• 비파괴검사학회지
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• 제32권2호
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• pp.131-141
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• 2012

A field theoretical approach to deformation and fracture of solid-state material is outlined, and its application to diagnosis of deformational status of metal specimens is discussed. Being based on a fundamental physical principle known as local symmetry, this approach is intrinsically scale independent, and capable of describing all stages of deformation on the same theoretical foundation. This capability enables us to derive criteria that can be used to diagnose transitions from the elastic to plastic regime, and the plastic to fracturing regime. For practical applications of these criteria, an optical interferometric technique known as electronic speckle-pattern interferometry is proved to be quite powerful; it is able to visualize the criteria as a whole image of the object on a real-time basis without numerical processing. It is demonstrated that this method is able to reveal loading hysteresis as well.

• 대한기계학회논문집A
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• 제24권3호
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• pp.676-684
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• 2000

In this study, behavior of $C_t$ which is a well-known fracture parameter characterizing creep crack growth rate, is investigated for weld interface cracks. Finite element analyses were per formed for a C(T) specimen under constant loading condition for elastic-plastic-creeping materials. In modeling C(T) geometry, an interface was employed along the crack plane which simulated the interface between weld and base metals. The $C_t$ versus time relations were obtained under various creep constant combinations and plastic constant combinations for weld and base metals, respectively. A unified $C_t$ versus time curve is obtained by normalizing $C_t$ with $C^*$ and t with $t_T$ for all the cases of material constant variations.

• 한국해양공학회지
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• 제14권1호
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• pp.44-51
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• 2000

Safety and integrity are required for reactor pressure vessels because they are operated in high temperature. There are single specimen method multiple specimen method and load ratio analysis method which used as evaluation of safety and integrity for reactor pressure vessels. In this study the fracture resistance curve(J-R curve) elastic-plastic fracture toughness($J_{IC}$) and material tearing modulus ($T_{mat}$) of SA 508 class 3 alloy steel used as reactor pressure vessel steel are measured and evaluated at room temperature 20$0^{\circ}C$ and 30$0^{\circ}C$ according to unloading compliance method and load ration analysis method. And then the comparison with experimental $J_{IC}$ and theoretical$J_{IC}$ by local fracture strain is managed.

• 한국항해항만학회지
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• 제26권4호
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• pp.435-440
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• 2002

잔류응력이 판의 파괴 특성에 미치는 영향의 정량적 평가를 위하여, 균열이 존재하는 CT(Compact Tension) 시편에 가스 토오치 (gas torch)를 이용한 국부 가열을 실시하여 인위적인 잔류응력을 생성시키고, 열탄소성 유한요소해석을 통하여 생성된 잔류응력장을 평가하였으며, 잔류응력이 존재하는 시편과 잔류응력이 존재하지 않는 시편에 대한 파괴인성 실험을 실시하여 이들의 결과를 파괴저항 선도 상에서 비교, 분석함으로써 압축 잔류응력이 파괴 특성에 미치는 영향을 정량화하였다.

• 터널과지하공간
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• 제9권1호
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• pp.64-71
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• 1999

균열면을 제어하는 발파방법의 하나로서 노치성형 발파공을 이용한 방법의 균열발생 특성을 2차원 및 3차원 유한요소 해석방법을 이용하여 고찰하였다. 균열제어를 위한 모델로는 노치가 성형된 발파공과 일반적인 원형 발파공을 대상으로 하였으며, 발파 압력에 대한 암반의 동적 반응, 탄성 및 소성 변형의 발생 특성, 그리고 이로 인한 발파 균열의 성장 전파 특성을 분석하여, 균열의 능동적 제어와 보다 효율적인 발파가 이루어 질 수 잇는 조건들을 규명하고자 하였다. 해석 결과 일반 발파공의 정하중 탄성 모델의 경우 공반경의 약 3배인 6cm 까지 집중된 응력의 크기가 파괴강도를 초과하는 것으로 나타났으며 탄소성 모델의 경우 균열이 전파거리는 공반경의 145배인 30cm 가지 확장되었다. 또한 폭 5mm 길이 30 mm 의 노치가 가공된 발파공의 경우 정하중하에서 공반경의 23배인 46cm 까지 균열이 진전되었으며, 균열의 방향은 노치 첨단의 방향으로 생성되는 것으로 나타났다.

• 기술사
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• 제19권4호
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• pp.5-10
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• 1986

On SWS 41 Plates jointed by the F11T M 20 high strength bolts the study on stress behavior and safety degree until rupture in static tensile tests were performed. By these results, in case of no clamping force stress concentration was extremed for strain of about 10% higher ratio. Elastic strain occurred to change of test specimens depth by the load and plastic strain occurred to local minute sleep after elastic strain. compared shear stress with tension stress from the fracture load it was showned lower values than the maximum shear stress theory and stress strain energy theory.

• 한국안전학회지
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• 제14권4호
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• pp.43-52
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• 1999

In this study, theoretical stress field analysis near the crack tip under tension-compression loading was performed. The results of the theoretical stress analysis were compared to the results of Finite Element Method(FEM). From this study, generation of tensile residual stress at crack tip was proved after 1-cycle of tension-compression loading, and the fracture toughness and the fracture load of a structure can be decreased by the residual stress.

• 대한조선학회논문집
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• 제48권1호
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• pp.42-48
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• 2011

To define ice as a solid material, mathematical and physical characteristics and their application examples are investigated for several materials' yield functions which include isotropic elastic, isotropic elastic-plastic, classical Drucker-Prager, Drucker-Prager Cap, Heinonen's elliptic, Derradji-Aouat's elliptic, and crushable foam models. Taking into account brittle failure mode of ice subject to high loading rate or extremely low temperature, isotropic elastic model can be better practicable than isotropic elastic-plastic model. If a failure criterion can be properly determined, the elastic model will provide relatively practicable impact force history from ice-hull interactions. On the other hand, it is thought that the soil models can better predict the ice spalling mechanism, since they contain both terms of shear stress-induced and hydrostatic stress-induced failures in the yield function.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.429-430
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• 2007

• Maxillofacial Plastic and Reconstructive Surgery
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• 제11권1호
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• pp.255-260
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• 1989

Unfavorable healing of maxillary fractures may impose functional and esthetic burdens upon the trauma victim. Malunited maxillary fractures are generally a result of treatment delay, incomplete or inaccurate immobilization of the fracture fragments, or infection. Dysfunctions of mastication, distortions in speech, gross defects in facial contour, and related psychic changes are problems which may require secondary correction. When it is necessary to delay definitive treatment or when inadequate maxillary fracture reduction is recognized within the first week following injury, the maxilla can be mobilized by heavy handed dental manipulation under anesthesia or by elastic traction to an external fixation appliance attached to the maxilla by arch bars or an acrylic splint. But malunited maxillary fracture that have progressed to bony malunion require osteotomy procedure in order to establish normal anatomic relationships. This report parents two cases of malunited unilateral maxillary fracture surgically corrected by unilateral Le Fort I osteotomy.