• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.434-439
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• 2000

In this paper, in order to study the geometric factor effect of a circular hole near a crack tip in a semi-infinite plate, the Dimensionless Stress Intensity Factor, $F(=\frac K {\sigma {\sqrt{\pi a}}})$ is analyzed at the crack tip using a two Dimensional Boundary Element Method (BEM) program which is known as superior in Fracture Mechanics. Kelvin's solution was used as a fundamental solution in BEM analysis and displacement extrapolation method was used to determine Stress Intensity Factor.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.5
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• pp.46-52
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• 1998

In fracture problems, stress intensity factors obtained theoretically and experimentally have been effectively utilized in the analytical evolution of the cracks effect. The effect of surface crack of a cylindrical and a hollow cylindrical bar is investigated, as well as the effect of the thickness of a hollow cylindrical bar and inclined crack of a hollow cylinder subjected to torsion moment. In this study, stress intensity factor Km of mode III which expresses the stress state in the neighborhood of a crack tip is used. stress analysis was conducted on the inside of hollow cylinder inthe axial direction of three dimensional crack tip subjected to torsion moment by combining the caustics method and the stress freezing method.

• Journal of Welding and Joining
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• v.26 no.6
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• pp.97-102
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• 2008

It is well known that there exist two typical fatigue crack initiation locations in ship structures: one is the weld toe and the other is the weld root where partial penetration weld is performed. In particular, it is important for fillet weldments to avoid weld root cracking in order to prevent catastrophic failure particularly in ship structures. Therefore detail considerations are required for cruciform joints with partial penetration when there is a possibility of weld root crack initiation. For these reasons, fatigue tests on welded joints were performed in this study. Concept of stress intensity factor(SIF) by means of fracture mechanics is applied for predicting fatigue life of fillet welded joints.

• Journal of the Korean Society of Safety
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• v.13 no.3
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• pp.24-31
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• 1998

Variable thickness plates are commonly encountered in the majority of mechanical/structural components of industrial applications. And, as a result of the unsymmetry of the structure or the load and the anisoptropy of the materials, the cracks in engineering structures are generally subjected to combined stresses. In spite of considerable practical interest, however, a few fracture mechanics study on combined mode crack in a variable thickness plate have carried out. In this respect, combined mode I/III stress intensity factors $K_I$ and $K_III$ at the crack tip for a variable thickness plate were obtained by 3-dimensional finite element analysis. Variable thickness plates containing a central slant crack were chosen. The parameters used in this study were dimensionless crack length $\lamda$, crack slant angle $\alpha$, thickness ratio $\beta$ and width ratio $\omega$. Stress intensity factors were calculated by crack opening displacement(COD) and crack tearing displacement(CTD) method.

• Steel and Composite Structures
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• v.25 no.2
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• pp.209-216
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• 2017

In this paper, the analysis of the behavior of surface cracks in finite-thickness plates repaired with a Boron/Epoxy composite patch is investigated using three-dimensional finite element methods. The stress intensity factor at the crack-front was used as the fracture criteria. Using the Ansys Parametric Design Language (APDL), the stress intensities at the internal and external positions of repaired surface crack were compared. The effects of the mechanical and geometrical properties of the adhesive layer and the composite patch on the variation of the stress intensity factor at the crack-front were examined.

• Geomechanics and Engineering
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• v.24 no.3
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• pp.227-235
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• 2021

A criterion and a method for solving a problem on the prevention of mine working fracture under the action of tectonic and gravitational forces are offered. Based on minimal criterion, theoretical analysis of the definition of the optimal shape of working in the rock mass weakened by arbitrarily located rectilinear cracks was carried out. A closed system of algebraic equations allowing to minimize the stress state and stress intensity factors depending on mechanical and geometrical characteristics of the rock, is constructed. The relation between the shape of the working and the stress intensity factors and also location and sizes of the cracks is obtained. The found optimal shape of working increases load-bearing capacity of the rock.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.4
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• pp.136-144
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• 1997

The characteristics of fatigue crack growth subject to out-of-plane bending fatigue are studied in terms of crack opening behavior by using pre-cracked smooth specimens. Crack opening stress is measured by an elastic compliance method which may precisely and continuously provide many date using strain gages during experiment. The results of the short crack and the long crack arranged by crack closure concept show that the effective stress gange ratio of short crack is grester than that of long crack, and ano- malous growth behavior of short crack may be elucidated by the variation of crack opening stress. When the variation of fatigue crack growth rate is arranged versus effective stress intensity factor range. Iinear relation is held also for the short crack. It shows that growth behavior of short crack can be quantitatively represent- ed by the fracture mechanics parameter using effective stress intensity factor range.

• The Journal of Engineering Geology
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• v.3 no.2
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• pp.125-148
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• 1993

Groundwater flow in fractured rock masses is controlled by combined effects of fracture networks, state of geostafic stresses and crossflow between fractures and rock matrix. Furthermore the scaie dependent, anisotropic properties of hydraulic parameters results mainly from irregular paftems of fracture system, which can not be evaluated properly with the methods available at present. The basic assumpfion of discrete fracture network model is that groundwater flows only along discrete fractures and the flow paths in rock mass are determined by geometric paftems of interconnected fractures. The characteristics of fracture distribution in space and fracture hydraulic parameters are represented as the probability density functions by stochastic simulation. The discrete fracture network modelling was aftempted to characterize the groundwater flow in the vicinity of existing large cavems located in Wonjeong-ri, Poseung-myon, Pyeungtaek-kun. The fracture data of $1\textrm{km}^2$ area were analysed. The result indicates that the fracture sets evaluated from an equal area projection can be grouped into 6 sets and the fracture sizes are distributed in longnormal. The conductive fracture density of set 1 shows the highest density of 0.37. The groundwater inflow into a carvem was calculated as 29ton/day with the fracture transmissivity of $10^{-8}\textrm{m}^2/s$. When the fracture transmissivity increases in an order, the inflow amount estimated increases dramatically as much as fold, i.e 651 ton/day. One of the great advantages of this model is a forward modelling which can provide a thinking tool for site characterization and allow to handle the quantitative data as well as qualitative data.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.10 no.2
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• pp.27-35
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• 2015

Objectives: The purpose of this study is to discriminate the cough-induced rib fracture with chest pain occurred after chuna therapy. Methods: A 68-year-old female patient who is suffering from left chest wall pain with chronic cough was treated by Korean medical treatment and chuna therapy from November 11th 2014 to November 15th 2014. The improvement of the patient's pain was measured by 100 mm Visual Analog Scale (VAS). For diagnosis the rib fracture, we conducted the radiography, computed tomography (CT), and bone scan. Results: After treatment, pain intensity was decreased and the rib fracture was negative in radiography and CT. But, in bone scan, the 5th-8th rib fractures in left side were detected. Conclusions: When the patient with chest pain visit the hospital after chuna therapy, a doctor keep in mind the possibility of coughinduced rib fracture.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.790-799
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• 2010

The Upper Devonian Grossmont Formation in Alberta, Canada reserves an estimated 50 billion cubic meters of bitumen and possess about 1/6 of the total bitumen resources in northern Alberta. However, unlike the overlying Athabasca oil sands, non conventional bitumen resources has not been developed as yet. The carbonate rocks of Grosmont Formation have been subject to various stages of diagenesis, including dolomatization and karstification with a strong effect on the distribution of porosity and permeability, which resulted in highly heterogeneous reservoirs. An extensive fracture logging and mapping was performed on total of six boreholes located in the study area to explore the characteristics of fracture geometry system and the subsurface structures of carbonates reservoir that holds bitumen. Fractal dimension was used as a measure of the statistical homogeneity of the fractured rock masses. The applicability of random Cantor dust, Dc, as a fractal parameter was examined systematically. The statistical homogeneity of fractured carbonates rock masses was investigated in the study area. The structural domains of the rock masses were delineated depthwise according to estimated Dc. The major fracture orientation was dominated by horizontal beddings having dip of $0-20^{\circ}$. Also, fractures having high dip angles existed with relatively low frequency. Three dimensional fracture network modeling for each structural domain has been performed based on fracture orientation and intensity, and some representative conceptual models for carbonates reservoir in the study area has been proposed. The developed subsurface conceptual models will be used to capture the geomechanical characteristics of the carbonates reservoir.