• Clinical and Experimental Pediatrics
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• v.48 no.12
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• pp.1310-1316
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• 2005

Mechanical ventilation in children has some differences compared to in neonates or in adults. The indication of mechanical ventilation can be classified into two groups, hypercapnic respiratory failure and hypoxemic respiratory failure. The strategies of mechanical ventilation should be different in these two groups. In hypercapnic respiratory failure, volume target ventilation with constant flow is favorable and pressure target ventilation with constant pressure is preferred in hypoxemic respiratory failure. For oxygenation, fraction of inspired oxygen($FiO_2$) and mean airway pressure(MAP) can be adjusted. MAP is more important than FiO2. Positive end expiratory pressure(PEEP) is the most potent determinant of MAP. The optimal relationship of $FiO_2$ and PEEP is PEEP≒$FiO_2{\times}20$. For ventilation, minute volume of ventilation(MV) product of tidal volume(TV) and ventilation frequency is the most important factor. TV has an maximum value up to 15 mL/kg to avoid the volutrauma, so ventilation frequency is more important. The time constant(TC) in children is usually 0.15-0.2. Adequate inspiratory time is 3TC, and expiratory time should be more than 5TC. In some severe respiratory failure, to get 8TC for one cycle is impossible because of higher frequency. In such case, permissive hypercapnia can be considered. The strategy of mechanical ventilation should be adjusted gradually even in the same patient according to the status of the patient. Mechanical ventilators and ventilation modes are progressing with advances in engineering. But the most important thing in mechanical ventilation is profound understanding about the basic pulmonary mechanics and classic ventilation modes.

• Korean Journal of Bronchoesophagology
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• v.1 no.1
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• pp.109-115
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• 1995

High frequency Jet ventilation (HFJV) via cricothyroid membrane puncture contols frequency of ventilation as 20-200/min and persuits adequate gas exchange. HFJV was known to have advantages such as improvement of PaO$_2$, lesser barotrauma, stable hemodynamic effects, good operative field and lesser movement of head. The purpose of this study was to clarify the advantages of HFJV in cases of microlaryngeal surgery which operating time was expected even within 30 minutes. Twenty-eight patients were divided two groups : 1)control group : general endotracheal Intubation anesthesia. 2)experimental group : HFJV via cricothyroid membrane puncture with intravenous anesthesia, frequency 40/min, I/E ratio 40%, driving pressure 40 psi. We analyzed blood pressure, arterial blood gas, score of general condition and recovery time after operation. In conclusion, HFJV via cricothyroid membrane puncture had a good score of general condition and rapid recovery of consciousness, although some accumulation of P$CO_2$and elevation of blood pressure.

• Journal of Biomedical Engineering Research
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• v.11 no.2
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• pp.195-202
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• 1990

The hypothesis of asymmetric resistance to explain the phenomenon of lung hyperinflation (LHI) during hlgh frequency ventilation (HFV) was quantitatively studied. LHI was predicted by modeling the ism-volume pressure-flow (IVPF) data from 5 human subjects using the empirical Rohrer's equation. Non-steadiness during HFV was compensated by em- ploying recently proposed volume-frequency diagram. Tidal volume and ventilation frequency were 100 ml and 20 Hz, respectively. Airflow pattern was a symmetric sinusoid. The predic- tion results of mean pressure drop across the airways were averaged for those 5 subjects, and compared with zero by one-sided student's t-test. A marginally significant (P<0.1) increase in mean pressure drop was observed during HFV at low lung volumes (below FRC) , which could increase mean lung volume up to one liter When the lung volume was above FRC, no significant LHI (P >0.25) was resulted. LHI seemed to be inversely related to the lung volume. These results recommend to clinically apply HFV only at lung volumes above FRC.

• Tuberculosis and Respiratory Diseases
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• v.75 no.1
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• pp.1-8
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• 2013

Several papers on respiratory and critical care published from March 2012 to February 2013 were reviewed. From these, this study selected and summarized ten articles, in which the findings were notable, new, and interesting: effects of high-frequency oscillation ventilation on acute respiratory distress syndrome (ARDS); safety and efficacy of hydroxyethyl starch as a resuscitation fluid; long-term psychological impairments after ARDS; safety and efficacy of dexmedetomidine for sedation; B-type natriuretic peptide-guided fluid management during weaning from mechanical ventilation; adding of daily sedation interruptions to protocolized sedations for mechanical ventilation; unassisted tracheostomy collar of weaning from prolonged mechanical ventilations; and effects of nighttime intensivist staffing on the hospital mortality rates.

• Wind and Structures
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• v.9 no.4
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• pp.297-313
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• 2006

The concentration of air pollution along roads is higher than the surrounding area because ventilation efficiency has decreased due to the high-density use of space along roads in recent years. In this study, ventilation efficiency around a heavily traffic road covered by an elevated highway and hemmed in along its side by buildings is evaluated using Visitation Frequency (VF, the frequency for pollutant to return to the objective domain) and Purging Flow Rate (PFR, the air flow rate for defining the local domain-averaged concentration). These are analyzed using Computational Fluid Dynamics (CFD) based on the standard $k-{\varepsilon}$ model. The VF and PFR characteristics of four objective domains are analyzed in terms of the changes in wind direction and arrangements of the fencing dividing up and down direction in the road center under the elevated highway. The resulting VFs are more than 1.0 for all cases, which means that pollutants return to the objective domain restricted by the elevated highway and side buildings. The influence of the arrangement of the buildings around the objective domain and the structure in the domain on the VF is substantial. In cases where there are no obstacles under the elevated highway, the local air exchange rate in the domain tends to be improved. Using these indices, the urban ventilation efficiencies between different urban areas can be compared easily.

• Journal of the Korean housing association
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• v.21 no.5
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• pp.93-101
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• 2010

The purpose of the study is to investigate the behaviors for ventilation to control indoor air quality and characteristics of the maintenance for ventilation equipments by multi-family housing residents. This study was conducted by the survey in the area of Seoul and Kyungki-do. The results of the study are as follows: the majority of respondents conduct ventilation once a day, below 20 minutes with opening some windows of the inside of the house. The time for ventilation is generally between 9-11 am. and 5-7 pm. Most of the wives are responsible for ventilation activities. In addition, so far building materials and furniture are not seriously considered as the source of indoor air pollution by the respondents. Their satisfaction for indoor air before and after ventilation is perceived as just the level of average. As the mechanical ventilation equipments such as a hood and an exhaust fan, half of the respondents are using them frequently. However, the ventilation equipments are not maintained well. Specially maintenance and checks for exhaust fans are hardly conducted. In conclusion, the frequency of ventilation is very limited and residents show passive attitudes about ventilation and maintenance of ventilation equipments. Therefore, for the actualization of healthy housing, educational programs and guidelines on the way of ventilation targeting the residents should be set up and a certain organization has to check periodically the performance of the ventilation equipments of each house in the multi-family housing complex.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.4
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• pp.241-247
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• 2010

Recently, indoor air quality (IAQ) has been one of the major concerns of people. Indoor parking lots are subject to be exposed to high concentrations of air pollutants emitted from vehicles. This study was performed to investigate indoor air quality (IAQ) at indoor parking lots. Sampling sites were selected 5 indoor parking lots. Target indoor air quality parameters include a number of criteria pollutants such PM$_{10}$, CO, CO$_2$, and HCHO. In addition, a variation of IAQ according to ventilation system operating was measured at C site (underground parking lot). In general, all pollutants were maintained below indoor air quality maintenance standards. The indoor air quality at indoor parking lots was affected by the availability of the ventilation facility and their operation frequency. At the underground parking lot (C site) with ventilation system, TVOC concentration according to ventilation system operating were found to be lower operating (488.2 ${\mu}g/m^3$) than non-operating (1,401.2 ${\mu}g/m^3$).

• Fire Science and Engineering
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• v.33 no.4
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• pp.83-88
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• 2019

This study examined the concentration of combustion gases while considering low ventilation and respiration frequency. A one-quarter-size ISO 9705 room corner test was performed. The concentrations of carbon monoxide and oxygen were measured in each case with the continuous inhalation of combustion gas with low ventilation (2, 6, and 10 LPM) and different respiration frequencies (2 s, 5 s, and infinity). The combustion of a gasoline pool fire in the compartment had a theoretical heat release rate of 5.34 kW. The results show that the deviation of the gas concentrations becomes higher as the low ventilation increases compared to the respiration frequency. In addition, as the respiration frequency increases, the variation in the minimum oxygen concentration is larger than the average value, while in the case of carbon monoxide, the variation in the average value is larger than the maximum value. These results show that the inhalation characteristics of refugees should be considered to investigate fires.

• KIEAE Journal
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• v.10 no.1
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• pp.19-24
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• 2010

Modern people are spending most of time in interior area. Indoor air environmental problem is one of the most effective factors influenceable to human health. Furthermore, saving energy and making ventilation system for pleasant indoor environment are necessary when it is faced shortage of energy over the world. In our country's case, it is already imposed that required quantity of air ventilation in buildings is 0.7 times per hour on "The regulation on building engineering system". As on the rise of the interests about Indoor air environment, Heat and Carbon dioxide emissions from User's metabolism, activity, furniture, and construction materials etc. could be the causes of Indoor air pollution. If these materials stays in Indoor air for so long, it could directly influence the user's health condition with a disease. As of building's sterilization improved that raised more mechanical ventilation. It also leads much energy waste in a period of high price of fossil fuel. Therefore, the way that saves energy and effective control of indoor ventilation is urgently needed. So, this study places the purpose on validating volume of indoor ventilation and user's comfortable degree by comparison CO2 emission rate through changing floor temperature.

• Archives of Craniofacial Surgery
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• v.9 no.2
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• pp.77-80
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• 2008

Purpose: The majority of nasal fractures have been treated by closed reduction. And they were manipulated under local anesthesia or general anesthesia. Under the local anesthesia, patients can feel the pain and fear, so general anesthesia through the endotracheal intubation became popularized recently to treat the nasal fracture. But it has still the drawbacks of postanesthetic complication. Therefore, under the mask ventilation anesthesia using oral airway, we tried to manipulate the nasal fracture. Methods: From July 2007 to November 2007, we worked with fifty patients that were manipulated the nasal fracture. Fifty patients were divided into two groups, general anesthesia with the endotracheal intubation group(n=25) and the mask ventilation using oral airway group(n=25). We checked up the anesthesia time, postanesthetic complication, postoperative aesthetic & functional problem of nose in two groups. Results: In total operation time and sore throat frequency among the postoperative anesthetic complications, there was statistically significant difference between the mask ventilation group and the endotracheal intubation group(p<0.05). But there was no difference statistically in nausea frequency(p>0.05). And no patients complained of postoperative nasal complication such as septal deviation, septal perforation, nasal obstruction and hump nose in two groups. Conclusion: Through the mask ventilation using oral airway, we could reach satisfactory results in the anesthetic time and postanesthetic complication.