• 한국세라믹학회지
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• 제44권1호
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• pp.43-51
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• 2007

Fluidity, setting time, hydration heat, bond water ratio, compressive strength, SEM and BET of OPC were measured by adding 1.0 wt% KCl and replacing 20 wt% mineral admixture in order to examine effects of blast furnace slag (BFS), limestone powder (LSP), and fly ash (FA) on fluidity and strength development of the cement contained much chloride. In general, the cement contained much chloride was high in heat of hydration, short in its setting time, low in its fluidity and low in its strength at 28 days due to the rapid hydration in its initial stage. As a result of the experiment, it has been demonstrated that fluidity became improved but the compressive strength at 28 days was decreased as replaced LSP to the cement contained much chloride. the fluidity and compressive strength at 28 days was improved as replaced BFS, the initial compressive strength development was improved due to the activation of initial reaction by KCl. Fluidity, initial compressive strength and late compressive strength at 28 days of cement contained much chloride replaced 5 wt% LSP and 15 wt% BFS concurrently was better than OPC, but the hydration heat was lower.

• 한국지구과학회지
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• 제31권3호
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• pp.205-213
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• 2010

옥천대 우라늄 광화대 부근 퇴적암 지하수에 대한 수리지화학적 연구를 수행하여 옥천대 우라늄 광화대와 대전지역 우라늄 지하수와의 성인적 관련성을 고찰하였다. 지하수의 pH는 6.4-8.1의 범위로 중성에서 약칼리성 특성을 보이며, Eh는 대체로 -50-225 mV의 범위로서 일부는 환원성 환경의 특성을 보인다. 지하수는 탄산염광물의 용해반응으로 $Ca^{2+}$ 및 $HCO_3^-$ 함량이 우세한 Ca-$HCO_3^$ 유형에 해당된다. 석탄광산 폐수에서는 $1165{\mu}g/L$의 우라늄이 검출되었으나 지하수내 우라늄 함량은 $3.2{\mu}g/L$ 이하로 매우 낮다. 우라늄 광화대 부근 지하수에서 낮은 우라늄 함량은 낮은 Eh를 보이는 수리지화학적 특성에 기인한다. 대전지역 지하수 내 우라늄은 옥천대 우라늄 광화대로부터 공급되지는 않은 것으로 판단된다.

• Advances in concrete construction
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• 제9권2호
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• pp.217-225
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• 2020

The recovery of waste proves a solution with two impacts: the environmental impact by the reduction of pollution and the gain of the occupied space by this waste, and the economic impact by the use of these lasts in the building and in the area of public works. The present research consists in recovering a waste marble (thrown powder exposed to the different meteorological phenomena) generated by the quarry marble of Fil-fila, located at the east side of Skikda in the north-east of Algeria, and add it, as sand in the composition of sand concrete. To carry out this research, we analyzed the evolution brought by the substitution of ordinary sand by marble waste sand, with 25%, 50%, 75% and 100% on the properties in the fresh state (density, workability and air content) and in the cured state (compressive strength, tensile strength, surface hardness and sound velocity). For durability we tested water absorption by immersion and chloride penetration. The results obtained are compared with control samples of 0% of substitution rate. In order to have a good filling of the voids in the granular skeleton; we added a quantity of limestone recycled fines from the quarries and for a good workability a super-plasticizing additive. The results showed that the partial substitution modified both the fresh and the hardened characteristics of the tested concretes, the durability parameters also improved.

• Advances in concrete construction
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• 제10권5호
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• pp.393-402
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• 2020

The given research focuses on examining the effect of relatively humidity (RH) and curing temperature on the hydrates as well as the porosity of calcium sulfoaluminate (CSA) cement pastes. Numerous tests, which consist of mercury intrusion porosimetry (MIP), thermosgravi metric (TG) and X-ray diffraction (XRD) were conducted. Various characterization techniques which include, scanning electron microscopy, Fourier transform microscopy along with X-ray diffraction evaluations were conducted on the samples to examine phase formation and crystallinity, morphology and microstructure along with bond formations and functional groups, respectively. During long-term study, the performance of concrete which consisted of limestone and flash-calcined was close to those from standard Portland cement concrete. Traditional classifications and methods of corrosion were widely used for the assessment of steel in concrete which may get employed to concrete which contains LC3 to recalibrate the range of polarization resistance for passitivity condition. For example, there is up to 79.5% and 146% respective flexural and compressive strengths. Moreover, they developed more advance electrical and thermo-mechanical performance with a substantial reduction in absorption of water of close to 400%. These advantages allow this research crucial to evaluate how these methods can be applied. Additionally, the research evaluates developed and more advanced cement preservation and repair techniques. The conclusion suggests concerted efforts by various stakeholders such as policy makers to enable low-carbon rates.

• 자원환경지질
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• 제29권5호
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• pp.597-613
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• 1996

The tonnage of copper and tungsten produced at Dalseong mine by Taehan Tungsten Mining Company from 1961 to 1971 was 48,704 tons (M/T) of 4 wt.% Cu and 1,620 tons (S/T) of 70wt.% WO, but the mine was closed in 1974. Kyeongsan mine is a small abandoned cobalt mine with no data of production. To investigate the pollution level of the mine areas, soils, plants (Ohwi and Pampanini), stream waters and stream sediments were taken and Fe, Mn, Cu, Pb, Zn, Ni, Co, Cd and Cr were analysed by ICP. Soils are considerably contaminated by the heavy metals related to ore deposits, The heavy metal contents in plants vary with the species and parts of plants. Stream waters are anomalously high in heavy metals in the vicinity of the mines but the contents decrease downstream in the process of dilution and precipiation. However, heavy metal contents increase very high in stream sediments due to precipiation. To protect environmental damages caused by acid mine drainages wetlands must be constructed outside pits, and it is necessary to fill pits with waters, limestone chips and organic materials, which give reducing and alkaline condition to ores. Under the condition pyrite is protected from oxidation and aqueous iron sulphates precipitate to form stable secondary pyrite.

• 한국도로학회논문집
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• 제19권5호
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• pp.77-88
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• 2017

PURPOSES : It is necessary to clarify the rheological properties of cement paste as a basic research in the development of mechanistic concrete mix design. The rheological properties of cement paste with different binder types, mix propositions, and with/without high range water reducers have been analyzed. METHODS : In this study, ordinary Portland cement, fly-ash, blast furnace slag, silica fume, and limestone powder were used as binders. The range of water-binder ratio was 0.3-0.5, and a total of 30 different mixes have been tested. The slump flow test, V-funnel test, and Dynamic Shear Rheometer (DSR) test were performed to analyze the rheological properties of cement paste. RESULTS : As a result of the slump flow test, it was found that the composition ratio of the binder contents greatly affected the paste flow when the high range water reducers were added. The results of V-funnel test showed that when the water-binder ratio was decreased without high range water reducers, the binder composition ratio had a large effect on the passing time of the V-funnel tester, but with high range water reducers the impact of the binder composition ratio was decreased. The slump flow and V-funnel have a certain relationship with the rheological factors (yield stress and plastic viscosity), but the correlation was not significant. Finally, we proposed the M-value considering the density and specific surface area of the binder. The correlation between rheological factors and M-value were better demonstrated than experimental values, but there is still a limit to predict the rheological factor in general mix design. CONCLUSIONS :In this study, the rheological properties of cement paste were analyzed. The binder type, composition ratio of binder, and with/without high range water reducers have combined to provide the complex effects on the rheological properties of cement paste. The correlation between the proposed M-value and rheological factor was found to be better than experimental results, but needs to be improved in the future.

• Asian-Australasian Journal of Animal Sciences
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• 제22권4호
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• pp.598-604
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• 2009

This work was carried out to study the carcass characteristics, the chemical composition and the fatty acid profile in Longissimus muscle (LM) of bull breeds Nellore, NEL (11), Caracu, CAR (12) and Holstein-Friesian, HFR (12) finished in a feedlot. The bulls were fed twice a day with corn silage, cotton meal, cracked corn, urea, limestone and mineral salt. NEL and CAR bulls had similar (p>0.05) final weight and hot carcass weight. However, NEL and CAR bulls had higher (p<0.05) final weight and hot carcass weight than HFR bulls. Carcass hot dressing, carcass conformation, cushion thickness, Longissimus muscle area and texture were similar (p>0.05) among NEL, CAR and HFR bulls. NEL and HFR bulls had higher (p<0.05) carcass length in comparison to the CAR breed. Nellore breed had higher (p<0.05) leg length in comparison to CAR and HFR breeds. Leg length was similar (p>0.05) between CAR and HFR breeds. Thickness fat, color and marbling score were lower (p<0.05) in NEL breed in comparison to CAR and HFR breeds. LM of NEL bulls had higher (p<0.05) meat moisture content in comparison to CAR and HFR bulls. In contrast, lipid content was lower (p<0.10) in HFR bulls. LM ash and crude protein contents were similar (p>0.05) among breeds. Saturated fatty acids (SFA) were higher (p<0.10) in HFR animals. Monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), n-6, n-3 and PUFA/SFA ratio were similar (p>0.05) among the different breeds. N-6/n-3 ratio was higher (p<0.05) in CAR animals.

• Asian-Australasian Journal of Animal Sciences
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• 제21권9호
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• pp.1296-1302
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• 2008

This work was conducted to study the performance, carcass characteristics, chemical composition and fatty acid profile of the Longissimus muscle (LM) of first-generation Purunã (n = 7, PUR1), second-generation Purunã (n = 9, PUR2), and 1/2 Puruna vs. 1/2 Canchin (n = 13, PUCA) bulls finished in a feedlot. The animals averaged 18 months of age at the beginning of the experiment. The animals were kept in a feedlot from 18 to 22 months of age. They were fed twice a day with corn silage ad libitum, along with soybean meal, cracked corn, urea, limestone and mineral salt. PUR1 bulls had greater (p<0.05) final weight (496.0 kg) than PUCA bulls (449.2 kg). However, there was no difference (p>0.05) between PUR1 and PUR2 (472.0 kg), and between PUR2 and PUCA. Hot carcass weight was similar (p>0.05) among the different genetic groups. Hot carcass dressing percentage was similar (p>0.10) between PUR1 (50.4%) and PUCA (53.8%), and higher (p<0.10) than PUR2 (48.6%). Cushion thickness was greater (p<0.05) in PUCA bulls (27.12 cm). The other parameters were similar (p<0.05) among the three genetic groups. Total lipid and cholesterol contents were higher (p<0.01) in PUR2. Moisture, ash and crude protein contents were similar (p>0.05) among the three genetic groups. Saturated fatty acid (SFA) levels were higher (p<0.10) in PUR1 and PUR2 (51.58% and 50.41%, respectively). Polyunsaturated fatty acid levels were higher (p<0.05) in PUR1 and PUCA (6.50% and 8.29%, respectively). N-6, n-3 and PUFA/SFA ratios were higher (p<0.05) in PUCA. MUFA and n-6/n-3 ratios were similar (p>0.05) among the different genetic groups.

• Asian-Australasian Journal of Animal Sciences
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• 제28권4호
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• pp.502-510
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• 2015

The objective of this study was to assess the use of peach pomace in total mixed ration (TMR) silages and clarify the differences in aerobic stability between TMR and TMR silages caused by lactic acid bacteria (LAB). The TMR were prepared using peach pomace, alfalfa hay or Leymus chinensis hay, maize meal, soybean meal, cotton meal, limestone, a vitamin-mineral supplement, and salt in a ratio of 6.0:34.0:44.4:7.0:5.0:2.5:1.0:0.1 on a dry matter (DM) basis. Fermentation quality, microbial composition, and the predominant LAB were examined during ensiling and aerobic deterioration. The results indicated that the TMR silages with peach pomace were well fermented, with low pH and high lactic acid concentrations. The aerobic stability of TMR silages were significantly higher than that of TMR. Compared with TMR silages with alfalfa hay, TMR silage with Leymus chinensis hay was much more prone to deterioration. Although the dominant LAB were not identical in TMR, the same dominant species, Lactobacillus buchneri and Pediococcus acidilactici, were found in both types of TMR silages after 56 d of ensiling, and they may play an important role in the aerobic stability of TMR silages.

• 자원리싸이클링
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• 제23권5호
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• pp.3-11
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• 2014

칼슘 페라이트는 기존 소결광용 결합제 및 제강용 융제보다 용융온도가 낮아 결합제 및 융제로서의 효과가 우수하다. 본 연구에서는 제조비용절감과 생산성 증대를 위해 기존 용융법이 아닌 시멘트 제조공정에서의 소성법으로 칼슘 페라이트를 제조하였다. 칼슘페라이트의 석회질 원료로 소성슬러지 및 석회석을 사용하였고, 철질 원료로 제강슬러지, 고로분진 및 철광석을 사용하였다. 이때 소성온도는 $950{\sim}1170^{\circ}C$이며, 저융점 특성을 가진 '소결광용 결합제' 또는 '전로 및 전기로용 융제'로의 사용 가능성을 검토하고자 원료를 분석하고 소결 특성을 평가하였다.