• Journal of the Korean Geotechnical Society
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• v.20 no.2
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• pp.47-58
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• 2004

Steel Pipelines were located in hillside and mountain areas where landslides occurred during the Northridge earthquake. This paper describes the investigations that were performed to identify and locate the different types of steel pipeline construction in the system using GIS (Geographical Information System). The paper explores the damage correlations of steel pipelines with PGV (peak ground velocity) and investigates the areas subjected to the landslide effects during the Northridge earthquake. One noticeable finding is that the repair rates for steel distribution pipelines after the Northridge earthquake are higher than those of CI (cast iron) pipelines. The relatively high susceptibility of steel piping to damage during the Northridge earthquake may be explained in part by utility practices, such as using steel pipe for the highest internal pressures, and increased susceptibility to corrosion also appears to play a role in steel pipeline performance.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.5
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• pp.120-129
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• 2000

This main study was the subject of the play facilities of children picnicking place which was installed in apartment complex. As to the production period of the facilities, the materiality and the materials of the play facilities, we examined the safety estimation about them. And we drew up a plan which could build and manage the children play facilities improved the better. According to the installation place, the result of safety estimation, the safety of play facilities in Ga-Kyeong-dong apartment complex which built up after 1997 years was the most excellent, the play facilities of Sa-Gik-Dong apartment Complex which built long ago have showed even poorer in all items of safety estimation. According to the materiality of play facilities, though the safety of association play rod in the safety estimation was the most excellent, the safety of swing was the very poor. According to the materiality of materials, the association of wood, stainless in the safety estimation was the safest. Especially, even though wood is soft and kind materials, as it has a shortcoming, the practical use depreciates. If iron materials like stainless associates with wood, we have thought that they have the good effect of the practical use. We have judged that the distance of contiguity facilities and the safety of corrosion or rottenness within the item of safety estimation as a subordination variable were the poorest. The arrangement of play facilities and the selection of materials happened to these problems. And we have known that they should get accomplished the construction work to make a plan thoroughly from it early.

• Advances in concrete construction
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• v.5 no.6
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• pp.671-683
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• 2017

Commonly used concrete in general, consists of cement, fine aggregate, coarse aggregate and water. Natural river sand is the most commonly used material as fine aggregate in concrete. One of the important requirements of concrete is that it should be durable under certain conditions of exposure. The durability of concrete is defined as its ability to resist weathering action, chemical attack or any other process of deterioration. Durable concrete will retain its original form, quality and serviceability when exposed to its environment. Deterioration can occur in various forms such as alkali aggregate expansion, freeze-thaw expansion, salt scaling by de-icing salts, shrinkage, attack on the reinforcement due to carbonation, sulphate attack on exposure to ground water, sea water attack and corrosion caused by salts. Addition of admixtures may control these effects. In this paper, an attempt has been made to replace part of fine aggregate by tailing material and part of cement by fly ash to improve the durability of concrete. The various durability tests performed were chemical attack tests such as sulphate attack, chloride attack and acid attack test and water absorption test. The concrete blend with 35% Tailing Material (TM) in place of river sand and 20% Fly Ash (FA) in place of OPC, has exhibited higher durability characteristics.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1892-1900
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• 2023

A protective oxide layer forms on the material surfaces of a Nuclear Power Plant during operation due to high temperature. These oxides can host radionuclides, the activated corrosion products of fission products, resulting in decommissioning workers' exposure. These deposited oxides are iron oxides such as Fe₃O₄, Fe₂O₃ and mixed ferrites such as nickel ferrites, chromium ferrites, and cobalt ferrites. Developing a new chemical decontamination technology for domestic CANDU-type reactors is challenging due to variations in oxide compositions from different structural materials in a Pressurized Water Reactor (PWR) system. The Korea Atomic Energy Research Institute (KAERI) has already developed a chemical decontamination process for PWRs called 'HyBRID' (Hydrazine-Based Reductive metal Ion Decontamination) that does not use organic acids or organic chelating agents at all. As the first step to developing a new chemical decontamination technology for the Pressurized Heavy Water Reactor (PHWR) system, we investigated magnetite dissolution behaviors in various HyBRID inorganic acidic solutions to assess their applicability to the PHWR reactor system, which forms a thicker oxide film.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.421-433
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• 2023

The final disposal of spent nuclear fuel(SNF) from nuclear power plants takes place in a deep geological repository. The metal canister encasing the SNF is made of cast iron and copper, and is engineered to effectively isolate radioactive isotopes for a long period of time. The SNF is further shielded by a multi-barrier disposal system comprising both engineering and natural barriers. The deep disposal environment gradually changes to an anaerobic reducing environment. In this environment, sulfide is one of the most probable substances to induce corrosion of copper canister. Stress-corrosion cracking(SCC) triggered by sulfide can carry substantial implications for the integrity of the copper canister, potentially posing a significant threat to the long-term safety of the deep disposal repository. Sulfate can exist in various forms within the deep disposal environment or be introduced from the geosphere. Sulfate has the potential to be transformed into sulfide by sulfate-reducing bacteria(SRB), and this converted sulfide can contribute to the corrosion of the copper canister. Bentonite, which is considered as a potential material for buffering and backfilling, contains oxidized sulfate minerals such as gypsum(CaSO4). If there is sufficient space for microorganisms to thrive in the deep disposal environment and if electron donors such as organic carbon are adequately supplied, sulfate can be converted to sulfide through microbial activity. However, the majority of the sulfides generated in the deep disposal system or introduced from the geosphere will be intercepted by the buffer, with only a small amount reaching the metal canister. Pyrite, one of the potential sulfide minerals present in the deep disposal environment, can generate sulfates during the dissolution process, thereby contributing to the corrosion of the copper canister. However, the quantity of oxidation byproducts from pyrite is anticipated to be minimal due to its extremely low solubility. Moreover, the migration of these oxidized byproducts to the metal canister will be restricted by the low hydraulic conductivity of saturated bentonite. We have comprehensively analyzed and summarized key research cases related to the presence of sulfates, reduction processes, and the formation and behavior characteristics of sulfides and pyrite in the deep disposal environment. Our objective was to gain an understanding of the impact of sulfates and sulfides on the long-term safety of high-level radioactive waste disposal repository.

• Conservation Science in Museum
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• v.27
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• pp.67-90
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• 2022

A C-46 transport aircraft, which can be thought of as a large cultural heritage item from the modern period, was subjected to paint analysis and conservation treatment in preparation for its exhibition. The C-46 is the first aircraft ever dispatched to overseas combat zones by the Korean Air Force and carried out missions during the Vietnam War. The aircraft is mainly made of aluminum and shows signs of corrosion on its surface, including pitting and etching, as well as gray and white powdery attachments. In the analysis of the paint, diatomite(SiO₂·nH₂O) was confirmed in the red paint, titanium dioxide(TiO₂) was identified in the white paint, black iron oxide(Fe₃O₄) was detected in the black paint, and colcothar(Fe₃O₄) mixed with putty was confirmed in the blue paint. Infrared spectroscopy revealed the use of alkyd resin in the paint on the main body and nitrocellulose in the Taegeuk pattern. During the conservation treatment, mechanical cleaning, such as sanding, was conducted to remove paint and varnish from the surface. Corrosion was removed by sanding and cleaning with chemical solvents, and new paints and varnishes were applied. Through the paint analysis and conservation treatment, the aircraft was made available for exhibition in a stable condition.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.11a
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• pp.7-7
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• 2001

The increasing interest in light weight materials coupled to the need for cost -effective processing have combined to create a significant opportunity for aluminum P/M. particularly in the automotive industry in order to reduce fuel emissions and improve fuel economy at affordable prices. Additional potential markets for Al PIM parts include hand tools. Where moving parts against gravity represents a challenge; and office machinery, where reciprocating forces are important. Aluminum PIM adds light weight, high compressibility. low sintering temperatures. easy machinability and good corrosion resistance to all advantages of conventional iron bm;ed P/rv1. Current commercial alloys are pre-mixed of either the AI-Si-Mg or AL-Cu-Mg-Si type and contain 1.5% ethylene bis-stearamide as an internal lubricant. The powder is compacted in closed dies at pressure of 200-500Mpa and sintered in nitrogen at temperatures between $580~630^{\circ}C$ in continuous muffle furnace. For some applications no further processing is required. although most applications require one or more secondary operations such as sizing and finishing. These sccondary operations improve the dimension. properties or appearance of the finished part. Aluminum is often considered difficult to sinter because of the presence of a stable surface oxide film. Removal of the oxide in iron and copper based is usually achieved through the use of reducing atmospheres. such as hydrogen or dissociated ammonia. In aluminum. this occurs in the solid st,lte through the partial reduction of the aluminum by magncsium to form spinel. This exposcs the underlying metal and facilitates sintering. It has recently been shown that < 0.2% Mg is all that is required. It is noteworthy that most aluminum pre-mixes contain at least 0.5% Mg. The sintering of aluminum alloys can be further enhanced by selective microalloying. Just 100ppm pf tin chnnges the liquid phase sintering kinetics of the 2xxx alloys to produce a tensile strength of 375Mpa. an increilse of nearly 20% over the unmodified alloy. The ductility is unnffected. A similar but different effect occurs by the addition of 100 ppm of Pb to 7xxx alloys. The lend changes the wetting characteristics of the sintering liquid which serves to increase the tensile strength to 440 Mpa. a 40% increase over unmodified aIloys. Current research is predominantly aimed at the development of metal matrix composites. which have a high specific modulus. good wear resistance and a tailorable coefficient of thermal expnnsion. By controlling particle clustering and by engineering the ceramic/matrix interface in order to enhance sintering. very attractive properties can be achicved in the ns-sintered state. I\t an ils-sintered density ilpproaching 99%. these new experimental alloys hnve a modulus of 130 Gpa and an ultimate tensile strength of 212 Mpa in the T4 temper. In contest. unreinforcecl aluminum has a modulus of just 70 Gpa.

• Journal of Conservation Science
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• v.33 no.2
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• pp.121-130
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• 2017

The currently used wax agents for preserving outdoor metal structures, despite their advantages, have disadvantages such as low endurance and reliability. These wax agents are easily damaged by acid rain, dust, moisture in the air, yellow dust, and air pollutants, resulting in corrosion within a short period after the initial conservation treatment. In addition, aged wax can also exhibit changes in the color or gloss, and also give a sense of difference in the surface. Given these existing problems, it is necessary to develop improved materials for metal preservation. Therefore, this study analyzed the characteristics and applications of the existing wax coating agents in order to identify their disadvantages and to develop a better material for metal preservation. In this regard, this study developed a perilla oil based compound wax and conducted experiments to test its endurance. The new compound wax agent was exposed to outdoor and acid rain conditions: it showed four times and 1.5 times the endurance of the existing wax agents in outdoor and acid rain conditions, respectively. In addition, the new agent seems to be more durable and protective as evidenced by the chromaticity, polish maintenance, and contact angle results. Further, although it is 1.3-1.8 times thicker than the existing agents, the new agent shows a more even surface. Based on these findings, it can be concluded that the new compound wax agent based on perilla oil is a better alternative to the existing was coating agents.

• Conservation Science in Museum
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• v.4
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• pp.23-32
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• 2003

As the kettle excavated from a site in Hwangnam-dong, Gyeongju was presumed to have been used as a melting crucible in a glass production workplace, we decided to prove its usage by scientific analysis. First, we performed conservation treatment to find the original status of the kettle, and then SEM-EDS and XRD analysis of the five corrosions created on the surface of the kettle. The fragment of the spout, which played a crucial role for the kettle to be considered as a melting crucible, was discovered during the conservation treatment. So the mouth rim of the kettle was restored to perfection. When we observed the microstructure of the metal sample, it was proved to be cast iron gradually cooled without heat treatment. In the corrosion products, the main components were Fe and O and other components such as P, Si, Ca, and S were found. The main compounds were quartz, vivianite, goetheite, akaganite, lepidocrocite, hematite, etc. Although these components were used as raw materials for making glass, these were found not in the melting status but mere raw materials. This can be an evidence to show these site where the kettle was excavated had been a glass production workplace. However, it is not sure that the kettle was used as a melting crucible. Moreover, if we consider the organic mold and sand clay accumulated in the well site when the kettle was excavated at first, we can see this as a formative factor of the corrosions of the kettle. Therefore, we concluded that the kettle is a typical cast iron and was not used as a melting crucible of glass.

• Conservation Science in Museum
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• v.25
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• pp.85-94
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• 2021

Conservation treatment of metallic artifacts contaminated with corrosion and foreign substances requires changes in the shape, characteristics, weight and thickness of the artifacts. Thus far, recording the changes after conservation treatment has mainly been performed through visual observation and photography, which lacks any quantitative description of the changes. In this study, the processes of removing foreign substances, joining cracks, and restoring an affected area were recorded using 3D scanning and then quantitatively analyzed to identify changes in form due to conservation treatment. The volume change after the conservation process was calculated based on the results of the 3D scanning, and numerical data on the changes to the form was analyzed. It was revealed that the foreign or corroded substances removed after the conservation accounted for 18.1 cm³, which is approximately 52% of the total volume of the ring pommel, and those substances were removed from about 98% of the surface of the ring pommel. This study confirmed that 3D form analysis was useful for recording the processes of conservation treatment and analyzing the results. It is therefore believed that this methodology can be applicable to not only metal artifacts, but to cultural heritage items in a range of materials.