• Journal of the Korean Society of Combustion
• /
• v.1 no.2
• /
• pp.31-39
• /
• 1996

This study was carried out to delvelop the burner for condensing gas boiler which can save energy by utilizing latent heat of combustion gas. A perforated can-type burner adopting premixed flame was chosen to reduce NOx emission and to simplify the manufacturing process. Basic experiments using unit cell combustor have been conducted to obtain data about the design parameters of perforated burner surface which can make stable flame for a wide operating conditions. Can-type burners designed on the basis of above data shows that flames are stable and also CO and NOx emission are low for a wide operating range.

• The KIPS Transactions:PartB
• /
• v.18B no.6
• /
• pp.397-404
• /
• 2011

In this paper, we were carried out experiments to apply parameter of voice analysis to measure changing characteristic articulator according to inhale the helium gas. The helium gas was used to overcome air embolism nitrogen gas to deal a fatal blow in body nitrogen gas by diver. However, the helium gas has been much trouble interpretation about abnormal voice of diver to cause squeaky voice of low articulation. Therefor, we was carried out experiments about pitch and spectrogram measurement, analysis based on to influence in acoustic organs before and after of inhaled helium gas.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.5
• /
• pp.51-57
• /
• 2011

Parametric studies based on analysis of lubrication system of a four cylinder gasoline engine are illustrated system in this paper. In development process of engine lubrication system, parts of failure cases are related with oil pull over and oil churning phenomenon. The crankcase & head system pressure by oil churning phenomenon are gradual increased. It cause oil pull over phenomenon at engine breather line and oil over-consumption. In order to improve oil reduction and oil pull over phenomenon are also considered in the developing state. For this study, the characteristics of engine lubrication system are measured at various tilting angle and drain hole sizes. In addition, the oil flow & oil quantity are tested by blow by meter and catch jar. Results are presented to stabilize the oil supply system at sever driving condition. The data from present study are available for the engine lubrication system.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.1
• /
• pp.28.2-28.2
• /
• 2021

We investigate the impact of ram pressure stripping due to the intracluster medium (ICM) on star-forming disk galaxies with a multiphase interstellar medium maintained by strong stellar feedback. We carry out radiation-hydrodynamic simulations of an isolated disk galaxy embedded in a 1011 M⦿ dark matter halo with various ICM winds mimicking the cluster outskirts (moderate) and the central environment (strong). We find that both star formation quenching and triggering occur in ram pressure-stripped galaxies, depending on the strength of the winds. HI and H2 in the outer galactic disk are significantly stripped in the presence of moderate winds, whereas turbulent pressure provides support against ram pressure in the central region, where star formation is active. Moderate ICM winds facilitate gas collapse, increasing the total star formation rates by ~40% when the wind is oriented face-on or by ~80% when it is edge-on. In contrast, strong winds rapidly blow away neutral and molecular hydrogen gas from the galaxy, suppressing star formation by a factor of 2 within ~200 Myr. Dense gas clumps with nH≳10 M⦿ pc-2 are easily identified in extraplanar regions, but no significant young stellar populations are found in such clumps. In our attempts to enhance radiative cooling by adopting a colder ICM of T=106K only a few additional stars are formed in the tail region, even if the amount of newly cooled gas increases by an order of magnitude.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.11
• /
• pp.3048-3053
• /
• 2009

Because of operating environment, the intake system of the small engine needs a serious design consideration. To capture oil particles from the blow-by gas, a grid of the intake system had been applied, but it has very low capturing efficiency and high manufacturing cost. To improve system performance, a new intake system has been developed using computational technique. The grid has been removed and the location of the blow-by hall has been re-designed. Total efficiency capturing oil particles has been improved about 5 times compared with that of previous model with the grid. By removing the grid, approximately 10% of the total manufacturing cast has been reduced.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1999.11a
• /
• pp.23-29
• /
• 1999

Experimental studies are conducted to investigate the flame stability and the thermal/fuel NOx formation characteristics of the low calorific value (LCV) coal derived gas fuel. Synthetic LCV fuel gas is produced by mixing carbon monoxide, hydrogen, nitrogen and ammonia on the basis that the thermal input of the syngas fuel into a burner is identical to that of natural gas. The syngas mixture is fed to and burnt with air on flat flame burner. With the variation of the equivalence ratio for specific syngas fuel, flame behaviors are observed to identify the flame instability due to blow-off or flashback and to define stable combustion range. Measurements of NOx content in combustion gas are made for comparing thermal and fuel NOx from the LCV syngas combustion with those of the natural gas one. In addition, the nitrogen dilution of the LCV syngas is preliminarily attempted as a NOx reduction technique, and its effects on thermal and fuel NOx production are discussed.

• 한국전산유체공학회:학술대회논문집
• /
• 2005.10a
• /
• pp.311-317
• /
• 2005

It has been the most progressive interruption technique to use the ablation gas from the surface of PTFE nozzle driven by arc plasma during switching process in $SF_6$ gas circuit breakers. This advanced interruption technique can reduce the required mechanical energy to compress and blow the gas for extinguishing the arc plasma between the electrodes due to using the ablation effect instead. In order to consider the phenomena during calculation of switching process, it is required to confirm the principles of ablation from PTFE nozzle as well as of arc plasma during switching process. In this study, we have calculated the switching process considered the ablation of PTFE nozzle driven by arc plasma using multidisciplinary simulation technique and compared the results with the data without the ablation effect. More $50\%$ difference of pressure rise inside expansion chamber has been found from the results and it should be indispensable for this type of computational work to consider and include the ablation effect of PTFE nozzle. Further study on turbulence and radiation will be followed.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.1
• /
• pp.1-6
• /
• 2008

There are some methods that have been used to manage a degasing process in recent years, such as an injection method that uses aluminum molten metal powder and chemicals supplier and input method that supplies argon and nitrogen, or chlorine gas by using a gas blow-tube. However, these methods show some problems, and it shows that it is a difficult process to handle, pollution due to producing a lot of toxic gases like chlorine and fluoride gas, irregular effects, and lowering work efficiency due to the excessive processing time. The problems that are the most fatal are the producing a lot of sludge due to the reaction of aluminum molten metal with chemicals, loss of metals, and decreasing the life of refractory materials. In order to solve these problems, this paper develops a technology that is related to aluminum continuous casting molten metal and monolithic degasing apparatus. A degasing apparatus developed in this study improved the existing methods and prevented environmental pollution with smokeless, odorless, and harmlessness by using a new method that applies argon and nitrogen gas in which the methods used in the West and Japan are eliminated. The method developed in this study decreases the molten metal processing and settling time compared to the existing methods and improves the workers' health, safety, and environment because there is no pollution in processes.

• Transactions of Materials Processing
• /
• v.26 no.4
• /
• pp.222-227
• /
• 2017

In order to respond to environmental regulations and increased demand for fuel economy, the demand for lightweight car bodies has grown. Hydroforming of aluminum is one possible solution as it eliminates the need for additional welding to develop closed cross-sectional parts. However, the low formability of aluminum is a limitation of its application. On the other hand, the ductility of materials can be improved at higher temperatures, and hot metal gas forming has been widely applied in the production of lightweight vehicle parts. In this study, aluminum alloy for pipe extrusion was developed by controlling the Mg:Cr:Mn ratio based on AA5083. Mechanical properties of the developed material were examined by tensile test and were applied to a forming simulation. Cold forming simulation for preforming and non-isothermal hot forming simulation for hot metal gas forming were carried out to validate process conditions. A prototype of the sidemember was manufactured under the given process condition. Finally, thickness distribution was compared with finite element analysis results.

• Fire Science and Engineering
• /
• v.28 no.3
• /
• pp.34-42
• /
• 2014

The concentrations of inert gases ($N_2$, Ar, $CO_2$ and He) required to induce the flame instabilities such as swing, rotation, lifted and blow-out were measured in a cup burner nonpremixed flames for $CH_4$ and $C_3H_8$ fuels. Quantitative differences in the extinguishing concentration with fire suppression criteria (i.e. blow-out or onset of flame instability) were also examined. It was found that the difference in extinguishing concentration was increased with the appearance of lifted flame and the low extinguishing performance of inert gaseous. The maximum difference in extinguishing concentration with the suppression criteria was approximately 35% at the highest fuel velocity condition (1.3 cm/s) for the $C_3H_8$-air nonpremixed flame. It can be also expected that the extinguishing concentration by the criteria based on the onset of flame instability will provide the useful information from the viewpoint of the accurate and economical design concentration.