• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.45-57
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• 2000

Results of environmental monitoring for 35 steel industry welders exposed to manganese and chromium fume were evaluated. Efficiency of respiratory protectors, welding face shields and local exhaust ventilation were also evaluated to establish more efficient preventive measures that can protect welders from occupational disease as related to welding fume. The results are as follows; 1. Total fume from $CO_2$ arc welding with mild steel occurred 1.5 to 2.2 times more than that from shielded metal arc welding. Chromium and nickel fume from welding with stainless steel occurred 27 to 59 times and 18 to 30 times, respectively, than those with mild steel. 2. Proportions of water-soluble chromium(VI) and insoluble chromium(VI) Compare to total chromium occurring from $CO_2$ arc welding with stainless steel were 10.5% and 8.7%, respectively, while those with mild steel were 57.1 to 63.2% and 31.6 to 38.1%, respectively. 3. The efficiencies of 4 types of respiratory protectors to reduce welding fume exposure were evaluated as 54.4 to 64.4%. 4. The reducing effect of head type welding face shield was 67.6%, and that of hand type welding face shield was 58.5%. The highest reducing effect was shown in air supply welding face shield as 99.2%, although it is not convenient to wear. 5. When welding face shield and respiratory protectors were worn together, the reducing efficiency increased to 79.0 to 87.5%. 6. When local exhaust ventilation was installed in workplace, the reducing efficiencies varied from 31.5 to 73.1% according to the types of welding.

• Journal of Conservation Science
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• v.26 no.4
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• pp.407-416
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• 2010

Bacteria with ability for iron reduction in the soil can use corrosion products of iron remains as energy source. The activities of this bacteria cause the change of corrosion products. As a result, it can be difficult to identify corrosion products promoting corrosion of iron remains. The purpose of this study, is to investigate the change in corrosion products that bacteria causes and to improve understanding about the corrosion of iron remains. To simulate corroded condition of excavated iron remains, carbon steel corroded by solution of NaCl and $Na_2SO_4$ was prepared. Then the prepared carbon steel was immersed in a liquid medium with bacteria. The incubation period was 42days. After experiment, the carbon steel was analyzed by SEM-EDS, X-ray diffraction method. The result is that the carbon was changed to green because of activity of bacteria and that the plate crystal and lozenge crystal were generated on the corrosion specimen. Also, we confirmed that the activities of bacteria differenciated colors and forms of corrosion products.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.144-148
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• 2001

In this study, to improve the color of iron oxide from waste pickling acid at the cold rolling mill, quality control technologies to improve color were investigated. During operation of the spray roaster, the charge amount of waste acid per hour, temperature, and numbers of spray nozzles were investigated. At the admixing process, titanium oxide, silica, and goethite were tested. The color character of iron oxide can be improved by process control of the spray roaster and the admixing process at a pigment factory. Iron oxide from this study is appropriate for use as a colorant of a concrete product.

• Progress in Superconductivity and Cryogenics
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• v.19 no.1
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• pp.22-25
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• 2017

Steel slag has been considered as an industrial waste. A huge amount of slag is produced as a byproduct and the steel slag usually has been dumped in a landfill site. However the steel slag contains valuable resources such as iron, copper, manganese, and magnesium. Superconducting magnetic separation has been applied on recovery of the valuable resources from the steel slag and this process also has intended to reduce the waste to be dumped. Cryo-cooled Nb-Ti superconducting magnet with 100 mm bore and 600 mm of height was used as the magnetic separator. The separating efficiency was evaluated in the function of magnetic field. A steel slag was ground and analyzed for the composition. Iron containing minerals were successfully concentrated from less iron containing portion. The separation efficiency was highly dependent on the particle size giving higher separating efficiency with finer particle. The magnetic field also effects on the separation ratio. Current study showed that an appropriate grinding of slag and magnetic separation lead to the recovery of metal resources from steel slag waste rather than dumping all of the volume.

• Transactions of Materials Processing
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• v.26 no.6
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• pp.365-371
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• 2017

During sling wear of a ferrous metal, a surface layer is formed. Its microstructure, constituting phases, and mechanical property are different from those of the original wearing material. Since wear occurs at the layer, it is important to characterize the layer and understand how wear rate changes with different layers. Various layers are formed depending on external wear conditions such as load, sliding speed, counterpart material, and environmental conditions. In this research, sliding wear tests of pure iron were carried out against two different counterparts (AISI 52100 bearing steel and $Al_2O_3$) in the air and in an inert Ar gas atmosphere. Pure iron was employed to exclude other effects from secondary phases in steel on the wear. Wear tests were performed at room temperature. Worn surfaces, wear debris, and cross-sections were analyzed after the test. It was found that these two different counterparts and environments produced diverse layers, resulting in significant changes in wear rate. Against the bearing steel, pure iron showed higher wear rate in an Ar atmosphere due to severe adhesion than that in the air. On the contrary, the iron showed much higher wear rate in the air against $Al_2O_3$. Different layers and wear rates were analyzed and discussed by oxidation, severe plastic deformation, and adhesion at wearing surfaces.

• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.376-380
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• 2012

A study on the iron-loss reduction of 110kW-class Interior Permanent Magnet Synchronous Motor (IPMSM) for Light Railway Transit (LRT) is conducted. In general, the iron loss of IPMSM depends on the characteristics of core material and non-oriented electrical steel is used as a core material of IPMSM. In order to reduce the iron-loss of IPMSM, both non-oriented electrical steel and grain oriented electrical steel are applied as core material. Iron loss of 110kW-class IPMSM can be reduced approximately 40% comparing to an existing IPMSM by applying grain oriented electrical steel to the stator teeth.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1071-1073
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• 2005

This paper investigates magnetic field behavior and its iron losses in the stator core using electrical steels. The analysis model is a brushless motor with the permanent magnet. The elliptical rotating and alternating flux distributions with non-sinusoidal waveforms are obtained by Finite Element Method and then their harmonic components are extracted. Based on these results, the local iron losses in the stator core caused by the harmonic flux are calculated. Furthmore, this paper explains the relation between the complex flux waveform and iron loss produced in each part of the stator core.

• Corrosion Science and Technology
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• v.18 no.3
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• pp.86-91
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• 2019

Generally, atmospheric corrosion is the electrochemical degradation of metal that can be caused by various corrosion factors of atmospheric components and weather, as well as air pollutants. Specifically, moisture and particles of sea salt and sulfur dioxide are major factors in atmospheric corrosion. Using galvanized steel is one of the most efficient ways to protect iron from corrosion by zinc plating on the surface of the iron. Galvanized steel is widely used in automobiles, building structures, roofing, and other industrial structures due to their high corrosion resistance relative to iron. The atmospheric corrosion of galvanized steel shows complex corrosion behavior, depending on the plating, coating thickness, atmospheric environment, and air pollutants. In addition, corrosion products are produced in different types of environments. The lifespans of galvanized steels may vary depending on the use environment. Therefore, this study investigated the corrosion behavior of galvannealed steel under atmospheric corrosion in two locations in Korea, and the lifespan prediction of galvannealed steel in rural and coastal environments was conducted by means of the potentiostatic dissolution test and the chemical cyclic corrosion test.

• Journal of the Korean institute of surface engineering
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• v.26 no.1
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• pp.23-30
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• 1993

Iron component in wasted hydrochloric etching solutions from steel works were recovered by electrolysis. The electric conductances of the solutions, as the function of the bath temperature and the ferrousion concen-tration, were measured and the result of the original solution was K=(0.0012+0.0005$\times$10-3T-0.1160$\times$10-6T2)$\times$102S.m-1(T in $^{\circ}C$) The current efficiency was better for the bath using a soluble steel plate anode than for the bath using an insoluble platinized titanium one. Densed electrolytic iron having the purity of higher than 99.99% was ob-tained at the electrolysis conditions of the cathodic current density of 15A/dm2, the bath temperature of $70\pm$$5^{\circ}C$ and the ferrous ion concentration of about 100g/l. The morphologies of the deposited iron were observed by SEM.

• Journal of Conservation Science
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• v.20
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• pp.67-80
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• 2007

Icheon Seolbong fortress is located in Saum-dong, Icheon, Gyeonggi-do Province that its date is founded as 4th century of Bakjae dynasty after excavation by Dankook university museum. Excavated artifacts show various kinds such as earthenwares, ceramics, metal artifacts and so on. Especially many iron artifacts were founded in where Bakjae earthenwares were found that it indicates iron artifacts were manufactured in Bakjae Dynasty. From 6 iron sickles, called Beollat and Millet, samples were taken to examine mircostructures and from the results used iron material, shape-forging, steel-making process, heat treatment were investigated. From this late 4th century Bakjae dynasty iron manufacture profess was established. From the result, different treatment were used in different area of the sickles according to the its use. Beollats were quenched in blade and it was used for special purpose that require Intensity. Millats did not have special treatment that it was used to cut rice plant and plant. Used material was steel, steel was previously made by certain steel-making process. It is formed to produce iron ware and the area where intensity is required heat treatment was employed to make it strong. From the investigation it is derived that iron ware manufacture process in Bakjae dynasty is steel making$\rightarrow$shape-forging$\rightarrow$and heat treatment.