• Journal of the Korean Society of Combustion
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• v.11 no.2
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• pp.28-36
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• 2006

A constant volume combustion chamber was used to investigate the combustion characteristics. of homogeneous charge of methane-air mixture under various initial pressure, equivalence ratio and ignition times. The constant volume combustion chamber(CVCC) mostly has been studied by the experiments of visualization until now. So it is needed the numerical analysis of fluid and combustion characteristics in chamber by the more detail simulation. In this paper, the numerical analysis is tried to approach basically the homogeneous charge combustion phenomena under the various conditions, and the combustion phenomena in chamber is numerically analyzed by the commercial FIRE code. As a results, the combustion phenomena which were mean temperature, OH radical and reaction rate in chamber were investigated and it showed that the smallest flame growth occurs for the lean state and the increase of initial charged pressure condition due to the reduced OH radical.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.1-12
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• 1997

A computer program was developed to simulate effect of the initial track tension on the tractive performance of tracked vehicles. The performance was evaluated in terms of drawbar pull, motion resistance, tractive coefficient and tractive efficiency. Results of the simulation showed that increase in track tension decreases the sinkage and mean maximum pressure in clay, making the ground pressure distribution more uniform. This tendency became more evident when the number of roadwheels increased. However, such change in MMPs was negligible in firm soils. Motion resistance was also decreased with increase in track tension and the number of roadwheels. Under weak soil conditions, tractive coefficient and efficiency increased generally as the track tension increased for a slip range of 10∼30%. For slippage less than 3∼4%, however, the tractive coefficient decreased with increase in track tension. In general, it was known that increasing track tension improves tractive performance in weak soil conditions. However, high track tension can reduce efficiency due to the increment of internal motion resistance caused by increased track tension.

• Clinical and Experimental Pediatrics
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• v.63 no.1
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• pp.3-7
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• 2020

High-flow nasal cannula (HFNC) is a relatively safe and effective noninvasive ventilation method that was recently accepted as a treatment option for acute respiratory support before endotracheal intubation or invasive ventilation. The action mechanism of HFNC includes a decrease in nasopharyngeal resistance, washout of dead space, reduction in inflow of ambient air, and an increase in airway pressure. In preterm infants, HFNC can be used to prevent reintubation and initial noninvasive respiratory support after birth. In children, flow level adjustments are crucial considering their maximal efficacy and complications. Randomized controlled studies suggest that HFNC can be used in cases of moderate to severe bronchiolitis upon initial low-flow oxygen failure. HFNC can also reduce intubation and mechanical ventilation in children with respiratory failure. Several observational studies have shown that HFNC can be beneficial in acute asthma and other respiratory distress. Multicenter randomized studies are warranted to determine the feasibility and adherence of HFNC and continuous positive airway pressure in pediatric intensive care units. The development of clinical guidelines for HFNC, including flow settings, indications, and contraindications, device management, efficacy identification, and safety issues are needed, particularly in children.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.361-368
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• 1998

The purpose of this study is to find out the factors affacting liquefaction potential by using DSC(disturded state concept) method and to verify these results through cyclic shear test (truly triaxial test and cyclic triaxial) on saturated sandy soil. Based on this reserch, the DSC method predictions were found to provide satisfactory correlation with the cyclic shear test. And the relationship between the factors affecting liquefaction characteristics--relative density(Dr0 and initial effective confining pressure and physical properties of the saturated sand --ξD and Dc--is found. If the relative density and the initial effective confining pressure increase, the number of cyclic grows up. This means that Dc is incresed and ξD is decreased. Therefore, the liquefaction potential can be evaluated and the factors affacting liquefaction potential can be investigated by using on DSC method. Finally, it is shown that the DSC method can capture the liquefaction mechanism.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.11
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• pp.937-942
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• 2003

In the present study, low-temperature low-pressure refrigerant storage method is proposed to achieve higher cooling capacity during a short period of time than that of a compressor in steady operation. Experimental apparatus was designed and set up to analyze the performance of the new-conceptual cooling system. Two reservoirs for sequential storage of refrigerant were used in the cooling system. Several on/off solenoid valves were installed for control of refrigerant flow. From the experimental results, the initial rapid cooling by low temperature low-pressure refrigerant storage method was ascertained for successful operation. This rapid cooling methodology shall be useful for other low-capacity refrigeration system.

• Journal of Trauma and Injury
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• v.35 no.3
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• pp.168-172
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• 2022

Purpose: The neck is a particularly critical region for penetrating injuries due to the close proximity of the trachea, esophagus, blood vessels, and the spinal cord. An open neck injury has the potential for serious morbidity and mortality. The purpose of this study is to evaluate the assessment and management of open neck injuries. Methods: In this retrospective study, open neck injury patients who were admitted to the Trauma Center of Daejeon Eulji Medical Center, Eulji University between December 2015 and December 2017 were analyzed for epidemiology, the mechanism of trauma, the injured organ, complications, and mortality. Results: Thirty-two patients presented with open neck injuries. All patients underwent computed tomographic angiography to evaluate their injuries once their vital signs stabilized. Among these patients, 27 required surgical treatment. The most commonly injured organ was the airway. There were five deaths, and the main cause of death was bleeding. Mortality was associated with the initial systolic blood pressure at the hospital and Glasgow Coma Scale. Conclusions: Mortality from open neck injuries was associated with initial systolic blood pressure at the hospital and Glasgow Coma Scale.

• Steel and Composite Structures
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• v.46 no.5
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• pp.669-672
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• 2023

In this research, the researcher has examined the factors affecting the movement of the soccer ball and will show that the effects such as air resistance, altitude above sea level, wind, air pressure, air temperature, air humidity, rotation of the earth, changes in the earth's gravitational acceleration in different areas. It, the geographical length and latitude of the launch point, the change of gravitational acceleration with height, the change of pressure with height, the change of temperature with height and also the initial spin (Magnus effect) affect the movement of projectiles (especially soccer ball). We modelled th ball based on shell element and derive the motion equations by energy method. Finally, using numerical solution, the wave of the ball is studied. The influences of various parameters are investigated on wave propagation of the ball. Therefore, in short, it can be said that the main factors that play a major role in the lateral deviation of the hit ball are the initial spin of the ball and the wind.

• Journal of Korean Society of Steel Construction
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• v.30 no.1
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• pp.25-35
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• 2018

Resisting strength of ring-stiffened cylindrical steel shell under uniform external pressure was evaluated by geometrically and materially nonlinear finite element method. The effects of shape and amplitude of geometric initial imperfection, radius to thickness ratio, and spacing of ring stiffeners on the resisting strength of ring-stiffened shell were analyzed. The resisting strength of ring-stiffened cylindrical shells made of SM490 obtained by FEA were compared with design strengths specified in Eurocode 3 and DNV-RP-C202. The shell buckling modes obtained from a linear elastic bifurcation FE analysis were introduced in the nonlinear FE analysis as initial geometric imperfections. The radius to thickness ratios of cylindrical shell in the range of 250 to 500 were considered.

• Textile Coloration and Finishing
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• v.20 no.3
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• pp.1-7
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• 2008

Three kinds of 135D/108F ITY were produced from raw yam 85D/72F + SDY 50D/36F with. interlacing pressure $1.5kg/cm^2$, $2.5kg/cm^2$, $3.5kg/cm^2$ respectively. 72 kinds of sized yams were manufactured from three ITYs by altering sizing speed, sizing temperature and sizing tension. The mechanical characteristics of 72 kinds of plain fabrics which were woven using the sized yam as a warp were analyzed after scouring. The initial modulus of scoured fabric responded sensitively to the sizing speed in high tension. The WT of scoured fabric recorded the. highest1n the conditions of sizing tension 30g, and air pressure $2.5kg/cm^2$ in interlacing treatment. When sizing temperature was high, the WT value appeared low, but when sizing speed was high, the WT value was much affected by air pressure in interlacing raw yam. The MIU value of fabric according to sizing tension variations increased up to sizing tension 40g, but decreased above it. The bulk density decreased up to sizing tension 30-40g, but increased above it. In addition, the bulk density decreased as sizing temperature increased.

• Journal of the Korean Society of Combustion
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• v.20 no.3
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• pp.21-26
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• 2015

This study was performed to provide the information of the combustion characteristics of n-butanol fuel in accordance with the n-heptane fuel mixing ratio. The closed homogeneous reactor model was used for the analysis. The analysis conditions were set to 800 K of the initial temperature, 20 atm of initial pressure and 1.0 of equivalence ratio. The results of analysis were compared in terms of combustion temperature, combustion pressure, CO, Soot and $NO_X$ emissions. The results of combustion and exhaust emission characteristics showed that ignition delay was decreased and the combustion temperature was increased as the n-heptane mixing ratio was increased. Also, the carbon monoxide(CO) was slightly decreased however, the soot and nitrogen oxides($NO_X$) increased a little in accordance with the n-heptane fuel mixing ratio. In addition, the pressure difference was almost the same in any conditions.