• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.36-42
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• 2018

GGBFS(Ground Granulated Blast Furnace Slag)-replacement is very effective for improving resistance to chloride attack and this can induce a long service life for RC(Reinforced Concrete) structures exposed to chlorides. In the work, the design parameters such as cover depth, surface chloride content, critical chloride content, and replacement ratio of GGBFS are considered, and optimum replacement ratio of GGBFS are derived with intended service life. The changes of surface chloride content and cover depth show 3.16~3.38 and 3.02~3.34 times of service life variation, which are most influencing parameters. Critical chloride content shows 1.53~1.57 times of service life variation regardless of w/b(Water to Binder) ratios. In the case of surface chloride content $18.0kg/m^3$, the most severe condition, cover depth over 70 mm and GGBFS replacement ratio over 42% are required with concrete containing w/b ratio under 0.42 for 100 years of intended service life. The condition of $13.0kg/m^3$, GGBFS replacement over 35% is required. For reasonable durability design, quantitative exterior condition and critical chloride content should be determined, and the criteria in Domestic Specification is evaluated to be conservative.

• Resources Recycling
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• v.22 no.1
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• pp.64-71
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• 2013

Mineral carbonation has been proposed as a possible way for $CO_2$ sequestration. The electric arc furnace slags consist of calcium, magnesium and aluminum silicates in various combinations. If they could be used instead of natural mineral silicates for carbonation, considerable energy savings and $CO_2$ emissions reductions could be achieved. Indirect aqueous carbonation of the slags consists of two steps, extraction of calcium and carbonation. Acetic acid leaching of electric arc furnace slags had been already studied to extract Ca in them, but it was reported that the carbonation of the extracted $Ca^{2+}$ in the leached solution would suffer from too slow kinetics, even at high pressure of $CO_2$. In this work, to develop more efficient extraction of the electric arc furnace slags, hydrochloric acid leaching to separate calcium from them was studied, and the results were compared with the acetic acid ones. The phase boundary between $Ca^{2+}$ and $CaCO_3$ in the solution with pH was determined by thermodynamic calculations. Hydrochloric acid was more effective than acetic acid for the extraction of Ca in electric arc furnace slag, and there is a possibility to recycle an unreacted hydrochloric acid in the leached solution by electrolysis or evaporation.

• Analytical Science and Technology
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• v.12 no.6
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• pp.540-549
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• 1999

The combustion temperature was controlled between $880^{\circ}C$ to $1070^{\circ}C$ to find the relation the combustion temperature and emission amount of PCDDs/PCDFs in the Municipal solid waste incinerator. The emission amount of PCDDs/PCDFs decreased when the temperature increased in the rear of the boiler. The PCDDs/PCDFs concentration were detected $7.82ng-TEQ/Nm^3$ at $880^{\circ}C$, $6.97ng-TEQ/Nm^3$ at $970^{\circ}C$ and $6.13ng-TEQ/Nm^3$ at $1070^{\circ}C$. Also, The chlorophenols, chlorobenzenes, and PCB concentration decreased by increasing the temperature from $880^{\circ}C$ to at $1070^{\circ}C$, and the isomer of the prescsors had a tendency to emit the higbly cbiorinated compounds.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.436-442
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• 2014

In this study, we developed an optical-fiber sensor using cobalt chloride solution to monitor temperature in real-time between long distance points unaffected by the electro-magnetic wave and the vibration. Cobalt chloride solutions were made using 10% water and 90% ethanol (v/v) solution. The transmittance of these solutions was analyzed on 655 nm using UV-Visible spectrometer regarding temperature change. Also 30.8 mM cobalt chloride solution was gelled by dissolving polyvinyl butyral and the transmittance of this was analyzed on 655 nm regarding temperature change. The results of transmittance and optical power measurement showed decrease of both transmittance and optical power with increase of temperature from 66.8% and 149.5 nW at $25^{\circ}C$ to 7.1% and 48 nW at $70^{\circ}C$, respectively. These results support the possibility of gelled cobalt chloride/polyvinyl butyral as an optical-fiber sensor to monitor temperature change.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.317-323
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• 2010

This study aimed to examine a suppression effect of salinity on extension rate of stem elongation of cucumber seedlings (Cucumis sativus L.) grafted with roots of figleaf gourd plant. The effects of application methods, timings, and concentrations of two salt types, sodium chloride (NaCl) and calcium chloride ($CaCl_2$), were compared to untreated control plants. In result, an obvious suppression effect on the excessive elongation of stem was obtained by both sub-irrigated and medium-mixed NaCl salt. An improvement in quality of transplants was also obtained by the sub-irrigated NaCl salt. Foliar-applied NaCl caused visible leaf injury when the concentration was higher than 40 mM; but, with no effect on suppressing the stem elongation. When the NaCl was applied at 7 days after grafting, a higher concentration of NaCl was demanded for suppressing the stem elongation compared to an application at the day of grafting. No effect of the NaCl salt on the fresh weights of 36-day grown plants was observed; but, there was a negative effect on the number of female flowers at a high temperature season. Overall, the NaCl salt was more effective on slowing down the stem elongation and had the lower incidence of leaf injury than the $CaCl_2$ salt.

• Journal of Preventive Medicine and Public Health
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• v.33 no.1
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• pp.117-124
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• 2000

Objectives : It is the objective of this study to compare hepatotoxicity of nickel chloride and cadmium chloride with each other through IPRL(Isolated Perfused Rat Liver) method. Methods : Biochemical indicator of hepatic function such as AST(aspartate aminotransferase), ALT(alanine aminotransferase), LDH(lactate dehydrogenase) and perfusion flow rate were used as the indicator of hepatotoxicity. Oxygen consumption rate were used as vability indicator. $300({\pm}50)g$ - weighted rats were allocated randomly to each group($0{\mu}M,\;50{\mu}M,\;200{\mu}M\;NiCl_2\;and\;CdCl_2$ exposure) by 5, totally 25. After Krebs-Ringer bicarbonate butler solution flowed into the penal vein and passed the liver cell, it flowed out of vena cava. Liver was administered with each $NiCl_2\;and\;CdCl_2$ of each concentration and observed with buffer solution sampling time. Butler which got out of liver was sampled and then biochemical indicator of hepatotoxicity was measured. Results : AST, ALT, and LDH in buffer increased with sampling time much more in $CdCl_2$ exposure group than $NiCl_2$ exposure group in both 50 and $200{\mu}M$ and statistical significance w3s verified with 2-way repeated ANOVA. Viability was decreased more and more in all substances during passed time. Conclusions : It is inferred that $CdCl_2$ has stronger hepatotoxicity than $NiCl_2$. IPRL method would be used widely for acute hepatotoxicity when considerating the benefit of it.

• Journal of the Korean Chemical Society
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• v.50 no.4
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• pp.328-337
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• 2006

purpose of this study was to find out problems in experiments for electrolysis of an aqueous CuCl2 solution in high school science textbooks and to suggest an improved experiment considering students' capability of experimenting and laboratory safety in high schools. For this study, the experiments for electrolysis of an aqueous CuCl2 solution presented in 11 high school science textbooks were classified by their experimental methods. After high school chemistry teachers performed the experiments as presented in the high school science textbooks, an analysis was performed on problems of the experiments, and an improved experiment was devised. According to the results of this study, in the experiments for electrolysis of an aqueous CuCl2 solution using a U type tube and a U type tube with branch, reaction velocity of the electrolysis was slow, therefore, a side reaction was generated. In the experiment using a beaker, reaction of each electrode could not be observed separately. And in the experiment using an electrolysis instrument, it was difficult to identify property of the reaction product. In the improved experiment using a reaction vessel of ㅂshape, reaction velocity of the electrolysis was fast, reaction of each electrode could be observed separately, and the side reaction decreased. From these results, it was suggested that the improved experiment would help high school students understand scientific conception regarding electrolysis.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.931-938
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• 2005

When concrete structures are exposed under marine condition for a long time, the steel in concrete is corroded due to the ingression of chlorides in the seawater. Because the damages of corrosion resulting from the chloride ion are very serious, many researches have been performed. Silver nitrate colormetric method that can measure easily penetration depth of chloride ion has been executed, recent)y. However, characteristics of silver nitrate colormetric method were not fully examined. Therefore, the objective of this paper Is to study the applicability of colormetric method. For the purpose of this, effect factors and reaction mechanism of colormetric method were investigated, and the colormetric method is applied for marine concrete structures. According to the results of silver nitrate colored method, two reactions such as white reaction of AgCl and brown reaction of AgOH were shown when $AgNO_3$ was sprayed in splited section. And velocity constant ratio(K) of two reactions appeared that white reaction, AgCl reacts with the fast speed by 3240. When the colormetric method was applied in concrete, it is reasonable that $AgNO_3$ solution more than 0.05N concentration was sprayed. It is confirmed that the colormetric method is useful tool for estimating the chloride of concrete structures in situ. The average chloride amount of colored parts indicates $0.9kg/m^3$ per concrete unit weight.

• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.4
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• pp.17-23
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• 2013

The purpose of this study was to provide information on management and apply it to a roadside ground cover plant understanding the capacity of calcium chloride in the plant. The experimental group was composed of the ratio control group of calcium chloride, 0.5%, 1.0%, and 3.0% in 500g of soil. Plant materials were selected and measured according to their ecological characteristics such as ground cover plant, Pachysandra terminalis, Hosta plantaginea, Trachelospermum asiaticum, Vitex rotundifolia, Euonymus japonica and Callicarpa japonica. The acidity of the amended soil was increased gradually depending on the treatment and conductivity was continually decreased. The EX-Ca increased after the treatment, but decreased in the middle of the experiment. Pachysandra terminalis, Trachelospermum asiaticum and Euonymus japonica were able to grow and survive at the ratio of 0.5%. Hosta plantaginea and Vitex rotundifolia were able to survive at the ratio of 1.0%. Hosta plantaginea, the possible state can absorb salts due to moisture and, can be applied to ground cover plants in the roadside. The growth and development of Callicarpa japonica was poor and the leaves were open to grow for calcium chloride treatment except the control group. It was concluded that Callicarpa japonica was very sensitive to calcium chloride.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.102-113
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• 2021

The deterioration environments caused by de-icing salt and airborne chlorides in the seashore, evaluated in the "Detailed guideline for safety and management practice of facilities (performance evaluation)", were reviewed in terms of penetrated chlorides into concrete on various road facilities. Target concrete structures, in this study, were 4 concrete barriers in Gangwon area, 3 concrete barriers and 1 retaining wall in Busan area, and 4 bridges in Gangwon-do, Seoul, Gyeonggi-do, and Busan. The deterioration environments were classified into three categories: direct and indirect de-icing salt attack, and airborne salt attack depending on the distance to seashore and the height of pier, and the penetrated chlorides in to concrete were analyzed. The results showed that (1) the regional deterioration environments were clearly classified by de-icing salt sprayed days (snowfall days), (2) the penetrated chlorides increased significantly when leakage occurred through slabs or expansion joints, and (3) the airborne chlorides affected to a height of 20 m concrete in the seashore, Busan. From these, it could be confirmed that the chloride ion penetration properties depend on the exposed aging environment, member location and height, and deterioration status, even on the same structure, so the selection of target members and location is very important in the inspection and maintenance. If the database of penetrated chlorides properties in various deterioration environments is constructed, it is expected that the proactive durability management on concrete structures will be possible in the field.