• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.501-504
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• 2006

Recycled aggregate mortar contains plenty of calcium hydroxide to improve the strength of blast furnace slag, although the surface mortar made of recycled aggregate deteriorates adhesion to cement paste and blast furnace slag has a low initial strength. Therefore, this study assumes that the combination with both recycled aggregate and blast furnace slag will produce a better performance. The results of the experiment show that dry mortar made of recycled aggregate provides with higher strength than wet mortar does at the 3-day and 7-day age, while lower at the 28-day age. It indicates that a large amount of cement mortar made of dry recycled aggregate has deteriorated adhesion strength. The mixes with 30% and 50% of blast furnace slag and 50% and 75% of recycled aggregate provide with much better strength at the 7-day age, although they usually have latent hydraulic property at the 28-day age. It indicates that calcium hydroxide($Ca(OH){_2}$) in recycled aggregate has affected ground granulated blast furnace slag.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.66-67
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• 2013

Replacing a large amount of ground granulated blast furnace slag is limited because early age strength is low due to latent hydraulic property despite excellence of long-term strength. This study aimed to examine produceableness of high-activated ground granulated blast furnace slag using slag by-product from steel process. As experimental variable, the properties of strength development were analyzed by setting fineness and replacement ratio of slag by-product, curing conditions, and W/B. The results of study showed that high-activated ground granulated blast furnace slag using slag by-product as an activator improve the compressive strength of mortar. It is expected to be used as binder for secondary product of concrete considering curing and mixing conditions because high-activated ground granulated blast furnace slag can be hydrated by itself.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.427-432
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• 2020

In this study, a multi-zone furnace analysis method that couples a 1D energy and mass balance calculation with a 3D radiative heat transfer calculation is tested in order to verify its reliability. The calculated results for a domestic 500 MW capacity coal-fired boiler furnace were compared with the design data of the boiler manufacturer and CFD analysis, and a good agreement was achieved. Although this calculation method is less sophisticated than the CFD furnace analysis, it has an advantage in terms of calculation time while being able to provide the furnace behavior according to the fuel characteristics and operational variable changes. Therefore, it is expected to be useful for boiler operation diagnosis and daily fuel/operation planning.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.33-34
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• 2023

Currently, research on construction materials using industrial by-products is being conducted in the Inhan construction industry due to CO₂ emissions during the cement production process and a shortage of aggregates. Among these, research has been conducted to use steel furnace slag as an aggregate by reducing the reactivity of free-CaO, which has the characteristic of expanding through open storage, aging, and rapid cooling. However, research on the use of powder as a cement admixture or substitute is insufficient. Therefore, this study aims to analyze the properties of fresh mortar using steel furnace slag powder. The mixing ratio of steel furnace slag powder was divided into three levels: 0, 20, and 40 (%), and the test items were flow and unit weight. The experimental results showed that as the mixing ratio of steel furnace slag powder increased, flow and unit weight tended to increase. Therefore, it is expected to have a positive effect on improving workability or strength as a cement admixture.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.153-160
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• 2010

This study aims to obtain technical data for improvement of utilization of Blast Furnace Slag(BFS), recycled aggregate in the future by complementing fundamental problems of BFS such as manifestation of initial strength and excessive alkali quantity as well as weakness of recycled fine aggregate through manufacturing of recycled fine aggregate mortar using BFS. The recycled aggregate includes the cement paste hardened as the surface and the type of the aggregate, which contains plenty of calcium hydroxide($Ca(OH)_2$) as well as the unhydrated cement. Accordingly, the objectives of this study are to inspect the manufacturing the recycled fine aggregate mortar used with blast furnace slag, to consider the effects of the recycled aggregate on the strength development of ground granulated blast furnace slag, and then to acquire the technical data to take into consideration the further usages of the recycled aggregate and blast furnace slag. In eluted ions from recycled aggregate, it showed that there were natrium($Na^+$) and kalium($K^+$), expected to be flown out of unhydrated cement, as well as calcium hydroxide($Ca(OH)_2$). Application of this water to mix cement mortar with ground granulated blast furnace slag was observed to expedite hydration as calcium hydroxide($Ca(OH)_2$) and unhydrated cement component were expressed to give stimuli effects on ground granulated blast furnace slag. The results of the experiment show that the recycled aggregate mixed with blast furnace slag has comparatively higher hydration activity in 7 day than the mortar not mixed with one in 3 day mortar does, causing the calcium hydroxide in the recycled fine aggregate to work on as a stimulus to the hydration of ground granulated blast furnace slag.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.611-625
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• 2021

Mg crowns were manufactured using domestic dolomite (Ca·Mg(CO₃)₂) (20~30 mm). In order to manufacture the calcined dolomite (CaO·MgO), (a) electric furnace (950 ℃, 480 min) and (b) microwave furnace (950 ℃, 60 min) processes were used. As a result of XRD analysis, it was analyzed as (a) CaO 56.9 wt%, MgO 43.1 wt% by electric furnace process and (b) CaO 55 wt%, MgO 45 wt% by microwave furnace process. Even when the decarbonation reaction time of dolomite was shortened by 1/8 in microwave furnace process compare with electric furnace process, the calcined dolomite could be produced. The hydration reaction (ASTM C 110) is a standard for the hydration reactivity of calcined dolomite, and the calcined dolomite produced by electric furnace process showed a high hydration reactivity (max temp 79.8 ℃/1.5 minutes). Such hydration reactivity was occurred by only CaO hydration reaction and that was confirmed by XRD analysis. The calcined dolomite produced by microwave furnace process showed low hydration reactivity (max temp 81.7 ℃/19.5 minutes). Such low hydration reactivity was occurred by CaO and MgO hydration reaction due to the hydration reaction of CaO thereafter occurring of the hydration reaction of MgO, and that was confirmed by XRD analysis. The prepared Mg crown were 58.8 g and 74.6 g by electric furnace and microwave furnace processes, respectively, under the reaction conditions of 1,230 ℃, 60 min, 5 × 10^-2 torr by silicothermic reduction.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1192-1192
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• 2001

Usually there are many furnaces in a ethylene plant and the performance of total furnaces can be improved if that of each furnace is monitored and controlled. For this purpose real-time data for the effluent of each furnace is necessary. However, it is very difficult to analyze the total effluent stream of a ethylene furnace by real-time because it is composed of so many components including heavy hydrocarbons. Fortunately, component data for lighter hydrocarbons is much more important than that of heavier ones for ethylene furnace. In ordinary case, the on-line measurement of light hydrocarbons is performed by on-stream gas chromatography, after separating gas-phase part from effluent. The main and important components of gas-phase are Methane, Ethane, Ethylene, and Propylene. If we can use Near-infrared spectroscopy for measuring those components within good reproducibility, shorter analysis time, better repeatability, easier maintenance and lower cost will make Near-infrared (NIR) analyzer replace on-stream gas chromatography in this process. Although it is known to be very difficult to measure gas components because of very weak absorption in Near-infrared region, we have studied the feasibility of the application of NIR for the measurement of gas-phase hydrocarbon in the effluent of ethylene furnace. The samples were obtained from actual process and NIR spectra were collected over 1100 to 2500nm range. NIR spectra and calibrations showed and demonstrated the possibility of extending NIR spectroscopy to the measurement of gas-phase hydrocarbon in the effluent of ethylene furnace.

• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.23-30
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• 2015

The properties of dust collected from electric arc furnace of ferro manganese production units was investigated, and also the metallic manganese was recovered from the dust by aluminothermy process. The ferromanganese dust collected from electric arc furnace contained about 15% of manganese oxide ($Mn_3O_4$) and 9% of carbon as the contaminant, and have a 5um of 50% median diameter and irregular particle shape. The carbon contaminant in the dust could be reduced until about 0.1~0.5% level by roasting in the air at a temperature of 600~900C for 60minutes. The recovery of manganese could not be carried out using only ferromanganese dust from electric arc furnace by aluminothermy process, but the ferromanganese which contained manganese of about 92% and iron of about 5% could be obtained from the mixture of ferromanganese dusts from electric arc furnace and converter. The best mixing condition of dust fixed at electric arc furnace dust / converter dust ratio of 1:9 and 2:8, and the mixing rato of 3:7 or more could not separated the metal and slag from the reactant after aluminothermy reaction.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.581-588
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• 2009

An amount of electric arc furnace slag, by-products generated in iron manufacture, is being increased. Therefore, it is required to recycle the electric arc furnace slag. Currently, it is possible to use the electric arc furnace slag as the aggregates of the concrete through the insurance of volume stability but not in the past because of the expansibility of f-CaO and f-MgO. In this study, simple beam tests via Ichinose method were performed to estimate the bond properties of reinforced concrete (RC) beams using the electric arc furnace slag. The results of the test showed that the showed that specimens using the electric arc furnace oxidizing slag aggregates have similar or more bond capacity relative to the specimen of natural aggregates. Especially, bond capacity of the specimens using the slag aggregates was almost one and a half times higher than a specimen using natural aggregates.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.301-306
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• 2015

For the purpose of developing high performance marine concrete with improved crack resistance and durability, this analytical study aimed to estimate strength, hydration heat characteristics, and chloride attack resistance of concrete with mineral admixture. Ground granulated furnace slag and fly ash were considered for mineral admixture. The replacement of ground granulated furnace slag and fly ash considered in the analysis was in the range of 0~70% and 0~40 %, respectively. The analysis results indicated that both ground granulated furnace slag and fly ash decreased compressive strength, and the effect of adding ground granulated furnace slag on mitigation of hydration heat was limited whereas fly ash had an noticeable influence on it. It was also found that the replacement with ground granulated furnace slag enhanced the chloride attack resistance but fly ash deteriorated the resistance. From the analytical studies, It could be expected that a ternary blended cement composition with proper amount of ground granulated furnace slag and fly ash might be effective to control crack resistance as well as chloride attack resistance of marine concrete.