• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.187-190
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• 2007

A combined hydrogen generator of plasma and catalytic reformers has been developed, and has been applied to stabilize unstable flame of 200,000 Kcal/hr LPG combustor. The role of the plasma reformer is to generate hydrogen in a short period and to heat-up the catalytic reformer during the start-up time. After the start-up period, the catalytic reformer generates hydrogen through steam reforming with oxygen (SRO) reactions. The maximum capacity of the hydrogen generator is 100 lpm that is sufficient to be used to stabilize the flame of the present combustor. In order to reduce NOx and CO emissions simultaneously, 1) FGR (Flue Gas Recirculation) technique has been adopted and 2) the hydrogen has been added into the fuel supplied to the combustor. Test results shows that 25 % addition of hydrogen and 30 % FGR rate lead to simultaneous decrease of CO and NOx emissions. The technique proposed in the present study shows good potential to replace $NH_3$ SCR technique, especially in the case of small-scale combustor applications.

• Korean Journal of Microbiology
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• v.11 no.2
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• pp.101-106
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• 1973

The microwave of 2450 MHz, generated by a household cooking oven, was evaluated for its applicability to melt various rehydrated media and to remove dissolved oxygen from tubed media for anaerobic culture. The effect on the sterilization of E. coli in selective media was also evaluated. The following results were obtained. 10 The microwave oven was useful in saving time for melting media and in eliminating heat and combustion gas from the laboratory, which were inevitable by-products in the conventional flame method. 2) Dissolved oxygen could be removed without boiling over by exposing the tubes of anaerobic culture medium after putting them in a wire basket in a beaker with water. 30 The count of E. coli during the melting of MacConkey and EMB agar were similar to those treated with open flame. The microwave treatment was not considered a possible mean to replace autoclaving even in these selective media.

• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.14-19
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• 2003

Generally the accident by gas explosion in the working place is occurred at the condition of non-uniform mixture rather than uniform one. This study could predict the explosion phenomenon of non-uniform mixture with model explosion chamber which realize various practical conditions As a result, the mixing level of gas in the chamber depends on discharge area and velocity when there is gas discharge in certain space. In addition, as non-uniform increases, explosion pressure and its increasing rate decrease. However, firing risk after the explosion flame by infrared heat increase due to the increase of residence time of flame.

• Fire Science and Engineering
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• v.26 no.6
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• pp.92-98
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• 2012

In this sturdy, large experimental (ISO 13785-2) was performed to analyze the building materials used in fire retardant materials for aluminum composite panel and in general properties. As a results, maximum temperature in the case of the general materials was measured in 210 seconds $1,021^{\circ}C$, the retardant materials was measured in 1,200 seconds early $1,190^{\circ}C$. The retardant material of aluminum composite panel, Fire behavior if the ignition is slow and the general materials in aluminum composite panel, fire ignition and combustion at the same time was growing rapidly. The general materials and flame-retardant material of aluminum composite panel was an obvious difference to the combustion ignition but after ignition combustion mode showed a similar pattern of the rapidly vertical spread of flame. The results of this study, in order to reduce the risk of aluminum composite panels for fire and the retardant materials used for ignition the slow should be actively encouraging. Also after the ignition, there is an urgent need to put out a fire in exterior materials for extinguishing facilities.

• International Journal of Automotive Technology
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• v.6 no.4
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• pp.323-332
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• 2005

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of a homogeneous charged methane-air mixture under various overall charge pressures, excess air ratios and ignition times. The flow characteristics, including the mean velocity and turbulence intensity, were analyzed with a hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer, a flame propagation image acquired by ICCD camera and exhaust emissions measured by 2-valve gas chromatography were used to investigate effects of initial pressures, excess air ratios and ignition times on the combustion characteristics. It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to a near-zero value after 3000 ms and that the combustion duration was shorten and the flame speed and laminar burning velocity had the highest value under the condition of an excess air ratio of 1.1, an overall charge pressure of 0.15 MPa and an ignition time of 300 ms in the present study. The $CO_2$ concentration was proportional to the ignition time and overall charge pressure, the $CO_2$ concentration was proportional to the excess air ratio, and the UHC concentration was inversely proportional to the ignition time and overall charge pressure.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.215-218
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• 2014

High combustion efficiency of hydrogen could make it an ideal source of green energy in the future. At this time, high pressure vessel is the most reasonable method of storing hydrogen. However, such a high pressurized vessel could pose a critical threat if ruptured. For this reason, it is important to understand the mechanism of hydrogen's self-ignition when a high-pressure hydrogen released into air. This paper presents several visualization images as experimental results using high-speed camera. From the visualization images, the ignition is initiated near rupture disk immediately after failure of disk. And the initial ignition and flame is stronger as a rupture pressure increases. However, this ignition region do not affect the general self-ignition mechanism when a high-pressure hydrogen is released into air through tue after failure of disk.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.3
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• pp.25-31
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• 1991

The formation process of hydrocarbon emissions was investigated in SI engine. The time- resolved concentrations of hydrocarbon emissions were measured using a high gas sampling valve and a gas chromatography. The gas was sampled at exhaust port, or the position of spark plug, or the wall of combustion chamber. The experiments were conducted using the Alpha engine of Hyundai Motor Company. The fuel used was methanol or propane. It was found that the effect of the quenching layer of combustion chamber wall on hydrocarbon emissions was not significant. The increasing rate of hydrocarbon concentration at combustion chamber wall near crevice and oil layer after flame was reached was much higher than that at the position of spark plug. The hydrocarbon concentrations at exhaust port had two peak values just after opening exhaust valve and just before closing it.

• KIEAE Journal
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• v.7 no.4
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• pp.135-140
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• 2007

In this study we settled the trouble of the MgO board of existence by this research. We changed the wooden one of the main ingredient of a board to a perlite and a mineral particle in the aluminum hydroxide group and proceeded with a study to physical character and fire resistance efficiency improvement. The result yellowing phenomenon could be improved and it was possible to reduce size decrease of pin hole and the frequency of occurrence. We found out that the in case of absorbed amount added 5~8% corresponding to the weight decreases the acrylic group emulsion suddenly. So this product is improved with the bending strength and water-resistance. After behavior stop time measurement of a mouse for experiments was measured at the time of a gas harmful effect test, an improved MgO board appeared more highly for an average of 138 seconds compared with a board of existence.

• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1246-1257
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• 2004

The objective of this paper is to characterize dynamic pressure traces measured at self-excited combustion instabilities occurring in two combustion systems of different hardware. One system is a model lean premixed gas turbine combustor and the other a fullscale bipropellant liquid rocket thrust chamber. It is commonly observed in both systems that low frequency waves at around 300㎐ are first excited at the onset of combustion instabilities and after a short duration, the instability mode becomes coupled to the resonant acoustic modes of the combustion chamber, the first longitudinal mode for the lean premixed combustor and the first tangential mode for the rocket thrust chamber. Low frequency waves seem to get excited at first since flame shows the higher heat release response on the lower frequency perturbations with the smaller phase differences between heat release and pressure fluctuations. Nonlinear time series analysis of pressure traces reveals that even stable combustion might have chaotic behavior with the positive maximum Lyapunov exponent. Also, pressure fluctuations under combustion instabilities reach a limit cycle or quasi-periodic oscillations at the very similar run conditions, which manifest that a self-excited high frequency instability has strong nonlinear characteristics.

• Journal of Advanced Research in Ocean Engineering
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• v.1 no.3
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• pp.148-156
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• 2015

Deck plates of ships or offshore structures would make out-of-plane distortion for their thin thickness. These distortions are usually straightened by thermal straightening such as flame heating method. After thermal straightening, the blocks are lifted and moved by cranes to assemble it at dry-dock stage. After this lifting process, out-of-plane deformation again happens frequently. And then, they continuously cause quality and accuracy problems in the final dry-dock process. So, it takes more time for repair and correction working. According to preceding research, the lifting process by cranes would offset the effect on thermal straightening. The target of this study is to develop a methodology analyzing the remaining efficiency of thermal straightening after block lifting. The development was based on the assumption of yield state at straightening region. Therefore the remaining efficiency was obtained by different stiffness slope while lifting & relieving. The efficiency formula was designed using inherent strain, and we made a table of zero-efficiency by cooling speed and class rule's steels. As a result, if the stress orthogonal to straightened line is calculated during lifting analysis by FEA, the efficiency can be obtained linearly to the values in the table. Finally, even optimized carling position can be designed by considering the regional data from series project and welding region on deck.