• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.10
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• pp.480-486
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• 2005

This paper proposes a method to consider an aging failure probability and survival probability of power system components, though only aging failure probability has been considered in existing mean life calculation. The estimates of the mean and its standard deviation is calculated by using Weibull distribution, and each estimated parameters is obtained from Data Analytic Method (Type H Censoring). The parameter estimation using Data Analytic Method is simpler and faster than the traditional calculation method using gradient descent algorithm. This paper shows calculation procedure of the mean life and its standard deviation by the proposed method and illustrates that the estimated results are close enough to real historical data of combustion turbine generating units in Korean systems. Also, this paper shows the calculation procedures of a probabilistic failure prediction through a stochastic data analysis. Consequently, the proposed methods would be likely to permit that the new deregulated environment forces utilities to reduce overall costs while maintaining an are-related reliability index.

• Journal of the Korean Society of Combustion
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• v.21 no.3
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• pp.32-38
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• 2016

This paper aims to predict oxidation amounts of catalyst and heat produced through passive regeneration on DPF according to different EGR rates and loads of off-road engines. Soot oxidation model and parameter assumption model were used for the test. Engine data were measureed with 25%, 50% and 75% of 1600 RPM loads and with 0% and 30% of EGR rates in order to estimate parameters. Oxygen levels calculated on the DPF downstream and oxygen levels measured were compared through all of the experimental conditions for validating the model. Oxidation rates on DPF according to different EGR rates and oxygen levels on the DPF downstream were estimateed successfully, which can be applied for off-road vehicles.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.5
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• pp.693-700
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• 2006

The important factor for the development of burner is the achievement of low emissions with maintaining combustibility. In case of maintaining high temperature flame and excess air to increase the combustibility, it is possible to achieve high combustion efficiency, due to the reduction of UHC(unborn hydrocarbon), carbon monoxide and soot. However, it is difficult to reduce the thermal NOx produced in the high temperature flame. To solve this problem, we developed externally oscillated oil burner which is possible for the high efficiency combustion and low NOx emission, simultaneously. The experiment of flame characteristics and NOx reduction were achieved according to the variation of frequency, amplitude and air velocity. Frequency, amplitude and air velocity are the most important parameter. The optimum operating conditions are frequency 1,900 Hz, amplitude 3 $V_{pp.}$ and air velocity 6.8 m/s. Reduction of NOx and CO are 47% and 22%, respectively.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.28-36
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• 1993

Present-day there are two of theories which have considerable scientific support to explain the knock phenomenon in S.I. engine, the detonation theory and the autoignition theory. But they still have some problems to explain effects of knock parameters, i.e.. compression ratio, spark timing, mixture quality, engine speed, ect, on knocking process in S.I. engine. Accordingly, it is essential to find out whish is more adequate theory of two and to develop the method of analyzing knock phenomenon, that is the aim of this paper. The Authors develop the method of predicting transient temperature and pressure at the end-gas zone during the combustion period and analyze knocking process by this method based on the knock theories. The caluculated values based on the autoignition theory show reasonablly correct relations between knock parameters and knock process but there is no evidence of knock occurred by detonation theory through the calculation according to the all parameters. The authors find out that the autoignition theory is more adequate than detonation theory to analyze knocking process in S.I. engine.

• Journal of the Korean Society of Combustion
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• v.10 no.4
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• pp.24-32
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• 2005

Various types of plasma source applied in $CH_4$ decomposition process are compared. DBD by pulse and AC power, spark by pulse and AC power, rotating arc and hollow cathode plasma are chosen to be compared. The results show that $CH_4$ conversion per given unit power is relatively high in hollow cathode plasma and rotating arc that induces rather high temperature condition and that is why both thermal dehydration and plasma induced decomposition contribute for the overall process. In case of DBD wherein high temperature electron and low temperature gas molecule coexist, the process shows low conversion rate, for in rather low temperature condition the contribution of thermal dehydration is lowered. Selectivity of $C_2H_6$ and $C_2H_2$ is shown to be a good parameter of the relative contribution of plasma chemistry in the overall process. From the results we concluded that required condition of plasma source for a cost effective and high yield $CH_4$ decomposition is to have characteristics of both thermal plasma and non thermal plasma in which temperature is high above a certain threshold state for thermal dehydration and electron induced collision is maximized in the same breath.

• Journal of the Korean Society of Combustion
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• v.17 no.4
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• pp.30-37
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• 2012

The flame lengths and NOx emission characteristics of syngas $H_2$/CO turbulent non-premixed jet flames were investigated. The flame length which is the main parameter governs NOx emission was studied for various syngas compositions. The flame length was compared with previous correlation between Froude number and flame height and it shows that they have good agreements. It was confirmed that the turbulent jet flames herein investigated are in the region of buoyancy-momentum transition. NOx emission was reduced with increased Reynolds number and CO contents in syngas fuel and with decreased fuel nozzle diameter which is attributed by decreased flame residence time. Previous EINOx scaling based on flame residence time of $L_f^3/(d_f^2U_f)$ satisfies only the jet flame in momentum-dominated region, not buoyancy-momentum transition region. The simplified flame residence time ($L_f/U_f$) was adopted in modified EINOx scaling. The modified scaling satisfies the jet flames not only in momentum-dominated region but in buoyancy-momentum transition region. The scaling is also satisfied with $H_2$/CO syngas jet flames.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.3
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• pp.27-39
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• 2009

The main objective of this study is to investigate the characteristics of combustion by analyzing fuel gases from a combustion equipment with various combustion conditions for refuse-derived fuels (RDFs). CO gas is a parameter for indicating of incomplete combustion during a combustion process. The lowest CO gas was produced when the experiment conditions were m=2 under air-fuel condition and $800^{\circ}C$. $CO_2$ gas is a final product after complete combustions. The highest amount of $CO_2$ gas was produced when the experiment conditions were m=2 under air-fuel condition and $800^{\circ}C$. The highest level of $SO_2$ gas was produced in S.1 sample containing the highest sulfur. The highest level of NOx gas was produced in S.1 sample with the highest nitrogen content and air-fuel condition of m=2 under temperature of $800^{\circ}C$. HCl gas that is generated by reacting with metals catalyst through oxygen catalyst reaction during combustion process is a precursor of dioxin formation. The higher level of HCl gas was produced in the sample with higher chlorine content. The lowest level of HCl gas was produced when the experiment conditions were air-fuel condition of m=2 and $800^{\circ}C$. The lowest level of $NH_3$ gas was generated when the experiment condition was m=2 under air-fuel condition and after 3 minutes. Air-fuel condition is more important to create $NH_3$ gas than operating temperatures. Higher level of $H_2S$ gas was generated in S.1 sample with the higher sulfur content and was created in RDFs that contain higher mixture ratios of sewage sludge and food wastes. A result of combustion, gases and gases levels from the combustion of S.1 and S.2 were very similar to the combustion of a stone coal. As results of this research, when evaluating the feasibility of the RDFs, the RDFs could be used as auxiliary and main fuels.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.4
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• pp.383-391
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• 2009

The detonation wave characteristics of JP-7 and oxygen mixture is investigated by one-step induction parameter model (IPM) obtained from a detailed chemistry mechanism. A general procedure of obtaining reliable one-step kinetics IPM for hydrocarbon mixture from the fully detailed chemistry is described in this study. The IPM is obtained by the reconstruction of the induction time database obtained from a detailed kinetics library. The IPM was confirmed by the comparison of the induction time calculations with that from detailed kinetics. The IPM is later implemented to a fluid dynamics code and applied for the numerical simulation of detonation wave propagation. The numerical results show the detailed characteristics of the detonation wave propagation in JP-7 and oxygen mixture at affordable computing time, which is not be possible by the direct application of the detailed chemical kinetics mechanism of hydrocarbon fuel combustion.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.92-99
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• 2013

High oil price and global warming problem are being continued all over the world. For this reason, fuel economy and emission of greenhouse gas are regulated by law in many countries. Therefore many companies are researching and producing hybrid electric vehicles (HEVs) which substitute conventional internal combustion engine vehicle. However, these researches and productions are restricted to mainly passenger cars. Because of cost and physical problems, commercial vehicles are difficult to evaluate fuel economy. So simulations are important and it is necessary to know how sensitive parameters that enter into simulation affect. In this paper, forward simulations using AVL Cruise were conducted for analysis of fuel economy for parallel hybrid bus and were repeated by changing each parameter. Based on these results, root mean square errors (RMSE) are calculated for analysis of fuel economy sensitivity. The number of target parameters are 15. These parameters were classified with high and low sensitivity parameter relatively.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.49-55
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• 1997

Destruction phenomena of structure by gas explosion is due to the explosion pressure and heat. Explosion pressure is a kind of energy converted from the gas mixture explosion. In this paper, we tried to find the relationship between explosion characteristics and combustion heat of the hydrocarbon-oxygen mixtures. Experiment were carried out with the volume of $5916cm^3$ cylindrical explosion vessel. Hydrocarbon gases which used in this study were methane, ethylene, propane, and buthane Experimental parameter was the concentration of the gas mixtures. Explosion characteristics were measured with strain type pressure transducer through the digital storage oscilloscope. From the experimental result, it was found that explosion pressure depend upon the combustion heat.