1,036 research outputs found
AN ASSIGNMENT METHOD FOR THE PART-MACHINE CELL-FORMATION PROBLEM IN THE PRESENCE OF MULTIPLE PROCESS ROUTES
No full textThis paper considers the part-machine cell formation decision of the generalized Group Technology (GT) problem in which multiple process routes can be generated for each part. The existing p-median model and similarity coefficient algorithm can solve only small-sized or well-structured cases. An assignment method for the cell formation problem is suggested. This method uses an assignment model which is a simple linear programming. Numerical examples show that the assignment method provides good separable cell formation even for large-sized and ill-structured problems
Kinematically Aligned Total Knee Arthroplasty with Patient-Specific Instrument
No full textKinematically aligned total knee arthroplasty (TKA) is a new alignment technique. Kinematic alignment corrects arthritic deformity to the patient's constitutional alignment in order to position the femoral and tibial components, as well as to restore the knee's natural tibial-femoral articular surface, alignment, and natural laxity. Kinematic knee motion moves around a single flexion-extension axis of the distal femur, passing through the center of cylindrically shaped posterior femoral condyles. Since it can be difficult to locate cylindrical axis with conventional instrument, patient-specific instrument (PSI) is used to align the kinematic axes. PSI was recently introduced as a new technology with the goal of improving the accuracy of operative technique, avoiding practical issues related to the complexity of navigation and robotic system, such as the costs and higher number of personnel required. There are several limitations to implement the kinematically aligned TKA with the implant for mechanical alignment. Therefore, it is important to design an implant with the optimal shape for restoring natural knee kinematics that might improve patient-reported satisfaction and function
Treatment of Femoral Neck Fractures in the Elderly: A Survey of the Korean Hip Society Surgeons
No full textPurpose: This study examined the methods for treatment of femoral neck fracture (FNF) preferred by members of the Korean Hip Society (KHS) and identified factors that influence decisions regarding the surgical intervention of choice. Materials and Methods: A total of 97 members of the KHS responded to the 16-question survey which includ-ed questions about the mean number of surgeries performed each month for treatment of femoral neck fractures, the cut-off age for deciding between internal fixation and arthroplasty, the implant used most often, usage of cement, and factors influencing each decision. Results: The mean cut-off age used when deciding between internal fixation and arthroplasty was 64 years old. Hemiarthroplasty (HA) (70%) was the most preferred option for treatment of displaced FNFs in cases where arthroplasty was indicated (total hip arthroplasty [THA] 19% and dual mobility THA 11%). The main reasons for selection of arthroplasty over reduction with internal fixation were age and pre-fracture ambulatory status. Pre-trauma ambulatory status and/or sports activity were the main factors in selection of HA over THA. Cement was used by 33% of responders. Poor bone quality and a broad femoral canal were factors that influenced the usage of cement. Conclusion: Management of FNFs in the elderly is a major health problem worldwide; thus, remaining alert to current trends in treatment is essential for surgeons. The mean cut-off age used in deciding between internal fixation and arthroplasty was 64 years old. HA is the preferred method for treatment of displaced FNFs for members of the KHS
Prevention of Venous Thromboembolism in Patients Undergoing Hip Fracture Surgery: A Survey of the Korean Hip Society
No full textPurpose: The aim of this study was to assess the current status of venous thromboembolism (VTE) prevention in Korean patients with hip fractures. Materials and Methods: A survey using a questionnaire on the experiences and protocols of VTE prevention was conducted among 570 members of the Korean Hip Society. Results: A total of 97 surgeons responded, with a response rate of 17.0%. Of the 97 participants, 61.9% answered that they had encountered one or more cases of symptomatic VTE in the past year. Mechanical prophylaxis was applied most often (30.9%) until the point of ambulation in standard-risk patients and most often (34.0%) extended until discharge in high-risk patients. Chemical prophylaxis was most often prescribed for a particular period of time rather than for recovery of walking ability (24.7% in standard-risk patients and 26.8% in high-risk patients). Dual prophylaxis was administered in the standard-risk group by 58.8% of the participants and in the high-risk group by 83.5%. Among the participants, 73.2% answered that they had been attentive to wound complications during chemical prophylaxis. More than half of the participants (59.8%) reported that they did not perform routine screening for VTE after surgery. Conclusion: The results of our survey provided information regarding the current status of VTE prevention for patients undergoing surgery for treatment of hip fractures in Korea as well as a baseline for establishment of edu-cational programs and guidelines in the future
The Morphology of a Kinematically Aligned Distal Femoral Osteotomy Is Different from That Obtained with Mechanical Alignment and Could Have Implications for the Design of Total Knee Arthroplasty
No full textBackground: Kinematically aligned total knee arthroplasty (KA-TKA) may lead to a different pattern of osteotomy from mechanically aligned total knee arthroplasty (MA-TKA). This paper aims to analyze the effects of KA and MA on the morphology of the distal femoral osteotomy surface. Methods: Computed tomography scans of 80 TKA candidates were reconstructed into 3D models. The measurement of bone morphology was performed after the distal femur cut according to two different alignment techniques. The aspect ratio, trapezoidicity ratio, and asymmetry ratio of the distal femur were assessed. Results: The aspect ratio and the asymmetry ratio in the KA group was significantly lower than that in the MA group in the general population (p < 0.001). The trapezoidicity ratio in the KA group was significantly higher than that in the MA group in the general population (p < 0.001). Conclusions: It was found that KA-TKA and MA-TKA presented different morphologies of the distal femoral osteotomy surface, and this difference was also influenced by gender. The surgery pattern of KA-TKA and MA-TKA and gender should be considered when surgeons choose femoral prostheses
One-fluid mixing rules for cubic equations of state : III. Solubility of pure solids in supercritical mixed solvents
No full textThe financial support of Korea Science and
En-gineering foundation is gratefully acknowledged
A 3-D X-ray microtomographic system with a CMOS image sensor
No full textHigh-resolution and three-dimensional X-ray imaging is becoming more and more popular. An X-ray microtomographic system with a CMOS image sensor has been developed. We have developed a novel area X-ray detector with a cost-effective CMOS image sensor. The sensing area of the detector is 55 x 55 mm(2) and the light from the phosphor screen is collected to the CMOS image sensor by a carefully designed optical system. Six lenses are assembled to reduce the radiation damage effect and increase the resolution and sensitivity. A microfocus X-ray tube that can reach up to 5 mum of focal spot size and microprecision motor system that can move in x-y-z directions for both alignment and magnification and rotate the object have been adopted. A conventional three-dimensional cone-beam Feldkamp reconstruction algorithm was used and a human cancellous; bone has been imaged with this system. Currently, the resolution of this system is about 40 mum but the application in microtomography seems very promising using this CMOS X-ray detector
ONE-FLUID MIXING RULES FOR CUBIC EQUATIONS OF STATE .1. SOLUBILITY OF PURE SOLIDS IN SUPERCRITICAL FLUIDS
No full textOne-fluid mixing rules for cubic equations of state: II. Solubility of solid mixtures in supercritical fluids
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