• Journal of the Korea Furniture Society
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• v.19 no.3
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• pp.172-179
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• 2008

The objective of this study was to investigate the influence of the water repellents' treatment on the water absorptivity and the dimensional stability of Korean red pine wood(Pinus densiflora). The alkylketene dimer(AKD), fluororesin emulsion(Wood-seal, WS), and paraffin wax emulsions(PW25, PW40, and PW1200) were used as water repellents. PW40 and WS were proved as excellent water repellents for pine wood, because the samples treated with these agents showed high contact angles and large reduction in water absorptivities. Also, the dimensional stability(antiswelling efficiency) of pine wood was considerably improved by water repellents treatments, such as PW40 and WS at the pressure of 2MPa. The water repellent treated woods with WS, PW40, and PW1200 at the pressure of 2MPa were relatively stable to the wet-dry cyclic leaching test.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.99-106
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• 2004

Although fly ash has possesses viable engineering properties, an overwhelming majority of fly ash from coal combustion is still placed in storage or disposal sites. This study was undertaken to investigate the physical and mechanical properties of clay-fly ash mixture and to furnish engineering data when fly ash utilized as engineering materials. This paper includes geotechnical properties of fly ash, clay-fly ash mixtures and results of compaction test, unconfined strength test, direct shear test, leaching test and stability analysis of clay-fly ash bank slope. If proper amount of fly ash was put in clay, the clay-fly ash mixture has an increase of unconfined strength and stability of bank slope.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.1
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• pp.71-82
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• 2017

It is necessary to conduct a detailed geotechnical investigation on the tunnel section in order to secure the tunnel design and construction stability. It is necessary for the importance of geotechnical investigation that needed for the analysis of distribution and size of fractured fault zone and distribution of groundwater in tunnel. However, if it is difficult to perform the ground survey in the tunnel design due to ground condition of the tunnel section and the limited conditions such as civil complaint, the tunnel design is performed using the result of the minimum survey. Therefore, if weathered fault zone exists in the face the reinforcement method is determined in the design process to secure the stability of the tunnel. The most important factor in reinforcing the tunnel excavation surface is to secure the stability of the tunnel by performing quick reinforcement. In particular, if groundwater leaching occurs on the excavation surface, more rapid reinforcement is needed. In this study, fractured fault zone exists on the tunnel excavation surface and displacement occurs due to weathered fracture zone. When the amount of groundwater leaching rapidly increased under the condition of displacement, the behavior of tunnel displacement was analyzed based on tunnel collapse. In the study, reinforcement measures were taken because the first stage displacement did not converge continuously. After the first reinforcement, the displacement was not converged due to increased groundwater leaching and the second stage displacement occurred and chimney collapse occurred.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.159-170
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• 2003

In this study, the mixed design of grout with hish strength.high permeation.high durability and environmental stability as the state of the art in material field was performed. Also, the subjects of grouting, grouting effects for ground conditions, and environmental effects were analyzed. According to these results, the fundamental data will be suggested as a design of grouting in the field application. The physical, mechanical and chemical characteristics with particle shape of the grouts were analyzed. Then, the gel-time of grouts, which is essential for workability and permeation range, were controlled. Also, the laboratory model grouting tests were performed to find the characteristics of solidification, permeation and durability with grouts. The ordinary portland, slag and microcement which have been used in the construction field were evaluated fur the environmental effects. To find the leaching of $Cr^{6+}$characteristics in cement grouts, $Cr^{6+}$ leaching tests were performed for the raw materials. Also, the results of leaching test were shorn by surrounding environment. Then, the unconfined compression strength tests were performed with the homo-gel samples, and the amount of changed $Cr^{6+}$ was measured by curing solution.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.3
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• pp.133-137
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• 2007

Ecological lightweight aggregates were made in order to recycle the dredged soils from the seaside construction area and the bottom ashes from the power plant. Various physical and chemical analysis were performed on them to identify their possibility for applying lightweight concrete fields. Lightweight aggregates were made of bottom ashes and dredged soils from Yongheung Island which is located 20km west away from Seoul, and all the raw materials were milled before mixing. The physical and chemical properties such as density, absorption rate, stability, alkali latency reaction, heavy metal leaching of the lightweight aggregates were tested and analysed by following the KS standard procedures. From the size analysis, the coarse aggregates showed a suitable fit on standard particle ranges; however, the fine aggregates showed a large deviation from the standard. The absorption rates were increased with decreasing weight of the aggregates. All the aggregates were turned out to be safe by the stability and heavy metal leaching test; however, some of the aggregates were confirmed on the border of harmless and possibly harmful region through the alkali latency reactivity test.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.189-196
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• 2003

Soil-cement column is often used as a contaminant barrier. This study presents the results of experimental study performed to investigate the changes of properties of soil-cement column under the attack of acids. Sulfuric nitric, and ascetic acid were used as contaminants. Specimen were made of clayey and sandy soils with addition of cement and water Permeability of soil-cement decreased with time during permeability test. When significant amount of acid percolated the specimen, permeability increased and compressive strength decreased due to the dissolution and leaching of cement and its chemical reaction compounds. Sulfuric and nitric acid were more effective than ascetic acid in deteriorating soil-cement column. Amount of acid required to lower the pH of soil cement below 12 was calculated from the results of permeability tests. This leads to a conclusion that, under the conditions employed in this study, the chemical stability of soil-cement column could be maintained against acid attack for longer than generally accepted lifetime of contaminant barriers.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.159-164
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• 2001

A novel fluidized-bed reactor was designed and installed for bioleaching in a semi-continuous way, by which a process for bioleaching-cyanidation of Guangxi Jinya refractory gold arsenical concentrate was studied. An arsenic extraction rate reaches 82.5% after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0, ftrric ion concentration 6.5g/L and pulp concentration 10%. And leaching rate of gold in the following gold cyanidation is over 90%. The parameters of three series fluid-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate. Arsenic in the concentrate can be got rid of 91% after 6-day leaching. Even after 4 days, 82% of arsenic extraction rate was still obtained. The recovery rates of gold are 92% and 87.5% respectively in cyaniding the above bioleached residues. The results will provide a base for further commercial production of gold development.

• Journal of Energy Engineering
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• v.26 no.4
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• pp.74-83
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• 2017

Coal-fired power plants supply roughly 50 percent of the nation's electricity but produce a disproportionate share of electric utility-related air pollution. Coal combustion technology can facilitate volume reduction of up to 90%, with the inorganic contaminants being captured in furnace bottom ash and fly ash residues. These disposal coal ash residues are however governed by the potential release of constituent contaminants into the environment. Accelerated carbonation process has been shown to have a potential for improving the chemical stability and leaching behavior of bottom ash residues. The aim of this work was to quantify the volume of $CO_2$ that could be sequestrated with a view to reducing greenhouse gas emissions and stabilize the contaminated heavy metals from bottom ash samples. In this study, we used PC boiler bottom ash, Kanvera reactor (KR) slag and calcined waste lime for measuring chemical analysis and heavy metals leaching tests were performed and also the formation of calcite resulting from accelerated carbonation process was investigated by thermo gravimetric and differential thermal analysis (TG/DTA).

• Journal of Industrial Technology
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• v.30 no.A
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• pp.37-43
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• 2010

Polymeric materials in addition to Portland cement and hydrated limes were used to solidify heavy metal contaminated tailings from five abandoned metal mines in Korea. Mine tailings were mixed separately with Portland cement and hydrated lime at a concentration of 20-30 wt% and 6-9 wt%, respectively and Ethylene Vinyl Acetate(EVA) powder was added to each specimen at a ratio of 2.5 and 5.0 wt% to binders. Polymer-added and polymer-free solidified forms were evaluated for their appropriateness in accordance with the suggested test methods. Regardless of addition of polymeric materials, all solidified forms satisfy the uniaxial compressive strength(UCS) requirements(0.35MPa) for land reclamation and show remarkably reduced leaching concentrations of heavy metals such as As, Cd, Cu, Pb and Zn less than the toxicity criteria of Korean standard leaching test(KSLT). The addition of polymeric materials increased the UCS of solidified forms to improve a long-term stability of solidified mine tailings.

• Resources Recycling
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• v.22 no.6
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• pp.26-32
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• 2013

In order to recover Pt from the hydrochloric acid leaching solution of spent catalysts, bench scale Karr reciprocating column was employed. At an optimum flow rate and vibration frequency, iron and Pt was completely extracted by using TBP and Aliquat 336. At the same vibration frequency, iron and Pt was completely stripped by HCl and $HClO_4$ after adjusting the flow rate. In the case of extraction of HCl from the raffinate with TEHA, it was difficult to maintain the stability of the column extractor. A comparison of the operation results between column extractor and mixer-settler is reported.