• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.4
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• pp.406-414
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• 1987

As one of the explosion suppression methods of LPG tank exposed to hot environment by an accident or fire, some material which has large heat capacity and thermal conductivity can be installed inside the LPG tank in order to suppress the temperature increasement of tank wall. In the present study, theoretical model for the horizontally locating cylindrical LPG tank with and without the aluminum explosion suppression material has been developed to predict the characteristics of system. As a parametric study, effects of two major parameters, thickness of material filling and initial vapor volume fraction, on the time variation of wall temperature, temperature and pressure in tank are numerically examined. The results of present study show that the thickness of material filling does not give big differences in the suppression characteristics when the thickness of filling is larger than three inches. In case of material filling, there are marked suppression effects to the increase-ment of wall temperature, average vapor temperature and pressure in tank compared with the case of no filling.

• The Korean Journal of Emergency Medical Services
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• v.26 no.3
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• pp.21-35
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• 2022

Purpose: The purpose of this study was to investigate the effects of firefighters' job stress and emotional labor on their turnover intention, and analyze the main factors impacting turnover intention in this context. Methods: Based on a descriptive survey study design, we administered a structured questionnaire among 231 firefighters at one fire station in G metropolitan city from November 13 to 27, 2020. Results: Regarding job stress, participants showed differences based on marital status (p<.05), health status (p<.001), total service period (p<.05), and assignment (p<.05). For emotional labor, a significantly higher rate was observed for female than male firefighters (p<.05), with differences also observed in age (p<.001), health status (p<.001), total service period (p<.05), rank (p<.001), and assignment (p<.05). Further, for turnover intention, significant differences were noted with respect to age (p<.001), education (p<.01), health status (p<.001), total service period (p<.01), work unit (p<.05), rank (p<.001), and assignment (p<.05). A significant correlation was found between job stress and emotional labor and turnover intention. Regarding the factors affecting turnover intention, significant differences were noted based on education, rank, job stress, and emotional labor; the explanatory power was 53.9% (F=13.806, p<.001). Conclusion: Tailored support programs must be developed to ease firefighters' job stress and reduce their emotional labor to facilitate effective manpower management and reduce firefighters' turnover intention.

• Journal of Urban Science
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• v.12 no.2
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• pp.19-30
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• 2023

The seismic design of water tanks for fire protection is important to prevent secondary earthquake damages due to fires. In this study, the seismic performance of stainless steel water tanks was evaluated considering both static and dynamic water pressure effects, and the influence of different panel shapes was investigated through numerical analysis. First, a basic water tank model comprised of flat panels was built, and then water pressure distribution including sloshing effects was evaluated. In the result of structural analysis, many panels of the basic water tank exceeded a specified allowable stress for load combinations including earthquake loads. In order to reduce the bending stress of the panel by increasing the moment of inertial of the panel section, alternative shapes of a truncated quadrangular pyramid were developed. Five water tanks with different alternative panel shapes were built and analyzed for the same load combinations. Based on the results of the numerical analysis, a number of effective aspect ratios were selected and modified to increase economic feasibility through additional analysis and structural safety check.

• The Korean Journal of Emergency Medical Services
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• v.28 no.2
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• pp.47-62
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• 2024

Purpose: This retrospective study analyzed the effects of advanced life support on the recovery of spontaneous circulation (SC) in patients with out-of-hospital cardiac arrest. Methods: The subjects of this study were out-of-hospital cardiac arrest patients transferred to the hospital by 119 paramedics in Gyeongsangbuk-do from January 1, 2021, to December 31, 2022, amounting to a total of 2,524 patients. Results: The younger the age, the higher the probability of recovery of spontaneous circulation, and it was higher when cardiac arrest occurred in a public place or was witnessed. If the patient's initial electrocardiogram rhythm is defibrillable, the probability of recovery from spontaneous circulation is high. The recovery of the spontaneous circulation rate decreased with time between the time of report and the time of contact with the patient. Recovery of the spontaneous circulation rate was high when mechanical chest compression devices and advanced airways were not used. Additionally, this study had positive effects on defibrillation, peripheral intravenous catheter insertion, and epinephrine infusion. Conclusion: Paramedics should actively perform peripheral intravenous catheter insertion and epinephrine infusion, and it should be possible to clearly determine whether defibrillation should be applied through electrocardiographic education.

• The Journal of Korean Medicine
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• v.18 no.2
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• pp.148-154
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• 1997

In the pharmacology of traditional Korean medicine, each drug has its own specific characters. The different characters of drugs are employed to treat diseases, rectify the hyperactivity or hypoactivity of yin or yang, and help the body restore its normal physiological functions, consequently curing the diseases and restoring health. The various characters and functions of these drugs concerning medical treatment include drugs' properties, flavours, actions of lifting, lowering, floating and sinking, channel tropism, toxicity, etc. Among these theories, theory of properties and flavours of drugs provides the basis for drug analysis and application. 'Property' refers to the cold, hot, warm or cool nature of a drug. These properties of drugs are so sorted out according to the different actions of the drugs on the human body and thier therapeutic effects. Drugs which cure heat syndrome(yang syndrome) have a cold or cool property, whereas drugs which cure cold syndrome (yin syndrome) have hot or warm property Drugs of cold and cool-natured and drugs of warm and hot natures are of opposite properties. A cold-natured drug is different from a cool-natured on only in degree, and so is a warm-natured drug from a hot-natured drug. Most of the cool- or cold- natured drugs have the effects of clearing heat, purging fire, removing toxic substances, and nourishing yin, and are uese to cure heat syndromes. On the contrary, drugs of warm or hot nature usually have the effects of dispersing cold, warming up the interior, supporting yang, and treating collapse, and are therefore used to treat cold syndromes. We thought that the property of drug may be related to the autonomic nervous system in western medicine. In other words, drugs of warm or hot nature increase heart rate or acts like sympathomimetics, and drugs of cool or cold nature decrease heart rate or acts like para sympathomimetics . According to this hypothesis, we administrated some drugs to isolated rat right atrium in magnus tube. But there is no correlation between 'property' in traditional Korean medicine and autonomic nervous system in western medicine.

• Geomechanics and Engineering
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• v.28 no.5
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• pp.437-454
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• 2022

The hydro-mechanical (HM) two-way sequential coupling in the TOUGH2-FLAC3D linking algorithm is validated completely and successfully in both M to H and H to M directions, which are initiated by mechanical surface loading for geomechanical validation and hydrological groundwater pumping for hydrogeological validation, respectively. For such complete and successful validation, a TOUGH2-FLAC3D linked numerical model is developed first by adopting the TOUGH2-FLAC3D linking algorithm, which uses the two-way (fixed-stress split) sequential coupling scheme and the implicit backward time stepping method. Two geomechanical and two hydrogeological validation problems are then simulated using the linked numerical model together with basic validation strategies and prerequisites. The second geomechanical and second hydrogeological validation problems are also associated with the Mandel effect and the Noordbergum and Rhade effects, respectively, which are three phenomenally well-known but numerically challenging HM effects. Finally, sequentially coupled numerical solutions are compared with either analytical solutions (verification) or fully coupled numerical solutions (benchmarking). In all the four validation problems, they show almost perfect to extremely or very good agreement. In addition, the second geomechanical validation problem clearly displays the Mandel effect and suggests a proper or minimum geometrical ratio of the height to the width for the rectangular domain to maximize agreement between the numerical and analytical solutions. In the meantime, the second hydrogeological validation problem clearly displays the Noordbergum and Rhade effects and implies that the HM two-way sequential coupling scheme used in the linked numerical model is as rigorous as the HM two-way full coupling scheme used in a fully coupled numerical model.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.142-147
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• 2010

Cryptand resins have been synthesized from 1-aza-18-crown-6 macrocyclic ligand attached to styrene (2th petroleum in 4th class hazardous materials) divinylbenzene copolymer with crosslinkage of 1%, 2%, 10%, and 18% by substitution reaction. The synthesis of these resins was confirmed by the content of chlorine, element analysis, surface area (BET), and IR-spectroscopy. The effects of pH, time and crosslinkage on adsorption of metal ion from water fire extinguishing agentby synthetic resin adsorbent were investigated. Metal ions showed a great adsorption over pH 3 and adsorption equilibriumof metal ions was about two hours. The adsorption selectivity determined in water was in the increasing order of sodium ($Na^{1+}$) > zinc ($Zn^{2+}$) > chromium ($Cr^{3+}$) ion. The adsorption was in the order of 1%, 2%, 10%, and 18% crosslinkage resin.

• Fire Science and Engineering
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• v.22 no.3
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• pp.234-238
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• 2008

Autoignition suppression of hydrogen/air premixed mixtures by $CF_3CHFCF_3(HFP)$ was investigated computationally. Numerical simulation was performed in isobaric and homogeneous system to evaluate the induction times. The detailed chemistry of 93 species and 817 reaction mechanism was introduced for hydrogen/air/HFP mixtures. The result of pure hydrogen/air mixture show that the resulting value of induction time depends relatively weakly on the definition used event though there are various criteria for defining the induction time such as the inflection of temperature, OH and $O_2$ concentrations generally. Also, the autoignition temperature of $H_2/air$ mixture is estimated to about 850K, which is corresponds to the literature value. In the case of HFP addition in $H_2/air$ mixture, the results shows that there are several inflection points of radical concentration, and hence it might be to use the temperature for defining ignition delay. When HFP is added to stoichiometric $H_2/air$ mixture, the effect of ignition delay is outstanding above 10% HFP concentration. As HFP concentration increases, both dilution and chemical effects contribute to delay the ignition. Also, the chemical effect on the ignition delay is more considerable with the higher HFP concentration.

• Fire Science and Engineering
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• v.31 no.3
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• pp.137-143
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• 2017

A sufficient number of ambulances are critical for preventing delayed vehicle dispatch for emergency patients. This study presents effective methodologies for evaluating the effects of ambulance quantities on availability. The statistical properties of the emergency requests and responses were analyzed for a city in Korea. The inter-request times were modeled by statistical distributions. The ambulance dispatch was modeled using simulation, reflecting the shared dispatch among the city districts. The simulation results revealed that the existing ambulance quantity could successfully meet the majority of the requests, but more vehicles were desirable for improvement. The locations of the additional vehicles were determined efficiently by simulations with a greedy approach. The simulations with added vehicles showed a significantly better coverage of the emergency calls. This research can help design improved emergency vehicle operations, and help save lives.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.2
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• pp.144-149
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• 2014

A ground firing test for hot-fire performance evaluation according to the characteristic length($L^*$) variation of thrust chamber was carried out for the hydrazine thruster which may be employed in space launch vehicles. A scrutiny into the performance characteristics of each thruster is made in terms of thrust, specific impulse, response characteristics, and characteristic velocity at steady-state firing mode with propellant inlet pressure of 2.41 MPa (350 psia). Through the test results, it has been verified that performance of characteristic velocity and specific impulse degrades as the characteristic length deviates from that of the standard model. Thus, it is confirmed that the thrust chamber configuration of standard model was suitably designed for the requirement specified.