• Tribology and Lubricants
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• v.36 no.1
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• pp.34-38
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• 2020

The powertrain of the waterjet system of a special-purpose vehicle makes use of the cardan shaft, which is composed of universal joints and shafts. These universal joints, composed of spiders and needle roller bearings, have to be designed with consideration for the bending and compressive stresses of the spiders and needle roller bearings, and the rating lives of the bearings. The bending and compressive stresses of the spider and bearing of a universal joint have been studied by many researchers. However, to design a universal joint effectively, overall consideration of the different specifications of needle roller bearings is necessary. In this study, the bending stresses of spiders and compressive stresses of needle roller bearings are calculated to design universal joints for powertrain cardan shafts with different roller diameters of bearing. Furthermore, the rating lives of the needle roller bearings are predicted using the calculated basic dynamic load ratings of the bearings. As a result, roller diameters less than 𝜙2.5 mm are found suitable through an analysis of the bending stress of the spider. All compressive stresses between spider and bearing, regardless of roller diameter, satisfy the requirements. Moreover, roller diameters of more than 𝜙2 mm are found suitable for the required rating life.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.592-599
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• 2014

A torsional vibration at driveline happens seriously at rapid vehicle acceleration. The torsional vibration at driveline can be reduced by optimization of joint angle and yoke phase angle of driveline. But, the joint angle of driveline is changed according to vehicle driving condition as acceleration, deceleration, forward and backward driving, so that excessive vibration is transmitted to vehicle body at specific driving condition. Especially under rapid acceleration condition, vibration transmitted to body could be maximized because excitation force at rapid acceleration is bigger than that at normal driving condition due to changed joint angle. The torsional vibration of driveline can be kept at low level by controlling suspension parameter to minimize rigid axle displacement as well as optimizing joint angles considering the vehicle acceleration condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.198-208
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• 1996

The plunge joints of C.V. Joint for vehicle tend to produce a cyclic axial disturbance at a frequency of three of six times shaft speed, in which this distrubance caused by internal frictional effect is related to joint angle, rotational speed, torque, and joint size. This principal axial thrust force might make vehicle shuddered when coinciding with vehicle frequency of tranverse direction, and be one of reasons to have driver feel uncomfortable, unesay, while driving vehicle. The paper makes analysis of axial thrust force & vehicle shudder through computer simulation, comparing the result with experimental data, and reviewing the effect by changing of variables such as dimensions and driving conditions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.153-159
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• 2018

This paper suggests a way to improve the strength of the driveshaft, which is a vulnerable part of the drive axle system, for a 3.5-ton commercial vehicle. The driveshaft is composed of a universal joint with a spider and yoke, yoke shaft, etc. The driveshaft is developed by choosing design parameters for the spider and yoke such as the diameter and distance through the structural analysis of the driveshaft's components. Some driveshaft design cases have been made and analyzed with ANSYS; the strength of the driveshaft parts are validated from these results to propose an optimal design case. Finally, we suggest a driveshaft system that satisfies the working conditions for a 3.5-ton commercial vehicle.

• Clinics in Shoulder and Elbow
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• v.18 no.1
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• pp.47-51
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• 2015

Iatrogenic damage of the rotator cuff followed by postoperative shoulder function loss is a potential complication after antegrade intramedullary nailing (AIN) for a humeral fracture. The authors present a case of arthroscopic rotator cuff repair and subacromial decompression of a non-healed rotator cuff tendon (mainly supraspinatus) and secondary impingement syndrome caused either by the tear or a proud nail after AIN for a mid-shaft humeral fracture. At presentation, the patient complained of right shoulder pain and 'snapping', especially during forward elevation and abduction of the shoulder, of 4 years duration. Right shoulder pain started sometime after pain due to the humeral shaft fracture, operation had subsided, and persisted after nail removal. Arthroscopic findings showed a longitudinal rotator cuff tear at the nail entry point that had not healed and severe fibrous hypertrophy on the acromion underspace, which is a unique finding since most longitudinal splits of tendon fibers are more likely to heal than conventional rotator cuff tears detached from bone. The torn rotator cuff was repaired after debridement and placing side-to-side sutures. At his 34-month follow-up after rotator cuff repair, the patient showed complete recovery and had excellent clinical scores.

• Clinics in Shoulder and Elbow
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• v.20 no.2
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• pp.95-99
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• 2017

Background: The purpose of this study was to investigate the clinical and radiological outcomes of locking plate fixation with fibular strut allograft to manage unstable osteoporotic proximal humerus fractures. Methods: We retrospectively reviewed 15 patients who underwent open reduction and locking plate fixation with fibular strut allograft for osteoporotic proximal humerus fracture between July 2011 and June 2015. For functional evaluation, we evaluated visual analogue scale (VAS) pain score, American Shoulder and Elbow Surgeons (ASES) score, University of California Los Angeles (UCLA) shoulder score, and active range of motion. For radiological evaluation, shoulder true anteroposterior (AP) and AP in $20^{\circ}$ external rotation, as well as the axillary view were taken at two weeks, six weeks, three months, six months, and one year. And the neck-shaft angle was measured on the AP view in $20^{\circ}$ external rotation view. Results: At the one-year follow-up, mean VAS pain score and all shoulder scores, including ASES score and UCLA shoulder score, exhibited satisfactory clinical outcomes. All patients obtained bone union between three and six months post-procedure. Moreover, the mean immediate postoperative neck-shaft angle was $138^{\circ}{\pm}4^{\circ}$, and at one-year follow-up, the neck shaft angle was $137^{\circ}{\pm}5^{\circ}$. There was no significant difference between the preoperative and postoperative values (p=0.105). Conclusions: For the unstable two-part and three-part osteoporotic proximal humerus fractures with medial calcar comminution, the use of fibular strut allograft with locking plate fixation was effective in maintaining the initial status of reduction and exhibiting the satisfactory functional and radiological outcomes.

• Journal of Korean Foot and Ankle Society
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• v.9 no.2
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• pp.135-139
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• 2005

Purpose: This study was performed to investigate the radiological characteristics of the degenerative arthritis of the ankle using the standing radiographs. Materials and Methods: From June 2001 to May 2005, 36 patients (56 ankles) who were treated for osteoarthritis of ankle were analysed. Angle of tibial shaft and tibial joint surface on AP view (TSA), angle of tibial joint surface on lateral view (TLS), tibial and medial malleolus angle (TMM) and talo-1st metatarsal angle were checked on standing radiograph. The patients with medial joint and total joint involvement were categorized into three stages according to the location of involvement. The degree of joint space narrowing was categorized into two groups. Results: There were no significant differences in TSA, TLS, TMM and talo-1st metatarsal angle with regard to the stage of arthritis. However, the difference between the less severe group and the severe group existed. Conclusion: Angular deformity was not correlated with stage, but correlated with severity. The deformity of distal tibial articular surface does not seem to be a cause of primary osteoartiritis, but rather a result from it.

• The Journal of Korean Society for Neurotherapy
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• v.22 no.3
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• pp.43-48
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• 2018

Purpose The purpose of this study is to identify the prevalence, risk factors, characteristics, and interventions of hip joint problems in children with cerebral palsy, and to be able to serve as leverage for early detection, prevention, and function recovery. Method The electronic journal site was searched by the search terms "cerebral palsy", "hip joint", "hip joint dislocation", we analyzed and descript the cited articles from domestic and foreign papers in Pubmed 9, Science Direct 7, and K RISS analysis and analysis. Results Children with cerebral palsy showed the different prevalence according to their disability type, severity, and functional level, and we knew that abnormal neuromuscular control, stiffness, and biomechanical changes could be risk factors. Migration Index, Acetabolum Index, Neck shaft angle using by radiography and passive ROM test, special tests were available for the diagnosis and evaluation of the hip joint. Combination of physical therapy and orthopedic surgery was very important intervention, and complementary alternative therapy, orthosis, and postural assistant are effective. Conclusion We suggested that early detection and prevention is the most important periodic examination and that a multidisciplinary approach is a major factor in intervention.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.2
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• pp.119-128
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• 2008

In the case of a circular shaft, it is expected that asymmetric loads should apply on the surface rather than symmetric loads due to geographical factors and the non-homogeneity of the jointed rock masses. In this study, discontinuous numerical analysis was carried in order to analyze the characteristics of asymmetric load distribution on the wall of the circular shaft due to anisotropy caused by heterogeneity of rock masses affected by the discontinuities like as a Joint. And it was also analyzed that the effect of the mechanical properties varied with the rock mass rating and horizontal stress with depth had influence in the asymmetric load on the wall of the shaft. In the case of considering the effect of the joint as variable, asymmetric load ratio $(R_p)$, which was defined as the ratio of the load subtracted minimum from maximum to minimum, was below 25% in the hard rock. As regarding the variation of the rock mass rating with depth as variable, the value of $R_p$ was below than 25% in the hard rock, and the value between 30% and 40% in the soft rock. On the other hand, the $R_p$ of fractures rock was between $45{\sim}50%$ which value was much higher than that in better rock mass rating.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.137-145
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• 1991

A universal joint is a connecting device of two hinges which can transmit torque from one shaft to another at fixed or at varying angles of intersection. It has been used properly not only as rotational but also as intermittent motion. For the particular kinematics condition of a universal joint, torsional and bending vibrations are produced excessively in an elastic driveline. In this paper only the torsional vibration behavior of a driveline with universal joints is analyzed numerically with the discrete model and a design method of the dynamic vibration damper is proposed, in order to reduce torsional vibrations especially in resonance region as a result of parametric variation.