• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.30-40
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• 1992

Spark knock obstructs any improvement in the efficiency and performance of an engine. As the knock mechanism of spark ignition engine, the detonation and the autoignition theory have been offered. In this paper, the knock model was established, which was able to predict the onset of knock and knock timing of spark ignition engine by the basis of autoignition theory. This model was a function of engine speed and equivalent air-fuel ratio. When this established knock model was tested from 1000rpm to 3000rpm of engine speed data, maximum error was crank angle 2 degrees between measured and predicted knock time. And the main results were as follows by the experimental analysis of spark knock in spark ignition engine. 1) Knock frequency was increased as engine speed increased. 2) Knock amplitude was increased as mass of end gas increased. 3) Knock frequency was occured above minimum 18% mass fraction of end gas.

• Journal of ILASS-Korea
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• v.5 no.4
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• pp.66-71
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• 2000

The present study is mainly motivated to investigate the vaporization, auto-ignition and combustion processes in the high-pressure engine conditions. The high-pressure vaporization model is developed to realistically simulate the spray dynamics and vaporization characteristics in high-pressure and high-temperature environment. The interaction between chemistry and turbulence is treated by employing the Representative Interactive Flamelet (RIF) Model. The detailed chemistry of 114 elementary steps and 44 chemical species is adopted for the n-heptane/air reaction. In order to account for the spatial inhomogeneity of the scalar dissipation rate, the multiple RIFs are introduced. Numerical results indicate that the RIF approach together with the high-pressure vaporization model successfully predicts the ignition delay time and location as well as the essential features of a spray ignition and combustion processes.

• Fire Science and Engineering
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• v.24 no.3
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• pp.52-57
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• 2010

Fire protection countermeasure were considered on the straw thatched roof and wooden structure. For the fire resistant treatment, rice straw was soaked in the fire resistant liquid with different soaking time. After treatment, some rice straw sample was washed with water then the rice straws were tested to check the fire resistance performance. And the wood was soaked in the fire resistant liquid at an atmospheric pressure, vacuum-pressure condition and painted with brush on the surface. To analyse the fire resistant performance of rice straw, ignition delay time was measured under the radiant heat flux of cone heater. And the fire resistant performance of wood samples were tested with 45 degree fire resistant test apparatus and cone heater. Based on the cone heater test, the rice straw which most easily ignitable material shows the longer ignition delay time than not treated ones and even in the water washed straw show a longer ignition delay time than not treated ones. And fire resistant treated woods of vacuum-pressure treated sample showed the most excellent performance on fire resistance. And the fire resistant treated by brush and soaking showed a longer ignition delay time than not treated ones. From this experiment, it was found that a fire resistant treatment of rice straw and wood of the house can be protected from the fire spread.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1121-1126
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• 2010

This study is to investigate the effects of aromatics and T90 for low cetane number (CN) fuels on combustion and exhaust emissions in low-temperature diesel combustion. We use a 1.9-L common rail direct injection diesel engine at 1500 rpm and 2.6 bar BMEP. Low temperature diesel combustion was achieved via a high external EGR rate and strategic injection control. The tested fuels four sets: the aromatic content was 20% (A20) or 45% (A45) and the T90 temperature was $270^{\circ}C$ (T270) or $340^{\circ}C$ (T340) with CN 30. Given the engine operating conditions, the T90 was the stronger factor on the ignition delay time, resulting in a longer ignition delay time for higher T90 fuels. All the fuels produced nearly zero PM because of the extension of the ignition delay time induced by the low cetane number. The aromatic content was the main factor that affected the NOx and the NOx increased with the aromatic content.

• Journal of the Korean Chemical Society
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• v.48 no.1
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• pp.99-102
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• 2004

• Journal of the Korean Chemical Society
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• v.46 no.6
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• pp.595-598
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• 2002

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.3
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• pp.285-291
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• 2022

In order to use the liquid rocket fuel, 1,5-diamino-4-methyltetrazolium azide, [DMT]⁺[N₃]^- and 1,5-diamino-4-methyltetrazolium cyanide, [DMT]⁺[CN]^- were synthesized and prepared the ionic liquid rocket fuel after dissolving the synthesized solid-type energetic chemicals in hydrazine, respectively. The thermal decomposition temperatures(T_d) and densities(d) of the prepared ionic liquid rocket fuels were about 200 ℃ and above 1.0 g/cm³ respectively. The ignition delay times(I_dt) of the ionic liqud rock fuels with [DMT]⁺[N₃]^- and [DMT]⁺[CN]^- were in a range of 26.6 - 82.5 ms and the 44.0 - 98.5 ms, respectively. These results mean that the synthesized tetrazolium salts could be used as an ionic liquid rocket fuels. The viscosities of the ionic liqud rock fuels with [DMT]⁺[N₃]^- and [DMT]⁺[CN]^-, which were dissolved in mixture solution of hydrazine/2-hydroxyethylhydrazine were to be 1.34 - 101 cP, and 1.29 - 80.5 cP, respectively. The synthesized ionic liquid rocket fuels in this study could be used as rocket fuel because the [I_dt(100 ms or less), T_d(150 ℃ or more), d(1.00 g/cm³ or more), and η(40.0~ 100 cP)] were achieved to satisfy the range of the used liquid rocket fuels.

• Journal of the Korean Society of Combustion
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• v.4 no.2
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• pp.11-22
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• 1999

Combustion characteristics of the wood chips(balsa chips) were experimentally investigated with respect to the thermal recycle system of the urban waste. The urban waste contains plastics, vegetable and wood materials. Wood was chosen as an example of the one of the component of urban dust. A small wood chip was burned in a electric furnace by the micro-electric balance. The mass reduction rate was normalized by the initial mass of test piece and the time of volatile combustion end. When the mass of the wood chips(balsa chips) was larger than 0.5g, the combustion similarity was found on the normalized mass reduction rate.

• Bulletin of the Korean Chemical Society
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• v.21 no.5
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• pp.487-492
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• 2000

The combustion characteristics of a mixture of acetaldehyde, oxygen and argon behind a reflected shock wave at temperatures ranging from 1320 to 1897 K at 100 torr were studied. The emission from the OH radical at 306.4 nm and the pressure profile behind the reflected shock were measured to monitor ignition delay time. The ignition delay times were computed from a proposed mechanism of 110 elementary reactions involving 34 species. The simulation and sensitivity analysis confirm that the main channel for oxidation of acetaldehyde at high temperature consists of the Rice-herzfeld mechanism, the decomposition and oxidation of HCO, and the reaction of H with $O_2$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.334-337
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• 2008

Three-dimensional unsteady reacting flowfield generated by transverse hydrogen injection into a supersonic mainstream are numerically investigated using DES and finite-rate chemistry model. Comparisons are made with experimental results to investigate the turbulent reacting flow physics. The numerical OH distribution describes well the experimental OH-PLIF result, while the numerical ignition delay time shows some disparity due to the restricted available experimental data.