• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.7
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• pp.485-496
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• 2018

In this paper, the smoke behavior in an underground station on operation of the fans in the ventiliation of the station was measured by the experimental method when the fire occurred in the underground station platform where the platfrom screen door was installed. The ventilation characteristics were compared when the ventilation system was operated and when the ventilation system was not operated when a fire occurred at the platform where the clean door was closed. To simulate the fire smoke, the smoke generated from the smoke generator was heated using a hot air fan. The transmittance was measured using a smoke density meter to quantitatively measure fire smoke. If the screen door is closed and the ventilation system of the underground station does not work, it is confirmed that if a fire occurs in the platform, smoke accumulates inside the platform, evacuating passengers is very difficult and can lead to a very dangerous situation. On the other hand, under the condition that the ventilation facility of the subway station is operated, the smoke evacuates to the outside through the ventilation facility of the underground station, and airflow is formed in the direction from the waiting room to the waiting area, so that the passenger located on the platform can safely evacuate toward the concourse. In the following paper, we will discuss the concurrent effect of tunnel ventilation through tunnel vent near the platform.

• Clinical and Experimental Pediatrics
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• v.53 no.1
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• pp.21-27
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• 2010

Purpose : In contrast with traditional time-cycled, pressure-limited ventilation, during volume-controlled ventilation, a nearly constant tidal volume is delivered with reducing volutrauma and the episodes of hypoxemia. The aim of this study was to compare the efficacy of pressure-regulated, volume controlled ventilation (PRVC) to Synchronized intermittent mandatory ventilation (SIMV) in VLBW infants with respiratory distress syndrome (RDS).Methods : 34 very low birth weight (VLBW) infants who had RDS were randomized to receive either PRVC or SIMV with surfactant administration : PRVC group (n=14) and SIMV group (n=20). We compared peak inspiratory pressure (PIP), duration of mechanical ventilation, and complications associated with ventilation, respectively with medical records. Results : There were no statistical differences in clinical characteristics between the groups. After surfactant administration, PIP was significantly lower during PRVC ventilation for 48hrs and accumulatevive value of decreased PIP was higher during PRVC ventilation for 24hrs (P<0.05). Duration of ventilation and incidence of complications was no significant difference. Conclusion : PRVC is the mode in which the smallest level of PIP required to deliver the preset tidal volume in VLBW infants with RDS, adaptively responding to compliance change in lung after surfactant replacement.

• Fire Science and Engineering
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• v.31 no.3
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• pp.88-96
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• 2017

The subway can transport a lot of people at a certain route at once, and the railway and the platform are underground, so it is advantageous to use the ground space efficiently. But If a fire occurs in a subway that is used by an unspecified number of people, such as the Daegu Subway Fire Disaster, many casualties can occur. As a result of the previous research, it was confirmed that the performance of the ventilation system of the old subway platform was remarkably degraded. Therefore, in this study, based on the experimental results of the previous research, we confirmed the flow of the hot and CO flows according to the ventilation mode in the case of fire by three - dimensional numerical analysis. As a result, it was found that the old ventilation system could not maintain the hot air temperature below the reference value for 4 minutes based on the evacuation time of the platform, and when the ventilation performance was enhanced by adding Oversized Exhaust Ports at the upper part of the platform, And the temperature of the heat flow can be maintained.

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.346-354
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• 2018

In this study, the condition of the hazardous materials in the bus was monitored according to the ventilation mode of the air conditioning system during bus service. The bus was surveyed using the indoor air quality measurement method of public transportation vehicles within one year of delivery. We evaluate the $CO_2$ and $PM_{10}$, which are the controlled parameters in buses by the Ministry of Environment, and VOCs and HCHO, the non-controlled parameters. The $PM_{10}$ concentration increased due to outdoor air intake; however the $CO_2$ concentration was found to decrease. In addition, the concentration of VOCs and HCHO was found to decrease due to the forced ventilation system and the outdoor air intake. These results show that the concentration of the other materials except $PM_{10}$ can be changed due to the outside air concentration and forced ventilation system. Therefore, through indoor air quality characteristics of the bus according to air condition system are intended to be used as the basis of an operation manual.

• Tuberculosis and Respiratory Diseases
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• v.82 no.3
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• pp.242-250
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• 2019

Background: Data on noninvasive ventilation (NIV) use in intensive care units (ICUs) are very limited in South Korea. Methods: A prospective observational study was performed in 20 ICUs of university-affiliated hospitals from June 2017 to February 2018. Adult patients (age>18 years) who were admitted to the ICU and received NIV treatment for acute respiratory failure were included. Results: A total of 156 patients treated with NIV were enrolled (mean age, $71.9{\pm}11.6years$). The most common indications for NIV were acute hypercapnic respiratory failure (AHRF, n=89) and post-extubation respiratory failure (n=44). The main device for NIV was an invasive mechanical ventilator with an NIV module (61.5%), and the majority of patients (87.2%) used an oronasal mask. After the exclusion of 32 do-not-resuscitate patients, NIV success rate was 68.5% (85/124); ICU and hospital mortality rates were 8.9% and 15.3%, respectively. However, the success rate was lower in patients with de novo respiratory failure (27.3%) compared to that of patients with AHRF (72.8%) or post-extubation respiratory failure (75.0%). In multivariate analysis, immunocompromised state, de novo respiratory failure, post-NIV (2 hours) respiratory rate, NIV mode (i.e., non-pressure support ventilation mode), and the change of NIV device were significantly associated with a lower success rate of NIV. Conclusion: AHRF and post-extubation respiratory failure were the most common indications for NIV in Korean ICUs. Overall NIV success was achieved in 68.5% of patients, with the lowest rate in patients with de novo respiratory failure.

• Tuberculosis and Respiratory Diseases
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• v.45 no.2
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• pp.380-387
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• 1998

Background: Minimal pressure support(PSmin) is a level of pressure support which offset the imposed work of breathing(WOBimp) developed by endotracheal tube and ventilator circuits in pressure support ventilation While the lower applied level of pressure support compared to PSmin could induce respiratory muscle fatigue, the higher level than PSmin could keep respiratory muscle rest resulting in prolongation of weaning period during weaning from mechanical ventilation PSmin has been usually applied in the level of 5~10 cm$H_2O$, but the accurate level of PSmin is difficult to be determinated in individual cases. PSmin is known to be calculated by using the equation of "PSmin = peak inspiratory flow rate during spontaneus ventilation$\times$total ventilatory system resistance", but correlation of calculated PSmin and measured PSmin has not been known. The objects of this study were firstly to assess whether customarily applied pressure support level of 5~10 cm$H_2O$ would be appropriate to offset the imposed work of breathing among the patients under weaning process, and secondly to estimate the correlation between the measured PSmin and calculated PSmin. Method : 1) Measurement of PSmin : Intratracheal pressure changes were measured through Hi-Lo jet tracheal tube (8mm in diameter, Mallinckroft, USA) by using pulmonary monitor(CP-100 pulmonary monitor, Bicore, USA), and then pressure support level of mechanical ventilator were increased until WOBimp was reached to 0.01 J/L or less. Measured PSmin was defined as the lowest pressure to make WOBimp 0.01 J/L or less. 2) Calculation of PSmin : Peak airway pressure(Ppeak), plateau airway pressure(Pplat) and mean inspiratory flow rate of the subjects were measured on volume control mode of mechanical ventilation after sedation. Spontaneous peak inspiratory flow rates were measured on CPAP mode(O cm$H_2O$). Thereafter PSmin was calculated by using the equation "PSmin = peak inspiratory flow rate$\times$R, R = (Ppeak-Pplat)/mean inspiratory flow rate during volume control mode on mechanical ventilation". Results: Sixteen patients who were considered as the candidate for weaning from mechanical ventilation were included in the study. Mean age was 64(${\pm}14$) years, and the mean of total ventilation times was 9(${\pm}4$) days. All patients except one were males. The measured PSmin of the subjects ranged 4.0~12.5cm$H_2O$ in 14 patients. The mean level of PSmin was 7.6(${\pm}2.5\;cmH_2O$) in measured PSmin, 8.6 (${\pm}3.25\;cmH_2O$) in calculated PSmin Correlation between the measured PSmin and the calculated PSmin is significantly high(n=9, r=0.88, p=0.002). The calculated PSmin show a tendancy to be higher than the corresponding measured PSmin in 8 out of 9 subjects(p=0.09). The ratio of measured PSmin/calculated PSmin was 0.81(${\pm}0.05$). Conclusion: Minimal pressure support levels were different in individual cases in the range from 4 to 12.5 cm$H_2O$. Because the equation-driven calculated PSmin showed a good correlation with measured PSmin, the application of equation-driven PSmin would be then appropriate compared with conventional application of 5~10 cm$H_2O$ in patients under difficult weaning process with pressure support ventilation.

• Tuberculosis and Respiratory Diseases
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• v.65 no.4
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• pp.292-300
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• 2008

Background: Respiratory failure is a common condition that requires intensive care, and has a high mortality rate despite the recent improvements in respiratory care. Previous reports of patients with respiratory failure focused on the specific disease or included a large proportion of surgical patients. This study evaluated the clinical characteristics, outcomes and prognostic factors of adult patients receiving mechanical ventilation in a medical intensive care unit. Methods: Retrospective chart review was performed on 479 adult patients, who received mechanical ventilation for more than 48 hours in the medical ICU of one tertiary referral hospital. Results: The mean age of the patients was $60.3{\pm}15.6$ years and 34.0% were female. The initial mean APACHE III score was $72.3{\pm}25$. The cause of MV included acute respiratory failure (71.8%), acute exacerbation of chronic pulmonary disease (20.9%), coma (5.6%), and neuromuscular disorders (1.7%). Pressure controlled ventilation was used as the initial ventilator mode in 67.8% of patients, and pressure support ventilation was used as the initial weaning mode in 83.6% of the patients. The overall mortality rate in the ICU and hospital was 49.3% and 55.4%, respectively. The main cause of death in hospital was septic shock (32.5%), respiratory failure (11.7%), and multiorgan failure (10.2%). Males, an APACHE III score >70, the cause of respiratory failure (interstitial lung disease, coma, aspiration, pneumonia, sepsis and hemoptysis), the total ventilation time, and length of stay in hospital were independently associated with mortality. Conclusion: The cause of respiratory failure, severity of the patients, and gender appears to be significantly associated with the outcome of mechanical ventilatory support in patients with respiratory failure.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.136-141
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• 2009

The platform screen door(PSD) is installed in the station of the Seoul Metro 9th line for passengers' safety and comfortable environment of the station. The track way exhaust system(TES) is also operated with PSD to exhaust heat released from train. TES can also be used for the purpose of the heat and smoke control in an emergency case of the carriage fire. When the fire is occurred, operation of TES is switched to the smoke exhaust mode form its normal ventilation mode. In the present study, a subway station of Seoul Metro 9th line is modeled, and a 3-D CFD simulation is performed to investigate effectiveness of designed TES in case of fire. A scenario that a train under fire is arriving the station is simulated for several possible operation modes of the TES using moving mesh technique. As a result, temperature and CO concentration distribution in the station is obtained for each operation modes of TES. The effectiveness of TES operation in case of fire is also discussed.

• Journal of Auto-vehicle Safety Association
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• v.8 no.1
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• pp.26-30
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• 2016

The steel road wheel on ventilation holes was cracked in the vehicle durability test. But the component durability test by uni-axial, CFT(Cornering Fatigue Test) and RFT(Radial Fatigue Test) had been satisfied. That is, the uni-axial component test could not forecast the crack of vehicle. Therefore this study developed the bi-axial test mode to reflect a vehicle condition(to reflect both vertical and lateral force simultaneously) based on real load data which was measured in Europe and China and developed CAE simulation too. It reproduced the cracks same as vehicle's and verified by bi-axial test machine in the LBF(Fraunhofer Institute for Structural Durability and System Reliability) durability research center in Germany. Finally this the durability CAE simulation by using HMC(Hyundai Motor Company)'s the bi-axial test mode predicts feasibly the steel wheel's durability performance before vehicle durability test.

• Tuberculosis and Respiratory Diseases
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• v.45 no.5
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• pp.1022-1030
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• 1998

Background : In volume-controlled ventilation, the use of inspiratory pause increases the inspiratory time and thus increases mean airway pressure and improves ventilation. But under the same I : E ratio, the effects of inspiratory pause on mean airway pressure and gas exchange are not certain. Moreover, the effects may be different according to the resistance of respiratory system. So we studied the effects of inspiratory pause on airway pressure and gas exchange under the same I : E ratio in volume-controlled ventilation. Methods: Airway pressure and arterial blood gases were evaluated in 12 patients under volume-controlled mechanical ventilation with and without inspiratory pause time 5%. The I : E ratio of 1 : 3, $FiO_2$, tidal volume, respiratory rate, and PEEP were kept constant. Results: $PaCO_2$ with inspiratory pause was lower than without inspiratory pause ($38.6{\pm}7.4$ mmHg vs. $41.0{\pm}7.7$ mmHg. p<0.01). P(A-a)$O_2$ was not different between ventilation with and without inspiratory pause $185.3{\pm}86.5$ mmHg vs. $184.9{\pm}84.9$ mmHg, p=0.766). Mean airway pressure with inspiratory pause was higher than without inspiratory pause ($9.7{\pm}4.0\;cmH_2O$ vs. $8.8{\pm}4.0\;cmH_2O$, p<0.01). The resistance of respiratory system inversely correlated with the pressure difference between plateau pressure with pause and peak inspiratory pressure without pause (r=-0.777, p<0.l), but positively correlated with the pressure difference between peak inspiratory pressure with pause and peak inspiratory pressure without pause (r=0.811, p<0.01). Thus the amount of increase in mean airway pressure with pause positively correlated with the resistance of respiratory system (r=0.681, p<0.05). However, the change of mean airway pressure did not correlated with the change of $PaCO_2$. Conclusion: In volume-controlled ventilation under the same I : E ratio of 1 : 3, inspiratory pause time of 5% increases mean airway pressure and improves ventilation. Although the higher resistance of respiratory system, the more increased mean airway pressure, the increase in mean airway pressure did not correlated with the change in $PaCO_2$.