• Journal of the Korean Society of Safety
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• v.22 no.5
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• pp.77-83
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• 2007

This study is conducted on spontaneous ignition temperature and activation energy of Hydroxypropyl Methyl Cellulose(HMC) powder. HMC is a kind of cellulose derivative and used as additives for building material, surface coating, printing ink, adhesives, cosmetics and medical supplies. So this material has been widely used as important additive in the chemical industry fields and a mount of production has increased year by year. Therefore, it is very important to find out the thermal ignition characteristics of its danger and the critical ignition temperature. This study was performed by the Spontaneous Ignition Tester(SIT) and so on. Based on the data of the SIT-II, the critical ignition point of HMC is about $186^{\circ}C$ which is slightly lower than normal cellulose.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.39-44
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• 2018

Dust explosions are occurring in a variety of industries. A dust explosion caused by a specific energy generates huge amount of energy in the ignition and releases decomposition gas. Damages can be increased since this released decomposition gas can cause second and subsequent explosions. In this study, the goal was to obtain practical information on what could affect the explosion by comparing the characteristics of two kinds of dusts with completely different chemical properties. Three kinds of dusts were measured and evaluated for explosion pressure, dust explosion index, explosion limit and minimum ignition energy. It is possible to grasp the characteristics of each dust and use it as useful accident prevention data in the production of raw material powder.

• Journal of Hydrogen and New Energy
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• v.28 no.1
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• pp.98-105
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• 2017

In recent years, compression ignition engine has been equipped with some control devices such as common rail injection system and turbocharger. In order to control the large number of input parameter appropriately in consideration of $NO_x$, HC and engine power as the engine output objectives. The model construction which reproduces the characteristic value of $NO_x$, HC and engine power from input parameter is needed. In this research, the stepwise method was applied to construct the compression ignition engine model. By using the preliminary experimental data of single cylinder compression ignition engine, the prediction model of $NO_x$, HC and engine power on single injection compression ignition engine was built and compared with the main experimental data.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.26-32
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• 2012

With a progress of electrical and electronic technology, radio-frequency including high frequency components are widely to various industrial installations. Some of them are used in hazardous locations where explosive or flammable gases exist. As a result, ignition of such gases may be induced by a spark discharge when the radio frequency circuits are switched on or off. The purpose of this study is to investigate the ignition hazards of some kind of flammable mixtures based on the IEC 60079-11 publication. In this experiment, we used a high frequency resistive circuit which consists of a co-axial cable, a 20 ${\Omega}$, 30 ${\Omega}$, 40 ${\Omega}$ and 50 ${\Omega}$ resistor and two kind of power amplifier with frequency range up to almost 1 MHz and 50 MHz. Experimental results show that the ignition of the acetyleneair, ethylene-air mixtures and methane-air mixtures due to spark discharge depends primarily on the frequency of the power source in the resistive circuit the minimum ignition voltage increases gradually with the increase of the frequency.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2353-2364
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• 1995

The ignition phenomena of a solid fuel plate of polymethyl-methacrylate(PMMA), which is vertically positioned and exposed to a thermal radiation source, is numerically studied here. A two-dimensional transient model includes such various aspects as thermal decomposition of PMMA, gas phase radiation absorption, gas phase chemical reaction and air entrainment by natural convection. Whereas the previous studies considers the problem approximately in a one-dimensional form by neglecting the natural convection, the present model takes account of the two-dimensional effect of radiation and air entrainment. The inert heating of the solid fuel is also taken into consideration. Radiative heat transfer is incorporated by th Discrete Ordinates Method(DOM) with the absorption coefficient evaluated using gas species concentration. The thermal history of the solid fuel plate shows a good agreement compared with experimental results. Despite of induced natural convective flow that induces heat loss from the fuel surface, the locally absorbed radiant energy, which is converted to the internal energy, is found to play an important role in the onset of gas phase ignition. The ignition is considered to occur when the rate of variation of gas phase reaction rate reaches its maximum value. Once the ignition takes place, the flame propagates downward.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.11a
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• pp.11-30
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• 1995

The ignition characteristics of a reactive solid with rough surface by constant heat flux were studied. The geometry of surface was represented by a set of identical protrusions having a shape of wedge based on the block of reactive solid. Several regimes of ignition were found, depending on the ratio of the protrusion length and the depth of the heated layer, formed in course of ignition process: 1) when the substance is ignited as the massive block, and the effect of roughness is not pronounced; 2) when ignited are the individual protrusions; and 3) in the intermediate region between the first two. Critical ignition conditions: ignition time and ignition criterion, are determined for the three regimes. The results are compared with the results for the one-dimensional ignition of the semi-infinite body. It is shown, that the effect of geometry on ignition results in the considerable reduction of ignition delay, and the amount of energy required for the successful ignition is less compared to the one- dimensional case.

• 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.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.966-969
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• 1998

Fast burning achieves higher efficiency, and reduces cycle variations which is able to improve vehicle driveability. Furthermore, the greater resistance to knock with fast burning can allow the fuel economy advantages associated with higher compression ratio to be realized. One way of increasing the combustion speed is to enhance the performance of ignition systems which were able to reduce the early period of combustion. It is well known that shortening the initial stage of combustion also reduces the cyclic variations. This literature survey deals with the papers which have studied the ignition process or various ignition systems. Those systems increasing the combustion speed, extending the lean misfire limit, reducing the exhaust gas and stabilizing the operating condition of the spark ignition engine by modifying the ignition process or increasing ignition energy.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.65-69
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• 2001

Research on the development of CNG dedicated engine that has important meaning both as a clean fuel and an alterna- tive energy to reduce the exhaust emission from diesel engine are actively going on these days. In this study, in order to present the direction and application of CNG engine, we tested the CNG engine performance experimented by changing the parameters such as ignition timing, equivalent ratio. The engine performance experimented by changing the parameters such as ignition timing, equivalent ratio. The engine performance and exhaust emission were measured by engine performance model at maximum load condition with increasing the rpm in the range of 1,000∼2,200rpm. Also, the testing engine was heavy-duty CNG dedicated engine with displacement of 11,050cc.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.1989-1998
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• 1995

Characteristics of the flame propagation for normal and abnormal combustion in hydrogen premixture in a cylindrical constant-volume combustion chamber are studied numerically. A detailed hydrogen oxidation kinetic mechanism, mixture transport properties and a model describing spark ignition process are used. The calculated pressure-time history of the stable deflagration wave propagation agrees well with the experiment. The ignition of the premixture in the unburned gas, initiated by the hot spot, causes a transition from deflagration to detonation under some initial temperature and pressure. Under the initial conditions with high temperature and pressure, excessive ignition energy initiates a strong blast wave and a detonation wave that follows. The chemical reaction in the detonation wave is much more vigorous than that in the deflagration wave and the peak pressure in the detonation wave is much higher than the equilibrium value.