• Resources Recycling
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• v.16 no.1 s.75
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• pp.44-53
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• 2007

The Jeonju-Il mine tailings contain large quantities of $SiO_2\;and\;Al_2O_3$ and lesser quantities of metallic components. In this study, we studied about the possibility of using mine tailings as a raw material in various industries. it was found that the sintered mine tailings had a good quality in every respect such as chromaticity, firing shrinkage and water absorption etc. Therefore if can substitute clay mineral in the ceramic industry. Also it can substitute about 2.94% of the raw materials of ordinary portland cement. We can use the coarse tailing as the fine aggregate for the ready-mixed mortar; and the fine tailing, as the filler for the bituminous paving mixture; because both products were not only suitable for Korea industrial standard in quality, but also environmentally harmless.

• Applied Biological Chemistry
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• v.27
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• pp.68-79
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• 1984

An increased population and rapidly expanding industrial development have led to enormous amounts of various domestic and industrial wastes. The proper disposal of ever-increasing wastes is a growing global problem. Land treatment is one of the rational approaches that are environmentally safe and economically practical. It has long been practised in many sites. Recycling of industrial wastes on agricultural land can provide better possible means for maintaining environmental quality and utilizing waste-resources. Even though industrial wastes are beneficial as soil amendment and fertilizer, they have some limitation on land application because of wide variability as well as physicochemical problem in their composition. A direct application of solid and liquid wastes on land is being practised in Korea and some experimental results are presented. The direct application of fermentation waste on rice resulted in a 6 percent yield increase. Another organic residue from glutamic acid fermentation is widely used not only as a direct application as a liquid fertilizer but also for a raw material of organic compound fertilizer. These wastes are much promising as sources of plant nutrients, since they have large amounts of nutrients, especially nitrogen with few toxic metals. On the other hand, fertilizers developed from inorganic industrial wastes include calcium silicate, calcium sulfate and ammonium sulfate. The calcium silicate fertilizer simply produced from slag, by-product of iron and steel manufacturing plant is one of the most successful example of the conversion of wastes to fertilizer and slag production capacity totals to over three million MT/year. About 200,000 MT of calcium silicate fertilizer is currently applied in the paddy rice every year. Calcium sulfate, a waste from the wet phosphoric acid process is to some extent used as a filler of compound fertilizers but quite large quantites are directly applied for the reclamation of tidal flat.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.53-59
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• 2003

Phosphogypsum is a by-product resulting from the phosphoric acid process for manufacturing fertilizers. It consists mainly of $CaSO_4{\cdot}2H_2O$ and contains some impurities such as $P_2O_5$, $F^-$, and organic substances. Recycling research of phosphogypsum is very limited to a field of study, especially, civil engineering. This study describes an application of phosphogypsum as dredged materials. For this purpose, experiments are performed to evaluate the physicochemical properties and environmental characteristics of dredged clay with phosphogypsum ; sedimentation test, pH, and leaching test. The result of this study are as follows : the settling velocity is increased due to the activity of phosphogypsum. And leaching and radioactive test results are far below than those of regulatory requirement of Waste Management Act in Korea. Therefore phosphogypsum can be used as dredged materials in reclamation.

• Journal of the Korean GEO-environmental Society
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• v.11 no.4
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• pp.25-31
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• 2010

The amount of dredging clay will be greatly increased by the eco-rive project and port development in Korea. Geotechnical engineers have thrown their efforts into the new ways for effective re-uses of the dredging clay such as the material for reclamation, and so on. However, very high initial water content and low strength causes unexpected difficulties in the aspect of trafficablility or time for consolidation. Therefore, the injection of cement stabilizer is used as one of ways to improve reclaimed ground. However, it also makes an argument by heavy metal from cement stabilizer. In this paper constant rate of strain consolidation test and normal consolidation test were performed to investigate behavior characteristics of the consolidation about soil-cement include lean mixed cement to reduce the environmental loads by the cement. The experimental results of consolidation characteristics about soil-cement include lean mixed cement influenced by mixing ratio. Especially it was observed that mixing ratio of 4%~6% leads not only the reduction of consolidation settlement, but time for consolidation.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.533-539
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• 2014

Mine wastes such as acid mine drainage (AMD) can cause the detrimental effects on surrounding environment, thereby eventually threatening human health. Main objective of this study was to evaluate the neutralizing effect of fly ash (FA) as a stabilizing material AMD. Field plot was constructed in a coal waste depot which has caused aluminium-whitening adjacent to the stream. Different mixing ratios of FA were applied on a top of the soil, and then the physicochemical properties of runoff and soil were monitored. Constructed plots were as following: control (mine waste only (W)), mine waste + 20% ($w\;w^{-1}$)of FA (WC20M), mine waste + 40% ($w\;w^{-1}$)of FA (WC40M), and WC40M dressed with a fresh soil at the top (WC40MD). Result showed that initial pH of runoff in control was 5.09 while that in WC40M (7.81) was significantly increased. For a plot treated with WC40M, the concentration of Al in runoff was decreased to $0.22mg\;L^{-1}$ compared to the W as the control ($4.85mg\;L^{-1}$). Moreover, the concentration of Fe was also decreased to less than half at the WC40M compared to the control. Application of FA can be useful for neutralizing AMD and possibly minimizing adverse effect of AMD in mining area.

• Journal of architectural history
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• v.15 no.5
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• pp.19-39
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• 2006

This study deals with construction contract bid-rigging by Japanese contractors who monopolized the construction market of the Korean Peninsula during the Japanese colonial rule, and investigates the abuses of the contract bid-rigging. First of all, construction contract bid-rigging in Korea was triggered by Japanese construction contractors and contract brokers, who had savored the benefits of bidrigging in Japan and had repeated the bid-rigging in Korea since 1903. Second, the agency played a significant role to mediate construction contractors, and existed throughout the Japanese colonial rule on the Korean Peninsula with changing their names. Most of them were engaged in major contract bid-rigging scandals. Among them was Construction Association of Korea, which existed for over 13 years. The agencies had took part in governmental services since the mid-1930s when Japan exploited Korean people during wartime, and focused on sweating human resources for the constructions. Third, one of the biggest construction bid-rigging scandals during the Japanese colonial rule was "the 1st and 2nd scandal on Daegu construction contract bid-rigging." Indeed, the second scandal paved the way for the serial scandals: "Kyeongseong construction contract bid-rigging scandal", "Busan construction contract bid-rigging scandal", and other cases throughout the nation. Fourth, along with the contract bid-rigging cases related to the Japanese Government-General of Korea and local authorities, bid-riggings firmly took rooted in local governments' farmland reclamation projects in the 1920s and the poor relief services in the 1930s. The "bid-rigging charges" forced contractors to compensate their losses with exploiting material costs and labor costs, generating serious problems. The construction contract bid-rigging enabled Japan to monopolize the construction industry and to sweat farmers on the Korean Peninsula. Against this backdrop, contract bid-rigging by Japanese construction contractors during the its colonization made Korean contractors ruled out, and helped Japanese monopolize the industry. A large amount of bid-rigging charges drove Japanese contractors to do fraudulent work with cheap materials and to exploit Korean labor force.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.1-9
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• 2016

While the amount of construction waste has not been changed much in discharge for last 10 years, the recycled resources refined from construction waste have been mainly applied to low-leveled one such as reclamation, back-fill, road base or subbase and so on. Thus this study addresses the applicability of recycled fine aggregate as a replaceable material in precast concrete. To evaluate the possibility, both of dry and wet processes were adopted as well as steam curing, widely used in the field for rapid producing. Most important experimental parameters were driven through preliminary experiments and were evaluated in terms of concrete properties. It is found from aggregate-replacement tests that all of consistency and strengths of concrete were decreased as the ratio of recycled fine aggregate increased, and the amount of decrease can be estimated using proposed equations. Though the recycled fine aggregate showed a decrease of concrete properties more or less, the applicability in large volume as a constituent of precast product was well noted from experimental results.

• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.5-11
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• 2013

This study introduces a densification technique of controlled low strength materials (CLSM) made with coal ashes by pump discharge pressure. Based on a small-scale laboratory test results, unit weight of CLSM around discharge pipe is greater than that of relatively some distant area from discharge pipe. It is also found that densification of CLSM depends on not only mixture rate of pond ash but also fly ash and location of discharge pipe.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.59-66
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• 1988

At the present time, annually about 2 million tons of coal ashes are generated from thermal power plants in Korea, however, they are dumped into ash ponds mixed with sea water very expensively. In this thesis, engineering characteristics of bituminous and anthracite ashes are studied to utilize them as construction materials. The coal ash is non-plactic material and its grain size falls in the range of silt, but it has better soil engineering characteristics than general soils of same grain size. For example, the permeability, shearing strength, CBR, and consolidation properties match to that of sandy soils, moreover, strengthening by hydration can be expected with the lapse of year because of CaO presence in the components. So, utilizing those coal ashes in a productive way as reclamation or banking materials is expected.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.342-347
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• 2015

This study is basic experiment which prevents indiscriminate reclamation and recycles the wasted tire in order to solve environmental pollution according to generation rate of the wasted tire from recently industrial development. By applying as the substitute material of the lightweight aggregate among the constructional materials in order to evaluate the lightness of the wasted tire chip and suggest the recycling plan of the wasted tire chip. The prior experiment did the replacement ratio of the wasted tire with 20%, 40%, 60%, 80%, 100%, etc. and made a study on the strength and density properties. Based on the prior experiment of wasted tire, the replacement ratio was fixed at 15, 20, 25%, particle size of wasted tire was fixed at 0.2, 0.8, 1~2, 3~5, 5~7(mm). As a result, it is supposed that the best replacement ratio and particle size are 15% and 1~2mm, respectively.