• Steel and Composite Structures
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• v.44 no.5
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• pp.633-649
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• 2022

This paper is first implemented with the bending behavior of three-dimensional functionally graded (3DFG) plates in the framework of level set-based topology optimization (LS-based TO). Besides, due to the suitable properties of the current design domain, the thin-plate spline (TPS) is recognized as a RBF to construct the LS function. The overall mechanical properties of the 3DFG plate are assessed using a power-law distribution scheme via Mori-Tanaka micromechanical material model. The bending response is obtained using the first-order shear deformation theory (FSDT). The mixed interpolation of four elements of tensorial components (MITC4) is also implemented to overcome a well-known shear locking problem when the thickness becomes thinner. The Hamilton-Jacobi method is utilized in each iteration to enforce the necessary boundary conditions. The mathematical formulas are expressed in great detail for the LS-based TO using 3DFG materials. Several numerical examples are exhibited to verify the efficiency and reliability of the current methodology with the previously reported literature. Finally, the influences of FG materials in the optimized design are explained in detail to illustrate the behaviors of optimized structures.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.137-142
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• 2008

Purpose: To evaluate the clinical and radiographic results of the treatment of a proximal humerus fracture with a locking compression plate(LCP). Materials and Methods: This study reviewed the results of 24 cases of a proximal humerus fracture treated with a LCP from January 2005 to April 2007, after a follow up of more than 12 months. There were 8 males and 16 females with a mean age of 68.9(33-90) years. The clinical results were evaluated using the Neer's evaluation criteria, and the radiographic results were evaluated using the bone union time and Paavoleinen method. Results: The mean time for bone union was 11.9 weeks. Using the Neer's functional evaluation, 21 cases of the 24 patients (87%) showed excellent or satisfactory results. Twenty two cases (91%) showed good results according to the Paavoleinen method. The complications encountered were metal failure (1 patient), AVN of the humeral head (1 patient) and joint stiffness (1 patient). Conclusion: The LCP demonstrated good results in the treatment of a proximal humerus fracture and has relatively fewer complications than other internal fixators.

• Journal of Korean Orthopaedic Sports Medicine
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• v.8 no.2
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• pp.115-120
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• 2009

Purpose: To evaluate the outcomes of three different surgical approaches in treating a distal radius fracture with dorsal communition. Materials and Methods: From April, 2006 to May, 2009, 49 patients over age of 60years old with unstable dorsal communition distal radius fracture were analyzed. We compared maintainability of reduction by radiological follow-up observations and clinical outcomes using Mayo wrist scores. One-Way ANOVA test was performed to examine the statistical correlation between the methods. Results: All three approaches provided satisfactory post-op reduction results. However, follow-up observations showed significant loss of reduction in the external fixation only group compared to the added bone graft group and the volar anatomical locking plate group (P<0.05). Mayo wrist score was indifferent between the three groups. Conclusion: Treatment of a distal radius fracture with severe dorsal communition using an external fixation only appears to be insufficient in maintaining reduction of a cancellous bone defect.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.396-401
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• 1997

Dynamic stability of cylindrical shells subjected to follower forces is analyzed in this paper. Motion of shells is formulated in curvilinear coordinates that is consistent with assumptions made in the Timoshenko beam and the Mindlin plate. Using the finite element method, the induced equations are reduced to an equation with finite degrees of freedom. The 9-node Lagrangian element is used, and reduced integration is used to avoid shear and membrane locking. The effects of thickness ratio on the dynamic stability of cylindrical shells are studied.

• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.27-34
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• 2011

Purpose: We examined the clinical and radiological outcomes for displaced proximal humerus fractures that were treated with a PHILOS angular stable plate. Materials and Method: Forty four patients who underwent surgery between March 2007 and February 2010 were included in this study. All the cases were followed up for an average of 12 months. All the patients were examined and interviewed using the Visual Analog Scale (VAS) score, the Constant score and standardized X-rays to check the neck-shaft angle (NSA) and the presence of medial support. Results: The average Visual Analog Scale score was 2.8 points and the average Constant score was 70.5 points. The average neck shaft angle was $122.5^{\circ}$ and this was statistically significant between the good result group and the poor result group. There were 36 cases of the presence of medial support and 8 cases of the absence of medial support and the difference was statistically significant. Complications such as fixation failure happened in 12 cases. Conclusion: PHILOS angular stable plate fixation as an operative treatment for displaced proximal humerus fractures is a good and reliable treatment option.

• Structural Engineering and Mechanics
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• v.87 no.3
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• pp.283-296
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• 2023

Free-vibration and buckling analyses of plate problems are investigated with the aid of the strain gradient notation finite element method (SGN-FEM). As SGN-FEM employs physically interpretable polynomials in developing finite elements, parasitic shear sources, which are the cause of shear locking, can be precisely identified and subsequently eliminated. This allows two mutually complementary objectives to be defined in this work, namely, evaluate the efficiency of free-vibration and buckling results provided by corrected models, and study the severity of parasitic shear effects on plate models performance. Parasitic shear are flexural terms erroneously present in shear strain polynomials. It is reviewed here that six parasitic shear terms arise during the formulation of the four-node Mindlin plate element. Two parasitic shear terms have been identified in the in-plane shear strain polynomial while other two have been identified in each of the transverse shear strain polynomials. The element is corrected a-priori, i.e., during development, by simply removing the spurious terms from the shear strain polynomials. The computational implementation of the element in its two versions, namely, containing the parasitic shear terms (PS) and corrected for parasitic shear (SG), allows for assessments of the accuracy of results and of the deleterious effects of parasitic shear in free vibration and buckling analyses. This assessment of the parasitic shear effects is a novelty of this work. Validation of the SG model is done comparing its results with analytical results and results provided by other numerical procedures. Analyses are performed for square plates with different thickness-to-length ratios and boundary conditions. Results for thin plates provided by the PS model do not converge to the correct solutions, which indicates that parasitic shear must be eliminated. That is, analysts should not rely on refinement alone. For thick plates, PS model results can be considered acceptable as deleterious effects are really critical in thin plates. On the other hand, results provided by the SG model converge well for both thin and thick plates. The effectiveness of the SG model is established via high-accuracy results obtained in several examples. It is concluded that corrected SGN-FEM models are efficient alternatives for free-vibration and buckling analysis of Mindlin plate problems, and that precise elimination of parasitic shear is a requirement for sound analyses.

• Structural Engineering and Mechanics
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• v.43 no.2
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• pp.253-271
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• 2012

To analyze the bending and transverse shear effects of laminated composite plates, a thirteen nodes triangular element will be presented. The suggested formulations consider a parabolic variation of the transverse shear strains through the thickness. As a result, there is no need to use shear correction coefficients in computing the shear stresses. The proposed element can model both thin and thick plates without any problems, such as shear locking and spurious modes. Moreover, the effectiveness of $w_{,n}$, as an independent degree of freedom, is concluded by the present study. To perform the accuracy tests, several examples will be solved. Numerical results for the orthotropic materials with different boundary conditions, shapes, number of layers, thickness ratios and fiber orientations will be presented. The suggested element calculates the deflections and stresses more accurate than those available in the literature.

• Clinics in Shoulder and Elbow
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• v.15 no.1
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• pp.25-31
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• 2012

Purpose: The clinical and radiographic outcomes of the internal fixation, which were executed on patients over the age of 65 with proximal humerus fracture by using a polyaxial angular stable locking compression plate (Non-Contact-Bridging proximal humerus plate, Zimmer, Switzerland, NCB), were evaluated. Materials and Methods: Thirty two patients over the age of 65 among the proximal humerus fracture treated with NCB plate, between August 2007 and January 2011, were chosen as the subjects. The average age of patients was 71 years, and the average postoperative follow-up period was 11.5 months. The fractures included 14 two-part and 18 three-part fractures. The clinical results were evaluated, using the visual analog scale (VAS) score and the Constant score. The radiological results were evaluated by time to union and Paavolainen method, which measures the neck shaft angle. Results: At the last follow-up examination, the mean VAS score was 3 points and the mean Constant score was 64.5 points, with bone union achieved after the average of 16.2 weeks following the surgery in all the cases. The mean neck shaft angle was 125.9 and 24 cases had good results, while 8 cases had fair results by Paavolainen method, at the last follow-up. There were 1 case of delayed union and cerclage wire failure, and 3 cases of subacromial impingement. There were no complications, such as loss of reduction, nonunion, screw loosening, or avascular necrosis of the humeral head. Conclusion: Internal fixation, using a NCB plate, was considered to be an effective surgical method in treating proximal humerus fracture in the elderly patients, on whom the fixation of the fracture and maintenance of reduction are difficult.

• Journal of Veterinary Clinics
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• v.31 no.2
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• pp.121-124
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• 2014

A 7-year-old, intact female Jindo dog was presented for assessment of weight-bearing lameness of the right hindlimb. On physical examination, crepitus and pain was noted in the right coxofemoral joint upon extension. Radiographs revealed a craniodorsal luxation of the right coxofemoral joint and degenerative joint disease (DJD) of both coxofemoral joints. Total hip replacement (THR) was performed for the right coxofemoral joint. Intraoperatively, dorsal acetabular rim (DAR) deficiency was noted, which can be related to a high risk for acetabular cup implant dislocation. Deficiency of the dorsal acetabular rim realigned with the acetabular cup using universal locking plate (ULP) and polymethylmethacrylate (PMMA) bone cement. After surgery, the patient had an uneventful course and a successful outcome. The ROM and thigh girth were dramatically improved. There were no complications associated with prosthesis implants. Hip luxation with dorsal acetabular rim deficiency in a dog was successfully repaired with THR and dorsal acetabular rim augmentation using ULP and PMMA bone cement. This technique should be considered when conventional THR is precluded by dorsal acetabular rim deficiency.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.255-262
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• 2013

In this paper, a shape design sensitivity analysis(DSA) method is presented for Mindlin plates using an isogeometric approach. The isogeometric method possesses desirable advantages; the representation of exact geometry and the higher order inter-element continuity, which lead to the fast convergence of solution as well as accurate sensitivity results. Unlike the finite element methods using linear shape functions, the isogeometric method considers the exact normal vector and curvature of the CAD geometry, taking advantages of higher order NURBS basis functions. A selective reduced integration(SRI) technique is incorporated to overcome the difficulty of 'shear locking' phenomenon. This simple technique is surprisingly helpful for the accuracy of the isogeometric shape sensitivity without complicated formulation. Through the numerical examples of plate bending problems, the accuracy of the proposed isogeometric analysis method is compared with that of finite element one. Also, the isogeometric shape sensitivity turns out to be very accurate when compared with finite difference sensitivity.