• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.113-116
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• 1990

In this paper, An expert system for electric furnace with time delay is proposed. The expert system uses Fuzzy control theory. The conventional controller uses Auto-Tuning control theory. From experiment, we can obtain that the response of expert system is superior to the response of the conventional controller. In this experiment, the expert controller is implemented with the IBM PC. The 8751 One chip processor controling the electric furnace is used.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1251-1257
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• 2004

In order to analyze the heat transfer phenomena in the plasma flames, a mathematical model describing heat and fluid flow in an electric arc has been developed and used to predict heat transfer from the arc to the steel bath in a DC Electric Arc Furnace. The arc model takes the separate contributions to the heat transfer from each involved mechanism onto account, that is radiation, convection and energy transported by electrons. The finite volume method and a SIMPLE algorithm are used for solving the governing MHD equations, that are conservation equations of mass, momentum and energy together with the equations describing a standard k-${\varepsilon}$ model for turbulence. The model predicts heat transfer for different currents and arc lengths. Finally these calculation results can be used as a useful insight into plasma phenomena of the industrial-scale electric arc furnace. From these results, it can be concluded that higher arc current and longer arc length give high heat transfer

• Journal of the Korean Society of Safety
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• v.38 no.2
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• pp.15-22
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• 2023

In this study, the process and the environment of a melting furnace, located in Workplace A in Chungnam Province was inspected, and the insulation resistances of electrical circuits and motors were measured, and their changes over five years (2017-2021) were analyzed. It was found that the exhaust fan, oil pumps #A and #B, and heater were installed in 2010. Their insulation resistances decreased from 2017. Specifically, the insulation resistance of Oil Pump #A decreased from 100 (㏁) in 2018 to 20(㏁) in 2021, an 80% reduction. The fast decrease in insulation resistance was due to the high temperature of the melting furnace affecting surrounding the electrical facilities. A safety management scheme on the electrical facility of the melting furnace was proposed.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.35-41
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• 2006

The steel foundries with electric arc furnaces handling metal scraps have recently gained an attention as a potential source of dusts. The present study focuses on the analysis of dust emissions and removals during furnace charging and melting processes by commercial CFD software named FLUENT. A body fitted grid system consisting of 880,000 meshes was first generated by Gambit for the electric arc furnace with the capacity of 60 ton/cycle and then FLUENT was invoked to solve the corresponding NavierStokers equation for the momentum, temperature and dust concentration. The entire processes from metal charging to metal melting were simulated to investigate the unsteady behaviors of fluid flows and dust concentrations. The model simulation results showed that as the top of the electric arc furnace opened for metal charging, hot plumes bursted out from the furnace rose strongly by buoyance and escaped mostly through the main hood. Therefore, the capacity of main hoods determined the vent efficiency in the metal charging process. As the furnace was closed after the metal charging and the metal melting processes was followed, the hot flow stream stretching from the furnace to the main hood was dissipated fast and the flow from the inlet of the bottom of the left hand side to the main and monitoring hoods constituted the main stream. And there was only a slow flow in the right hand side of the furnace. Therefore, the dust concentrations were calculated higher in the left hand side of the furnace, which was consistent with observations.

• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.233-244
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• 2015

In order to study the phase transformation of pyrite and to determine the maximum Fe leaching factors, pyrite samples were an electric furnace and microwave oven and then ammonia leaching was carried out. The rim structure of hematite was observed in the sample exposed in an electric furnace, whereas a rim structure consisting of hematite and pyrrhotite were found in the microwave treated sample. Numerous interconnected cracks were only formed in the microwave treated sample due to the arcing effect, and these cracks were not found in the electric furnace treated sample. Under XRD analysis, pyrite and hematite were observed in the electric furnace treated sample, whereas pyrite, hematite and pyrrhotite were found in the microwave treated sample. The results of the pyrite sample leaching experiments showed that the Fe leaching was maximized with the particle size of -325 mesh, sulfuric acid of 2.0 M, ammonium sulfate of 1.0 M, and hydrogen peroxide of 1.0 M. The electric furnace and microwave treated samples were tested under the maximum leaching conditions, the Fe leaching rate was much greater in the microwave treated sample than in the electric furnace treated sample and the maximum Fe leaching time was also faster in the microwave treated sample than in the electric furnace treated sample. Accordingly, it is expected that the microwave heating can enhance (or improve) Fe leaching in industrial minerals as well as pyrite decomposition in gold ores.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.153-160
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• 2006

This paper presents a new compensating system, which consists of a shunt active filter and passive components for mitigating voltage and current disturbances arising from an Electric Arc Furnace (EAF). A novel control strategy is presented for the shunt active filter. An extended method based on instantaneous power theory in a rotating reference frame is developed for extraction of compensating signals. Since voltages at the point of common coupling contain low frequency interharmonics, conventional methods cannot be used for dc voltage regulation. Therefore, a new method is introduced for this purpose. The passive components limit the fast variations of load currents and mitigate voltage notching at the Point of Common Coupling (PCC). A three-phase electric arc furnace model is used to show power quality improvement through reactive power and harmonic compensation by a shunt active filter using the proposed control method. The system performance is investigated by simulation, which shows improvement in power quality indices such as flicker severity index.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.8
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• pp.48-53
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• 2006

An electric arc furnace being used in the steel industry is a time-varying non-linear load causing voltage fluctuations to the power system. Flicker can be defined as the effect produced on the human visual perception by a changing emission of light lamps subjected to magnitude fluctuations of their supply voltage. The level of flicker depends on the amplitude, frequency and duration of the voltage fluctuations. In this paper, the voltage fluctuation problem in an 154[kV] system due to the electric arc furnace loads is investigated and the analysis results of the static var compensator application for the voltage flicker mitigation are presented and evaluated by the IEC 61000-3-7.

• International Journal of Highway Engineering
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• v.17 no.1
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• pp.25-33
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• 2015

PURPOSES : This paper, presents the results of a laboratory study aimed to verify the suitability of a particular type of Electric Arc Furnace (EAF) steel slag to be recycled in the lithic skeleton of both dense graded and porous asphalt mixtures for flexible pavements. METHODS : Cyclic creep and stiffness modulus tests were performed to evaluate the mechanical performance of three different asphalt mixtures (dense graded, porous asphalt, and stone mastic) prepared with two types of EAF steel slag. For comparison purposes, the same three mixtures were also designed with conventional aggregates (basalt and limestone). RESULTS : All the asphalt mixtures prepared with EAF steel slag satisfied the current requirements of the European standards, which support EAF steel slag as a suitable material for flexible pavement construction. CONCLUSIONS : Based on the experimental work, the use of waste material obtained from steel production (e.g. EAF steel slag) as an alternative in the lithic skeleton of asphalt mixtures can be a satisfactory and reasonable choice that fulfills the "Zero Waste" objective that many iron and steel industries have pursued in the past decades.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.65-71
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• 2007

Since pop-outs are occurred recently on concrete surface occasionally, it is needed to find out accurate causes and to suggest appropriate methods. On this study, it is investigated the occurrence mechanism of pop-outs caused by electric arc furnace Oxidizing slags as fine aggregate for concrete. As a result, it is investigated the cause of pop-outs that extremely small quantities of free CaO and free MgO in the electric furnace slag react with water to produce $Ca(OH)_2$ and $Mg(OH)_2$, so that their volumes are expanded and erupted about two times. As a resolution, it is needed to remove the potential cause of expansion by replacing the deteriorated concrete section up to the depth to secure the safe of structural element with repairing polymer mortar, especially more than 50MPa.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.40-48
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• 2012

This study evaluates the shear performance of reinforced concrete beams with electric arc furnace oxidizing slag aggregates generated from iron manufacture. A total of six simple supported specimens were cast and tested in shear. The main test variables were the type of aggregates and the amount of shear reinforcements. The specimens under four point loading had a shear span-to-depth ratio of 2.5 and a rectangular section with a width of 200mm and an effective depth of 300mm. Existing equations to predict the shear strength of the specimens were used in this study. Furthermore, a finite element analysis using shear analytical model was performed to trace the shear behavior of the specimens with electric arc furnace oxidizing aggregates. From the test results, the shear performance of specimens with electric arc furnace oxidizing aggregates is similar to that of specimens with natural aggregates.