• Computers and Concrete
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• 제8권6호
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• pp.617-629
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• 2011

In this investigation, reservoir sediment and municipal sewage sludge were sintered to form the artificial lightweight aggregates. The sintered aggregates were compared with the commercialized lightweight aggregates to in terms of potential alkali-silica reactivity and chemical stability based on analyses of their physical and chemical properties, leaching of heavy metal, alkali-silica reactivity, crystal phase species and microstructure. Experimental results demonstrated that the degree of sintering of an aggregate affected the chemical resistance more strongly than did its chemical composition. According to ASTM C289-94, all potential alkali-silica reactivity of artificial lightweight aggregates were in the harmless zone, while the potential reactivity of artificial lightweight aggregates made from reservoir sediment and municipal sewage sludge were much lower than those of traditional lightweight aggregates.

• 한국결정성장학회지
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• 제21권3호
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• pp.129-135
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• 2011

제철공업에서 부산물로 발생되는 EAF(Electric Arc Furnace) dust는 유해한 철분 성분을 다량 함유하고 있어 환경파괴를 일으킬 위험이 있는 지정폐기물이다. EAF dust의 자원화를 위하여 석탄화력 발전소에서 발생되는 바닥재와 준설토에 EAF dust를 첨가하여 세라믹 다공체의 제조 가능성을 연구하였다. 또한 등유는 비교적 저온에서 발포기구에 작용하는 탄소(C)의 효과를 보기위해 첨가하였다. 혼합은 건식 공정으로 했으며, 소결 방법은 $1050^{\circ}C$부터 $1200^{\circ}C$까지 $50^{\circ}C$ 간격으로 10분간 직화소성 하였다. 소결된 시편의 비중, 흡수율 및 미세구조를 관찰한 결과, EAF dust는 시편 내의 발포 현상을 용이하게 하여 초경량 다공체 골재를 얻을 수 있었다. $1150{\sim}1200^{\circ}C$의 소결온도에서 10 wt% EAF dust를 첨가한 인공경량골재는 비중 1.0 g/$cm^3$ 이하의 초경량 인공 경량 골재를 만드는 것이 가능할 것으로 판단되었다.

• 에너지공학
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• 제28권1호
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• pp.10-16
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• 2019

본 연구에서는 경량기포콘크리트의 침하안정성 및 경제성을 확보하기 위해 수행되었다. OPC에 fly ash와 Calcium sulfaluminate(CSA)를 일정함량 치환한 배합비를 선정하고 기초물성을 검토하였다. CSA에 의해 조기 ettringite 생성으로 경량기포콘크리트의 플로우가 감소한 것을 확인하였다. 압축강도는 CSA 10%까지 혼입할 경우 경량기포콘크리트의 경화시간 단축으로 인해 초기강도는 증가한 것을 확인하였다. 침하깊이는 CSA를 치환할 경우 응결시간을 단축하여 기포가 소포되는 것을 방지하였기 때문에 침하안정성이 향상되었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.97-98
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• 2018

Despite of its advantange on shortening framework period of a super-tall building, gangform is prone to high safety risk due to its heavy weight during operation. Thus, this study is conducted to investigate the applicability of a lightweight gangform made of engineering composite materials. Compared to the conventional gangform, the proposed gangform showed greater performance not only in reduction of safety accidents on-site, but also in constructability and environmental aspects. The results of this study are expected to be served as the basis for developing the lightweight gangform in future.

• Journal of Electrochemical Science and Technology
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• 제14권2호
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• pp.120-130
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• 2023

PEMFC has high potential for future development due to its high energy density, eco-friendliness, and high energy efficiency. When it becomes small, light and flexible, it can be competitive as an energy source for portable devices or flexible electronic devices. However, the use of hard and heavy materials for structural rigidity and uniform contact pressure transmission has become an obstacle to reducing the weight and flexibility of PEMFCs. This review intends to provide an example of the application of a new structure and material for lightweight and flexibility. As a lightweight PEMFC, a tubular design is presented and structural advantages through numerical modeling are explained. Manufacturing methods to realize the structural advantages and possibilities of tubular PEMFCs are discussed. In addition, the materials and manufacturing processes used to fabricate lightweight and flexible PEMFCs are described and factors affecting performance are analyzed. Strategies and structural improvements of light and flexible movements are discussed according to the component parts.

• 한국자동차공학회논문집
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• 제15권3호
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• pp.41-46
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• 2007

Lightweight multi-layered boards with high stiffness for the automotive interior trims were developed, which were composed of a single material. The boards were constructed in the form of substrate/core/substrate with newly developed materials. The materials which have high tensile strength and elongation were selected for the substrate materials, and those which have high compressive strength and low density were selected for the core materials. 25 types of multi-layered boards were fabricated using the selected substrate and core materials. The compatibility with the skin materials, the formability and the tensile strength and flexural strength of the specimens were evaluated. The results show that three types of multi-layered boards(Kenboard/EPP foam/Kenboard, Twintex/PP honeycomb/Twintex, Curv sheet/EPP foam/Curv sheet) are appropriate for the automotive interior trims. Considering the ease of materials supply and the economical aspect, Kenboard/EPP foam/Kenboard is thought to be the most realistic alternative.

• International Journal of Concrete Structures and Materials
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• 제5권2호
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• pp.125-131
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• 2011

Five all-lightweight alkali-activated (AA) slag concrete mixes were tested according to the variation of water content to examine the significance and limitation on the development of cementless structural concrete using lightweight aggregates. The compressive strength development rate and shrinkage strain measured from the concrete specimens were compared with empirical models proposed by ACI 209 and EC 2 for portland cement normal weight concrete. Splitting tensile strength, and moduli of elasticity and rupture were recorded and compared with design equations specified in ACI 318-08 or EC 2, and a database compiled from the present study for ordinary portland cement (OPC) lightweight concrete, wherever possible. Test results showed that the slump loss of lightweight AA slag concrete decreased with the increase of water content. In addition, the compressive strength development and different mechanical properties of lightweight AA slag concrete were comparable with those of OPC lightweight concrete and conservative comparing with predictions obtained from code provisions. Therefore, it can be proposed that the lightweight AA slag concrete is practically applicable as an environmental-friendly structural concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.109-110
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• 2022

Recently, it tend to increase the high-rise and large-scale of buildings and the developtment of construction technology can to be applied reinforced concrete structures to high-rise buildings. However, when a high-rise buildings is constructed with reinforced concrete, it has a disadvantage that buildings weight increases. In order to resolve the weight of reinforced concrete structures, various types of lightweight aggregates become development and research. Although lightweight aggregates can be reduced the weight of concrete, the strength of ITZ(Interfacial Transition Zone) is lowered due to its less strength than natural aggregates. In this study, an experimental study was conducted to coat the surface of lightweight aggregates with GGBFS(ground granulated blast furnace slag) to improve the strength of cement matrix mixed with lightweight aggregates. Result of this experimental study shows that the compressive strnegth of the surface coating lightweight aggregates was higher than general lightweight aggregates. Also, it was considered that this is because the pore at the ITZ of the surface-coated lightweight aggregates mixed cement matrix are filled with GGBFS fine particle.

• 한국결정성장학회지
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• 제18권3호
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• pp.125-130
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• 2008

소형 전기로 및 이동장치가 있는 시뮬레이터를 사용하여 로타리킬른에서 생산되는 인공경량골재의 물성을 예측 할 수 있다면 대규모 로타리 킬른을 사용하여 인공경량골재 시제품 생산할 때 필요한 물자와 시간을 대폭 절감할 수 있다. 본 실험에서는 생산될 인공경량 골재의 물성을 정확히 예측할 수 있는 시뮬레이터를 제작하여 실제 로타리 킬른에서 생산된 골재의 물성과 비교함으로써 그 유용성을 검토하고자 하였다. 골재의 물성을 예측하기 위해서 8 mm 크기의 에코 인공경량 골재를 사용하였고 시뮬레이터의 분위기를 탄소를 이용해 조절하였다. 시뮬레이터와 로타리킬른에서 소성된 골재의 비중, 흡수율, 골재의 단면의 면적을 측정하고 비교하였다. 산화 분위기와 달리 환원분위기에서 소성된 시편은 탄소량이 증가할수록 비중이 증가하였으며 흡수율은 탄소 첨가량이 증가할수록 증가하는 경향을 보였다. 소성분위기는 환원 분위기 조성을 위해 탄소분말 0.7g을 첨가하였을 때 로라리 킬른과 가장 흡사한 분위기가 형성되는 것으로 판단되며, 두 골재의 물성 역시 비슷하였다.

• 한국기계가공학회지
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• 제21권1호
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• pp.102-110
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• 2022

This paper proposes a solution to the problems of manufacturing cost and processability by applying discrete material and thickness optimization (DMTO) and minimizing the use of high-strength, lightweight materials in the optimization process. A simple infant pop-up seat model was selected as the application target, and the weight reduction effect and variation in strength according to the optimization results were observed. In this study, a simplified finite element model of an infant pop-up seat frame was first constructed. The model was used to perform a static structural analysis to verify the weight and strength of each part. The D-optimal design of the experimental method was then used to observe the influence of each part on the weight and strength. This process was applied using discrete thickness optimization (DTO) (which applies high-strength, lightweight materials and optimizes only the thickness) and DMTO (which considers both the material and thickness). The DTO and DMTO results were compared to verify the design method that determines the major parts and simultaneously considers the material and thickness. Accordingly, in this study, an optimal lightweight design that satisfied the strength standards of the seat frame was derived. Furthermore, discretization parameters were used to minimize the application of high-strength, lightweight materials.