• Geotechnical Engineering
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• v.12 no.6
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• pp.101-114
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• 1996

Even though the Coulomb's earth pressure theory has been mainly used in practice, the general equation does not exist yet, which is applicable to retaining wall backfilled by cohesive soils. Here, for gravity walls backfilled by cohesive soils, some equations have been derived by newly using the Coulomb's theory, for the cases oi drained and untrained analyses. and for the cases of neglecting and considering the tension crack, respectively. Both the active earth thrust and the depth of tension crack under different conditions were tabulated.

• Geotechnical Engineering
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• v.13 no.4
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• pp.135-148
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• 1997

Coulomb's theory has been usually used in practice to obtain lateral earth pressure against retaining wall. Such theory is based in the assumption that the lateral pressure is a tai angular distribution, since the point of applying the lateral thrust cannot be obtained by using it. However, the results of laboratory and field tests showed that the lateral pressure was not a triangular but a nonlinear distribution. To overcome the drawback of the Coulomb's theory, the different theoretical approaches(Handy, 1985. Kingsley, 1989 : Kellogg, 1993, Chung et at,1993, 1996a) were performed for gravity wall backfilled by cohesionless soil. On the other hand, for retaining wall backfilled by ,cohesive soil, theoretical analyses were carried out only on the basis of the Rankine's or Coulomb's concepts, but the equations showed different results. Here was newly derived the equations of lateral pressures under undrained condition against gravity wall backfilled by cohesive soil. They were based on the Coulomb's wedge, adopted the arching concept. Some of the equations were derived by neglecting tension crack, while the others by considering it. Comparative results for applying different examples showed that the equation considering tension crack might be reasonable.

• Journal of Korea Game Society
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• v.15 no.5
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• pp.143-152
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• 2015

Unlike simulating general 'particle-based fluid explosion', simulating fluid with elasticity requires various experimental methods in order to show the realistic deformation of the matter. The existing studies on particle-based viscoelastic fluid only focused on matters' plastic deformation which can be found in mud or paint, based on the maximum distortion energy theory and maximum shear stress theory. However, these former researches could not simulate the brittle deformation which can be seen from silicon or highly elastic rubber when great external forces above limits are applied. This study suggests a brittle simulation method based on the Coulomb-Mohr theory, the idea that a yield occurs when maximum stress on a matter reaches to its rupture stress. This theory has a significant difference from the existing particle-based simulations which measures the forces on a matter by length or volume. Using a strong-elastic semifluid which Coulomb-Mohr theory is applied, realistic deformation process of a matter was observed as its forced surface reached to the rupture stress. When semifluid hit the ground, the impact of deformation can be explained by using Coulomb-Mohr theory.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.512-517
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• 1994

The control system of a precise positioning mechanism with resonance and Coulomb friction has been designed using H$_{\infty}$ control theory, and the control performance has been verified by computer simulation and experimental analysis. The DGKF type H$_{\infty}$ control theory with scalar weighting factors was utilized for designing the control system. The followings have been confirmed from the present study: (1) The system with H$_{\infty}$ control presents better convergence and stability than the system with conventional control (PI-notch filter control). (2) The H$_{\infty}$ control system have good robustness properties for a wide range of operating conditions in the presence of external disturbances such as Coulomb friction and changing mechanical resonant frequency.ncy.

• Geotechnical Engineering
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• v.4 no.1
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• pp.7-16
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• 1988

The safety factor has been used widely and uniquely at present to check the safety of the structure . However, probability of failure would be logically attempted to check the reliability of the structure in future Coulomb's theory or Rankine's theory has been applied in practice to retaining earth structure in spite of the fact that the lateral earth pressure, which is the primary factor in the determination of wall structure, depends on the modes of wall movement . This study is concentrated on the two modes of , wall movement (active case rotation about bottom(AB) , active case rotation about top(AT)) of the overturning'failure of vertical wall with horizontal sand backfill . The static active earth pressure is determined by applying each of Coulomb's theory, Dubrova's redistribution theory and Chang's method The earthquake active earth pressure is determined by adding Seed and Whitman's earthquake pressure to the static earth pressure , On the condition that design variables are fixed with each of the above earth pressure, reliability is analyzed using the recently developed method of AFOSM (Advanced First Order Second Moment)

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1691-1697
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• 2018

Employing the density functional theory, we have investigated the roles of Coulomb and Hund's interactions in the electronic and magnetic properties of newly discovered ${\alpha}-RuCl_3$ having the $R{\overline{3}}$ symmetry, which is in close proximity of the Kitaev system. We show that both the size and the direction of local magnetic moment are highly dependent on Coulomb and Hund's interactions, and the spin and orbital parts show different behaviors. The validity of the so-called $j^{eff}$ picture is accessed upon interaction parameters, and the explicit roles of Hund's interaction in the local electronic structures and magnetic properties are discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.947-954
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• 2014

In general, Fracture of the material is not occurring of the maximum normal stress or the maximum shear stress failure in the state. Maximum normal stress and maximum shear stress in the state of Critical coupling from being destroyed based on the Mohr-Coulomb theory. Couple of different mixtures, including permeable asphalt pavement, SMA and dense-graded asphalt mixture, were used for compression triaxial test at $45^{\circ}C$ and $60^{\circ}C$. Mohr-Coulomb theory to the analysis of compression triaxial test result of the internal friction angle $38.9^{\circ}{\sim}46.9^{\circ}$ measured somewhat irregularly, but in the case of cohesion, depending on whether the temperature and immersion of the specimen appeared differently. In addition, Indirect tensile test and compression triaxial test of the asphalt mixture to determine the correlation between compression triaxial test results assessed as cohesion and internal friction angle calculated using the theoretical Indirect tensile strength and measured indirectly tensile strength were analyzed. The Measured & Predicted IDT St values tended to be proportional.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.127-136
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• 2004

The soil arching in the backfill, which affects the magnitude and distribution of active earth pressure on a retaining wall, has also an effect on the stability and cross-sectional area of the retaining wall. In this study, results obtained from Paik's equation that includes arching effect on active earth pressure are compared with those from Coulomb theory to investigate the influence of the soil arching on active earth pressure, overturning moment, stability and cross-sectional area of translating rigid retaining walls. The comparisons show that the active forces including arching effects are always higher than those from Coulomb theory, irrespective of $\phi$ and $\delta$ values. The overturning moments, shear force and moment on the rigid wall are also higher when considering arching effects than when not considering arching effects. The deviation of shear forces and moments by including and excluding arching effects becomes maximum at the height of 0.02-0.08 times wall height from the base of the wall. Therefore, if a translating rigid retaining walls is designed based on Coulomb theory, the wall may reach sliding and overturning failures due to arching effect in the backfill and the cross-sectional area of the wall, especially at lower part of the wall, may not be sufficient to resist to shear force and moment.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.308-315
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• 1991

The structure and thermodynamic properties of body centered cubic structure of simple Coulombic liquids are computed from the perturbation theory for one-component plasma. A comparison of perturbation theory (PT) and Monte Carlo (MC) simulation shows excellent agreement. The hardsphere perturbation theory is applicable to a long-range attractive system, such as the one-component plasma. A comparison of the radial distribution function (g(r)) and the structure factor (S(q)) for PT data and MC data shows agreement. Thus the perturbation theory is an applicable method to explain the structure and thermodynamic properties of Coulomb liquids.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.781-784
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• 2002

Adhesion phenomenon is more significant for smaller objects, because adhesional force is proportional to size of the objects while gravitational force is proportional to the third power of it. For the purpose of microassembly, theoretical understanding is required for the Adhesion phenomenon. Authors have developed a force measurement system in an ultra-high vacuum chamber of Auger electron spectroscopy. The force between arbitrary combination of materials can be measured at a pressure less than 100 nPa after and before Ar ion sputtering and chemical analysis for several atomic layers of the surface. The results are successfully interpreted with a theory of contact mechanics. Since surface energy is quite important in the interpretation, electronic theory is used to evaluate the surface energy. In the manipulation of small objects, the adhesional force is always attractive. Repulsive force is essential for the manipulation. It can be generated by Coulomb interaction. The voltage required for detachment is theoretically analyzed and the effect of boundary conditions on the detachment is obtained. The possibility and limitations of micro-manipulation using both the adhesion phenomenon and Coulomb interaction are theoretically clarified. Its applicability to nano-technology is found to be expected.