• Corrosion Science and Technology
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• v.23 no.3
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• pp.221-227
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• 2024

During hot stamping of hot-dip zinc-coated steel sheets such as hot-dip galvanized steel sheets and hot-dip galvannealed steel sheets, an oxide mainly composed of ZnO is formed on the sheet surface. However, excessive formation of ZnO can lead to a decrease in the amount of metal Zn in the coating layer, decreasing the corrosion resistance of hot-stamped members. Therefore, it is important to suppress excessive formation of ZnO. While the formation of Al oxides and Mn oxides along with ZnO layer during the hot stamping of hot-dip zinc-coated steel sheets can affect ZnO formation, crystal structures of such oxides have not been elucidated clearly. Thus, this study aimed to analyze structures of oxides formed during hot stamping of hot-dip galvannealed steel sheets using transmission electron microscopy. Results indicated the formation of an oxide layer comprising ZnAl₂O₄ at the interface between ZnO and the coating layer with Mn₃O₄ at the outermost of an oxide layer.

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.459-470
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• 1989

Single crystals of rare-earth iron garnets were grown from solutions of molten lead oxide, lead fluoride, baric oxide, iron oxide, and the oxides of yttrium, samarium orgadolinium. The crystals were grown by slow cooling technique. A convenient composition was 41.8mol% PbO, 20.59mol% PbF2, 8.23mol% B2O3, 20.00mol% Fe2O3 and 10.00mol% R2O3 where R is Y, Sm or Gd. For this experiment, platinum crucibles of size 20, 30cc and a vertical siliconit tube furnace were used. The precipitation temperature of YIG was observed in the range of 115$0^{\circ}C$-112$0^{\circ}C$ and the optimum growth conditions in this experiment were determined. The nucleation rate was controlled by the holding time after the fast colling, the growth rate by the slow cooling conditiions. The form of the grown YIG crystals showed a combination of {110} and {211}, and the size of the crystals grown in this experiment was up to about 9mm under the conditions of holding time 16hour, cooling rate 2$^{\circ}C$/hr. and temperature range 115$0^{\circ}C$-90$0^{\circ}C$. The precipitatin temperature of SmIG was observed in the range of 105$0^{\circ}C$-98$0^{\circ}C$ and the size of the crystals grown in this experiment was up to about 5mm under the conditiions of holding time 16hours, cooling rate 2$^{\circ}C$/hr. and temperature range 100$0^{\circ}C$-80$0^{\circ}C$.

• Journal of Korea Foresty Energy
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• v.22 no.2
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• pp.36-43
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• 2003

This study was carried out to evaluate the fungicidal, anti-sapstain and termiticidal efficacy of commercial Dan-Chung which are currently being used for painting to decorate and to provide durability with structures of temples. Two binders (Polysol and Gelatine), and eleven pigments (Iron Oxide Red, Lead Red, Toluidine Red, Chrome Yellow, Titanium Dioxide, Ultramarine Blue, Chrome Oxide Green, Permanent Black, Cyanine Green and Ho-bun(Chalk)) were applied for the evaluation. The fungicidal and anti-sapstain activity of each pigment were depended on the types of binders. When the Polysol was used as a binder, the fungicidal efficacy of Toluidine Red treated specimen was close to the standard value (above 80) with grater than 70 against to two wood decay fungi (T. palustris and T. versicolor). The anti-sapstain efficacy of Lead Red treated specimens was excellent against to three sapstain fungi (P. funiculosum, T. viride and R. nigricans), and that of Ultramarine Blue treated specimens was also excellent to T. viride. The other pigments had little efficacy to these micro-organisms. Although there were some different trends of the effectiveness depending on the types of binders, the anti-termite effectiveness of Chrome Oxide Green and Chrome Yellow was outstanding to termite tests.

• Electronic Materials Letters
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• v.14 no.6
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• pp.678-688
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• 2018

The repeated-bending properties of Sn-0.7Cu, Sn-0.3Ag-0.7Cu (SAC0307), and Sn-3.0Ag-0.5Cu (SAC305) solders mounted on flexible substrates were studied using highly accelerated stress testing (HAST), followed by repeated-bending testing. In the Sn-0.7Cu joints, the $Cu_6Sn_5$ intermetallic compound (IMC) coarsened as the HAST time increased. For the SAC0307 and SAC305 joints, the $Ag_3Sn$ and $Cu_6Sn_5$ IMCs coarsened mainly along the grain boundary as the HAST time increased. The Sn-0.7Cu solder had a high contact angle, compared to the SAC0307 and SAC305 solders; consequently, the SAC0307 and SAC305 solder joints displayed smoother fillet shapes than the Sn-0.7Cu solder joint. The repeated-bending for the Sn-0.7Cu solder produced the crack initiated from the interface between the Cu lead wire and the solder, and that for the SAC solders indicated the cracks initiated at the surface, but away from the interface between the Cu lead wire and the solder. Furthermore, the oxide layer was thickest for Sn-0.7Cu and thinnest for SAC305, regardless of the HAST time. For the SAC solders, the crack initiation rate increased as the oxide layer thickened and roughened. $Cu_6Sn_5$ precipitated and grew along the grain and subgrain boundaries as the HAST time increased, embrittling the grain boundary at the crack propagation site.

• Journal of the Korea Convergence Society
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• v.12 no.10
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• pp.129-136
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• 2021

Radiation shields used in medical institutions mainly use lead to manufacture products and fitments. Although lead has excellent processability and economic efficiency, its use is being reduced due to environmental issues when it is disposed of. In addition, when used for a long time, there is a limit to using it as a shielding film, shielding wall, medical device parts, etc. due to cracking and sagging due to gravity. To solve this problem, copper, tin, etc. are used, but tungsten is mostly used because there is a difficulty in the manufacturing process to control the shielding performance. However, it is difficult to compare with other shielding materials because the characteristics according to the type of tungsten are not well presented. Therefore, in this study, a medical radiation shielding sheet was manufactured in the same process using pure tungsten, tungsten carbide, and tungsten oxide, and the particle composition and shielding performance of the sheet cross-section were compared.As a result of comparison, it was found that the shielding performance was excellent in the order of pure tungsten, tungsten carbide, and tungsten oxide.

• Architectural research
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• v.21 no.1
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• pp.21-29
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• 2019

Recent years in Korea, some new developed buildings are only using electricity as power for heating, cooling, bathing and even cooking which means except electricity, there is no natural gas or other kinds of energy used in such kind of building. In vehicle industry area, scientists already invented electric vehicle as an environment friendly vehicle; after that, in architecture design and construction field, buildings only using electricity appeared; the curiosity of the environment impact of energy consumption by such kind of building lead me to do this research. In general, electricity is known as a clean energy resource reasoned by it is noncombustible energy resource; however, although there is no environmental pollution by using electricity, electricity generation procedure in power plant may cause huge amount of environment pollution; especially, electricity generation from combusting coal in power plant could emit enormous air pollutants to the air. In this research, the yearly amount of air pollution by energy using under traditional way in research target building that is using natural gas for heating, bathing and cooking and electricity for lighting, equipment and cooling is compared with yearly amount of air pollution by only using electricity as power in the building; result shows that building that only uses electricity emits much more air pollutants than uses electricity and natural gas together in the building. According to the amount of air pollutants comparison result between two different energy application types in the building, residential SOFC (Solid oxide fuel cell) is simulated to apply in this building for decreasing environment pollution of the building; furthermore, high load factor could lead high efficiency of SOFC, in the scenario of simulating applying SOFC in the building, SOFC is shared by two or three households in spring and autumn to increase efficiency of the SOFC. In sum, this research is trying to demonstrate electricity is a conditioned environment friendly energy resource; in the meanwhile, SOFC is simulated efficiently applying in the building only using electricity as power to decrease the large amount of air pollutants by energy using in the building. Energy consumption of the building is analyzed by calibrated commercial software Design Builder; the calibrated mathematical model of SOFC is referred from other researcher's study.

• Journal of the Korean GEO-environmental Society
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• v.2 no.3
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• pp.17-35
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• 2001

In this study, we conducted a combined adsorption-sequential extraction analysis(CASA) to investigate temperature effects of single adsorption of lead, copper, zinc and cadmium on natural clays. As a result, it was found that in a single adsorption of lead and copper, about 50% of adsorption was occluded in carbonate phase, and in case of cadmium, about 80% of adsorption was occluded in exchangeable phase. At temperature below $25^{\circ}C$ about 60% of zinc was occluded in exchangeable phase but above $40^{\circ}C$ about 50% of zinc was occluded in carbonate phase. The effect of temperature on each occluded phase was largely observed in Fe-oxide, Mn-oxide and organic occluded phases. Besides, the adsorption of metals on natural clays was an endothermic reaction with the exception of exchangeable phase adsorption.

• Korean Journal of Materials Research
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• v.30 no.8
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• pp.426-434
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• 2020

The performance characteristics of a lead acid battery are investigated with the content of Sodium Perborate Tetrahydrate (SPT, NaBO₃·4H₂O) in a positive plate active material. SPT, which reacts with water to form hydrogen peroxide, is applied as an additive in the positive plate active material to increase adhesion between the substrate (positive plate) and the active material; this phenomenon is caused by a chemical reaction on the surface of substrate. A positive plate with the increasing content of SPT is prepared to compare its properties. It is confirmed that the oxide layer increases at the interface between the substrate and the active material with increasing content of SPT; this is proven to be an oxide layer through EDS analysis. Battery performance is confirmed: when SPT content is 2.0 wt%, the charging acceptance and high rate discharge properties are improved. In addition, the lifetime performance according to the Standard of Battery Association of Japan (SBA) S0101 test is improved with increasing content of SPT.

• Journal of the Korean GEO-environmental Society
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• v.11 no.11
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• pp.63-75
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• 2010

There are several remediation technologies for heavy metal contaminated soils but increasing cost limits the application of the technology if the contaminated area is large. Therefore, stabilization, which blocks the release of heavy metals or makes slow the release, is one of the applicable technology for the heavy metal contaminated soil. Current study is an applicability test for a smelter area with various stabilizer such as magnetite, hematite, zeolite-A, zeolite-X, zeolite-Y, zinc oxide, calcium oxide, carbon trioxide, manganese oxide, manganese dioxide, fish bone, sodium phosphate. The soil contaminated with arsenic, lead, copper, nickel, and zinc could not be stabilized only one stabilizer which is known to have stability for certain metal. Many of the stabilizer works for a few metal but not all of the heavy metal. In several cases, stabilizers increase the release of the other metals while they stabilize some metals. In general, the stabilizing efficiency was increased with time. For Ni, Pb, calcium oxide, carbon trioxide, manganese oxide had good stabilizing effect in water extractable portion. For Cu, manganese oxide, zeolite showed good results especially in the exchangeable portion of the sequential extraction. For As, magnetite had good ability but most of the metal oxide which showed good result for other heavy metals increased with the release of As. Current study suggest that multiple stabilizers are needed for the contaminated soil and dose of the stabilizer and stabilizing time should be carefully considered for the soil contaminated with various metals.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.252-253
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• 2011

ZnO-based thin film transistors (TFTs) are of great interest for application in next generation flat panel displays. Most research has been based on amorphous indium-gallium-zinc-oxide (IGZO) TFTs, rather than single binary oxides, such as ZnO, due to the reproducibility, uniformity, and surface smoothness of the IGZO active channel layer. However, recently, intrinsic ZnO-TFTs have been investigated, and TFT- arrayss have been demonstrated as prototypes of flat-panel displays and electronic circuits. However, ZnO thin films have some significant problems for application as an active channel layer of TFTs; it was easy to change the electrical properties of the i-ZnO thin films under external conditions. The variable electrical properties lead to unstable TFTs device characteristics under bias stress and/or temperature. In order to obtain higher performance and more stable ZnO-based TFTs, HZO thin film was used as an active channel layer. It was expected that HZO-TFTs would have more stable electrical characteristics under gate bias stress conditions because the binding energy of Hf-O is greater than that of Zn-O. For deposition of HZO thin films, Hf would be substituted with Zn, and then Hf could be suppressed to generate oxygen vacancies. In this study, the fabrication of the oxide-based TFTs with HZO active channel layer was reported with excellent stability. Application of HZO thin films as an active channel layer improved the TFT device performance and bias stability, as compared to i-ZnO TFTs. The excellent negative bias temperature stress (NBTS) stability of the device was analyzed using the HZO and i-ZnO TFTs transfer curves acquired at a high temperature (473 K).