• Journal of the Korean Society of Safety
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• v.39 no.3
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• pp.7-13
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• 2024

This study examines the physical characteristics of self-regulating heating cables caused by increased temperature and fire risk due to local degradation. A thermo hygrostat system, a convection dryer, a digital multimeter (Agilent 34465 A), NI DAQ, and the LabVIEW program were used to assess the physical properties in response to temperature fluctuations. As the temperature increases, the resistance of the self-regulating heating cable increases; however, when the critical point is exceeded, the resistance sharply decreases. A problem arises when the resistance value cannot return to its original state even though the temperature is lowered to the initial state. Moreover, when the ambient temperature rises while power is applied, the resistance value initially increases, and the flowing current decreases, maintaining a constant state. However, when the critical temperature is exceeded, the flowing current increases because of a rapid decrease in the resistance value, progressing to ignition. When the resistance value decreases because of the deterioration of one local area, the total resistance value becomes less than the initial resistance value. Therefore, the flowing current increases and an ignition problem occurs at one location where deterioration occurs. Despite the sustained flames and arcs resulting from the changes in the overall physical properties of the self-regulating heating cable and resistance variations due to local decline, the fire continued as the flowing current was lower than the operating current of the circuit breaker, failing to cut the power. In the case of self-regulating heating cables and heating wires, which are the leading causes of fires in winter, efforts are needed to ensure the need for periodic maintenance and the use of KS-certified products.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.85-91
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• 2015

A gasoline engine automobile uses high voltage generation of the ignition coil, igniting and burning mixed fuel in the combustion chamber, which drives the engine. When the electronic control unit intermits a current supplied to the power transistor, counter electromotive force with a low voltage is generated by self induction action in the ignition primary coil and a high voltage is induced by mutual induction action with the primary ignition coil in the second ignition coil. The high voltage is supplied to the ignition plug in the combustion chamber, causing a spark, igniting the compressed mixed fuel. If a very small defect occurs inside the insulating material when a voltage is applied in said ignition coil, the performance of the insulation material will get worse and breakdown by a partial discharge of corona discharge. Thus, in this experiment, we are to contribute to improve the performance and ensure the reliability of the ignition coil by investigating partial discharge characteristics according to the change of voltage and temperature when a voltage is applied to the specimen of the epoxy molding ignition coil.

• Journal of Hydrogen and New Energy
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• v.23 no.6
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• pp.628-633
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• 2012

It was found that the pure hydrogen-air pre-mixture was self-ignited at a high compression ratio without any assisting method in room temperature, thus refuting the preconception that compression ignition of hydrogen engine was impossible. Therefore, in order to analyze the correlation of compression ignition condition at cold start with hydrogen HCCI engine clearly, the possibility of compression igniting compression ratio is investigated with the change of equivalence ratio and engine speed, experimentally. As the results, it is confirmed that the possibility of compression-igniting compression ratio at cold start was decreased by increasing equivalence ratio due to decreasing auto-ignition temperature. In addition, it is grasped that the possibility of compression-igniting compression ratio at cold start is decreased around 14.9% by increasing engine speed at same supply energy.

• Journal of Power System Engineering
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• v.8 no.3
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• pp.5-10
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• 2004

This work deals with a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. In order to keep a homogeneous air-fuel mixing, the fuel injector is water-cooled by a specially designed coolant passage. Investigated are the engine emission characteristics under the wide range of operating conditions such as 40 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, $150\;to\;180^{\circ}C$ in the inlet-air temperature, and $80^{\circ}$ BTDC to $20^{\circ}$ ATDC in the injection timing. A controlled auto-ignition gasoline engine which has the ultra lean-burn with self-ignition of gasoline fuel can be achieved by heating inlet air. It can be achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxides had been significantly reduced by CAI combustion compared with conventional spark ignition engine.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.79-85
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• 2004

This work treats a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. Investigated are the engine emission characteristics under the wide range of operating conditions such as 32 to 63 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, and 150 to $180^{\circ}C$ in the inlet-air temperature. A controlled auto-ignition gasoline engine can be achieved the ultra lean-burn with self-ignition of gasoline fuel by heating inlet air. It can be achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxides had been significantly reduced by CAI combustion compared with conventional spark ignition engines.

• Journal of Powder Materials
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• v.17 no.1
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• pp.29-35
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• 2010

We produced cylindrical porous TiNi bodies by Self-propagating High-temperature Synthesis (SHS) process, varying the heating schedule prior to ignition of a loose preform compact made from (Ti+Ni) powder mixture. To investigate the effect of the heating schedule on the behaviour of combustion wave propagation and the structure of porous TiNi shape-memory alloy (SMA) body, change of temperature in the compact during SHS process was measured as a function of time and used for determining combustion temperature and combustion wave velocity. Microstructure of produced porous TiNi SMA body was observed and the results were discussed with the combustion characteristics. From the results it was concluded that the final average pore size could be controlled either by the combustion wave velocity or by the average temperature of the preform compact prior to ignition.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.298-302
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• 2008

In this study, we have carried out the test to examine the ignition characteristics, such as a relation of moisture content and combustibility, and ignition temperature using KRS-RG-9000 tester, living leaves and dead leaves of significant 7 species of Young Dong Provinces of Korea after and before the rainfall. After 144 hours at normal temperature, the percentage of water content of the needle-shaped leaves was less than 10%. So it is suppose to be ignite easily. On the other hand, the self-temperature to ignite of broadleaf is higher. So the retard time at lower temperature is more long than needle-shaped leaf. Consequently, the fire-resistant qualities of broadleaf is higher than needle-shaped leaf.

• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.235-241
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• 1996

Self-Propagating high temperature synthesis(SHS) technique was used to synthesize the spinel phase of MgAl2O from MgO and Al powder. Processing factors such as mixing time preheating temperature and ignition catalyst were varied to determine the optimum condition to form MgAl2O4 phase. The reaction products were heat treated at the temperature range of 120$0^{\circ}C$ and 150$0^{\circ}C$. to observe phase transformation of unreacted materials. Processing factors such as 48 hrs-mixing 80$0^{\circ}C$-preheating and 20wt% KNO3-ignition catalyst were effective of the formation of MgAl2O spinel. An activation energy 49.7kcal/mol. was calculated to form a MaAl2O4 spinel from unreacted materials.

• Journal of Mechanical Science and Technology
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• v.16 no.6
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• pp.851-860
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• 2002

In this study, it was attempted to obtain the fundamental data for the formation and oxidation of soot from a diesel engine. Combustion of spray injected into a cylinder is complex phenomenon having physical and chemical processes, and these processes affect each other. There are many factors in the mechanism of the formation and oxidization of soot and it is necessary to observe spray combustion microscopically. In order to observe with that view, free fuel droplet array was used as an experimental object and the droplet array was injected into an atmospheric combustion chamber with high temperature. Ambient temperature of the combustion chamber, interdroplet spacing, and droplet diameter were selected as parameters, which affect the formation and oxidation of soot. In this study, it was found that the parameters also affect ignition delay of droplet. The ambient temperature especially affected the ignition delay of droplet as well as the flame temperature after self-ignition. As the interdroplet spacing that means the local equivalence ratio in a combustion chamber was narrow, formation of soot was increased. As diameter of droplet was large, surface area of the droplet was also broad, and hence evaporation of the droplet was more active than that of a droplet with relative small diameter.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.13-23
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• 2006

A propellant mainly consisting of nitric ester including nitrocellulose and nitroglycerine is characteristic of being decomposed naturally. And this phenomenon is known as being affected mostly by its storing temperature and humidity. In this research, the effect of storing temperature and humidity on self life has been studied by measuring the contained quantity of residual stabilizer of propellant KM30Al, which are parts of 155MM propelling charge K676 and K677; the method for the measurement is acceleration aging test, and decomposition reaction equation, Eyring Equation and Berthlot Equation were used for the calculation. As result of this study, it was found that the storing temperature influenced seven times as large as the storing humidity upon the self life of the propellant KM30Al, Furthermore, especially in the high temperature region, the storing temperature had a dominant effect on the self life.