• 한국지반공학회논문집
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• 제30권2호
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• pp.19-32
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• 2014

중동지역 Sabkha층 탄산질 모래는 패각류가 퇴적되어 생성되었으며, 내부간극을 포함한 다공질의 입자로 구성되어 있다. 일반적으로 흙은 항복하중에서 구조가 파괴되어 간극수압 및 침하량이 급격히 증가하게 된다. 그러나 석영질 모래와는 달리 탄산질 모래의 경우 항복하중에 따른 입자파쇄시 내부간극이 외부로 노출되어 간극수압이 감소 될 수 있다. 탄산질 모래에서 발생된 과잉간극 수압은 하중 재하시 상대밀도 증가로 인한 과잉간극수압과 입자파쇄에 따른 내부간극 노출로 인한 과잉간극수압, 파쇄입자의 재배열로 인한 과잉간극 수압의 합에 의해 결정되며, 내부간극의 노출량에 따라 음(-)의 값이 나타날 수 있다. 입자파쇄량이 크면 간극수압이 작게, 입자파쇄량이 작으면 간극수압이 크게 나타난다. 삼축압축시험 결과 음(-)의 간극수압이 나타난 구간은 외부간극 감소에 비해 입자파쇄가 우세한 영역이며, 현장 Sabkha층에서 확인된 입자파쇄 우세 영역의 크기는 1.50~3.46%의 값을 나타내었다.

• 한국터널지하공간학회 논문집
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• 제19권2호
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• pp.265-281
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• 2017

얕은 터널의 시공에 있어 지표 침하는 주요 관리 사항으로 쉴드 TBM 기술을 적용함으로써 굴착 중 지반 변형의 제어를 통하여 침하를 경감시키는 것이 가능하며, 특히 뒤채움 주입은 침하 경감의 목적으로 쉴드 공법에서는 일반적으로 적용되는 기술이다. 투수성이 낮은 지반에서의 TBM 시공에 의한 지표 침하는 터널 시공 중에 발생할 뿐만 아니라, 터널 관통 후에도 장기간에 걸쳐 발생한다. 장기 침하는 주로 터널 주변의 압밀에 의해 발생되고, 이 압밀 과정은 터널 주변에 과잉간극수압을 유발하는 뒤채움 주입에 의해 영향을 받게 되며 결과적으로 쉴드 TBM 터널에서는 뒤채움 주입이 장기 침하에 큰 영향을 주게 된다. 본 연구에서는 쉴드 TBM 공법 중 뒤채움 주입이 지표 침하에 미치는 영향을 파악하기 위해 3차원 응력-간극수압 연계해석을 수행하였다. 해석 결과 뒤채움 주입압의 증가는 단기 침하를 경감시키지만, 다수의 경우에서 장기 침하의 감소에 기여를 하지 않는 것으로 나타났다. 또한, 장기 침하를 최소한으로 제한할 수 있는 한계 주입압의 존재를 확인하였다.

• Journal of the Korean Wood Science and Technology
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• 제38권2호
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• pp.108-116
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• 2010

This paper explains the effects of wood drying on treatability (as determined by water uptake) of Japanese red pine (Pinus densiflora S. et Z.) at the sevenmoisture content (MC) levels above and below the fiber saturation point (FSP). According to the experimental results, it was found that water uptake (as the percentage of void volume filledwith distilled water, VVF%) was influenced by level of moisture content and percentage of void volume filled was improved effectively by kiln drying process. A significant relationship between moisture content and treatability was established. Permeability and liquid uptake were decreased above the FSP due to the effect of the less void space available in wood. Even though increased liquid uptake was observed at lower moisture content, no significant differences was observed moisture content below 20%. Therefore, this species need to be initially dried below FSP before treated with liquids. But drying moisture content below 10% might not be economical for the commercial purpose comparing drying the wood between 10 and 20% moisture content. The result of this study inferred that the treatability of pine wood can be improved by reducing the moisture content up to a certain level of 10~20% for allowing better performance.

• 대한기계학회논문집A
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• 제32권4호
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• pp.319-326
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• 2008

In this study, we investigate the deformation behavior of F.C.C. single crystals containing micro- or submicron-sized voids by using three dimensional finite element methods. The locally homogeneous constitutive model for the rate-dependent crystal plasticity is integrated based on the backward Euler method and implemented into a finite element program (ABAQUS) by means of user-defined subroutine (UMAT). The unit cell analysis has been investigated to study the effect of stress triaxiality and crystallographic orientations on the growth and coalescence of voids in F.C.C. single crystals.

• 한국건축시공학회지
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• 제5권1호
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• pp.105-109
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• 2005

Classified with concrete as placing ways - direct ways, sheath way - and placing directing flange direction, web direction - is analyzed section and strength of hardened concrete. The results of this study is belows the more fluid of concrete, the more useful to top-down method. To minimize the voids of the reverse placement joints, It is more effect to use the sheath method than direct method in concrete placement. If the joint face is a plane, it is impossible to extract the air bubbles which caused voids, so we should consider about this, and decide to select which type of joints.

• 한국인쇄학회지
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• 제18권1호
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• pp.1-11
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• 2000

The influence of the first coating layer on the properties of the second coating layer is reported. For various model coating composition, ratios of first and second coating weights are used to generate coating layers. The void volume, pore size distribution and light scatter coefficient of the coatings are measured. In some cases, the fine material from the second layer seems to penetrate the first layer to reduce the void fraction of the total system. Rapid setting coating, for example thin layers on porous first layer tends to generate porous coating layers.

• 한국표면공학회지
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• 제42권5호
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• pp.232-239
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• 2009

This study presented the effect of membrane thickness on hydrogen permeability. Microvoids on the surface of the membrane should not exist for the exact values of hydrogen permeability. Pd-Cu-Ni hydrogen alloy membranes were fabricated by Ni powder sintering, substrate plasma pretreatment, sputtering and Cu reflow process. And this leaded to void-free surface and dense film of Pd-Cu-Ni hydrogen alloy membrane. Hydrogen permeation test showed that hydrogen permeability increased from 2.7 to $15.2ml/cm^2{\cdot}min{\cdot}atm^{0.5}$ as membrane thickness decreased from 12 to $4{\mu}m$. This represented the similar trend as a hydrogen permeability of pure palladium membrane based on solution-diffusion mechanism.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.775-780
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• 2002

Sandwich panel made by foamed styrene and ployuretane has been used generally in the construction area because of the high thermal conductivity and light weight but they occur harmful gases to both bodies and environments in the high temperature over $50^{\circ}C$. So, the purpose of this study is to investigate the physical properties of light-weight panel using the non-structural lightweight aggregate as a part of the substitution of foamed styrene and ployuretane. This paper dealt with the effect of the addition of polymer dispersion such as SBR, St/BA-1 and St/BA-2 having polymer-cement ratio as 5, 10, 15% and the filling ratio of continuous void as 50, 60% on the strength of polymer-modified sandwich panel core. From the results, we could know that the compressive and flexural strength of the sandwich panel core using non-structural lightweight aggregate and polymer dispersion such as SBR, St/BA-1 and St/BA-2 tended to be increased with an increase in the polymer-cement ratio and the filling ratio of continuous void.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.255-258
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• 1999

In recent years, the study on the porous concrete which has excellent permeability is actively advanced in the field of architectural and civil engineering. But porous concrete has a reciprocal concept in the aspect of comparative large and continuos void structure and reduction of void for insurance of the necessary strength on the mixing proportion, must have satisfied of the properties of these. Therefore this study is series of experiment for the strength elevation and evaluated the effect according to fine replacement ratio and levels of cement content. As a result, the strength of porous concrete was elevated by an increase of fine replacement ratio and cement content.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.783-788
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• 2001

Voids created with concrete construction or deterioration result in serious weakness from the aspects of both structural and durable function. Ultrasonic method using image processing technique was used for detecting pattern of voids in concrete in this study Experimental investigation was carried out for three types(patterns) of void in concrete. The effect of curing period of concrete and ultrasonic measurement method was also investigated. As a result it has been verified that the semi-direct measurement method is more effective than the other methods for detecting pattern of voids in concrete in ultrasonic method using image processing technique. The longer the curing period of concrete is, the better the detection accuracy of void pattern can be obtained.