• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.341-348
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• 2001

A Mixed Volume and Boundary Integral Equation Method is applied for the effective analysis of plane elastostatic problems in unbounded solids containing general anisotropic inclusions and voids or isotropic inclusions. It should be noted that this newly developed numerical method does not require the Green's function for anisotropic inclusions to solve this class of problems since only Green's function for the unbounded isotropic matrix is involved in their formulation for the analysis. This new method can also be applied to general two-dimensional elastodynamic and elastostatic problems with arbitrary shapes and number of anisotropic inclusions and voids or isotropic inclusions. Through the analysis of plane elastostatic problems in unbounded isotropic matrix with orthotropic inclusions and voids or isotropic inclusions, it will be established that this new method is very accurate and effective for solving plane elastic problems in unbounded solids containing general anisotropic inclusions and voids or isotropic inclusions.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.48-49
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• 2017

In order to examine the effect of voids on the ultrasonic wave velocity, specimens made of Silica-Sand with voids were prepared for the measurements. The volume fraction of 0, 15, and 30% of voids were used to compare the differences. Because of its more homogeneous distribution of materials properties, the Silica-Sand specimens were used, as compared to mortar specimens. The results showed clear change in ultrasonic wave velocity with different volume fraction of voids. This result is to be used for the estimation of the integrity of concrete structures using ultrasonic wave velocity method as nondestructive testing.

• 대한기계학회논문집A
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• 제26권4호
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• pp.775-786
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• 2002

A Mixed Volume and Boundary Integral Equation Method is applied for the effective analysis of elastic wave scattering problems and plane elastostatic problems in unbounded solids containing general anisotropic inclusions and voids or isotropic inclusions. It should be noted that this newly developed numerical method does not require the Green's function for anisotropic inclusions to solve this class of problems since only Green's function for the unbounded isotropic matrix is involved in their formulation for the analysis. This new method can also be applied to general two-dimensional elastodynamic and elastostatic problems with arbitrary shapes and number of anisotropic inclusions and voids or isotropic inclusions. In the formulation of this method, the continuity condition at each interface is automatically satisfied, and in contrast to finite element methods, where the full domain needs to be discretized, this method requires discretization of the inclusions only. Finally, this method takes full advantage of the pre- and post-processing capabilities developed in FEM and BIEM. Through the analysis of plane elastostatic problems in unbounded isotropic matrix with orthotropic inclusions and voids or isotropic inclusions, and the analysis of plane wave scattering problems in unbounded isotropic matrix with isotropic inclusions and voids, it will be established that this new method is very accurate and effective for solving plane wave scattering problems and plane elastic problems in unbounded solids containing general anisotropic inclusions and voids/cracks or isotropic inclusions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.41-52
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• 1998

A volume integral equation method and a mixed volume and boundary integral equation method are presented for the solution of plane elastostatic problems in solids containing orthotropic inclusions and voids. The detailed analysis of the displacement and stress fields are developed for orthotropic cylindrical and elliptic-cylindrical inclusions and voids. The accuracy and effectiveness of the new methods are examined through comparison with results obtained from analytical and boundary integral equation methods. Through the analysis of plane elastostatic problems in unbounded isotropic matrix containing orthotropic inclusions and voids, it is established that these new methods are very accurate and effective for solving plane elastostatic and elastodynamic problems in unbounded solids containing general anisotropic inclusions and voids or cracks.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.217-220
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• 2003

The effective thermoelastic properties of porous metals are discussed herein after each material forming process such as hot pressing or extrusion. The voids in metal matrix are assumed to be initially spherical in shape and to be distributed randomly. Once the porous material deforms plastically due to each material forming process, the voids change their shape from a sphere to an ellipsoid and align in one direction. Since the voids are compressible in nature, the void volume fraction is assumed to be decreasing during each material forming process.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.91-92
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• 2016

Structural integrity of reinforced concrete structures including nuclear power plants needs to be evaluated on a regular basis. Deterioration inside the concrete structures can be represented by voids. In this study, the varied volume fraction of voids inside mortar specimens was studied as a parameter using ultrasonic testing equipments. Both direct and indirect measurement methods were employed. The results show that there is a clear distinction between the specimens with different void volume fractions.

• Geomechanics and Engineering
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• 제21권5호
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• pp.423-432
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• 2020

Hydraulic conductivity is one of the engineering properties of soil. This study focusses on the influence of cement content on the hydraulic conductivity of cemented sand, which is investigated based on the results from numerical analysis and laboratory testing. For numerical analysis the cemented samples were scanned using X-ray Computed Tomography (CT) while laboratory testing was carried out using a triaxial setup. Numerical analysis enables us to simulate flow through the sample and provides insight to the microstructure. It quantifies the pore volume, proportion of interconnected voids and pore size distribution in both cemented and uncemented samples, which could be computed only through empirical equations in case of laboratory testing. With reduction in global voids, the interconnecting voids within the samples also reduce with cement content. Gamma cumulative distribution function is used to predict the percentage of voids lesser than a given pore volume. Finally, the results obtained from both numerical analysis and laboratory testing are compared.

• 한국임상수의학회지
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• 제34권3호
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• pp.178-184
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• 2017

The aim of this study was to determine whether Hounsfield units (HUs), volume, and various void parameters can predict stone fragility in extracorporeal shock wave lithotripsy (ESWL). HU, volume, porosity, number of voids/stone volume, and void distribution of 30 struvite stones were estimated using helical computed tomography (CT) and micro-CT. The number of shock waves necessary for full fragmentation was accepted as a measure of the stone fragility in ESWL. The correlations between the number of shock waves and the HU, volume, porosity, and number of voids/stone volume were examined. The number of shock waves of the two groups according to the void distribution was also compared. Stone volume correlated with the number of shock waves. Shell-patterned struvite stones were significantly less susceptible to fragmentation in ESWL than non-shell-patterned struvite stones. Stone volume and void distribution may be predictors of the outcome of ESWL treatment.

• 한국지진공학회논문집
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• 제28권4호
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• pp.223-231
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• 2024

For the OPR1000, a standard power plant in Korea, an analytical model of the containment building considering voids and deterioration was built with multilayer shell elements. Voids were placed in the vulnerable parts of the analysis model, and the deterioration effects of concrete and rebar were reflected in the material model. To check the impact of voids and deterioration on the seismic performance of the containment building, iterative push-over analysis was performed on four cases of the analytical model with and without voids and deterioration. It was found that the effect of voids with a volume ratio of 0.6% on the seismic performance of the containment building was insignificant. The effect of strength reduction and cross-sectional area loss of reinforcement due to deterioration and the impact of strength increase of concrete due to long-term hardening offset each other, resulting in a slight increase in the lateral resistance of the containment building. To determine the limit state that adequately represents the seismic performance of the containment building considering voids and deterioration, the Ogaki shear strength equation, ASCE 43-05 low shear wall allowable lateral displacement ratio, and JEAC 4601 shear strain limit were compared and examined with the analytically derived failure point (ultimate point) in this study.

• Structural Engineering and Mechanics
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• 제42권1호
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• pp.25-38
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• 2012

Recently, investigated failures of external post-tensioned (PT) tendons have called attention to the corrosion of strands in PT bridges, and the prevention of ongoing corrosion is required to secure their structural integrity. Since voids inside ducts can be a source for the ingress of water or deleterious chemicals, the vacuum grouting (VG) method and a volumeter for estimating amount of repair grouts were employed to fill voided ducts. However, the VG method is expensive and time-consuming for infield application because it requires an air-tight condition of entire ducts. Thus, latest research assessed three different repair grouting methods, and the pressure vacuum grouting (PVG) method was recommended in the field because it showed good filling capability in voided ducts and did not require an air-tight condition. Thus, a new method is required to estimate the volume of repair grouts because the PVG method is not applied in air-tight ducts. This research assesses the relationship between voided areas on ducts identified with soundings and required grout volume for repair using experimental results. The results show that the proposed equations and assumptions for estimating repair grout volume provide a sufficient amount of repair grouts for filling voided ducts.