• 한국터널지하공간학회 논문집
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• 제18권2호
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• pp.129-142
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• 2016

지표침하를 발생시키는 다양한 원인 중에 하나로 알려진 지하에서 발생되는 공동은 지반의 불연속적 특징이다. 그러므로 기존의 연속체해석으로 분석하기에는 한계가 있을 것으로 판단된다. 본 연구에서는 지표침하를 발생시키는 구형지하공동에 대해서 개별요소법을 활용하여 분석하였다. 지표침하에 영향을 미치는 구형지하공동의 특성인자로서 지반의 물성치, 구형지하공동의 심도 및 크기를 선택하였고, 각 특성인자들의 값의 변화가 지표침하에 미치는 영향에 대해 분석하였다. 또한 지하공동의 직경에 대한 상대적 깊이와 지표침하의 관계를 분석하였고, 이를 통해 지하공동의 붕괴 예측 및 보강유무를 결정하기 위한 근간을 제시하였다.

• Geomechanics and Engineering
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• 제25권4호
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• pp.283-294
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• 2021

This paper presents a rigorous solution for spherical cavity expansion in unsaturated soils under constant suction condition. The hydraulic behavior that describes the saturation-suction relationship is modeled by a void ratio-dependent soil-water characteristic curve, which allows the hydraulic behavior to fully couple with the mechanical behavior that is described by an extended critical state soil model for unsaturated soil through the specific volume. Considering the boundary condition and introducing an auxiliary coordinate, the problem is formulated to a system of first-order differential equations with three principal stress components and suction as basic unknowns, which is solved as an initial value problem. Parameter analyses are conducted to investigate the effects of suction and the overconsolidation ratio on the overall expansion responses, including the pressure-expansion response, the distribution of the stress components around the cavity, and the stress path of the soil during cavity expansion. The results reveal that the expansion pressures and the distribution of the stress components in unsaturated soils are generally higher than those in saturated soils due to the existence of suction.

• Structural Engineering and Mechanics
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• 제78권3호
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• pp.297-303
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• 2021

In this paper, a mathematical model is used to the evaluation of thermoelastic interactions in fiber-reinforced material with a spherical cavity. With the goal of establishing the generalized thermoelastic model with thermal relaxation time are exploited. inner surface of the spherical cavity is tractions free and loaded by the uniform step in temperature. The finite element scheme is used to get the problem numerical solutions. The numerical results have been discussed graphically to show the impacts of the presence and the absence of reinforcement.

• Geomechanics and Engineering
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• 제29권1호
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• pp.1-11
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• 2022

A semi-analytical solution to responses of overconsolidated (OC) unsaturated soils surrounding an expanding spherical cavity under constant suction condition is presented. To capture the elastoplastic hydro-mechanical property of OC unsaturated soils, the unified hardening (UH) model for OC unsaturated soil is adopted in corporation with a soil-water characteristic curve (SWCC) and two suction yield surfaces. Taking the specific volume, radial stress, tangential stress and degree of saturation as the four basic unknowns, the problem investigated is formulated by solving a set of first-order ordinary differential equations with the help of an auxiliary variable and an iterative algorithm. The present solution is validated by comparing with available solution based on the modified Cam Clay (MCC) model. Parametric studies reveal that the hydraulic and mechanical responses of spherical cavity expanding in unsaturated soils are not only coupled, but also affected by suction and overconsolidation ratio (OCR) significantly. More importantly, whether hydraulic yield will occur or not depends only on the initial relationship between suction yield stress and suction. The presented solution can be used for calibration of some insitu tests in OC unsaturated soil.

• 전자공학회논문지A
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• 제32A권2호
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• pp.19-30
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• 1995

Diffraction patterns of the copolarized and the crosspolarized total electric fields by a spherical air cavity in a dielectric medium are analyzed in the forward near-field region when the wavelength of the incident plane wave is comparable to one half of the cavity radius. It is shown that double nulls and dips of the copolarized and the crosspolarized total electric fields exist in the measurement plane tansverse to the propagating direction of the incident field, and their dependences on the frequency, the distance of the measurement plane, and the measurement angle are analyzed.

• Coupled systems mechanics
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• 제9권4호
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• pp.325-342
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• 2020

A mathematical model of electro-thermoelasticity subjected to memory-dependent derivative (MDD) heat conduction law is applied to a one-dimensional problem of a thermoelectric spherical cavity exposed to a warm stun that is an element of time in the presence of a uniform magnetic field. Utilizing Laplace transform as an instrument, the issue has been fathomed logically within the changed space. Numerical inversion of the Laplace transform is carried for the considered distributions and represented graphically. Some comparisons are shown in the figures to estimate the effects of MDD parameters and thermoelectric properties on the behavior of all considered fields.

• 한국전자파학회논문지
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• 제10권3호
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• pp.378-391
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• 1999

시간조화 평면파가 손실 매질내에 있는 high-contrast 구형 공동에 입사되었을 때 순방향에서 입사파 진행방향에 대해 수직인 측정면에서 계산된 입사파 분극방향(co-polarized) 총전계 전력을 주파수 평균하여 incoherent shadow 전계 전력패턴을 얻었다. 공동의 incoherent 영상은 구좌표 회전측정구조에서 얻은 incoherent shadow 전계 전력패턴을 역투시하여 얻었다. 비유전율이 2이고 도전율이 0.001, 0.003S/m인 손실매질내에 있는 공기로 채워진 구형 공동의 영상재현으로 이 영상재현법의 타당성을 보였으며, 보다 좋은 영상을 얻기 위한 조건들을 조사했다.

• 대한전자공학회논문지
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• 제27권11호
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• pp.25-31
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• 1990

공진기(cavity)이론을 적용하여 등각면을 이루는 구면사각패치 마이크로스트립 공진기를 해석한다. 후린징전자계(fringing field) 때문에 발생되는 공진주파수의 오차를 줄이기 위하여 실효유전상수를 고려하여 공진주파수를 계산한다. 해석된 결과식에 따라 Epsilam 10기판으로 3GHz에서 동작하는 전송형 구면사각패치 마이크로스트립 공진기를 설계 제작하였다. 측정 결과는 공진주파수 2.985GHz, 반사손실 -44.4dB로써 이론값과 거의 일치하였다.

• 한국지반공학회지:지반
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• 제5권1호
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• pp.35-46
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• 1989

사질토에 있어서의 말뚝지지력을 해석하기 위하여 아세톤 고형, 수지충진기법을 사용한 모형말뚝 실험을 하여 흙의 변형을 조사하였다. 이 결과로부터 새로운 변형형태가 가정되었으며, 구형공동확장이론을 적용하여 새로운 해석법을 제시하였다. 새로운 해석법에 의한 말뚝지지력은 극한 구형공동확장압력과 지지력 상관계수로 표시된다. 본 해석법의 결과는 공동확장이론을 근거로 한 타 해석법과 비교되었다. 비교 결과, 본 해석법은 공동확장이론에 의한 말뚝지지력 해석의 결점으로 지적되는 실제보다 높은 지지력을 주는 문제점을 해결할 수 있을 것으로 기대된다.

• Bulletin of the Korean Chemical Society
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• 제10권3호
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• pp.309-314
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• 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.