• 한국세라믹학회지
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• 제18권3호
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• pp.192-200
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• 1981

This study deals with the low temperature ($25^{\circ}C$-$600^{\circ}C$) properties of Kaolin-Phosphate-water systems. Phosphoric acid, mono aluminum phosphate, mono ammonium phosphate, the mixture of phosphoric acid and mono aluminum phosphate, and the mixture of phosphoric acid and mono ammonium phosphate were used to characterize the M.O.R. of the systems with to quantity of phosphates, curing time, and firing temperature. Firing shrinkage, viscosity, surface tension, DTA, TGA, and X-ray diffraction patterns were also measured in order to investigated the factors of strengthening. The results of this study were summarized as follows: 1. The M.O.R. of kaolin-phosphate systems were stronger than that of Kaolin-water system at room temperature or low temperature($25^{\circ}C$-$600^{\circ}C$). Though it was increased according to the longer curing time, the higher temperature, and the more addition of phosphate, the M.O.R. were decreased in the case of 10 wt% phosphate addition in the system of phosphoric acid, mono aluminum phosphate and phosphoric acid-mono aluminum phosphate. 2. When the concentration of Phosphate was at 4 wt%, the M.O.R. of specimen cured at $25^{\circ}C$ and added to the phosphoric acid was strongest among the specimens in added to the others phosphates. Whereas, when the concentration of phosphate was above 6wt%, the M.O.R. of specimen cured at $25^{\circ}C$ and added to the phosphoric acid mono ammonium phosphate system cured at $25^{\circ}C$ was the strongest. 3. The M.O.R. of the specimen heated, in the temperature range of 15$0^{\circ}C$-1$600^{\circ}C$, and added to the mixture of phosphoric acid-mono aluminum phosphate system or phosphoric acid-mono ammonium phosphate system was stronger than that of specimen added to Phosphoric acid, mono-aluminum Phosphate or mono-ammonium phosphate alone. 4. The bonding force of phosphate binders was more closely related to surface tension than viscosity and it tended to be inversely proportional to surface tension. The bonding force after heating treatment seemed to be caused by the change of structure of phosphate according to heating.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.685-688
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• 2008

최근 들어 석탄회의 재활용에 관한 연구는 환경문제와 관련되어 활발히 진행되어 왔으며 미국, 일본과 같은 선진국에서는 이미 석탄회를 각종 산업분야에 적용함으로써 환경오염 저감 및 경제적 이익 측면에서 상당한 성과를 이루고 있다. 이에 국내에서도 지속적인 연구개발을 통해 시멘트 및 레미콘분야 등에서 시멘트 클링커 원료나 콘크리트 혼합재로 석탄회를 사용함으로써 2005년도 기준 전체 석탄회 발생량 중 약 58.5%정도를 재활용하고 있다. 그러나, 이는 석탄회 중 플라이애시(Fly Ash)에 한정된 것으로, 전체 석탄회 발생량 중 10$^{\sim}$20%에 달하는 바텀애시(Bottom Ash)에 대한 재활용은 극히 미미한 실정이며, 현대 대부분 매립처분되어 심각한 환경오염을 야기하고 있다. 이에 본 연구에서는 국가적인 사회간접자본의 투자가 증대됨에 따라 초고강도콘크리트 및 매스콘크리트와 같은 특수콘크리트에 수요가 증대되고 있는 저발열 혼합시멘트(Low Heat-Blended Cement)의 혼합재로써 바텀애시의 사용 가능성 여부를 검토하고자 바텀애시의 첨가량 변화에 따른 저발열 혼합시멘트 및 콘크리트의 기초물성 변화를 비교검토 하였다.

• 한국분말재료학회지
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• 제23권1호
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• pp.43-48
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• 2016

Waste SiC powders obtained from silicon wafer sludge have very low density and a narrow particle size distribution of $10-20{\mu}m$. A scarce yield of C and Si is expected when SiC powders are incorporated into the Fe melt without briquetting. Here, the briquetting variables of the SiC powders are studied as a function of the sintering temperature, pressure, and type and contents of the binders to improve the yield. It is experimentally confirmed that Si and C from the sintered briquette can be incorporated effectively into the Fe melt when the waste SiC powders milled for 30 min with 20 wt.% Fe binder are sintered at $1100^{\circ}C$ upon compaction using a pressure of 250 MPa. XRF-WDS analysis shows that an yield of about 90% is obtained when the SiC briquette is kept in the Fe melt at $1650^{\circ}C$ for more than 1 h.

• 한국세라믹학회지
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• 제52권6호
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• pp.435-440
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• 2015

It is a challenge from an industrial point of view to fabricate silicon nitride substrates with high thermal conductivity and good mechanical properties for power devices from high-purity Si scrap powder by means of thick film processes such as tape casting. We characterize the residual carbon and oxygen content after the binder burnout followed by nitridation as a function of the temperature in the temperature range of $300^{\circ}C-700^{\circ}C$ and the atmosphere in a green tape sample which consists of high-purity Si powder and polymer binders such as polyvinyl butyral and dioctyl phthalate. The optimum condition of binder burnout is suggested in terms of the binder removal temperature and atmosphere. If considering nitridation, the burnout of the organic binder in air compared to that in a nitrogen atmosphere could offer an advantage when fabricating reaction-bonded $Si_3N_4$ substrates for power devices to enable low carbon and oxygen contents in green tape samples.

• 한국구조물진단유지관리공학회 논문집
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• 제8권4호
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• pp.195-202
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• 2004

본 연구에서는 결합재인 시멘트 외에 플라이애쉬, 고로슬래그 및 석회석 미분말을 사용하고 고성능감수제 등의 혼화제를 사용하여 고유동 무다짐이면서도 수화열을 적게 발생하는 콘크리트의 최적배합을 도출하였다. 이와 같이 선정된 배합으로 제조한 콘크리트의 장 단기거동을 기존 원전 콘크리트의 거동과 비교 검토하는 실험을 실시하였다. 연구결과 석회석이 혼합된 다성분계 고유동 콘크리트가 기존 원전용 콘크리트 보다는 시공성과 내구성이 향상되었음을 확인할 수가 있었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.221-224
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• 2010

최근에 인공위성을 궤도에 올리는데 막대한 비용이 들어가므로, 소형이면서 좀 더 신뢰도가 높은 인공위성이 요구되어 왔다. 추진제의 새로운 바인더(HTPB, GAP)와 산화재(CL20, ADN)의 발명은 로켓의 추력을 다양하게 하는데 많은 기여를 했다. 제조 공정을 획기적으로 변화시키는 낮은 온도에서 녹는 열가소성 추진제는 비용을 상당히 절감시켰다. 인공위성을 궤도에 정확하게 안착시키는데 어려움이 있었던 고체 연료 로켓은 액체추진제를 사용하는 PBS를 상단에 추가 설치함으로 정확도를 증진시켰다. 이 논문에서 또한 선진화된 노즐재료와 연소관에 대해서도 방향을 제시한다.

• Journal of Magnetics
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• 제16권3호
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• pp.318-321
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• 2011

A new Fe-based amorphous compound powder was prepared from Fe-Si-B amorphous powder by crushing amorphous ribbons as the first magnetic component and Fe-Cr-Mo metallic glassy powder by water atomization as the second magnetic component. Subsequently by adding organic and inorganic binders to the compound powder and cold pressing, the new Fe-based amorphous compound powder cores were fabricated. This new Fe-based amorphous compound powder cores combine the superior DC-Bias properties and the excellent core loss. The core loss of 500 kW/$m^3$ at $B_m$ = 0.1T and f = 100 kHz was obtained When the mass ratio of FeSiB/FeCrMo equals 3:2, and meanwhile the DC-bias properties of the new Fe-based amorphous compound powder cores just decreased by 10% compared with that of the FeSiB powder cores. In addition, with the increasing of the content of the FeCrMo metallic glassy powder, the core loss tends to decrease.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.31-34
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• 2006

The characteristic of carbon nano fiber (CNF) as electron emitters was described. Carbon nano fiber (CNF) of herringbone was prepared by thermal chemical vapor deposition(CVD), mixed with binders and conductive materials, and then were formed by screen-printing process. In order to increase effectively field emissions, the surface treatment of rubbing & peel-off was applied to the printed CNF emitters on cathode electrode. The measurements of field emission properties were carried out by using a diode structure inline vacuum chamber. CNF of herringbone type showed good emission properties that a turn on field was as low as $2.5V/{\mu}m$ and current density was as large as $0.15mA/cm^2$ of $4.5V/{\mu}m$ with electric field. After the vacuum packaged panel of 5-inch in diagonal, the measured white brightness was as high as $7000cd/m^2$ at 1900V of anode and 700V of gate voltage.

• Computers and Concrete
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• 제24권5호
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• pp.453-458
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• 2019

Today, concrete remains the most important, durable, and reliable material that has been used in the construction sector, making it the most commonly used material after water. However, cement continues to exert many negative effects on the environment, including the production of carbon dioxide (CO2), which pollutes the atmosphere. Cement production is costly, and it also consumes energy and natural non- renewable resources, which are critical for sustainability. These factors represent the motivation for researchers to examine the various alternatives that can reduce the effects on the environment, natural resources, and energy consumption and enhance the mechanical properties of concrete. Geopolymer is one alternative that has been investigated; this can be produced using aluminosilicate materials such as low calcium (class F) FA, Ultra-Fine GGBS, and high calcium FA (class C, which are available worldwide as industrial, agricultural byproducts.). It has a high percentage of silica and alumina, which react with alkaline solution (activators). Aluminosilicate gel, which forms as a result of this reaction, is an effective binding material for the concrete. This paper presents an up-to-date review regarding the important engineering properties of geopolymer formed by FA and slag binders; the findings demonstrate that this type of geopolymer could be an adequate alternative to ordinary Portland cement (OPC). Due to the significant positive mechanical properties of slag-FA geopolymer cements and their positive effects on the environment, it represents a material that could potentially be used in the construction industry.

• Structural Engineering and Mechanics
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• 제71권3호
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• pp.317-327
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• 2019

The aim of this paper is to present the most important issues on the implementation, operation and maintenance of foundation for machines. The article presents the newest solutions both in terms of technology implementation as well as materials used in construction of such structures. Foundations for machines are special building structures used to transfer loads from an operating machine to the subsoil. The purpose of these foundations is not just to transfer loads, but also to reduce vibrations occurring during operation of the machine, i.e. their damping and preventing redistribution to other elements of the building. It should be noted that foundations for machines (particularly foundations for hammers) are the most dynamically loaded building structures. For these reasons, they require precise static and dynamic calculations, accuracy in their implementation and care for them after they have been made. Therefore, the paper in detail present the guidelines regarding: design, construction and maintenance of structures of this type. Furthermore, the most important parameters and characteristics of materials used for the construction of these foundations are described. As a result of the conducted analyzes, it was found that the concrete mix, in foundations for machines, should have a low water/binder ratio. For its execution, it is necessary to use broken aggregates from igneous rocks and binders modified with mineral additives and chemical admixtures. On the other hand, the reinforcement of composites should contain a large amount of structural reinforcement to prevent shrinkage cracks.