• 대한정형외과학회지
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• 제54권4호
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• pp.336-342
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• 2019

목적: 자기공명영상(magnetic resonance imaging, MRI)을 이용하여 보존적 치료를 시행한 흉요추부 골다공증성 압박 골절 환자에서 후만 변형의 예측 인자를 조사하고자 하였다. 대상 및 방법: 2007년 1월부터 2016년 3월까지 흉요추 압박 골절 의심하에 진료를 본 환자들 중 보존적 치료를 시행한 환자를 따로 분류하였고 그들 중 골밀도 -2.0 미만의 골감소증 및 골다공증, 단일 분절 골절을 가진 환자 89명을 대상으로 후향적 연구를 시행하였다. 골절된 척추체에서 전·후종 인대 손상, 상부 또는 하부 종판 파열, 상부 또는 하부 추간판 손상, T2 강조 영상에서 저 신호 강도의 존재, 척추체의 골 부종 정도를 MRI를 통해 확인하였다. 결과: 상부 종판이 파열된 사례나 척추체 골 부종 수준이 높은 사례의 경우 후만각, 설상각, 전방 척추 압박이 현저하게 진행되었다. 전종 인대 손상이나 상부 추간판 손상이 있는 경우에는 후만각만 현저하게 진행되었다. T2 강조 영상에서 저 신호 강도의 병변을 보인 경우 설상각과 전방 척추 압박이 높게 나타났다. 그러나 후종 인대 손상과 하부 종판 파열 및 하부 추간판 손상의 경우는 후만 변형 및 척추 압박의 진행과 유의미한 상관관계는 없었다. 후만각이 5° 이상 증가될 위험 요인으로는 전종 인대의 손상 유무, 상부 종판 파열, 상부 추간판 손상이 있는데 손상 받지 않은 사례에 비해 각각 21.3, 5.1, 8.5배 위험했고 골 부종 수준에 따라 각각 위험도가 달랐다. 결론: 골감소증 및 흉요추부 골다공증성 압박 골절일지라도 전종 인대 손상, 상부 종판 및 추간판 손상 또는 MRI상 높은 수준의 부종이 있을 경우 후만 변형의 위험도가 증가한다.

• Journal of Chest Surgery
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• 제56권1호
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• pp.64-65
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• 2023

• 대한기계학회논문집
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• 제19권1호
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• pp.122-131
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• 1995

The research trends for metal matrix composites have been on basic mechanical properties, fatigue behavior after aging and fractographic observations. In this study, the fatigue crack initiation as well as the fatigue crack growth behavior and the fracture mechanism were investigated through observations of the fracture surface on silicon carbide particles reinforced aluminum metal matrix composites(SiCp/Al). Based on the fractographic study done by scanning electron microscope and replica, crack growth path model and fracture mechanism are presented. The mechanical properties, such as the tensile strength, yield strength and elongation of SiCp/Al composites are improved in a longitudinal direction, however, the fatigue life is shorter than the basic Al6061 alloys. From fractographic observations, it is found that the failure mode is ductile in basic Ai6061 alloys. And because some SiC particles were pulled out from the matrix and a few SiC particles could be seen on the fracture surface of SiCp/Al, crack growth paths are believed to follow the interface of the matrix and its particles.

• 대한족부족관절학회지
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• 제2권2호
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• pp.93-96
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• 1998

폐쇄성 족관절 양과 골절에 동반된 후경골근 건파열 1례를 치험 하여 우수한 결과를 얻고 그 임상적 중요성을 고찰하였기에 보고하는 바이다.

• Structural Engineering and Mechanics
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• 제28권6호
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• pp.749-765
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• 2008

Free axisymmetric vibrations of layered cylindrical shells of variable thickness are studied using spline function approximation techniques. Three different types of thickness variations are considered namely linear, exponential and sinusoidal. The equations of axisymmetric motion of layered cylindrical shells, on the longitudinal and transverse displacement components are obtained using Love's first approximation theory. A system of coupled differential equations on displacement functions are obtained by assuming the displacements in a separable form. Then the displacements are approximated using Bickley-spline approximation. The vibrations of two-layered cylindrical shells, made up of several types of layered materials and different boundary conditions are considered. Parametric studies have been made on the variation of frequency parameter with respect to the relative layer thickness, length ratio and type of thickness variation parameter.

• Journal of Mechanical Science and Technology
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• 제16권8호
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• pp.1064-1071
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• 2002

Stainless steel pipe of type 304 the with a wall thickness of 26.9 mm and the outer diameter 406.4 mm is welded by manual arc welding process. Mechanical properties and fracture toughness of type 304 stainless steel are investigated in the temperature ranging from room temperature to -162$^{\circ}C$ The results obtained are summarized as follows. The tensile strength noticeably increases as the temperature becomes lower while the yield strength is relatively insensitive to temperature. The Charpy impact energy and CTOD values become higher in the case that crack propagation direction is aligned to the transverse axis upon the rolling direction than longitudinal direction. The drop of fracture toughness is associated with the noticeable diminution of plastic component as temperature seduces from room temperature to -162$^{\circ}C$ .

• 연구논문집
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• 통권30호
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• pp.121-128
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• 2000

The failed tube received for this study has been used for approximately 10 year at $330^{\circ}C$ in a steam production boiler tube was fractured in the transversed direction to tube length, and fracture mode was typically intergranulas type without the plastic deformation. The fracture surface was covered by the oxide scale formed from the intermal high pressure steam at high temperature. The microstructure was not nearly thermal-degraded during the service. From this result, we can conclude that the oxide film was proferentialy formed into the grainboundary and this grainboundary oxide film was brittle-fractured by the thermal stress in the longitudinal direction to the tube brittle intergranular fracture mode.

• Archives of Plastic Surgery
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• 제35권5호
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• pp.553-559
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• 2008

Purpose: The lateral orbital wall fractures have been previously classified by some authors. As there are some limitations in applying in their own classifications, we hope to present a refined classification system of the lateral orbital wall fracture and to identify the correlation between the specific type of the fracture and clinical diagnosis. Methods: The facial bone CT scans and medical records of 78 patients with the lateral orbital wall fractures were reviewed in a retrospective manner. The classification is based on the CT scan. In type I, the fracture and its segments are away from the lateral rectus muscle and in type II, they are next to or slightly pushing the muscle in axial CT scan. In type III, the fracture segments compress and displace the longitudinal axis of the muscle or the optic nerve in axial view of CT scan. Type IV fracture includes multiple fractures found around the orbital apex or optic canal in coronal view of CT scans of the type I and type II fractures. Results: The most common fracture pattern was type I(43.6%), followed by type IV(29.5%), type II(20.5%), and type III(6.4%). As diplopia and restriction of extraocular muscles were found in type I and II fractures, severe ophthalmic complications such as superior orbital fissure syndrome, orbital apex syndrome, and traumatic optic neuropathy were found in type III and IV fractures almost exclusively. Conclusion: We propose an easy classification system of the lateral orbital wall fracture which correlates closely with ophthalmic complications and may help to make further treatment plan. In Type III and IV fractures, severe ophthalmic complications may ensue in higher rates, so early diagnosis and treatment should be performed.

• Geomechanics and Engineering
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• 제22권2호
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• pp.133-142
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• 2020

The evolution of the mining-induced fracture network formed during longwall top coal caving (LTCC) has a great influence on the gas drainage, roof control, top coal recovery ratio and engineering safety of aquifers. To reveal the evolution of the mining-induced stress and fracture network formed during LTCC, the fracture network in front of the working face was observed by borehole video experiments. A discrete element model was established by the universal discrete element code (UDEC) to explore the local stress distribution. The regression relationship between the fractal dimension of the fracture network and mining stress was established. The results revealed the following: (1) The mining disturbance had the most severe impact on the borehole depth range between approximately 10 m and 25 m. (2) The distribution of fractures was related to the lithology and its integrity. The coal seam was mainly microfractures, which formed a complex fracture network. The hard rock stratum was mainly included longitudinal cracks and separated fissures. (3) Through a numerical simulation, the stress distribution in front of the mining face and the development of the fracturing of the overlying rock were obtained. There was a quadratic relationship between the fractal dimension of the fractures and the mining stress. The results obtained herein will provide a reference for engineering projects under similar geological conditions.

• Steel and Composite Structures
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• 제47권6호
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• pp.709-728
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• 2023

Experimental and analytical studies were conducted to clarify the influencing mechanisms of the longitudinal reinforcement on performance of axially loaded Reinforced Concrete-Filled Steel Tube (R-CFST) short columns. The longitudinal reinforcement ratio was set as parameter, and 10 R-CFST specimens with five different ratios and three Concrete-Filled Steel Tube (CFST) specimens for comparison were prepared and tested. Based on the test results, the failure modes, load transfer responses, peak load, stiffness, yield to strength ratio, ductility, fracture toughness, composite efficiency and stress state of steel tube were theoretically analyzed. To further examine, analytical investigations were then performed, material model for concrete core was proposed and verified against the test, and thereafter 36 model specimens with four different wall-thickness of steel tube, coupling with nine reinforcement ratios, were simulated. Finally, considering the experimental and analytical results, the prediction equations for ultimate load bearing capacity of R-CFSTs were modified from the equations of CFSTs given in codes, and a new equation which embeds the effect of reinforcement was proposed, and equations were validated against experimental data. The results indicate that longitudinal reinforcement significantly impacts the behavior of R-CFST as steel tube does; the proposed analytical model is effective and reasonable; proper ratios of longitudinal reinforcement enable the R-CFSTs obtain better balance between the performance and the construction cost, and the range for the proper ratios is recommended between 1.0% and 3.0%, regardless of wall-thickness of steel tube; the proposed equation is recommended for more accurate and stable prediction of the strength of R-CFSTs.