• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.862-867
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• 2013

Torsional interaction between electrical network phenomena and turbine-generator shaft cause torsional stress on turbine-generator shaft and torsional fatigue fracture on vulnerable component, but the prediction of the torsional stress is difficult because the torsional stress is occurred instantly and randomly. Therefore continuous monitoring of the torsional stress on turbine-generator shaft is necessary to predict the torsional fatigue, but installing the sensors on the surface of the shaft directly to monitor the stress is impossible practically. In this study torsional vibration was measured using magnetic sensor at a point of turbine-generator rotor kit, the torsional stress of whole train of rotor kit was calculated using rotor kit's stress model and the calculated results were verified in comparison with the measured results using strain gauge at several point of turbine-generator rotor kit. It is expected that these experiment results will be used effectively to calculate the torsional stress of whole train of turbine-generator rotor in power plants.

• Clinics in Shoulder and Elbow
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• v.13 no.1
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• pp.1-6
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• 2010

Purpose: To evaluate the results and complications of antegrade intramedullary interlocking nailing in humerus shaft fractures. Materials and Methods: We evaluated the clinical outcomes, radiologic results and complications in 47 patients with humerus shaft fracture treated with antegrade intramedullary interlocking nailing, and followed up until bony union. Bony union was confirmed by serial plain radiographs and the clinical outcomes were assessed according to the ASES scoring system. Results: Bony union was confirmed in 41 (87.2%) out of a total 47 patients, and the mean union period was 14.5 weeks. Major complications were as follows: 6 non-union, 3 delayed union, 2 intraoperative posterior cortex fracture in the distal humerus and 2 permanent shoulder pain, including 1 case of adhesive capsulitis. The clinical outcomes were as follows: 29 excellent, 11 good, 4 fair and 3 poor. Satisfactory outcomes were demonstrated in 40 patients (85.1%). Conclusion: Anterograde intramedullary interlocking nailing as treatment for humerus shaft fracture showed satisfactory bony union and clinical outcomes. It is considered an efficacious treatment, especially in patients with associated injury, such as multiple fractures and segmental fracture.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.979-986
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• 2016

The tripod shafts of constant-velocity joint are used in both the trains KTX and KTX-sanchon. It is an important component that connects the motor reduction unit and the axle reduction unit in a power bogie. The tripod shaft not only transmits drive and brake torque in the rotational direction, but also slides in the axial direction. If the drive system is loaded with an excessive torque, the fuse part of the shaft will be fractured firstly to protect the other important components. In this study, a rig was developed for conducting torsion tests on the tripod shaft, which is a type of mechanical fuse. The tripod shafts were subjected to torsional fracture test and torsional fatigue test on the rig. The weak zone of the tripod shaft was identified, and its fatigue life was predicted using finite element analysis (FEA). After analyzing the FEA results, design solutions were proposed to improve the strength and fatigue life of the tripod shaft. Furthermore, the deterioration trend and time for failure of the tripod shaft were verified using the hysteresis loops which had been changed with the advancement of the torsional fatigue test.

• Journal of Korean Foot and Ankle Society
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• v.22 no.3
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• pp.95-99
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• 2018

Purpose: The purpose of this study was to evaluate the radiologic outcomes of distal fibular fractures and to analyze the risk factors associated with nonunion. Materials and Methods: Between January 2009 and March 2016, 13 patients who had final nonunion with ankle fracture were included. In the control group, 370 patients who had undergone bony union and removed metal implants were included. All patients underwent the same surgical procedure and had the same treatment method, ultimately achieving satisfactory open reduction results with less than 2 mm fracture gap. Surgical treatment of fracture was considered to have the same effect on nonunion, and factors that might be associated with nonunion were evaluated. SPSS ver. 13.0 (SPSS Inc., USA) was used for all statistical analyses. Pearson's chi-square test and multi-variate regression analysis were performed to determine the factors affecting nonunion of distal fibular fracture. A p-value less than 0.05 was considered statistically significant, and relative risk was assessed. Results: The mean age of 13 patients was 46.9 years (range, 16~57 years); there were 8 men and 5 women. Among the 13 patients with nonunion, atrophic was the most common (12 cases). The association between the injury mechanism and the Lauge-Hansen classification and diabetes mellitus was not statistically significant. Distal fibular fractures with tibia shaft fracture (p=0.015) and Danis-Weber type C fracture (p=0.023), open fracture (p=0.011), and smoking (p=0.023) were significantly associated with nonunion. Conclusion: In this study, the combined injury of the ipsilateral tibia shaft fracture, open fracture, and Danis-Weber type C fracture may increase the possibility of nonunion. Therefore, caution is advised to prevent nonunion.

• Journal of Korean Foot and Ankle Society
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• v.27 no.3
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• pp.87-92
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• 2023

Purpose: Concomitant ankle injuries associated with tibial shaft fractures can affect postoperative ankle joint pain and various postoperative ankle complications. This study compared the clinical outcomes between surgical treatment and conservative treatment of concomitant ankle injuries associated with tibial shaft fractures. Materials and Methods: From January 2015 to June 2020, a retrospective study was conducted on 118 tibia shaft fractures at the orthopedics department of the hospital. Associated ankle injuries were analyzed using plain radiographs, computed tomography (CT), magnetic resonance imaging (MRI), and intraoperative stress exams. The clinical outcomes were compared using the pain visual analog scale (pain VAS), American Orthopaedic Foot and Ankle Society Ankle-Hindfoot score (AOFAS score), and Karlsson-Peterson ankle score (KP score). Results: Seventy-two (61.02%) of the 118 cases were diagnosed with associated ankle injuries. Fifty-six cases underwent surgery for the ankle injury, and 16 cases underwent conservative treatment. The clinical results (according to the pain VAS score, AOFAS score, the KP score) were 1.79±1.26, 94.48±4.03, and 94.57±3.60, respectively, in the surgical treatment group, and 3.00±1.03, 91.06±3.02, and 91.25±3.31, respectively, in the conservative treatment group. Conclusion: Surgical treatment showed better clinical outcomes than conservative treatment in concomitant ankle injury in tibia fractures. Therefore, surgical treatment produces better clinical outcomes than conservative treatment in concomitant ankle injuries in tibia fractures. Hence to improve the clinical outcomes, more attention is needed on ankle joint injury in tibial shaft fractures for selecting suitable surgical treatments for those patients.

• Journal of Trauma and Injury
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• v.27 no.4
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• pp.151-157
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• 2014

Purpose: We report the surgical outcomes for femoral shaft fractures in polytrauma patients who were temporarily treated with external fixation and subsequently converted to internal fixation. Methods: From August 2008 to April 2012, we enrolled 13 patients with multiple traumas due to high-energy injuries and concurrent femoral shaft fractures in which temporary external fixation was carried out. The mean age was 39 years, with a range from 18 to 55 years. Ten were men and 3 were women. According to the AO/OTA classification of fractures, type A was found in 5 patients, type B in 6, and type C in 2, with open fractures being found in 6 patients and femoral artery rupture occurring in 2. For internal fixation, intramedullary nailing was performed in 7 patients, and minimally-invasive fixation of locking compression plates was used in 6. Results: Of the 7 patients converted to intramedullary nailing, 1 experienced delayed union. Of the 6 patients treated with minimally-invasive plate fixation, delayed union occurred in 5, and an auto-bone graft was performed within, on average, 8 months (range: 5~10 months), leading to bone union in all cases in the final follow-up. None of the patients experienced infections or complications involving other organs after having been converted to internal fixation. During the mean follow-up of 19 months, patients achieved satisfactory functional outcomes. Conclusion: In polytrauma patients with a femoral shaft fracture who have been treated with temporary external fixation and who may need internal fixation due to the occurrence of delayed union, an appropriate internal fixation method needs to be selected based on the patient's physical status, and the fracture type.

• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.1-8
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• 2023

Power transmission shafts in rotary wing aircraft use a hollow shaft to reduce weight. We can apply linear elastic fracture mechanics to predict crack propagation behavior. This paper predicted crack growth life of a hollow shaft with a circumferential through-type crack by finite element analysis. A 2D finite element model was created by applying a torsion and forming elements considering cracks. We defined the initial crack length and performed the finite element analysis by increasing the crack length to derive stress intensity factor at crack tips. We defined the length just prior to the stress intensity factor exceeding the fracture toughness as the crack limit length. We calculated the crack limit length using a handbook and numerically integrated the crack growth rate equation to derive growth life of each crack. The growth life of each crack was compared to verify the proposed finite element analysis method.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.72-79
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• 2008

To meet demand of big capacity and high speed rotation for washing machine, more stress from bending and twisting are complexly loaded onto the shaft supporting the horizontal drum, causing problems in fracture strength and fatigue life. Shafting system is mainly divided into flange and shaft. Shaft and flange connected by inserting shaft serration into flange on the process of die casting. When the system is operating, the gap is formed between serration and flange. But, Serration has various design factors and the optimal values can't be easily determined. Using a design of experiment (DOE) based on the FEM (Finite Element Method), this study was performed investigating the interaction effect between the various design factors as well as the main effect of the each design factor under bending, twist and vibration and proposed optimum design using box-behnken method among response surface derived from regression equation of simulation-based DOE.

• Transactions of Materials Processing
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• v.14 no.9 s.81
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• pp.779-784
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• 2005

MTS(Monobloc Tube Shaft) has been used for the reduction in weight of shaft and increase in supply of power in the auto industry nowadays. Cold drawing process having high productivity and reduction in the cost has been regarded as the effective technology that is able to substitute for swaging process as forming MTS with constant outer diameter or hollow shaft without surface defects. The objective of this study is not only to (md out the optimal process conditions understanding the effect of process parameters on carrying out cold drawing process of SIS(Steering Input Shaft) but also to control the defects resulted from inappropriate process conditions. Therefore, the proper drawing conditions are presented using FE-Analysis and experiment in the paper.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.431-434
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• 2005

MTS(Monobloc Tube Shaft) has been used for the reduction in weight of shaft and increase in supply of power in the auto industry nowadays. Cold drawing process having high productivity and reduction in the cost has been regarded as the effective technology that is able to substitute for swaging process as forming MTS with constant outer diameter or hollow shaft without surface defects. The objective of this study is not only to find out the optimal process conditions understanding the effect of process parameters on carrying out cold drawing process of SIS(Steering Input Shaft) but also to control the defects resulted from inappropriate process conditions. Therefore, the proper drawing conditions are presented using FE-Analysis and experiment in the paper.