• Journal of the Korean Society of Safety
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• v.7 no.4
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• pp.105-114
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• 1992

This paper presents an study on the knowledge based system for diagnosing the fire causes using the Fuzzy Possibility Measure( FPM ) about the electric-fire ignition. The Ignition values needed for causes diagnosis is computed as FPM for electric-fire ignition based on the internal scale technique that assigns numerically the characteristic difference of facts to the-tin-ear scale. For the convinience of inference, ignition sources are classified into seven types : short, ground fault, leakge of electricity, overcurrent, cord junction overheating, bad Insulation and spark. The system for causes diagnosis of electric-fire is composed of Knowledge Acquisition System, Inference Engine and Man-Machine Interface, The diagnosis system is wrritten in an artificial intelligence langusge “PROLOG” which uses depth-first search and backward chaining schemes in reasoning process.

• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.181-188
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• 1993

The sintering and renitridation behaviors of ultrafine Si3N4 powder compacts, which were heavily oxidized and/or free-Si rich, were investigated with particular attentiion to microstructures. The specimens were heated without restoring to additives and pressure by controlling heating process attained a Xe image apparatus. The effect of particle size, free-Si contents, decomposition and renitridation, were investigated. When fired to 1$650^{\circ}C$ within 15 sec and then immediately held at 135$0^{\circ}C$ for 10min N2 atmosphere, significant densification took place in the limited region, in addition to decreasing oxygen contents to less than 0.3wt%. On the other hand, specimens decomposed due to overheating at the initial stage were rapidly renitridated at the relatively lower temperature of the holding stage. And, then, the activation energy for the renitridation was calculated to be 49kcal/mole.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.314-315
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• 2007

As a section of electric power system linked with Kepco was changed, the decrease in qulity of the electric power transmitted to the Hapcheon hydraulic power station occurred. The actual state bring about the overheating and capability decline of electricity accommodation equipment. From now, let's improve the efficiency on the maintenance of generating equipment by studying about the cause and the method for this problem.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.87-90
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• 2004

This paper describes development of power transformer maintenance system using intelligent dissolved gases in oil analysis. The used gases are acetylene(C2H2), hydrogen(H2), ethylene(C2H4), methane(CH4), ethane(C2H6), carbon monoxide(CO) and carbon dioxide(CO2). The rule and neural network based gas analysis methods are used for artificial intelligent diagnosis. It is indicated that this program is efficient for diagnosis of oil immersed transformers diagnosis from application of gas analysis data of serviced transformer which has local overheating

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.4
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• pp.40-53
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• 1989

Boiling heat transfer phenomena is widely applied to BWR and electrical heating system because of its high heat transfer coefficient. In these systems, steady state heat transfer is dependent on nucleate boiling. When the heat generating rate is sharply increased or the cooling capacity of coolant is sharply decreased, sharp wall temperature rise is occurred under the critical heat flux(CHF) condition. This paper presents the simple wall temperature fluctuation model of transition mechanism in the repeating process of overheating and quenching, when coalescent bubble passes relatively slowly on the wall and simultaneously the transition from nucleate boiling to film boiling is carried at especially onset of the CHF state. The values calculated by the present model are resulted comparatively good with the measured.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.147-148
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• 2006

Recently, due to increasing the application of power electronic equipment, harmonics generated from the non-liner load are fairly produced. Harmonics can cause a variety of problems such as the overheating of distribution transformer, the breakdown of device and communication interference. Interest about power quality decline of power system is very increased. In this paper, we are measured the harmonic voltage and current o( power system to analyze harmonic characteristics, and it is analyzed Total Harmonic Distortion(THD). Also, we Ere modeled power system using PSCAD/EMTDC. And it is analyzed harmonic voltage and current in steady-state. The study results have been indicated the utility about harmonics analysis and modelling for power system.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.260-270
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• 2015

One-dimensional packed bed reactor model accounting for interfacial and intra-particle gradients was developed and based on it numerical analyses were performed to investigate the dynamic behavior of a commercial scale methanation reactor. Methanation reaction was almost complete near the reactor inlet and gases with equilibrated composition were discharged from the reactor. Both the intra-particle temperature gradient and differential surface temperature rise were found to be severe near the reactor inlet. To reduce the possible degradation or fracture of catalyst particles and prevent local overheating on the catalyst, addition of inert material can be an effective way.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.2
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• pp.72-75
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• 2005

In oil-filled equipment such as transformers, partial discharge or local overheating will precede a final shutdown. Accompanied with such problems is a decomposition of insulating material into gases, which are dissolved into the transformer oil. The gases dissolved in oil can be separated with some membranes based on the differences in permeability of membranes to different gases. This paper discuss the permeability characteristics of several membranes for separation hydrogen gas in oil. With result of this paper, it may become possible to detect fault-related gases from transformer oil and predict incipient failures in the

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.243-247
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• 2014

In this paper, we design two types of the sensor module to measure the partial discharge causing failures and electric fires for power incoming/distributer. And evaluate the performance thereof. Analyze the correlation of the phase current and the partial discharge and overheating. Proposes to apply the stability index by utilizing the analyzed information and use in order to prevent the failure or electrical fire of the power incoming/distributer.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.3
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• pp.26-33
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• 1994

A new reliable method to prediet the axial vapor fraction distribution from the measured probability density of the liquid bulk temperature is suggested in this paper. And also the actual quality of the subcooled boiling flow is easily calculated from the liquid bulk temperature. When the heat generating rate is reached to the CHF value, the sharp wall temperature increasing by the wall temperature fluctuation is occurred under the CHF condition. This paper presents the simple wall temperature fluctuation model of transition boiling by the repeating process of overheating and quenching, when the coalescent bubble passes slowly near the wall. Experiments for the subcooled R-113 flow are carride-out in the range of(0.9399~4.461)${\times}10^6$kg/$m^2$hr mass velocity and 10~3$0^{\circ}C$ intel subcooling condition.