• JOURNAL OF ELECTRICAL WORLD
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• no.9 s.69
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• pp.34-38
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• 1982

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1909-1911
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• 2005

The electrical and chemical characteristics in transformer insulations are changed due to thermal stress. In the chemical property, as the Kraft paper ages, the cellulose polymer chains breakdown into shorter lengths with a corresponding decrease in both tensile strength and degree of polymerization(DP). Furthermore, cellulous chains breakdown is accompanied by an increase in the content of various furanic compounds within the dielectric liquid. It is known that furanic components in transformer oil come only from the decomposition of insulating paper rather than from the oil itself. Therefore the analysis of furan products provides a complementary technique to dissolved gas analysis for monitoring transformers when we evaluate the aging of insulating paper by the total concentration of carbon monoxide and carbon dioxide dissolved in oil only. In this paper the accelerated aging process of oil--paper samples have been investigated at a temperature up to $140^{\circ}C$ for 500 hours. The oil-paper insulation samples have been measured at intervals of 100 hours. For analysis we used high performance liquid chromatography(HPLC) in accordance with IEC 61198 method.

• Analytical Science and Technology
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• v.19 no.6
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• pp.512-518
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• 2006

The evidence containing some kind of petroleum at the fire spot was analyzed by gas chromatography to identify a fire's sources. To extract some petroleum from fire evidence, 10.0 mL of n-hexane was added in this solution, and it was shaken for 30 minutes. To identify a kind of petroleum in fire evidence, the prepared n-hexane solution was injected and analyzed in the gas chromatograph. The chromatogram of sample was different from those of thinner and gasoline that have low boiling point, and shown different peak pattern to heating and boiler oils. But it was similar to the chromatogram of diesel oil. After small amount of diesel oil was added to the sample, the area of characteristic peaks was increased more than those of raw sample. From the results, the kind of petroleum in the fire evidence was diesel oil.

• Journal of Hydrogen and New Energy
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• v.20 no.2
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• pp.87-94
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• 2009

There are several types of compressors which are appropriate for hydrogen gas station. Diaphragm type of compressor is the one of them and it satisfies the requirements for that purpose in terms of maintaining gas purity and making high pressure over 700 bar. The objective of this study is to find an optimal design of oil distribution hole configuration. The number of holes is changed maintaining total cross-sectional area of holes. Five cases(1 hole, 4, 8,16 and 24 holes) were studied through Fluid Structure Interaction(FSI) analysis method. Gas and oil pressure, the deflection and stress of the diaphragm were analysed during compression and suction process respectively. There is no specific difference among the cases during compression. An additional deflection due to the existence of hole was found during suction for all case. But the highest deflection and stress were found in the 1 hole case. It was seen that 60% decrease of stress in magnitude in 24 hole case compare to the 1 hole case.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.3
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• pp.563-570
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• 2018

This paper proposes an efficient dissolved gas analysis(DGA) and classification method of an oil-filled transformer using machine learning algorithms to solve problems inherent in IEC 60599. In IEC 60599, a certain diagnosis criteria do not exist, and duplication area is existed. Thus, it is difficult to make a decision without any experts since the IEC 60599 standard can not support analysis and classification of gas date of a power transformer in that criteria. To address these issue. we propose a dissolved gas analysis(DGA) and classification method using a machine learning algorithm. We evaluate the performance of the proposed method using support vector machines with dissolved gas dataset extracted from a power transformer in the real industry. To validate the performance of the proposed method, we compares the proposed method with the IEC 60599 standard. Experimental results show that the proposed method outperforms the IEC 60599 in the classification accuracy.

• International Area Studies Review
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• v.14 no.1
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• pp.99-119
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• 2010

This study explores the natural gas market and the oil market in the U.S. and the European oil market. It focuses on two kinds of analyses; one is to confirm whether there is the predictive power between spot and futures within homogeneous commodity market(or inter-heterogeneous commodity market) through Granger-causality test in terms of the return rate and the volatility. The other is to examine the spot price stabilizing effect of futures price through regression analysis. When it comes to the predictive power of inter-commodity market, there was a conflicting aspect between the return rate of spot and futures. Overall, however, its statistical significance was low. With respect to the volatility, we found that the natural gas market has little influence on the oil market unlike the predictive power of oil market on natural gas market. Concerning the return rate of the predictive power within homogeneous commodity market, we found that the return rate of spot has the predictive power on futures only in the European market. In addition, we identified that there is feedback between spot and futures in the all commodity markets regarding volatility. As a result of the spot price stabilizing effect analysis of futures price, futures volatility increased the spot volatility.

• Journal of Energy Engineering
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• v.11 no.3
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• pp.187-193
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• 2002

IGCC (Integrated Gasification Combined Cycle) power plant is becoming more attractive because it allows that various fuels like coal, heavy oil md even residue oil and wood are used in a gas turbine. This paper presents a prediction of performances of gas turbine when low caloric value syngas fuels produced from the IGCC is used in it originally designed with natural gas fuel. Using a systemic method which predicts a gas turbine behavior with limited design data, when natural gas, design fuel and four other types of syngas are used in GE 7FA gas turbine, its performances are predicted on design and off-design conditions.

• Journal of Energy Engineering
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• v.10 no.3
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• pp.188-194
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• 2001

The process simulations are made on the IGCC power plant using heavy residue oil from refinery process. In order to model combined power block of IGCC, the present study employs the gas turbine of MS7001FA model integrated with ASU (Air Separation Unit), and considers the air extraction from gas turbine and the combustor dilution by returned nitrogen from ASU. The exhaust gas energy of gas turbine is recovered through the bottoming cycle with triple pressure HRSG (Heat Recovery Steam Generator). Clean syngas fuel of the gas turbine is assumed to be produced through Shell gasification of Visbreaker residue oil and Sulfinol-SCOT-Claus gas cleanup processes. The process optimization results show that the best efficiency of IGCC plant is achieved at 20% air extraction condition in the case without nitrogen dilution of gas turbine combustor find at the 40% with nitrogen dilution. Nitrogen dilution of combustor has very favorable and remarkable effect in reducing NOx emission level, while shifting the operation point of gas turbine to near surge point.

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.1-9
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• 2022

Selection of a suitable artificial lift is important in terms of efficient operation and economics for oil production. In general, process of well design includes the selection of artificial lift, but the oil recovery could be enhanced by use of hybrid system combined with two types of artificial lift method according to reservoir condition for oil production. Electric submersible pump (ESP), as a presentative artificial lift method, is a manner for supplying the pressure in the lower part of oil well by using of a multi-stage centrifugal pump with an electric energy. However, there is a disadvantage that has a limit to the application period because of mechanical defection on ESP. Accordingly, it is possible to reduce the shutdown time of production well by applying the ESP/Gas lift hybrid system, which is to switch to a gas lift when an ESP is defective. This study describes the effect of ESP/gas lift hybrid system compared with ESP method for a onshore horizontal well locating in the of Permian basin, USA. As a result of study, ESP/gas lift hybrid system could make more effective productivity than ESP method. Also, we quantitatively predicted how much economic benefit would be obtained when the hybrid system was applied in the production well.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.129-135
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• 1999

We developed a new measuring equipment which makes it possible to perform on-line measurements with the merits of its implicity and the time-saving characteristics. By using the newly developed measurement system, the amount of aeration is directly measured on several parameters, i.e, engine speed, oil quantity, oil deterioration, oil temperature and viscosity, etc. It showed that oil aeration is strongly related to be gas movements in crankcase and the residence time of circulating oil in oil pan. In addition, in order to clarify the mechanism of aeration and to quantify the degree of aeration, a modelling analysis to predict aeration was performed , and as a guiding parameter, Aeration Index was defined. Finally, the parameter was compared with the actual amount of aeration, and it was confirmed that they gave a good correlation with each other.