• Journal of Korean Biological Nursing Science
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• 제18권4호
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• pp.193-202
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• 2016

Purpose: The study was to analyze clinical outcomes and risk factors of for complications associated with the hip fracture surgery in the elderly before and after interdisciplinary treatment. Methods: A retrospective method was used to investigate the general and therapeutic characteristics, frequency of complications and clinical outcomes. The subjects of the study were 553 patients who underwent hip fracture surgery from January, 2009 to December, 2014. Results: The interdisciplinary group was older and less likely to walk independently even before the fracture than a usual care group. The incidence of complications was higher in the interdisciplinary group than the usual care group. The prevalence of complications in both groups was 66.5%. Multivariate logistic regression analysis showsed that the risk factors for complications of hip fracture surgery were as follows: advanced age, stroke, Parkinson disease, time interval from emergency room to operation, pre & post ambulatory status, American Society of Anesthesiologists (ASA) classification quality of postop intensive care unit (ICU) care and foley indwelling. Conclusion: This study has implications in that it recognized the necessity for interdisciplinary treatment and provided the basic base data for nursing intervention of the elderly patients who underwent hip fracture surgery.

• 터널과지하공간
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• 제19권4호
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• pp.366-372
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• 2009

최근, 암반발파에서 평활한 파단면과 굴착손상영역을 제어하기 위한 목적으로 전자지발뇌관 및 노치장약공 등을 이용한 제어발파기술들이 개발되어 오고 있다. 본 연구에서는 날개형 노치 장약공을 이용한 SB발파에서 암반 내 파괴과정을 모사하여 파단면과 암반손상제어에 미치는 영향인자에 대하여 고찰하였다. 최종적으로 장약공 노치의 파단면 제어효과에 관한 수치해석적 고찰을 날개형 노치장약공과 전자뇌관을 이용한 새로운 SB발파법으로, ED-Notch SB발파법(Elerectronic Detonator Notched Charge Hole Smooth Blasting Method)을 제안하였다.

• 한국해양공학회지
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• 제21권1호
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• pp.51-58
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• 2007

This study on the effects of local wall-thinned location on the fracture behavior of pipes was carried out, and the results were compared with the analytical results. Local wall-thinning for the bending test was machined with various sizes on the outside of pipes, in order to simulate the metal loss, due to erosion/corrosion. In addition, we had carried out FE analysis for the pipes with local wall thinning on the inside, and its results were comparatively studied with that of the outside. Three-dimensional elasto-plastic analyses were able to accurately simulate fracture behaviors of inner or outer wall thinning. Fracture types, obtained from the experiments and analyses, could be classified into ovalization, local buckling and crack initiation, depending on the thinned length and thinned ratio. Based on the results, the fracture behaviors of pipes with the outer wall thinning can be applied to estimate the fracture behaviors of pipes with the inner wall thinning.

• 한국정밀공학회지
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• 제17권1호
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• pp.153-163
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• 2000

The size effect on fracture toughness was investigated by introducing $J-A_2$ theory. For this application,small size specimens were chosen to establish $J-A_2$ assessment curve with FEM analysis. Two-dimensional FEM analysis was conducted with plane strain model using ABAQUS by domain integral method to calculate both crack tip stress and fracture toughness which were used to establish $J-A_2$ curve. The assessment curve predicted the fracture toughness of large specimens very well when compared to the test values. The results showed good prediction for deep crack specimen, though there were acceptable deviations in shallow cracked specimens, presumably caused by constraint effect. When the curve applied to reactor vessel in order to predict end of life fracture toughness with assumption of on-power pressure test condition, it provided the reasonable pressure compared to the existing design value. Better predictions would be possible if more test data were available.

• Coupled systems mechanics
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• 제6권1호
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• pp.97-111
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• 2017

The present paper reports an analytical study of delamination fracture in the Mixed Mode Flexure (MMF) functionally graded beam with considering the material non-linearity. The mechanical behavior of MMF beam is modeled by using a non-linear stress-strain relation. It is assumed that the material is functionally graded along the beam height. Fracture behavior is analyzed by the J-integral approach. Non-linear analytical solution is derived of the J-integral for a delamination located arbitrary along the beam height. The J-integral solution derived is verified by analyzing the strain energy release rate with considering the non-linear material behavior. The effects of material gradient, crack location along the beam height and material non-linearity on the fracture are evaluated. It is found that the J-integral value decreases with increasing the upper crack arm thickness. Concerning the influence of material gradient on the non-linear fracture, the analysis reveals that the J-integral value decreases with increasing the ratio of modulus of elasticity in the lower and upper edge of the beam. It is found also that non-linear material behavior leads to increase of the J-integral value. The present study contributes for the understanding of fracture in functionally graded beams that exhibit material non-linearity.

• 소성∙가공
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• 제30권1호
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• pp.16-21
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• 2021

A new concept of ammunition without the use of explosive gunpowder has been recently studied, which achieves performance equal to or higher than that of high explosives. Frangible Armor Piercing (FAP) is one of the concepts, which utilizes a tungsten alloy penetrator specialized for fragmentation. To investigate the fracture behavior of the tungsten alloy penetrator, Taylor impact tests were conducted at various impact velocities. Additionally, finite element analysis was performed to predict the fracture behavior of the tungsten alloy. Compression tests were also carried out at six strain rates for dynamic material properties and the dynamic hardening behavior was successfully predicted with the Lim-Huh model. Finally, the Mohr-Coulomb fracture model based on the mean stress was adopted to predict impact failure in Taylor impact simulation. The analysis predicts the deformation and fracture behaviors of the tungsten alloy successfully.

• 소음진동
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• 제11권3호
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• pp.437-442
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• 2001

In this study, the fracture phenomena of optical disks are discussed by theoretical and experimental approaches and then some recommendations are presented to prevent the fracture. Linear equations of motion are discretized by using the Galerkin approximation. From the discretized equations, the dynamic responses are computed by the generalized- time integration method. As a fracture criterion for optical disks, the critical crack length is presented. From experimental methods, the fracture procedure is analyzed. The fracture occurs when disks have crack on the inner radius of the disks. Since the crack growth and the fracture result from the stress concentration on the tip of the crack, a measure should be taken to overcome the stress concentration. This problem can be resolved by the structural modification of a disk. This study proposes 3 types of improved optical disks.

• 열처리공학회지
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• 제26권4호
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• pp.178-184
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• 2013

The effects of thickness and surface grinding condition on the fracture strength of Si wafer with a thickness under $100{\mu}m$ were investigated. Fracture strength was measured by ball breaker test for about 330 dies (size: $4mm{\times}4mm$) per each wafer. For statistical analysis of the fracture strength, scale factor was determined from Weibull plot. Ball breaker fracture strength was observed to increase with decreasing thickness of silicon die. For the silicon dies of different surface conditions, ball breaker fracture strength was high in the order of polished, ground (#4800), and ground (#320 grit) specimen. Probabilistic fracture strength (i.e., scale factor) increased with decreasing surface roughness of silicon die.

• Steel and Composite Structures
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• 제23권3호
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• pp.263-271
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• 2017

A theoretical study was carried-out of mode II delamination fracture behavior of the End Loaded Split (ELS) functionally graded beam configuration with considering the material non-linearity. The mechanical response of ELS was modeled analytically by using a power-law stress-strain relation. It was assumed that the material is functionally graded transversally to the beam. The non-linear fracture was investigated by using the J-integral approach. Equations were derived for the crack arm curvature and zero axes coordinate that are needed for the J-integral solution. The analysis developed is valid for a delamination crack located arbitrary along the beam height. The J-integral solution was verified by analyzing the strain energy release rate with considering material non-linearity. The effects of material gradient, non-linear material behavior and crack location on the fracture were evaluated. The solution derived is suitable for parametric analyses of non-linear fracture. The results obtained can be used for optimization of functionally graded beams with respect to their mode II fracture performance. Also, such simplified analytical models contribute for the understanding of delamination fracture in functionally graded beams exhibiting material non-linearity.

• Journal of Welding and Joining
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• 제21권6호
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• pp.55-63
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• 2003

Welded joint generally has heterogeneity of strength, material, and fracture toughness and it is important to understand the characteristics of material strength and fracture of welded joint considering heterogeneous effect. Characteristics of strength and fracture of an undermatched joint under dynamic loading was studied by round-bar tension tests and thermal elastic-plastic analyses in this paper. The strength and fracture of the undermatched joints should be evaluated based on the effects of the strain rate and the temperature including temperature rise during the dynamic loading. The differences of fracture characteristics like such as ductile-to-brittle transition behavior are well precisely explained from the stress-strain distribution obtained by numerical analysis.