• Analytical Science and Technology
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• v.7 no.1
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• pp.115-124
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• 1994

The corroded surface of cold rolled steel sheet in the process of rinsing after alkali-cleaning was examined by means of X-ray Photoelectron Spectroscopy(XPS). In addition, the surface-treated cold rolled steel with 0.05wt% $Na_5P_3O_{10}$ solution for the purpose of preventing the corrosion was examined by means of XPS and the results were compared with those for the non-treated cold rolled steel. It was found that the corroded surface consists of $Fe_2O_3$, FeO and $Fe(OH)_3$ and the thickness of the oxide layer is about $1500{\AA}$. On the other hand, in the case of surface-treated cold rolled steel, the phosphate layer of $60{\AA}$ thickness was found to act as a protective film over the relatively thin Fe oxide layer.

• Journal of Conservation Science
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• v.35 no.4
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• pp.317-329
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• 2019

Slag was collected from the iron-producing furnace site in Saengsoegol, Baegun mountain, where iron was manufactured by a righteous army against Japan in the Gwangyang region; then, the iron-manufacturing technique of the early modern period was investigated through scientific analysis. In the microstructure analysis results of the selected samples, iron bloom was mainly observed together with magnetite and fayalite. In the component analysis results of the compounds, it was confirmed that the furnace was built by using gangue of alkali feldspar or plagioclase series, and the ironmaking work was performed at a high temperature of at least 1050℃, because mullite was identified together with cristobalite and hercynite. Based on the chemical composition, it was speculated that low-grade iron ores were used as raw materials, and it seemed that the yield was low, because the total Fe content of the smelting slag samples was 37.72-49.93%. It was difficult to confirm whether a slag former was used, and it seemed that materials easily obtained nearby were used when the furnace was built, without considering the corrosion resistance. It appeared that the ironmaking work was performed at the Gwangyang Saengsoegol iron-producing furnace based on the direct ironmaking method in an environment that could escape the vigilance of the Japanese Empire to produce weapons that would be used for the resistance against Japan. It seemed that there was neither an advanced ironware production system nor a mass production system, and small-scale works were performed in short periods of time.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.211-220
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• 2005

The concrete structure is being considered for the main engineered barrier of low and intermediate level radwaste disposal facility. Concrete of low permeability can minimize infiltration of water and effectively prevent release of nuclide to ecosystem. But if concrete degrades, structural stability of disposal structure will decrease while permeability increase, resulting in increased possibility of nuclide release due to water infiltration. Therefore disposal concrete structure degradation shall be minimized to maintain capacity of nuclide isolation. The typical causes of concrete structure degradation are sulfide attack, reinforcement corrosion due to chloride attack, leaching of calcium hydroxide, alkali-aggregate reaction and repeated freezing-thawing. The common cause of these degradation processes is infiltration of water or adverse chemicals into concrete. Based on the study of these degradation characteristics and mechanisms of concrete structure, the methodology of design and service life evaluation of concrete structure as an engineered barrier are reviewed to ensure its long-term durability.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.140-146
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• 2010

This paper addresses recent status and trends of carbon dioxide capture technologies using dry sorbents in the flue gas. The advantages of dry sorbent $CO_2$ capture technology are broader operating temperature range, less energy loss, less waste water, less corrosion problem, and natural properties of solid wastes. Recently, U.S.A. and Korea have been developing processes capturing $CO_2$ from real coal flue gas as well as sorbents improving sorption capacity to decrease total $CO_2$ capture cost. New class of dry sorbents have been developed such as chemisorbents with alkali metals of which material cost is low, amines physically adsorbed on silica supports, amines covalently tethered to the silica support, carbon-supported amines, polymer-supported amines, amine-containing solid organic resins and metal-organic framework. The breakthrough is needed in the materials on dry sorbents to decrease capture cost.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.715-722
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• 2019

The durability of concrete structures deteriorates due to the corrosion of rebars and concrete deterioration by harmful ions (CO₃^2-, Cl^-, SO₄^2-) penetrating and diffusing from the outside into concrete. Therefore, the use of surface-protection finishing mortar is very important for preventing or delaying the deterioration of concrete. In this study, the possibility of the prevention of deterioration or delay of deterioration of concrete was investigated using natural latex modified with silica sol and calcium ions for cement mortar, which can be used to repair the mortar of deteriorated concrete or for finishing the mortar of concrete. As a result, fine calcium silicate hydrate was formed in the pores of the cement material due to the calcium ions and silica sol components contained in the modified latex component that reduce the pore distribution of the cement mortar, thereby reducing the penetration and diffusion of harmful ions (CO₃^2-, Cl^-, and SO₄^2-). Furthermore, the latex component was found to be present in the pores of the cement to improve the alkali resistance and carbonation resistance.

• Journal of Adhesion and Interface
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• v.12 no.4
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• pp.111-116
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• 2011

The characteristics of natural resin, sap of the lacquer tree were examined as an adhesive for the ceramic conservation since it has such outstanding properties like corrosion resistance against acid and alkali, heat-resistance, waterproof, antiseptic and protection against insects. In order to utilize raw lacquer as an adhesive not under the hardening conditions of lacquer like high humidity (RH 75 to 85%) and high temperature (120 to $170^{\circ}C$), but under normal condition, isinglass and animal glue were added to raw lacquer at certain ratio. In addition, the viscosity and the drying time were measured and their possibilities of application were also investigated through measurement of tensile and adhesive strength. As a result of experiment, it was possible to dry at room temperature and RH $50{\pm}5%$ to mix with raw lacquer and glue, and the drying time of sample with animal glue was faster than that of isinglass. Furthermore, the adhesion of sample with glue was increased more than raw lacquer. It seems to be possible to use the environmental friendly traditional adhesive for the ceramic conservation and restoration, if there are studies or examinations of safety of applications on objects and weathering resistance.

• Clean Technology
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• v.26 no.4
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• pp.239-250
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• 2020

Biomass is an abundant renewable energy resource that can replace fossil fuels for the reduction of greenhouse gas (GHG). Indonesia has a large number of cheap biomass feedstocks, such as reforestation (waste wood) and palm residues (empty fruit bunch or EFB). In general, raw biomass contains more than 20% moisture and lacks calorific value, energy density, grindability, and combustion efficiency. Those properties are not acceptable fuel attributes as the conditions currently stand. Recently, torrefaction facilities, especially in European countries, have been built to upgrade raw biomass to solid fuel with high quality. In Korea, there is no significant market for torrefied solid fuel (co-firing) made of biomass residues, and only the wood pellet market presently thrives (~ 2 million ton yr-1). However, increasing demand for an upgraded solid fuel exists. In Indonesia, torrefied woody residues as co-firing fuel are economically feasible under the governmental promotion of renewable energy such as in feed-in-tariff (FIT). EFB, one of the chief palm residues, could replace coal in cement kiln when the emission trading system (ETS) and clean development mechanism (CDM) system are implemented. However, technical issues such as slagging (alkali metal) and corrosion (chlorine) should be addressed to utilize torrefied EFB at a pulverized coal boiler.