• Computers and Concrete
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• v.16 no.4
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• pp.643-667
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• 2015

3-dimentional precast recycled aggregate concrete (RAC) finite element models were developed by means of the platform OpenSees to implement sophisticated nonlinear model subjected to seismic loads. Efforts were devoted to the dynamic responses (including dynamic characteristics, acceleration amplifications, displacements, story drifts) and capacity curve. In addition, this study extended the prediction on dynamic response of precast RAC model by parametric study of material properties that represent the replacement percentage of recycled coarse aggregate (RCA). Principles and assumptions that represent characteristics of precast structure and influence of the interface between head of column and cast-in-place (CIP) joint on the stiffness of the joints was put forward and validated by test results. The comparison between simulated and tested results of the precast RAC frame shows a good correlation with most of the relative errors about 25% in general. Therefore, the adopted assumptions and the platform OpenSees are a viable approach to simulate the dynamic response of precast frames made of RAC.

• Clinics in Shoulder and Elbow
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• v.25 no.2
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• pp.154-157
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• 2022

Periprosthetic joint infection (PJI) is one of the most devastating complications that can occur after shoulder arthroplasty. Although staged revision arthroplasty is the standard treatment in many cases, surgical intervention with debridement, antibiotics, and implant retention (DAIR) can be an effective option for acute PJI. We report a complex case of infected reverse shoulder arthroplasty (RSA) in a 73-year-old male. The patient had been previously treated for infected nonunion of a proximal humerus fracture caused by methicillin-resistant Staphylococcus epidermidis. He presented with a sinus tract 16 days after the implantation of RSA and was diagnosed with PJI caused by Serratia marcescens. The patient was successfully treated with DAIR and was free of infection at the last follow-up visit at 4 years postoperatively.

• Journal of Korean Foot and Ankle Society
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• v.26 no.4
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• pp.151-156
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• 2022

The proportion of patients with end-stage ankle arthritis is increasing. The leading surgical methods for treating patients with end-stage ankle arthritis are ankle arthrodesis and total ankle arthroplasty. Ankle arthrodesis is considered the standard treatment for end-stage ankle arthritis. Many studies have been conducted on the two procedures, but it is unclear which is superior, and total ankle arthroplasty cannot be said to be a clear indication. Therefore, this review compares the advantages and disadvantages of two representative surgical methods for treating end-stage ankle arthritis.

• Journal of Korean Association for Spatial Structures
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• v.23 no.4
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• pp.71-79
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• 2023

In this study, a prefabricated buckling brace (PF-BRB) was proposed, and a test specimen was manufactured based on the design formula for the initial shape and structural performance tests were performed. As a result of the experiment, all standard performance requirements presented by KDS 41 17 00 and MOE 2021 were satisfied before and after replacement of the reinforcement module, and no fracture of the joint module occurred. As a result of the incremental load test, the physical properties showed a significant difference in the stiffness ratio after yielding under the compressive load of the envelope according to the experimental results. It is judged necessary to further analyze the physical properties according to the experimental results through finite element analysis in the future.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.535-543
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• 2017

For column-beam gussets of wooden structures, slit-processed members inserted with a steel plate are used in general. In this study, a rigid portal frame bonded with a joint was fabricated and a semi-rigid portal frame was fabricated by making a wooden gusset, a replacement for steel plate, of which a half was integrated into the column member and the other half was joined with the beam member by drift-pins. The lateral strength performance of the wooden portal frame was compared with that of the steel plate-inserted joint portal frame. The lateral strength performance was evaluated through a perfect elasto-plasticity model analysis, sectional stiffness change rate, and short-term permissible shear strength. As a result of the experiment, the maximum strength of the rigid portal frame was lower than that of the steel plate-inserted joint portal frame. The yield strength and ultimate strength were calculated as 0.58 and 0.48, respectively, but the measurements of initial stiffness and cumulative ductility improved by 1.35 and 1.1, respectively. As a result of the perfect elasto-plasticity model analysis of the semi-rigid portal frame, the maximum strength was lower than that of the rigid portal frame, but the toughness after failure was excellent. Thus, the ultimate strength was higher by 1.05~1.07. The steel plate-inserted portal frame showed rapid decrease in stiffness with the progress of repeated tests, but the stiffness of the portal frames with a wooden joint decreased slowly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5947-5955
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• 2013

This study was intended to estimate the axial deformation of joint between pavement modules in the rapid-constructible modular pavement system, and to investigate the applicability of two-phase composites for a joint material, which was composed of cement paste, epoxy, or polyurethane as a matrix and sand as particles. A case which had supports under the pavement module as well as a case which the module was put on roadbed directly were considered in FEM analysis for the axial deformation. The effect of self-weight, live load, thermal change, and drying shrinkage were estimated and the thermal change was found to cause the largest deformation compared to the others. Deformation capacity of two-phase composites was predicted using the modified shear-lag model. In the analytical results for the elastic modulus and maximum tensile strain with different volume fractions of sand, 20~30 % replacement of sand was revealed to satisfy the required strain capacity with economy when if the width of joint was designed to be 15~20 mm.

• Journal of the Korean Orthopaedic Association
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• v.54 no.4
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• pp.317-326
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• 2019

Purpose: To compare and analyze the rate of prevention of two venous thromboembolism prophylaxis guidelines in patients with artificial joint arthroplasty and hip joint fracture. Proper prophylaxis for preventing thromboembolism in orthopedic surgery is significant because of this fetal complication. Materials and Methods: This study compared and retrospective analyzed the rate of prevention using the medical records and radiographs of patients who underwent orthopedic surgery from March 2009 to February 2011 according to the American College of Chest Physicians (ACCP) guidelines and from March 2012 to February 2014 according to the American Academy of Orthopedic Surgeons (AAOS) guidelines. Results: The guidelines for venous thromboembolism prophylaxis have been applied to patients with artificial joint replacement and hip joint fracture, the compliance rate of the ACCP guidelines was 56.0% before surgery, 67.0% after surgery with chemical prophylaxis, and 80.5% with mechanical prophylaxis. In addition, the compliance rate of the AAOS guidelines was 74.1% with chemical prophylaxis, and 88.3% with mechanical prophylaxis, which was higher than the ACCP guidelines. The compliance rates of mechanical and chemical prophylaxis before and after surgery of the ACCP guidelines, and the compliance rate of mechanical and chemical prophylaxis of the AAOS guidelines were compared and analyzed. The results revealed statistical significance (p<0.05) before and after total knee replacement arthroplasty and hip joint fracture internal fixation and total high risk orthopedic surgery. Conclusion: Raising the compliance rate of prophylaxis of venous thromboembolism in high risk orthopedic surgery is necessary and people should follow the guidelines for a unified direction depending on which situation they are in.

• The Journal of the Korean bone and joint tumor society
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• v.10 no.2
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• pp.120-123
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• 2004

Benign and malignant bone tumors occur most commonly around the knee. The proximal tibia is the most technically demanding site for limb salvage surgery. The most difficult problem using an endoprothesis for proximal tibial resection has been reconstruction of the extensor mechanism. After excision of proximal tibia, we resected distal femur and made a composite with resected distal femur, low heat treated autogenous proximal tibia and endoprothesis. Patella was fixed into the resected down-loaded distal femur. This article shows the new technique and the results of reconstruction of extensor mechanism after prosthetic replacement of the proximal tibia.

• Advances in concrete construction
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• v.2 no.4
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• pp.249-259
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• 2014

Mortar is a masonry product which is matrix of concrete. It consists of binder and fine aggregate and moreover, it is an essential associate in any reinforced structural construction. The strength of mortar is a special concern to the engineer because mortar is responsible to give protection in the outer part of the structure as well as at a brick joint in masonry wall system. The purpose of this research is to investigate the compressive strength and tensile strength of mortar, which are important mechanical properties, by replacing the cement and sand by stone dust. Moreover, to minimize the increasing demand of cement and sand, checking of appropriateness of stone dust as a construction material is necessary to ensure both solid waste minimization and recovery by exchanging stone dust with cement and sand. Stone dust passing by No. 200 sieve, is used as cement replacing material and retained by No. 100 sieve is used for sand replacement. Sand was replaced by stone dust of 15%, 20%, 25%, 30%, 35%, 40%, 45% and 50% by weight of sand while cement was replaced by stone dust of 3%, 5%, and 7% by weight of cement. Test result indicates that, compressive strength of specimen mix with 35% of sand replacing stone dust and 3% of cement replacing stone dust increases 21.33% and 22.76% respectively than the normal mortar specimen at 7 and 28 days while for tensile it increases up to 13.47%. At the end, optimum dose was selected and crack analysis as well as discussion also included.

• Journal of Biomedical Engineering Research
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• v.29 no.3
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• pp.212-221
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• 2008

The total hip replacement (THR) has been used as the most effective way to restore the function of damaged hip joint. However, various factors have caused some side effects after the THR. Unfortunately, the success of the THR have been decided only by the proficiency of surgeons so far. Hence, It is necessary to find the way to minimize the side effect caused by those factors. The purpose of this study was to suggest the definite data, which can be used to design and choose the optimal hip implant. Using finite element analysis (FEA), the biomechanical condition of bone cement was evaluated. Stress patterns were analyzed in three conditions: cement mantle, procimal femur and stem-cement contact surface. Additionally, micro-motion was analyzed in the stem-cement contact surface. The 3-D femur model was reconstructed from 2-D computerized tomography (CT) images. Raw CT images were preprocessed by image processing technique (i.e. edge detection). In this study, automated edge detection system was created by MATLAB coding for effective and rapid image processing. The 3-D femur model was reconstructed based on anatomical parameters. The stem shape was designed using that parameters. The analysis of the finite element models was performed with the variation of parameters. The biomechanical influence of each parameter was analyzed and derived optimal parameters. Moreover, the results of FE A using commercial stem model (Zimmer's V erSys) were similar to the results of stem model that was used in this study. Through the study, the improved designs and optimal factors for clinical application were suggested. We expect that the results can suggest solutions to minimize various side effects.