• Nuclear Engineering and Technology
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• 제26권4호
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• pp.507-515
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• 1994

국내의 석탄화력발전소에서 발생하는 석탄비회와 국내산 벤토나이트 중에서 시료를 선정하였으며 특성분석을 수행하였다. 석탄비회는 입도분포에 있어서 벤토나이트와 유사하였으나 미세구조는 매우 다르게 나타났다. 석탄비회의 가장 큰 특징은 물과 섞었을 때에 나타나는 높은 알칼리성이었다. 석탄비회와 벤토나이트를 섞었을 때 나타나는 Cs과 CO의 분배계수의 특성을 조사하기 위한 실험을 수행하였다. 실험결과, 석탄비회의 경우, Co의 분배계수가 Cs보다 높게 나타났다. 여러종류의 실험을 통하여 벤토나이트와 석탄비회 혼합물의 Co와 Cs에 대한 분배 계수에 영향을 미치는 요인을 확인하였다. 또한, 벤토나이트와 석탄비회 혼합물의 Cs에 대한 분배계수와 벤토나이트와 모래 혼합물의 동일핵종에 대한 분배계수 비교를 통하여 벤토나이트와 석탄비회를 적절한 혼합비율로 섞는다면 석탄비회가 효과적인 첨가제로 유용함을 보였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.99-102
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• 1999

In the study, the effect of the replacement content(20, 40, 60, 80%) and particle fineness and the chemical activator of the fly-ash on the flow and strength development of mortar was investigated. We found that the higher raito of the fly-ash replacement produced the lower the mortar strength and the higher fineness of the fly-ash yielded the higher strength. Also, we used Na2SO4 as activator of fly-ash to rise compressive strength mortar. The result as follows: the fly-ash mortar which stimulated by chemical activator, was higher strength development at early than the fly-ash mortar without chemical activator. But in the late age, the result indicated adversely.

• 한국환경과학회지
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• 제19권1호
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• pp.105-114
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• 2010

The objective of the paper is to experimentally investigate the compressive strength of the concrete incorporating fly ash. Ordinary Portland cement(OPC). Water to binder ratio(W/B) ranging from 30% to 60% and curing temperature ranging from $-10^{\circ}{\sim}65^{\circ}C$ were also adopted for experimental parameters. Fly ash was replaced by 30% of cement contents. According to the results, strength development of concrete contained with fly ash is lower than that of plain concrete in low temperature at early age and maturity. In high curing temperature, the concrete with fly ash has higher strength development than that of low temperature regardless of the elapse of age and maturity. Fly ash can have much effect on the strength development of concrete at the condition of mass concrete, hot weather concreting and the concrete products for the steam curing.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.209-210
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• 2019

Current international concerns are the energy crisis due to climate change and depletion of fossil fuels due to global warming. Korea has a very high dependency on energy imports 93%. In Korea, 63% of the country is forested, and a power plant using wood biomass is being built in Korea. Biomass fly ash, a by-product of biomass energy generation, is now being discarded. There is little research to utilize discarded biomass fly ash. Therefore, this study aims to solve the environmental problems, develop new mixed materials, improve the quality and utilize the biomass fly ash, which is a by-product of the industrial waste. As a result of the experiment, the flowability decreased as the replacement ratio of biomass fly ash increased. As the replacement ratio of biomass fly ash decreased, the amount of air content.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.185-188
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• 2004

The effect of fly ash to prevent detrimental expansion due to alkali -silica reaction was investigated through the ASTM C 1260 method that is one of the most commonly used method because results can be obtained within about 16 days. Reactive aggregate used is a netamorphic rock and sedimentary rock. The replacement proportions of portland cement by fly ash were respectively 0, 5, 10, 15, 25 and 35 percent. Expansion of mortar bars due to alkali-silica reaction decreased with the increase of fly ash content. The results show that the expansion due to alkali-silica reaction is dramatically reduced in the presence of high volume fly ash. When the fly ash content examine from all angles (strength and a flow), the replacement proportions of fly ash is about $25\%$ in order to control on expansion.

• Computers and Concrete
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• 제25권1호
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• pp.83-94
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• 2020

The use of fly ash in modern-day concrete technology aiming sustainable constructions is on rapid rise. Fly ash, a spinoff from coal calcined thermal power plants with pozzolanic properties is used for cement replacement in concrete. Fly ash concrete is cost effective, which modifies and improves the fresh and hardened properties of concrete and additionally addresses the disposal and storage issues of fly ash. Soft computing techniques have gained attention in the civil engineering field which addresses the drawbacks of classical experimental and computational methods of determining the concrete compressive strength with varying percentages of fly ash. In this study, models based on soft computing techniques employed for the prediction of the compressive strengths of fly ash concrete are collected from literature. They are classified in a categorical way of concrete strengths such as control concrete, high strength concrete, high performance concrete, self-compacting concrete, and other concretes pertaining to the soft computing techniques usage. The performance of models in terms of statistical measures such as mean square error, root mean square error, coefficient of correlation, etc. has shown that soft computing techniques have potential applications for predicting the fly ash concrete compressive strengths.

• Carbon letters
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• 제7권1호
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• pp.27-33
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• 2006

Carbon-ceramic composites were fabricated by using fly ash and PANOX fibers as reinforcement. Fly ash, because of its small size particles e.g. submicron to micron level can be effectively dispersed along with fibrous reinforcements. Phenolic resin was used as carbon precursor. Both dry as well as wet methods were used for forming composites. The resulting composites were characterized for their microstructure, thermal and mechanical properties. The microstructure and mechanical properties of composites are found to be dependent on type of the fly ash, fibrous reinforcements as well as processing parameters. The addition of fly ash improves hardness and the fibers, which get co-carbonized on heat treatment, increase the flexural strength of the carbon-ceramic composites. Composites with dual reinforcement exhibit about 30-40% higher strength as compared to the composites made with single reinforcement, either with fly ash as filler or with chopped fibers.

• 한국토양비료학회지
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• 제28권4호
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• pp.334-339
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• 1995

석탄회의 농업적 활용 방안을 모색하기 위하여 포트에 수수를 재배하였다. 토양은 무연탄회와 유연탄회로 각각 0, 6, 12, 18, 24% 처리되었다. 생육시기중 초장과 줄기의 마디수는 무처리 보다 석탄회처리에서 그리고, 무연탄회보다 유연탄회처리에서 효과가 더 좋았다. 석탄회처리는 24%까지 수수의 생육에 좋은 영향을 미쳤다. 성숙기의 고엽화(枯葉化)율은 석탄회처리에서 현저히 심하였고 석탄회의 농도가 증가할수록 그 율이 증대되었다. 줄기와 잎을 포함한 전수확량은 무처리보다 석탄회처리에서 그리고, 무연탄회보다 유연탄회처리에서 더 높았다. 알곡수량은 무처리보다 석탄회처리에서 그리고, 무연탄회보다 유연탄회처리에서 효과가 더 좋았다. 일반적으로 석탄회처리는 12%까지 수량이 증가되었다. 수수 생육은 pH가 높은 토양에서 왕성하므로 유연탄회 처리는 권장될 수 있다.

• Computers and Concrete
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• 제5권6호
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• pp.559-572
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• 2008

The effects of fly ash and superplasticizer (SP) on workability of concrete are quite difficult to predict because they are dependent on other concrete ingredients. Because of high complexity of the relations between workability and concrete compositions, conventional regression analysis could be not sufficient to build an accurate model. In this study, a workability model has been built using artificial neural networks (ANN). In this model, the workability is a function of the content of all concrete ingredients, including cement, fly ash, blast furnace slag, water, superplasticizer, coarse aggregate, and fine aggregate. The effects of water/binder ratio (w/b), fly ash-binder ratio (fa/b), superplasticizer-binder ratio (SP/b), and water content on slump were explored by the trained ANN. This study led to the following conclusions: (1) ANN can build a more accurate workability model than polynomial regression. (2) Although the water content and SP/b were kept constant, a change in w/b and fa/b had a distinct effect on the workability properties. (3) An increasing content of fly ash decreased the workability, while raised the slump upper limit that can be obtained.

• ETRI Journal
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• 제41권1호
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• pp.124-132
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• 2019

The energy balance (EB) model of a primary side regulation (PSR) fly-back converter in the discontinuous conduction mode (DCM) is discussed in this paper. Based on this EB model, the stability of a PSR fly-back converter in the pulse skipping mode (PSM) is analyzed, and a self-adapting modulation factor control strategy is proposed. Theoretical analysis and simulation results show that by saving an optocoupler and correlative circuits, which are necessary in traditional PSM fly-back converters, the modulation factor tolerance controlled by this method is 1.26% on average, corresponding to the ideal value. Compared with traditional fly-back PSM controllers, the power saved in the sampler/comparator modules is 87% on average for a load range of $1{\Omega}$ to $1k{\Omega}$.