• Geomechanics and Engineering
• /
• v.37 no.1
• /
• pp.9-19
• /
• 2024

This study presents an energy analysis for large-strain cavity expansion problem based on the general strength criterion and energy theory. This study focuses on the energy dissipation problem during the cavity expansion process, dividing the soil mass around the cavity into an elastic region and a plastic region. Assuming compliance with the small deformation theory in the elastic region and the large deformation theory in the plastic region, combined with the general strength criterion of soil mass and energy theory, the energy dissipation solution for cavity expansion problem is derived. Firstly, from an energy perspective, the process of cavity expansion in soil mass is described as an energy conversion process. The energy dissipation mechanism is introduced into the traditional analysis of cavity expansion, and a general analytical solution for cavity expansion related to energy is derived. Subsequently, based on this general analytical solution of cavity expansion, the influence of different strength criterion, large-strain, expansion radius, cavity shape and characteristics of soil mass on the stress distribution, displacement field and energy evolution around the cavity is studied. Finally, the effectiveness and reliability of theoretical solution is verified by comparing the results of typical pressure-expansion curves with existing literature algorithms. The results indicate that different strength criterion have a relatively small impact on the displacement and strain field around the cavity, but a significant impact on the stress distribution and energy evolution around the cavity.

• Bulletin of the Korean Chemical Society
• /
• v.10 no.3
• /
• pp.309-314
• /
• 1989

The interaction energies of Xenon in n-alkanes were estimated by using three models for the cavity formation process, Hildebrand's regular solution theory, Pierotti's scaled particle theory and Sinanoglu-Reiss-Moura-Ramos' solvophobic theory in an attempt to examine the validity of three models. It appears that Pierotti's implementation of scaled particle theory yields a reasonable estimate of cavity formation energy over a considerable range in solvent size provided that the solute is spherical enough as are the inert gases.

• Solar Energy
• /
• v.17 no.1
• /
• pp.35-46
• /
• 1997

In this study comparison of experiment results with the computed results of linear theory and nonlinear theory using singularity method was obtainable. Specially singularity points like sources and vortexes on hydrofoil and freestreamline were distributed to analyze two dimensional flow field of supercavitating cascade using nonlinear theory, and governing equations of flow field were derived and hydraulic characteristics of cascade were calculated by numerical analysis of the governing equations. The results compared linear theory and nonlinear theory with the experiment results of the study are as follows: The tolerances of nonlinear theory were larger than those of linear theory in case of ${\alpha}<10^{\circ}$. Moreover the computational range of attack angles could be expanded from ${\alpha}=10^{\circ}$ to ${\alpha}=25^{\circ}$, the flow field of supercavitating cascade could be analyzed in the condition which the wake thickness and the length of cavity are a variable. The shapes of cavity were changed sensitively according to various variable such as attack angles, pitches and wake thickness, and the pressure distribution of hydrofoil surface was identical almost disregarding wake thickness but changed largely according to attack angle and the length of cavity. Lift coefficient and drag coefficient were reduced according to increasing of wake thickness but the influences of wake thickness were very little in the situation of small pitch and long cavity.

• International Journal of Internet, Broadcasting and Communication
• /
• v.4 no.2
• /
• pp.22-27
• /
• 2012

The design characteristics of circular vertical-cavity surface-emitting lasers are studied by using a newly developed equivalent network. Optical parameters, such as the stop-band or the reflectivity of periodic mirrors and the resonance wavelength, are explored for the design of these structures. To evaluate the differential quantum efficiency and the threshold current density, a transverse resonance condition of modal transmission-line theory is also utilized. This approach dramatically reduces the computational time as well as gives an explicit insight to explore the optical characteristics of circular vertical-cavity surface-emitting lasers (VCSELs).

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.9 s.180
• /
• pp.2302-2312
• /
• 2000

An active control of the transmission of noise through an aircraft fuselage is investigated numerically. A cylinder-cavity system was used as a model for this study. The fuselage is modeled as a fi nite, thin shel cylinder with constant thickness. The sound field generated by an exterior monopole source is transmitted into the cavity through the cylinder. Point force actuators on the cylinder are driven by error sensor that is placed in 3D cavity. Modal coupling theory is used to formulate the numerical models and describe the system behavior. Minimization of the acoustic potential energy in the fuselage is carried out as a performance index. Continuous parameter genetic algorithm is used to search the optimal actuator position and both results are compared.

• Korean Journal of Acupuncture
• /
• v.32 no.3
• /
• pp.124-129
• /
• 2015

Objectives : The purpose of this study is to understand truncus area conception to be explained in the pyobon and geungyul (Root-Stem and Origin-End relationships; PG) of meridian theory as to do the macro organic spatial conception in bio-mechanic system for human body. Methods : The extremity areas and truncus area to be explained in PG theories were classified spatially, and the reason was discussed that human body was classified as the extremities and truncus areas for the people of old times. It was considered the structural characteristics, exercise species and movement characteristics of truncus area in human body also. Results : The truncus area were made of cranium, vertebrae, sternum, ribs, clavicle, scapula, sacrum and the hipbone. It was the hollow structure and classified as cranial cavity, pleural cavity(thoracic cavity) and pelvic cavity. These cavities had mutually organic relationships, and because of cavity structures in the truncus and full structures in extremities would act in different direction about gravity with each other for movements. So it would be estimated that the old peoples had to need to separate the truncus and the extremities. Conclusions : In this study, the truncus area and the extremity areas in the PG of meridian theory could be recognized as the spatial conception of bio-mechanic system in human body. Although this study was the theoretical study not to be proven, it will be used to understand for the meridian theory as basic reference for spatial conception and bio-mechanic system.

• Journal of electromagnetic engineering and science
• /
• v.2 no.2
• /
• pp.100-104
• /
• 2002

A proper equivalent circuit model for coupling iris has been derived in order to compensate the length of cavity in a $TE_{011}$TEX> mode cylindrical cavity filter. A method to resolve the difference in bandwidth and feature or ripple systematically has been proposed. This method can be applied to other types of waveguide cavity filter.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.231-238
• /
• 2000

Sand piling method is one of the most widely used methods to improve soft soils. There are several methods to install sand piles, but driven pile method is considered as one of the easiest method. This method simply pushes down the sand piles into soft soils, so that the excess pore pressure would be generated if the soil is saturated. This pore pressure acts as consolidation load. If the amount of sand pile induced pore pressure can be predicted in reasonable ways, the effects of sand piling to improve soft soils would be predicted, and the height of preload can be reduced. In this article, sand pile induced excess pressure was predicted by cavity expansion theory, and the predicted values were compared with the field measured values. The results showed fair agreements between the measured and the predicted excess pore pressure.

• Geotechnical Engineering
• /
• v.5 no.1
• /
• pp.35-46
• /
• 1989

To analyse the end bearing capacity of a single pile in cohesionless soils, the mode of deformation due to a pile penetration has been intestigated through model pile penetration tests using acetone hardening and resin impregnation technique. A new mode of deformation has been assumed from the experimental results and a new solution compeying with the theory of spherical cal.its expansion has been proposed. The end bearing capacity according to the proposed solution is expressed as the product of the limit spherical cavity expansion pressure multiplied by a col.relation factor. The results has been compared with other solutions based on the theory of cavity expansion. From the comparison, the proposed solution is expected to provide a way to solve the problem of pile bearing capacity prediction based on the theory of cavity expansion which often has been criticized as giving higher value of pile bearing capacity than the actual value.

• Journal of the Society of Naval Architects of Korea
• /
• v.28 no.2
• /
• pp.159-173
• /
• 1991

This paper describes a potential-based panel method formulated for the analysis of a super-cavitating two-dimensional hydrofoil. The method employs normal dipoles and sources distributed on the foil and cavity surfaces to represent the potential flow around the cavitating hydrofoil. The kinematic boundary condition on the wetted portion of the foil surface is satisfied by requiring that the total potential vanish in the fictitious inner flow region of the foil, and the dynamic boundary condition on the cavity surface is satisfied by requiring thats the potential vary linearly, i.e., the tangential velocity be constant. Green's theorem then results in a potential-based integral equation rather than the usual velocity-based formulation of Hess & Smith type. With the singularities distributed on the exact hydrofoil surface, the pressure distributions are predicted with improved accuracy compared to those of the linearized lilting surface theory, especially near the leading edge. The theory then predicts the cavity shape and cavitation number for an assumed cavity length. To improve the accuracy, the sources and dipoles on the cavity surface are moved to the newly computed cavity surface, where the boundary conditions are satisfied again. This iteration process is repeated until the results are converged. Characteristics of iteration and discretization of the present numerical method are much faster and more stable than the existing nonlinear theories. The theory shows good correlations with the existing theories and experimental results for the super-cavitating flow. In the region of small angles of attack, the present prediction shows and excellent comparison with the Geurst's linear theory. For the long cavity, the method recovers the trends of the Wu's nonlinear theory. In the intermediate regions of the short super-cavitation, the method compares very well with the experimental results of Parkin and also those of Silberman.