• 대한토목학회논문집
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• 제26권6C호
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• pp.369-376
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• 2006

1차원 압밀시험에서 구해진 결과는 상사법칙을 적용하여 원지반의 침하량과 압밀시간을 추정하고 있다. 하지만 점토의 변형의존성, 층두께, 재하시간, 하중증분비 등에 의해 변화하기 때문에 상사법칙의 성립은 명확하게 밝혀지지 않고 있다. 본 연구는 재하시간과 층두께를 달리하여 압밀시험과 투수시험을 병행하여 상사법칙의 적용성을 나타내었다. 그 결과, f(=1+e)-logk관계는 점토의 특성을 잘 나타내고 있으며, $c_{\nu}$와 k는 보정이 필요없는 것으로 나타났으며, 상사법칙은 f-logp관계의 위치와 1차 압밀선에 의존하고 있다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.1148-1154
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• 2006

Composite discharge capacity tests and smear effect tests are carried out to estimate the parameters for the reliability-based design of vertical drain method. Also the probabilistic and deterministic solutions of radial consolidation theory are presented. It compared to the result of reliability-based design and that of deterministic design using the tested and estimated parameters. The results indicated that the drain spacing is larger the deterministic method than the probabilistic method because the former is not considered the uncertainties in the properties of soil. The divergence of methods is dependent on the probability of achieving target degree of consolidation by a given time and the coefficient of variation(COV) of the coefficient of horizontal consolidation$(c_h)$.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.454-456
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• 2009

N-Type $SbI_3$ doped $95%Bi_2Te_3+5%\;Bi_2Se_3$ compounds were newly fabricated by the combination of gas atomization process and Magnetic Pulsed Compaction process. The thermoelectric properties of the MPCed bulks according to consolidation temperatures were investigated by a combination of microscopy, XRD and thermoelectric property testing. The microstructure of MPCed bulk shows homogeneous and fine distribution through consolidated bulks due to the high solidification of compound powders. The research presented the challenges toward the successful consolidation of thermoelectric powder using magnetic pulsed compaction (MPC) and analysis of thermoelectric properties of the consolidated bulks.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.525-527
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• 2008

N-Type $SbI_3$-doped $95%{Bi_2}{Te_3}-5%{Bi_2}{Se_3}$ compounds were prepared by a gas atomization and Magnetic Pulsed Compaction process. The dynamic recrystallization and thermoelectric properties of the MPCed bulks with consolidation temperatures and times were investigated by a combination of microscopy, XRD and thermoelectric property testing. The microstructure of MPCed bulk shows homogeneous and fine distribution through consolidated bulks due to dynamic recrystallization during hot MPC. This research presented the challenges toward the successful consolidation of thermoelectric powder using magnetic pulsed compaction (MPC).

• 한국지반공학회논문집
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• 제24권7호
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• pp.75-80
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• 2008

지중에서 채취한 불교란 포화점토시료는 응력해방으로 인해 연직방향으로 늘어나고 수평방향으로 수축한다. 현행 압밀시험법은 이와 같이 변형된 점토시료를 그대로 압밀링과 같은 크기로 성형하여 압밀시험을 수행하기 때문에 원지반의 거동을 명확히 나타내고 있다고 할 수 없다. 채취시료의 연직 신장변형량은 보링공에서 채취한 점토시료와 완전 되비빔한 슬러리로부터 재구성한 점토시료를 이용하여 측정한 결과, $1{\sim}2%$의 범위로 나타났다. 원위치의 압밀특성을 모사하는 시험방법은 표준압밀시험용 공시체보다 직경이 작고, 높이가 높은 공시체를 사용하여 원지반의 유효상 재압이 재하되었을 때 눌려 퍼져 압밀링의 내벽에 밀착하는 방법을 제안하였다.

• 한국지반공학회논문집
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• 제26권8호
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• pp.49-58
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• 2010

본 연구에서는 점성토지반에서의 이차압밀특성을 규명하기 위해 정규압밀 영역에 대해 표준압밀시험을 수행하고, Yoshikuni가 제안한 탄-점성 압밀이론의 유한차분해석결과를 이용하여 점성토지반의 압밀특성을 조사하였다. 압밀시험은 초기압밀하중 0.8, 1.6, 3.2, 6.4kgf/$cm^2$의 4케이스에 대해 압밀하중 증분비(${\Delta}p/p_0$)를 1.0으로 하여 수행하였다. 또한 압밀하중증분비의 영향을 명확히 하기 위해 압밀하중 증분비를 변화시킨 장기압밀시험을 수행하였다. 얻어진 실내실험결과에 대해 탄-점성 압밀이론을 이용한 수치해석을 실시한 결과, 수치해석결과가 1차압밀과정에서 약간지연(또는 조기진행)되는 결과가 얻어졌지만, 이차압밀과정에 대해서는 잘 일치한 것으로부터 그 적용성을 검증하였다. 또한 일반적인 점성토지반의 모델지반을 작성하고 압밀특성에 영향을 미치는 압밀정수에 대해 수치모델링을 수행하고 그 영향에 대해서 분석하였다.

• 한국지반공학회지:지반
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• 제13권3호
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• pp.5-20
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• 1997

본 연구에서는 유한변형률 이론에 근거하여 3차원 압밀 지배 방정식을 유도하였다. 이 방정식은 비교적 압밀층의 두께가 두꺼운 경우, 비선형 물성치, 공극비에 따른 비선형 투수계수를 갖는 지반에 적합하다. 기존의 유한차분 수치해석 기법(FTCS)은 지배 방정식이 비선형 이며 복잡한 경우 안정된 해를 얻을 수 없기 때문에 본 연구에서는 특수 유한 차분 기법을 도입하였다. 이 수치해석 기법을 지배 방정식에 적용하면 시간에 따른 압밀량을 예측할 수 있다. 본 해석기법에 의해 구해진 값들을 윅드레인을 설치한 여러 가지 고압축성 토질에서의 실험 결과와 비교한 결과, 최종 압밀량과 시간에 따른 압말량이 잘 일치하고 있다.

• 한국분말재료학회지
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• 제7권4호
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• pp.237-243
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• 2000

The property and performance of the $Al_2O_3/Ni$ nanocomposites have been known to strongly depend on the structural feature of Ni nanodispersoids which affects considerably the structure of matrix. Such nanodispersoids undergo structural evolution in the process of consolidation. Thus, it is very important to understand the microstructural development of Ni nanodispersoids depending on the structure change of the matrix by consolidation. The present investigation has focused on the growth mechanism of Ni nanodispersoids in the initial stage of sintering. $Al_2O_3/Ni$ powder mixtures were prepared by wet ball milling and hydrogen reduction of $Al_2O_3$ and Ni oxide powders. Microstructural development and the growth mechanism of Ni dispersion during isothermal sintering were investigated depending on the porosity and structure of powder compacts. The growth mechanism of Ni was discussed based upon the reported kinetic mechanisms. It is found that the growth mechanism is closely related to the structural change of the compacts that affect material transport for coarsening. The result revealed that with decreasing porosity by consolidation the growth mechanism of Ni nanoparticles is changed from the migration-coalescence process to the interparticle transport mechanism.

• 한국분말재료학회지
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• 제15권1호
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• pp.31-36
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• 2008

In this study, the bottom-up powder metallurgy and the top-down severe plastic deformation (SPD) techniques for manufacturing bulk nanomaterials were combined in order to achieve both full density and grain refinement without grain growth of rapidly solidified Al-20 wt% Si alloy powders during consolidation processing. Continuous equal channel multi-angular processing (C-ECMAP) was proposed to improve low productivity of conventional ECAP, one of the most promising method in SPD. As a powder consolidation method, C-ECMAP was employed. A wide range of experimental studies were carried out for characterizing mechanical properties and microstructures of the ECMAP processed materials. It was found that effective properties of high strength and full density maintaining nanoscale microstructure are achieved. The proposed SPD processing of powder materials can be a good method to achieve fully density and nanostructured materials.

• Geomechanics and Engineering
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• 제1권3호
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• pp.241-257
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• 2009

The one-dimensional compressibility of sand is an important property for the estimation of settlement or deformation of sand deposits. The $K_0$ value of sand is also an important design parameter. Experimental results are presented in this paper to study the compressibility of sand in $K_0$ consolidation tests. The $K_0$ consolidation tests were carried out using a triaxial cell and a plane-strain apparatus. Specimens prepared using both the moist tamping and the water sedimentation methods were tested. The testing data demonstrate that the type of testing apparatus does not affect the $K_0$ measurement if proper boundary conditions are imposed in the tests. The data also show that the compressibility and the $K_0$ value of loose sand specimens prepared using the moist tamping method are very sensitive to the variation of void ratio. The $K_0$ values measured from these tests do not agree with the $K_0$ values calculated from Jaky's equation. The compressibility and $K_0$ values of sand obtained from tests on specimens prepared using different preparation methods are different which may reflect the influence of soil fabrics or structures on the one dimensional compression behavior of sand.