• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1C
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• pp.9-17
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• 2008

In this research, an analytical solution for the coefficient of permeability of soils during consolidation is suggested. The pore pressure and the flow rate measurements at different locations during consolidation are utilized. The void ratio and volume compressibility of soils under consolidation are also estimated. A large consolidation testing device, possible in both vertical and radial drainage is designed and manufactured. And consolidation test with kaolinite soils were performed under radially inward drainage direction. Pore pressures in varying radial distances and flow rate with time were measured as well as vertical deformations. From the test results, the changes of permeability, volume compressibility and void ratio under consolidation and their spatial variations are estimated. Thus the proposed solution is verified by comparing with the experimentally estimated test results. In addition, it is confirmed that permeability, void ratio and volume compressibility decrease as consolidation and loading steps progress. Also, these soil characteristics increase with radial distant from drainage boundary, where lowest values observed, and slightly decrease as approaching undrained boundary.

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.96-99
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• 1992

섬유강화 복합재료의 동탄성계수와 감쇠특성을 규명하기 위하여 랜덤하게 분포된 무한 실린더 형상의 산란체를 가진 매질내에서, 조화운동을 하는 압축 및 SV탄성파의 전파에 관하여 연구하였다. 단일 실린더에 대한 산란계수로부터 La의 준결정근사법을 이용하여 다중산란에 관한 이론을 유도하였고, 매질내에서의 파동전파 특성을 내포하는 분산관계식을 얻었다. 수치적으로 분산관계식의 해를 구함으로써 2 차원 유효체적강성, 횡방향 유효전단강성 및 각 파동의 전파에 따른 감쇠계수를 주파수와 체적비의 함수로서 제시하였다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.2
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• pp.61-69
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• 1999

When the repeated loading, such as vehicel etc, acts on soft ground, consolidation behaviors due to repeated loading wil show different from standard one. A series of tests was performed to investigate the characteristics of consolidation of lowly organic soil subjected to repeated loadings. Lowly organic soil with Lig. 23.5% was sampeld in Chonbuk Province and tested using a partially and a fully repeated loadings. From test results it was found that void ration, volume change, consolidation coefficient, permeability and secondary consolidation coefficient were greatly affected according to the repetition number and the load weight. The secondary consolidation coefficient was decreased with increase of the repetition number. The results obtained from this research can be used as basic for the improvement of soft ground.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.558-561
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• 2010

본 연구에서는 나노복합재의 탄소성 거동과 항복응력을 예측하기 위해 분자동역학 전산모사를 수행하였다. 나일론 기지와 실리카 나노입자가 포함된 단위 셀 구조로부터 나노입자의 체적분율 변화에 따른 응력-변형률 선도를 등변형률을 적용한 등온등압 앙상블 전산모사로부터 도출하였다. 4%의 변형률 범위에서 나노복합재의 탄성계수를 도출하였고, 이를 이용하여 2% 오프셋 방법으로 항복응력을 예측하였다. 나노입자의 유무에 따른 항복평면의 변화와 고분자 재료에서 나타나는 정수압 효과가 항복평면에 미치는 영향을 확인하기 위해 일축 인장/압축 그리고 이축 인장/압축을 수행하였고, 각각의 경우에 나타나는 나노복합재 내부의 자유체적 변화에 대한 분석을 통해 나노입자의 강화효과를 고찰하였다. 또한 고분자 기지로 인해 발생하는 정수압 효과를 반영한 von-Miss 항복평면을 도출하고, 입자의 체적분율 변화에 따른 항복응력의 예측이 가능하도록 정수압효과에 대한 파라메터를 체적분율의 함수로 근사하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1181-1187
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• 2009

과잉간극수압의 소산 속도는 일반적으로 압밀방정식에서 정의하는 압밀계수에 의해 결정 되는데, 이 압밀계수는 투수계수와 체적압축계수의 관계로 얻어지는 흙이 특성이며 동일한 성질의 지반에서라도 측정위치에 따라 그 값의 편차가 심한 특성을 보인다. 이에 본 연구에서는 위치적 이질성이 있는 점성토 지반의 압밀과정이 균질한 지반에서의 압밀과 어떤 차이를 보이고, 위치적 이질성으로 인한 불확실성이 압밀소요시간이나 압밀속도에 미치는 영향에 대해 유한차분법을 이용한 수치적인 방법으로 고찰하였다.

• Geotechnical Engineering
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• v.12 no.2
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• pp.9-18
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• 1996

The results of a series of triaxial compression tests on remolded normally consolidated clay are compared with the predictions .by the isotropic single -hardening constitutive model, which incorporates eleven parameters. The parameters can be determined from undrained triaxial compression tests on isotropically consolidated specimens of remolded clay. The model with the determined parameters is applied to predict the stress-strain and pore pressure behaviors for untrained triaxial compresion tests on anisotropically consolidated specimens. Also the model is utilized to predict the stress strain and voltmetric strain behavior for drained triaxial compression tests on both isotropic and anisotropic specimens. The predicted response agrees well with the measured behavior for undrained triaxial compression tests on not only isotropically but also anisotroically but also anisotropically consolidated specimens. The initial volumetric strain is, however, predicted to be less than the measured value from drained triaxial compression tests, while the predicted volumetric strain close to failure is greater than the measured value. Nevertheless, it may be stated generally that overall acceptable predictions are produced. Therefore, the results of this study indicate that the applicability of the model on prediction of the behavior of normally consolidated clay is achieved sufficiently.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.11
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• pp.841-848
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• 2008

DME(Di-methyl Ether) has been expected to be one of the promising alternative fuels for compression ignition engines due to its low emission characteristics for particulate matter. However, its physical properties such as density, bulk modulus and viscosity are not comparable to those of conventional diesel fuel. Especially, problems caused by low lubricity and high compressibility need to be understood more thoroughly, when a DME fuel is used for compression ignition engine, especially with mechanical fuel supply system. In this study, measurement and calculation of DME's bulk modulus were carried out over the range of temperatures from $-3^{\circ}C$ to $53^{\circ}C$, and pressures from 50 bar to 250 bar using an experimental apparatus built in this work. The results show that DME is prone to be compressed more easily compared to diesel fuel. A comparison of bulk modulus with butane and propane were also made in this work.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.17-23
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• 2004

Strength and deformation characteristics of oyster shell-sand mixtures were investigated to utilize waste oyster shell being treated as a waste material. Standard penetration test (SPT) is a common method to obtain in-situ strength in sand. However, in case of oyster shell-sand mixtures, there was no information between SPT N-value and internal friction angle of mixture soils. In this paper SPT experiments from several large scaled model chamber tests and large scaled direct shear tests were carried out with varying unit weight of oyster shell-sand mixtures. Appropriate correlations were in tile study observed among N-value, unit weight and internal friction angle, which make it possible to estimate in-situ strength from SPT and the coefficient of volume compressibility from the confined compression tests to compute the settlement of oyster shell-sand mixtures.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.115-121
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• 2010

To evaluate the engineering characteristics of aggregate base materials, cyclic triaxial, CBR and permeability tests were performed for 15 samples. The CBR values of aggregate base materials have wide range from 32 to 110(average 81) and the amount of swelling in submerged conditions has below 0.04mm. The Modulus of aggregate base materials were significantly affected by volumetric stress, linear volumetric model was best for fitting. The modulus of aggregate base materials were determined within range of 100MPa~600MPa, 80~270 and 0.1~0.6 for model coefficient $k_1$ and $k_2$ respectively. The empirical correlation model was suggested that prediction the modulus from the basic properties obtained from particle size distribution test and compaction test. The coefficient of determination of the proposed correlation model was 0.423 for model coefficient $k_1$, 0.920 for model coefficient $k_2$ and 0.872 for modulus with stress level.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.249-257
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• 2005

Garnet is one of the major minerals down to the top of lower mantle approximately 660 km with spinel and pyroxenes. Garnet transforms into perovskite and corundum in the lower mantle, however its sequence is still in controversy. We measured the compressibility of a natural almandine at high-pressure up to 62 CPa using Mao-Bell type diamond anvil cell (DAC) at room temperature. Chemical formula of the specimen is ($Fe_{2.52}Ca_{0.21}Mg_{0.18}Mn_{0.12})Al_{2.23}Si_{2.97}O_{12}$. Results of this compression study are as follows: a : $10.175\;{\AA}$, V : $1251.16\;{\AA}^{3}$, $D_{x}$ : $5.265\;g/cm^{3}$ at 62 GPa; bulk modulus is 156 GPa using Birch-Murnaghan equation of state (EoS) with a fixed $K_{0}\;'$ of 4. This study would be the first time attempt accomplished with the high pressure DAC using synchrotron radiation at the Pohang Light Source (PLS) in Korea.