• 한국세라믹학회지
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• 제34권9호
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• pp.979-985
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• 1997

The three-dimensional particle packing process is simulated using Lahey FORTRAN 90 as a programming language running on a personal computer. Particle clusters constructed with rearrangement which occurs during packing have higher average coordination number and packing density than particle clusters rearranged after packing. Rearranging particles can not completely block other particles from entering pore volume in 3-dimensional packing unlike in 2-dimensional packing. It is found that there is a region of instability where lower packing density results from the destruction of the ordered packing.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.750-751
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• 2006

We investigated the mechanism how the high green density can be provided during die lubricated warm compaction (WD). We observed and analyzed the densification processes of iron powders including different contents of an inner lubricant, and measured the lateral pressure at the die wall during WD in comparison with conventional compaction and warm compaction. As a result, the high density in WD was due to not only the particles-deformation enhanced by warming powders but also the particles-rearrangement promoted by reducing an amount of the inner lubricant rather than the die lubrication.

• 한국세라믹학회지
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• 제29권12호
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• pp.956-962
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• 1992

The predominant sintering mechanisms of low firing temperature ceramic substrate which consists of borosilicate glass containing alumina as a filler are the rearrangement of alumina particles and the viscous flow of glass powders. In this system, sintering condition depends on the volume ratio of alumina to glass and on the particle size. When the substrate contains about 35 vol% alumina filler and the average alumina particle size is 4 $\mu\textrm{m}$, the best firing condition is obtained at the temperature range of 900∼1000$^{\circ}C$. The extensive rearrangement behavior occurs at these conditions, and the optimum sintering condition is attained by smaller size of glass particles, too. The formation of cristobalite during sintering causes the difference of thermal expansion coefficient between the substrate and Si chip. This phenomenon degradates the capacity of Si chip. Therefore, the crystallization should be prevented. In the alumina filled borosilicate glass system, the crystallization does not occur. This effect may have some relation with aluminum ions in alumina. For aluminum ions diffuse into glass matrix during sintering, functiong as network former.

• 한국세라믹학회지
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• 제32권5호
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• pp.527-534
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• 1995

In this research, the emphasis was focused on the rearrangement and densification behavior of CaO particles when the aluminum was added to improve the hydration resistance. For the case of 0.5vol% Al added specimen, the rearrangement of CaO particles due to liquid aluminum was terminated near 140$0^{\circ}C$ where the theoretically calculated fractional volume of solid reached 0.74 under Ar atmosphere. The density of the specimen sintered at 155$0^{\circ}C$ for 5hrs reached 96% of relative theoretical density when the ambient was switched to O2 at intermediate and final stages of the sintering. The weight gain due to the hydration after 60 days under 72% of relative humidity at 26$^{\circ}C$ was less than 1%.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2002년도 추계총회 및 연구발표회 초록집
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• pp.66.2-66
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• 2002

• 한국세라믹학회지
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• 제50권6호
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• pp.434-438
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• 2013

Monodispersed 3Y-$ZrO_2$ spherical agglomerates were synthesized by thermal hydrolysis process followed by crystallization processes (hydrothermal treatment and calcination). The crystallization process affected the properties of the final particles, such as the primary particle size, the agglomeration state, and the fraction of $ZrO_2$ monoclinic phase. The hydrothermal treated spherical particles were porous microstructures (weak agglomerates) composed of small primary particles with a size of 14 nm, but the calcined spherical particles had a dense microstructure due to the hard aggregation between primary particles. While the calcined particles had a low green density due to the hard aggregation, hydrothermal treated ones were soft agglomerates and had a deflection point at 50 MPa due to the rearrangement of secondary spherical particles and the filling of the interstices with the primary particles. Finally, the green density of hydrothermally treated $ZrO_2$ particles was 58% at 200 MPa.

• International Journal of Concrete Structures and Materials
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• 제9권4호
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• pp.453-462
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• 2015

A critical review on existing creep theories in calcium-silicate-hydrate (C-S-H) is presented with an emphasis on several fundamental questions (e.g. the roles of water, relative humidity, temperature, atomic ordering of C-S-H). A consensus on the rearrangement of nanostructures of C-S-H as a main consequence of creep, has almost been achieved. However, main disagreement still exists on two basic aspects regarding creep mechanisms: (1) at which site the creep occurs, like at interlayer, intergranular, or regions where C-S-H has a relatively higher solubility; (2) how the structural rearrangement evolutes, like in a manner of interlayer sliding, intra-transfer of water at various scales, recrystallization of gelled-like particles, or dissolution-diffusion-reprecipitation at inter-particle boundary. The further understanding of creep behavior of C-S-H relies heavily on the appropriate characterization of its nanostructure.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.68-69
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• 2006

When an alloy such as Ni-W is liquid phase sintered, heavy solid W particles sedimentate to the bottom of the container, provided that their volume fraction is less than a critical value. The sintering process evolves typically in two stages, diffusiondriven macrosegregation sedimentation followed by true sedimentation. During macrosegregation sedimentation, the overall solid volume fraction decreases concurrently with elimination of liquid concentration gradient. However, in the second stage of true sedimentation, the average solid volume fraction in the mushy zone increases with time. It is proposed that the true sedimentation results from particle rearrangement for higher packing efficiency.

• 한국지반공학회논문집
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• 제23권6호
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• pp.103-114
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• 2007

제주도 해안지역에 분포하고 있는 모래는 화산암류가 풍화되어 형성된 모래와 조개 등의 어패류가 풍화되어 탄산염 $(CaCO_3)$ 함유량이 많은 모래, 그리고 이들 두 가지 특징이 혼재한 모래로 분류할 수 있었다. 분류된 모래들 중 삼양, 김녕, 제주외항 지역의 모래에 압축 특성을 알고자 압축시험을 수행한 결과, 삼양인 경우 초기압축이 다른 모래에 비해 큰 것으로 나타났으며 김녕, 제주외항 모래인 경우 초기압축외의 추가적인 압축도 상당히 발생하였으며, 이는 압축시험 전·후의 모래의 입도분포 분석 결과 입자의 파쇄와 재배열에 의한 것으로 나타났다. 또한 현재 제주외항 항만시설 축조공사에 따른 지반의 침하특성을 분석한 결과 초기 압축 외에도 모래의 파쇄성과 재배열에 의해 상당시간동안 압축이 일어난 것을 알 수 있으며, 파쇄성과 재배열이 고려되지 않은 기존 탄성침하량 산정법을 이용한 침하량과 기존의 침하시간 산정 시 과소평가 될 우려가 있는 것으로 나타났다.

• 한국추진공학회지
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• 제21권4호
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• pp.96-106
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• 2017

압축형 복합화약에서는 압축 시 화약입자들의 재배열 및 변형으로 인하여 화약입자들의 압착화가 이루어지게 된다. 만약 깨지기 쉬운 화약입자들이 입자들의 최대 무질서밀집충진율보다 높아질 때까지 압축되면 큰 입자들은 깨짐으로써 빈 공간을 채울 수 밖에 없다. 본 연구에서는 다성분 입자계를 적용하여 압축 시 화약입자들의 손상을 막음으로써 둔감하면서도 고도로 충진된 압축형 복합화약을 얻고자 하였으며 실험결과, 2성분 입자계보다 3성분 입자계에서 더 고밀도이면서도 둔감한 ?감도를 갖는 압축형 복합화약을 얻을 수 있었다.