• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.129-132
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• 2002

A unified elastic-viscoplastic ocnstitutive model based on dislocation density considerations is described. A combination of a kinetic equation, which describes the mechanical response of a material at a given microstructure in terms of dislocation glide and evolution equations for internal variables characterizing the microstructure provide the constitutive equations of the Model. Microstructural features of the material, such as the grain size, spacing between second phase particles etc., are directly implemented in the constitutive equations. The internal variables are associated with the total dislocation density in the simple version of the model. The model has a modular structure and can be adjusted to describe a particular type of metal forming processes.

• Clinics in Shoulder and Elbow
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• v.1 no.1
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• pp.78-82
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• 1998

The following will describe a method of evaluating the SLAP lesion in the recurrent anterior dislocation of the shoulder. We have named it the biceps load test. The biceps load test is performed with the patient in the supine position and the arm to be examined is abducted 90/sup°/, and the forearm is in the supinated position. First, the anterior apprehension test is performed. When the patient become apprehensive, the patient is allowed active flexion of the elbow, while the examiner resists elbow flexion. If the apprehension is relieved or diminished, the test is negative. If aggravated or unchanged, the test is positive. A prospective study was performed, in which 75 patients who were diagnosed as having recurrent unilateral anterior instability of the shoulder underwent the biceps load test and arthroscopic examination. The biceps load test showed negative results in 64 of these patients, of which the superior labral-biceps complex was intact'in 63 cases and only I shoulder revealed a type n SLAP lesion. E]even patients with a positive test were confirmed to have type n SLAP lesions. A positive biceps load test represents an unstable SLAP lesion in a patient with recurrent anterior dislocation of the shoulder. The biceps load test is a reliable test for evaluating the SLAP lesion in the recurrent anterior dislocation of the shoulder(sensitivity: ,9] .7%, specificity: 100%, positive predictive value: 1.00 and negative predictive value: 0.98). Biceps contraction increases the torsional rigidity ?of the glenohumeral joint and long head of biceps tendan act as internal rotator of the shoulder in the abducted and externally rotated position. These stabilize the shoulder in abduction and external rotation position in the biceps load test.

• Clinics in Shoulder and Elbow
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• v.13 no.2
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• pp.217-222
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• 2010

Purpose: We wanted to evaluate the clinical outcomes after operative treatment using two suture anchors and Kirschner wire for treating acute Rockwood type V acromioclavicular joint dislocation Materials and Methods: Between May 2006 and May 2009, 10 patients underwent surgical treatment for acute Rockwood type V acromioclavicular joint dislocation using two suture anchors and Kirschner wire and they were followed for a mean of 12.0 (range: 7-31) months. We analyzed the functional results by the Korean shoulder score, the Constant-Murley score and the reduction state of the acromioclavicular joint at the last follow-up. Results: All the cases achieved a satisfactory outcome. The mean Korean shoulder score was 89.9 (range: 81-100) points and the mean Constant-Murley score was 87.8 (range: 82-93) points. According to the radiologic findings, 8 patients achieved anatomical reduction of the acromioclavicular joint: there was a slight loss of reduction in one patient and a partial loss of reduction in one patient. None of the patients had deep infection or re-dislocation. Conclusion: The operative treatment using two suture anchors and Kirschner wire may be used for acute Rockwood type V acromioclavicular joint dislocation, and it has an advantage in that it can prevent chondral injury of the joint.

• Clinics in Shoulder and Elbow
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• v.4 no.1
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• pp.24-29
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• 2001

Purpose: To describe a technique of the modified Neviaser method and to evaluate the clinical outcome of the technique in the treatment of the complete acromioclavicular joint dislocation, Materials and Method: We evaluated 20 patients who were treated by a modified Neviaser method from June 1996 to January 1999, They were followed up for a minimum of two years. The operative technique includes fixation of the acromioclavicular joint, repair of coracoclavicular ligament and transfer of the anterolateral band of coracoacromial ligament. Results: The 20 patients were evaluated clinically using Kang's criteria. The satisfactory results obtained in 85%. The mean coracoclavicular interval ratio was decreased from 2.22 preoperatively to 1.07 postoperatively. At the time of two year follow-up, the mean ratio was 1.20. There was no definite complication such as re-dislocation of the joint. Conclusion: In above type 3 acromioclavicular dislocation, the modified Neviaser method provided the advantage of strong and stable fixation with a low complication rate. Therefore, it is thought to be one of the useful operative technique.

• Journal of the Korean Chemical Society
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• v.21 no.5
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• pp.330-338
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• 1977

In order to elucidate the plastic deformation of solids, the following assumptions were made: (1) the plastic deformation of solids is classified into two main types, the one which is caused by dislocation movement and the other caused by grain boundary movement, each movement being restricted on a different shear surface, (2) the dislocation movement is expressed by a mechanical model of a parallel connection of various kinds of Maxwell dislocation flow units whereas the grain boundary movement is also expressed by a parallel connection of various kinds of Maxwell grain boundary flow units; the parallel connection in each type of movements indicates that all the flow units on each shear surface flow with the same shear rate, (3) the latter model for grain boundary movement is connected in series to the former for dislocation movement, this means physically that the applied stress distributes homogeneously in the flow system while the total strain rate distributes heterogeneously on the two types of shear planes (dislocation or grain boundary shear plane), (4) the movement of dislocation flow units and grain boundary units becomes possible when the atoms or molecules near the obstacles, which hinder the movement of flow units, diffuse away from the obstacles.Using the above assumptions in conjunction with the theory of rate processes, generalized equations of shear stress and shear rate for plastic deformation were derived. In this paper, four cases important in practice were considered.ted N${\cdot}{\cdot}{\cdot}$O hydrogen bond and the second of two normal N${\cdot}{\cdot}{\cdot}$O hydrogen bonds, both of which exist between the amino group and the perchlorate, groups. A p-phenylenediamine group is approximately planar within an experimental error and bonded to twelve perchlorates: ten perchlorates forming hydrogen bonds and two being contacted with the van der Waals forces. A perchlorate group is surrounded by six p-phenylenediamines and four perchlorates; among the six p-phenylenediamines, five of them are hydrogen-bonded, and the rest contacted with the van der Waals force.

• Korean Journal of Materials Research
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• v.25 no.2
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• pp.81-89
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• 2015

A strain-gradient crystal plasticity constitutive model was developed in order to predict the Hall-Petch behavior of a Ni-base polycrystalline superalloy. The constitutive model involves statistically stored dislocation and geometrically necessary dislocation densities, which were incorporated into the Bailey-Hirsch type flow stress equation with six strength interaction coefficients. A strain-gradient term (called slip-system lattice incompatibility) developed by Acharya was used to calculate the geometrically necessary dislocation density. The description of Kocks-Argon-Ashby type thermally activated strain rate was also used to represent the shear rate of an individual slip system. The constitutive model was implemented in a user material subroutine for crystal plasticity finite element method simulations. The grain size dependence of the flow stress (viz., the Hall-Petch behavior) was predicted for a Ni-base polycrystalline superalloy NIMONIC PE16. Simulation results showed that the present constitutive model fairly reasonably predicts 0.2%-offset yield stresses in a limited range of the grain size.

• Structural Engineering and Mechanics
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• v.67 no.3
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• pp.277-281
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• 2018

The analytical solution of two functionally graded layers with Volterra type screw dislocation is investigated under anti-plane shear impact loading. The energy dissipation of FGM layers is modeled by viscous damping and the properties of the materials are assumed to change exponentially along the thickness of the layers. In this study, the rate of gradual change ofshear moduli, mass density and damping constant are assumed to be same. At first, the stress fields in the interface of the FGM layers are derived by using a single dislocation. Then, by determining a distributed dislocation density on the crack surface and by using the Fourier and Laplace integral transforms, the problem are reduce to a system ofsingular integral equations with simple Cauchy kernel. The dynamic stress intensity factors are determined by numerical Laplace inversion and the distributed dislocation technique. Finally, various examples are provided to investigate the effects of the geometrical parameters, material properties, viscous damping and cracks configuration on the dynamic fracture behavior of the interacting cracks.

• Clinics in Shoulder and Elbow
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• v.17 no.1
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• pp.36-39
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• 2014

Clavicular hook plate is known to be an effective treatment on acromioclavicular (AC) joint injury, but there have been some reports of complications, like osteolysis and bony erosion of the undersurface of acromion. Fifty-five year old male underwent open reduction and hook plate insertion on Rockwood type 5 acromioclavicular joint dislocation. He complained of protrusion of posterior acromion at 1 month after the surgery, and acromial fracture was noted in simple radiographs. The hook plate was removed and any other treatment for osteosynthesis was refused by the patient. At the 18 months after the surgery, the patient had no pain and a full range of motion with no tenderness around the shoulder joint. After two years, plain radiographs revealed complete bony union of the acromion fracture.

• Journal of Yeungnam Medical Science
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• v.9 no.2
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• pp.302-311
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• 1992

Talus is a important structure of the ankle joint and its function is critical for ambulation and weight bearing. The talus fracture is rare, but the complications of fracture and dislocation are serious and resulting in avascular necrosis, osteoarthritis. So its treatment is carefully considered at initial status. Authors reviewed 11 cases of fracture and dislocation of the talus treated at Yeungnam university hospital from 1984 to 1991. The longest follow up was 8 years and shortest, 1 year. The results were as follows. 1. There were all males, the average age was 30 years old. 2. The most common cause was fall down(8 cases), and next traffic accident(2cases), sports injury(1 case). 3. According to Marti-Weber classification, 1 cases was type I, 1 in type II, 4 in type III and 5 in type IV. 4. The method of treatment were open reduction and internal fixation in 6 cases, the others were closed reduction in 5 cases. 5. Final results(by Hawkins grading system) were as follows, 3 cases were excellent, 4 cases were good, 1 case was fair and 3 cases were poor. 6. Complications were AVN in 2 cases, degenerative arthritis in 8 cases, malunion in 1 case. 7. The range of motion of the ankle joint was relatively preserved(74%), but in the subtalar joint it was decreased(43%).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.796-803
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• 1998

Intrinsic and proximity gettering are popular processes to get higher cumulative production yield and usually adopt multi-step annealing and high energy ion implantation, respectively. In order to test the combined processed of these, high energy \ulcornerAs\ulcorner ion implantation and 2-step annealing process were adopted. After the ion implantation followed by 2-step annealing, the wafers were cleaved and etched with Wright etchant. The morphology of cross section on samples was inspected by FESEM. The concentration profile of As was measured by SRP. The location and type of secondary defects inspected by HRTEM were dependent on the 1st annealing temperatures. That is, a line of dislocation located at $1.5mutextrm{m}$ apart from the surface at $600^{\circ}C$ lst annealing was changed to some dislocation lines or loops nearby the surface at 100$0^{\circ}C$. The density of dislocation line was reduced but the size of the defects was enlarged as the temperature increased.