• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.578-584
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• 2021

This study comparatively analyzed the properties of hydration reaction and strength development of four types of pond ash(PA) and fly ash(FA), aiming for the effective use of PA. The PA whose chlorine content was highest due to the seawater movement method had a faster setting time, higher cumulative heat, and greater initial strength development than those of FA due to the acceleration of the cement hydration reaction. However, the activity factor increase rate decreased after seven days of curing due to the rapid generation of early hydrates. The PA that contained impurities, such as a large amount of unburned carbon, had a delayed setting time due to the lower hydration reaction. Moreover, the strength was degraded in all curing ages. The PA whose chlorine content was lower due to the freshwater movement method and the amorphous content exhibited similar hydration reactivity and strength development characteristics compared to that of FA. The thermogravimetric analysis results verified that it had a similar level of Ca(OH)₂ consumption and pozzolanic reactivity with that of FA. Conclusively, it is necessary to expand the application of the freshwater movement method and manage the ignition loss to raise PA's usability.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.445-449
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• 2005

Present study was designed to evaluate the practical application of triethyl amine(TEA) injection for improving the collection efficiency of electrostatic precipitator(ESP) connected to a real operating plant. The major fuels used at the domestic power stations were bituminous coals imported from Australia, China, South Africa, and USA. Although the values of the electric resistance would be more or less different according to the type of the coals used, the unique electric resistance values of fly ash from the coals were mostly higher than $1{\times}10^{12}\;{\Omega}-cm$ and therefore, back corona problems were always expected to occur in the electrostatic precipitator. The particulates concentrations, smoke concentrations and their electric resistivity measured at the outlet of ESP, and the inspection of collection indicated that the injection of TEA improved the collection efficiency of particulate at collection plates of ESP. The electric resistance for, fly ash with the injection concentration of TEA 15 ppm(Purity 99.7%) was lowered to $2.1{\times}10^{11}\;{\Omega}-cm$ after injection from $1.9{\times}10^{12}\;{\Omega}-cm$ before injection. Under this condition, the dust emission content at the stack was reduced to approximately 80%, lowering the average outlet concentrations of particulates from $70\;mg/Sm^3$ to $14\;mg/Sm^3$.

• Economic and Environmental Geology
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• v.51 no.5
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• pp.429-438
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• 2018

Since concrete is a hardened aggregates of various materials, it needs to be crushed for chemical analyses. However, the effect of sample crushing on the analytical results has not been precisely assessed till today. In this study, we prepared concrete test pieces using Portand cements and fly ashes as binding materials, and ponded ashes and sands as aggregates and analyzed the heavy metals of the test pieces using Standards for Fair Testing of Soil Contamination (SFTSC) and Wastes (SFTW). For this, each test piece was partially crushed at first and sieved for separation of grains of <0.15 mm, 0.15-0.5 mm, and 0.5-5 mm from the same crushed samples (Crushing Method I). Results of those samples using SFTSC showed a clear trend that analyzed heavy metal concentrations are higher in the finer fractions. Particularly, fractions with <0.15 mm indicated much higher concentrations than the theoretical ones, which were calculated based on the concentrations of individual materials and their mixing fractions. In contrast, the analytical results were generally comparable with the theoretical ones when the test pieces were totally pulverized such that all the crushed grains were <0.15 mm in size (Crushing Method II). These results are associated with the fact that cement materials and fly ashes, which are high in heavy metals relative to other materials, are enriched in the fine fractions. The analytical results using the SFTW derived very low concentrations in most of parameters and did not indicate the dependence of concentrations on the crushing methods due to using distilled water as leaching agent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.1-6
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• 2021

Mercury, once released, is not destroyed but accumulates and circulates in the natural environment, causing serious harm to ecosystems and human health. In the United States, sulfur-impregnated activated carbon is being considered for the removal of vapor mercury from the flue gas of coal-fired power plants, which accounts for about 32 % of the anthropogenic emissions of mercury. In this study, a high-efficiency porous mercury adsorption material was developed to reduce the mercury vapor in the exhaust gas of coal combustion facilities, and the mercury adsorption characteristics of the material were investigated. As a result of the investigation of the vapor mercury adsorption capacity at 30℃, the silica nanotube MCM-41 was only about 35 % compared to the activated carbon Darco FGD commercially used for mercury adsorption, but it increased to 133 % when impregnated with 1.5 % sulfur. In addition, the furnace fly ash recovered from the waste copper regeneration process showed an efficiency of 523 %. Furthermore, the adsorption capacity was investigated at temperatures of 30 ℃, 80 ℃, and 120 ℃, and the best adsorption performance was found to be 80 ℃. MCM-41 is a silica nanotube that can be reused many times due to its rigid structure and has additional advantages, including no possibility of fire due to the formation of hot spots, which is a concern when using activated carbon.

• Korean Journal of Veterinary Research
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• v.63 no.3
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• pp.27.1-27.9
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• 2023

Lespedeza cuneata (LC) is a perennial plant used in herbal medicine to treat numerous diseases, including prostatic hyperplasia, diabetes, early atherosclerosis, and hematuria. Reference collections of bioactive compounds of LC are crucial for the determination of their pharmacological properties. However, little is known regarding its anti-oxidative and anti-inflammatory effects in alveolar macrophage (MH-S) cells. This study examined whether LC can inhibit reactive oxygen species and Coal fly ash (CFA) induced inflammation in MH-S cells. The anti-oxidative effects of LC were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, anti-inflammatory effects were examined using nitric oxide (NO) assay, and cytotoxicity was analyzed using methyl thiazolyl tetrazolium assay. The expression of inflammatory cytokine genes was assessed through a reverse-transcription polymerase chain reaction. Our results revealed that LC exhibited high radical scavenging activity and a dose-dependent (7.8-1,000 ㎍/mL) inhibition of oxidation as compared to ascorbic acid and Trolox. It also inhibited CFA-induced NO production in MH-S cells. Moreover, it suppressed the CFA exposure-mediated expression of pro-inflammatory mediators and cytokines, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. These results suggest that LC is a potent antioxidant and anti-inflammatory agent that can be useful as a nutraceutical product.

• Journal of the Korean GEO-environmental Society
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• v.21 no.10
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• pp.5-10
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• 2020

As the demand for the recycling of industrial by-products increases due to various environmental restrictions including the prohibition of ocean disposal, various studies regarding the recycling of industrial by-products are currently being carried out. One of the industrial by-product, coal ash is produced from thermal power generation; studies on the recycling of fly ash have been actively carried out and it is currently recycled in various fields. In the case of bottom ash, however, only a portion of the total amount generated is primarily processed into a particle size of 2~4mm or less than 2mm to be used for gardening purpose and light weight aggregate and so on. The remaining amount is buried at ash disposal sites. Therefore, various studies are needed to develop measures to use bottom ash. This study aimed at identifying the optimal particle size and mixing ratio of bottom ash to be used as CLSM aggregate. To this end, it evaluated the usability of bottom ash as CLSM aggregate, by investigating the flowability and strength change characteristics of CLSM produced with regard to the mixing ratio of weathered granite soil and bottom ash, particle size of bottom ash to be mixed and soil binder addition rate and conducting a heavy metal leaching test.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.418-424
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• 2016

This study is an experimental study on the recycling of bottom ash in coal ash discharged from a thermal power plant. Bottom ash has limited research on recycling because it has more porous and higher water absorption ratio than fly ash. In this paper, the bottom ash was pulverized to a specific surface area of $4,000cm^2/g$ in order to use as a binder, and the flow, compressive strength test and microstructure analysis of the bottom ash based geopolymer mortar were performed. The flow measurement results of the geopolymer mortar showed that the flow rate was improved by increasing mixing water as the molar concentration of activator was increased. Compressive strength increased with increasing curing temperature and molar concentration. Through the microstructure analysis, we could confirm the geopolymer gel produced by the reaction of the condensation polymerization. It is considered that it is possible to make the bottom ash based geopolymer concrete through proper molar concentration of activator and high temperature curing.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.103-106
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• 2014

Recycling of bottom ash from municipal solid waste (MSW) incinerator has been strictly limited due to its composition of high level chlorine and other unfavorable substances. The composition of MSW has been, however, changed after the introduction of garbage-bag sales system, extended producer responsibility (EPR) policy and the prohibition of direct landfill of food waste. Recent waste shows reduced moisture and chlorine content, increased calorific value due to the separation of food waste, incombustible materials and PVC. The main purpose of this study is to investigate the trend of composition changes of MSW incinerator bottom ash and to compare the analytical results with those before the separation system was introduced. CaO content of bottom ash, one of the major component of cement clinker, increased from 26.7% in 2001 to 34.0% in 2006. The chlorine content showed a dramatic decrease from 1.84% in 2001 to 0.00655% in 2006, which is closely compatible with that of the fly ash of coal-utilizing thermal power plants, which is mainly due to the changes of MSW composition. It is eventually considered that there is a possibility of utilizing the incinerator bottom ash as a raw material of cement clinker feed substances.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.361-363
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• 2008

탄소 개질반응은 $1200^{\circ}C$(도1) 이상에서 모든 탄화물질과 수분 또는 $CO_2$ 사이에서 흡열/환원반응이 일어나서 합성가스를 생성한다. 개질반응로는 산화반응로와 연결되어, 수소가스와 CO 가스의 혼합인,합성가스가 산화반응로 내에서 산소가스와 연소하여 열과 $H_2O+CO_2$를 생성하여 환원 반응로 내로 유입되어, 환원 반응로를 $1200^{\circ}C$ 이상으로 유지하고, $H_2O$와 $CO_2$는 석탄 속의 모든 탄소를 CO로 개질한다(도2). 동시에 수소가스가 생성되어 합성가스를 생성하게 된다. 석탄 속의 비탄소 물질인 슬래그(Slag)는 개질로 내에 남게 되는데, 개질로를 슬래그 융점(non-fluid point) 이하에서 고체상태로 포집함으로서 Fly-ash로 처리된다. 개질로 내의 온도를 $1200{\sim}1300^{\circ}C$(석탄 슬래그 융점)로 유지함으로서 개질반응이 지속되어 합성가스가 생성된다. IGCC 시스템에서는 합성가스를 가스터빈 속에서 $O_2E가스와 연소하여 고온의 가스를 생성하여 터빈을 가동해 발전을 하고 배출가스를 $1500{\sim}1700^{\circ}C$에서 배출한다. 재래식 IGCC(도4)에서는 ${\sim}1500^{\circ}C$의 배출가스를 열교환 시스템에 의해 증기를 생성하여 Steam turbine(증기터빈)을 가동하여 추가 전력을 생산했다. 그러나 본 시스템에서는 배출가스(증기와 $CO_2E 가스)를 위의 개질로에 유입하여 개질로 온도를 $1200{\sim}1300^{\circ}C$로 유지함으로서 더 많은 합성가스를 생성 하게 된다(도3). 이렇게 하여 Oxidation-reduction cycle을 형성하게 된다. 새로운 IGCC 시스템에서 가스 터빈의 배출가스가 석탄 개질로에 연결되고 석탄개질로의 합성가스 출구가 가스터빈의 가스 입구에 연결됨으로서,외부에너지 주입 없이 지속 가능한 가스화 반응과 터빈 사이클(Cycle)을 완성하여 IGCC 시스템의 석탄 열효율을 1단계 상승시켰다. 이렇게 설계된 석탄가스화기는 Lurgi형 석탄가스화 기와 달리 석탄개질반응의 효율을 높일 수 있고, 슬래그 처리가 간단하기 때문에 석탄가스화기가 소형화 될 수 있으며 슬래그(Slag)용융에 따른 석탄가스화기의 외벽손상을 피할 수 있다.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.6
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• pp.789-803
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• 2003

The purpose of this study is to compare the usefulness between Gaussian dispersion model and receptor model with the experimental result of the dispersion tracing of the particulate pollutants from Taean coal-fired power plants. For this purpose, the component analysis of the collected PM 10 samples was performed. In order to trace the pollution sources, factor analysis was done with the result of the component analysis. As a result of the correlativity analysis of the fifteen power plants' profiles offered by US EPA, the correlativity of No.11202 source profile showed highest rate up to 84.5%. Thus it was adopted as proper one and the contribution rate by each pollution source was calculated by Chemical Mass Balance (CMB)-8 model. The contribution rate, which was the effect rate of the power plants on each measuring point, were calculated with a range of 24∼52％ and the standard error was below 0.9 $\mu\textrm{g}$/㎥. This indicates the selection of the source profile was appropriate. Also, the concentrations of each point were calculated by the ISCST3 which is suggested by US EPA as one of the regulatory Gaussian dispersion model. The calculation result showed that the predicted concentration was 50∼58 $\mu\textrm{g}$/㎥, comparing with the measured result of 9∼65 $\mu\textrm{g}$/㎥. It was found that the concentration calculated by ISCST3 was underpredicted. It was thought that the receptor model was more favorable than the Gaussian dispersion model in estimating the effect of the particulate matter on a certain receptive point.