RFID-DCV were applied to DCV simulations for a theoretical public assembly space served by a dedicated outdoor air system (DOAS) with enthalpy recovery device. A numerical model for predicting realtime occupant number, ventilation rate, and $CO_2$ concentration under given conditions was developed using a commercial equation solver program. It was found that the current ventilation standard causes unstable ventilation system control in DCV applications, especially under $CO_2$-DCV. It is because the ventilation rate (per person) used in Korea is the sum of the outdoor air required to remove or dilute air contaminants generated by both occupant and building itself, and not a pure function of occupant numbers. Finally, it makes DCV control unstable when ventilation flow is regulated only by the number of occupants. In order for solving this problem, current Korean ventilation standard was modified as a form of ASHRAE Standard 62.1-2007 showing good applicability to various DCV approaches. It was found that this modification enhances applicability of the current ventilation standard to DCV significantly.

• Proceedings of the SAREK Conference
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• 2006.11a
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• pp.68-68
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• 2006

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.610-619
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• 2022

Hydrogen is emerging as an alternative fuel for eco-friendly ships because it reacts with oxygen to produce electrical energy and only water as a by-product. However, unlike regular fossil fuels, hydrogen has a material with a high risk of explosion due to its low ignition point and high flammability range. In order to safely use hydrogen in ships, it is an essential task to study the flow characteristics of hydrogen leakage and diffusion need to be studied. In this study, a numerical analysis was performed on the effect of leakage, ventilation, etc. on ventilation performance when hydrogen leaks in an enclosed space such as inside a ship. ANSYS CFX ver 18.1, a commercial CFD software, was used for numerical analysis. The leakage rate was changed to 1 q, 2 q, and 3 q at 1 q = 1 g/s, the ventilation rate was changed to 1 Q, 2 Q and 3 Q at 1 Q = 0.91 m/s, and the ventilation method was changed to type I, type II, type III to analyze the ventilation performance was analyzed. As the amount of leakage increased from 1 q to 3 q, the HMF in the storage room was about 2.4 to 3.0 times higher. Furthermore, the amount of ventilation to reduce the risk of explosion should be at least 2 Q, and it was established that type III was the most suitable method for the formation of negative pressure inside the hydrogen tank storage room.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2006.06a
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• pp.62-62
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• 2006

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.116-118
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• 2005

The ASHRAE first ventilation standard was established in 1973. This standard has been revised regularly, and recently the ventilation standard for residential building was issued separately. Two ASHRAE ventilation standards are introduced in this article.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.521-530
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• 2009

This study has been made to execute a research in order to lead the improvement of indoor air quality, examining the indoor ventilation characteristics by using a numerical analysis method. To this end an extensive parametric investigation are made according to various external flow variables such as main wind direction and wind speed by season, building layout design, and location of ventilators, etc. in Daedeok Techno Valley, one of large-scaled apartment in Daejeon. It is observed there was a significant difference of main wind direction between summer and winter. The main wind direction in summer was a south wind, and on the contrary the direction in winter is northnorthwest, which is similar to the average main wind direction for 10 years. One of the important calculation results is that the change of wind direction causes a significant effect on the apartment ventilation by the change of pressure difference around each complex of apartment. In case of favorable area of ventilation, the indoor ventilation rate can meet 0.7 ACH from the standard value only with natural ventilation. On the contrary, in other area the value was much lower than the standard value. If the calculation result applies to the design of layout apartment or placement of ventilators, it will be greatly helpful to the energy saving because it can be parallel with the natural ventilation to help securing ventilation rate, not much depending on the mechanical ventilation.

• Tunnel and Underground Space
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• v.22 no.3
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• pp.163-172
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• 2012

As more diesel engines have been employed in underground limestone mines with large cross section, underground space environment is worsened by diesel exhausts and heat flow. This paper aims for the ultimate goal to optimize the work place environment through assuring the optimal required ventilation rate based on the analysis of the airflow, diesel exhaust gas concentrations and the effects of mechanization and deepening working face on temperature and humidity. Due to the insufficient capacity of the main exhaust fan and poor airway management, stagnant airflows were observed at various locations, while the flow direction was reversed instantly with passing diesel equipment and the flow reversal was also made by the seasonal variation of the outside surface weather. During the loading operation, CO concentration measurements were found to be frequently higher than the threshold limit of 50 ppm, and most of the $NO_2$ measurements during drilling and loading operations shows even more serious levels surpassing the permissible limit of 3 ppm. The actual ventilation quantity was considerably less than the required quantity estimated by the mine health and safety law, and this shortage problem was less serious in colder winter showing more effectiveness of the natural ventilation.

• Fire Science and Engineering
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• v.31 no.2
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• pp.113-118
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• 2017

The purpose of this study was to compare the ventilatory volume and airway pressure using Oxylator EM-100, MicroVenT CSI-3000, OXY-LIFE II. The data were obtained from February 13 in 2017 andanalyzed using the SPSS WIN 18.0 program. The results of theventilatory volume showed the Oxylator EM-100 551.44 ml (${\pm}18.70$), MicroVenT CSI-3000 527.26 ml (${\pm}17.98$), and OXY-LIFE II 369.46 ml (${\pm}12.30$). The airway pressure showed the Oxylator EM-100 $11.89cmH_2O$ (${\pm}.41$), MicroVenT CSI-3000 $11.66cmH_2O$ (${\pm}.34$), and OXY-LIFE II $8.02cmH_2O$ (${\pm}.25$). This study will provide the basic data for an appropriate ventilation method by an oxygen supply device including Oxylator EM-100, MicroVenT CSI-3000, and OXY-LIFE II.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4001-4007
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• 2011

In this study, we selected ten normal women in their 20's and 4 weeks measured Exercise Intensity, Voluntary Ventilation, Respiratory Exchange Ratio, Oxygen and Calorie Consumption and Ventilation Equivalent of them during Normal Gait, Splint-equipped Gait and Crutch Gait With Splint in order to find out whether the movement limitation and the weight of orthosis could have an effect on energy consumption. Each gait was conducted at a comfortable speed, 2.74 km/h for 30 minutes equipped with splint whose average weight is 1.2 kg. In the result of the study, The Crutch Gait With Splint showed high Exercise Intensity compaired to Normal Gait and Splint-equipped Gait. In addtion, in The Voluntary Ventilation and Oxygen Consumption, The Crutch Gait showed higher figures than two the others and the difference was significant as well(p<0.05). As for The Calorie Consumption, it also showed higher figures than two the others but the difference was not statistically significant. Finally, in The Respiratory Exchange Ratio and The Ventilation Equivalent, there was no significant difference among three conditional variables.