• 자원환경지질
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• 제33권6호
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• pp.547-556
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• 2000

The purpose of this study is to analyze shear fracture system using landslide location occurred 1998 at Janghung area. For the geological implication, foliation was surveyed and analyzed, and location of landslide, geological structure and topography were constructed into spatial database using GIS. With the constructed spatial database, shear fracture system was assessed by the relation analysis between strike and dip of the foliation and aspect and slope of the topography. We compared strike and dip of foliation and aspect and slope of topography and recognized the typical fracture pattern, strike and dip of joint, that coincided with shear fracture system. The result tells us that foliation of gneiss has geometrical relation to joint or fault that leading landslide. GIS was used to analyze vast data efficiently and the result can be used to assess the landslide susceptibility as important factor.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.783-789
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• 2003

An experimental method to investigate the fracture strength and fracture toughness for the silicon nitrides sintered at various sintering temperature is established. The erosion rate for these materials in the various concentration of NaOH solution is also investigated. In result, the fracture strength of Si3N4 is decreased with the increase of sintering temperature. On the other hand, the fracture toughness KIC is increased with the increase of sintering temperature. The erosion rate of silicon nitride in the NaOH solution depend largely on the grain size and the concentration of NaOH solution. The erosion rate of silicon nitride sintered at $1800^{\circ}C$ was much higher than that at $1950^{\circ}C$. These results are due to the unique columnar structure of silicon nitride.

• Structural Engineering and Mechanics
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• 제18권1호
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• pp.91-112
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• 2004

Concrete is a composite material and at meso-level, may be assumed to be composed of three phases: aggregate, mortar-matrix and aggregate-matrix interface. It is postulated herein that although non-linear material parameters are generally used to model this composite structure by finite element method, linear elastic fracture mechanics principles can be used for modelling at the meso level, if the properties of all three phases are known. For this reason, a novel meso-mechanical approach for concrete fracture which uses the composite material model with distributed-phase for elastic properties of phases and considers the size effect according to linear elastic fracture mechanics for strength properties of phases is presented in this paper. Consequently, the developed model needs two parameters such as compressive strength and maximum grain size of concrete. The model is applied to three most popular fracture mechanics approaches for concrete namely the two-parameter model, the effective crack model and the size effect model. It is concluded that the developed model well agrees with considered approaches.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.674-679
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• 2004

In this study, we investigated the cause analysis on fracture of diesel locomotive engine liner, which was trouble assuming the inflow of cooling water. In order to reveal the cause of fracture, we studied the use history of engine, the drawing of production appearance and the stress distribution of engine in use. Also, we conducted experiments such as tension strength test, bending test and hardness test. Next, we observed fractured sections by SEM for the purposed of explaining the fracture mechanism of engine liner. Test results showed that fracture mechanism was brittle fracture due to coarse casting structure and stress concentration caused by manufacturing badness.

• 한국해양공학회지
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• 제16권2호
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• pp.67-71
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• 2002

Damage process of CFRP laminates was characterized by Acoustic Emission (AE). The main objective of this study is to determine if the sources of AE in CERP laminates could be identified from the characteristics of the waveform signals recorded during monotonic tensile test. The time history and power spectrum of each individual wave signal recorded during test were examined and classified according to their special characteristics. The wave from and frequency of AE signal from a specimens is an aid to the determination of the extent of the different fracture mechanism such as matrix crack, debonding, fiber pull-out and fiber fracture as load is increased. Four distinct types of signals were observed regardless of specimen condition. The result showed that the AE method could be effectively used for analysis of fracture mechanism in CFRP laminates.

• Geomechanics and Engineering
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• 제14권2호
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• pp.187-193
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• 2018

Water inrush through the destruction of water resisting rock mass structure was divided into direct water inrush, key block water inrush and splitting water inrush. In the direct water inrush, the Reynolds numbers has a significant effect on the distribution of the water flow and vortex occurred in the large Reynolds numbers. The permeability coefficient of the fracture is much larger than the rock, and the difference is between 104 and 107 times. The traditional theory and methods are not considering the effect of inertia force. In the position of the cross fracture, the distribution of water flow can only be linearly distributed according to the fracture opening degree. With the increase of Reynolds number, the relationship between water flow distribution and fracture opening is studied by Semtex.

• Computers and Concrete
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• 제24권1호
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• pp.51-61
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• 2019

Compressive ability is one of the most important mechanical properties of concrete material. The compressive failure process of concrete is pretty complex with internal tension, shear damage and friction between cracks. To simulate the complex fracture process of concrete at meso level, methodology for meso-structural analysis of concrete specimens is developed; the zero thickness cohesive elements are pre-inserted to simulate the crack initiation and propagation; the constitutive applied in cohesive element is established to describe the mechanism of crack separation, closure and friction behavior between the fracture surfaces. A series of simulations were carried out based on the model proposed in this paper. The results reproduced the main fracture and mechanical feature of concrete under compression condition. The effect of key material parameters, structure size, and aggregate content on the concrete fracture pattern and loading carrying capacities was investigated. It is found that the inner friction coefficient has a significant influence on the compression character of concrete, the compression strength raises linearly with the increase of the inner friction coefficient, and the fracture pattern is sensitive to the mesostructure of concrete.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제19권2호
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• pp.181-189
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• 1997

The mandible plays a crucial role in the vital human functions of breathing, eating, and speaking. No other bone in the body has such a distinctive shape and function. Because of its prominence in the facial structure, the mandible is highly prone to fracture. A clinical study on 122 patients with mandibular fracture who visited Kangnam General Hospital during 4 year(1992-1995) was done by analysing sex, age, cause, fracture site, teeth involvement, treatment method, complication and involvement of other body part. The results obtained were as follows : 1. The occurrence was more frequent in male than in female with the ratio of 5.4 : 1 and most frequently in twenties. 2. Violence was the most common cause of facial mandibular fracture. 3. In mandibular fracure, fracture site was average 1.5 sites, most frequently in symphysis and simple fracture was 86.1%. 4. As treatment methods, open reduction(78.6%) was used more frequently than closed reduction(21.4%). 5. Post-operational complication occurred in 27.0% of the cases. 6. Other injuries that were related to maxillofacial fracture occurred in 25.4%.

• Structural Engineering and Mechanics
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• 제64권4호
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• pp.487-494
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• 2017

The present paper deals with a theoretical study of delamination fracture in the Crack Lap Shear (CLS) functionally graded beam configuration. The basic purpose is to analyze the fracture with taking into account the material non-linearity. The mechanical behavior of CLS was described by using a non-linear stress-strain relation. It was assumed that the material is functionally graded along the beam height. The fracture was analyzed by applying the J-integral approach. The curvature and neutral axis coordinate of CLS beam were derived in order to solve analytically the J-integral. The non-linear solution of J-integral obtained was verified by analyzing the strain energy release rate with considering material non-linearity. The effects of material gradient, crack location along the beam height and material non-linearity on fracture behavior were evaluated. The J-integral non-linear solution derived is very suitable for parametric studies of longitudinal fracture in the CLS beam. The results obtained can be used to optimize the functionally graded beam structure with respect to the fracture performance. The analytical approach developed in the present paper contributes for the understanding of delamination fracture in functionally graded beams exhibiting material non-linearity.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.345-350
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• 2001

In order to perform elastic-plastic fracture mechanical analyses, fracture resistance curves for concerned materials are required. 1T-CT specimen was used to obtain fracture resistance curves. But the fracture resistance curve by the 1T-CT specimen was very conservative to evaluate the integrity of the structure. And fracture resistance curve was affected by the specimen geometry and crack plane orientation. The objective of this paper is to be certain the conservativeness of the fracture resistance curve by the 1T-CT specimen and to provide the additional safety margin. For these, the fracture tests using the real pipe specimen and standard 1T-CT specimen test were performed. 4-point bending jig was manufactured for pipe test and direct current potential drop method was used to measure the crack extension and length for pipe test. From the pipe and the 1T-CT specimen test results, it was observed that the J-integral of the 1T-CT specimen test at the crack initiation point was very small compare to that of the pipe specimen test.