• Clinics in Shoulder and Elbow
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• v.10 no.1
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• pp.50-58
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• 2007

Purpose: To report our experience with nine cases of pathologic synovial plica on radiohumeral joint which symptom of painful snapping elbow was improved by arthroscopic resection. Materials and Methods: Between 1999 and 2004, 43 cases of elbow arthroscopy were performed by one surgeon. Eight patients with nine cases showed pathologic synovial plica in conjunction with snapping or posterolateral elbow pain. The mean age of eight patients (man: 7, woman: 1) was 29 years (range $16{\sim}56$ years). All patients had a trial of conservative treatment at least six months (range $6{\sim}16$ months). The diagnosis was confirmed before surgery in six cases and at the time of surgery in three cases. Pain, snapping, and subjective results were evaluated at least 12 months in the average(range $12{\sim}24$). Results: All patients showed a hypertropic lateral synovial plica with local synovitis. Seven of them had an associated lesion of chondromalacia on radial head. One of them was associated with radiocapitellar arthritis and had a wrapping over the radial head. Six patients experienced improved posterolateral pain at the end of study (VAS<1). However, the other two patients had occasional pain with activity. One of them persisted with mechanical symptoms, which was treated with additional arthroscopic procedure. Conclusion: Synovial plica in elbow should be considered as an important entity of common elbow disease, especially when pain in the lateral aspect of the elbow with a snapping sensation during motion is featured in patients. The arthroscopic resection seems to be safe and efficient in the short and long term treatment of plica in the elbow joint.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.19-24
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• 2020

The interest in renewable energy is increasing due to the depletion of fossil fuels. In particular, active research on wave power, which is highly predictable and abundant, is being conducted. The coaxial accelerator-type wave power generator used in this study was designed to improve the power generation efficiency by converting bidirectional linear motion into a rotational force. In an offshore engineering basin, waves were generated, and case tests were performed according to the wave period and wave height. The experimental results were verified by the theoretical method related to the frequency response, and the overall trend was confirmed to be consistent. These results are expected to be useful in estimating the power of wave generators and designing parameters to improve the efficiency of wave energy in the design stage before manufacturing. In addition, the manufacturer can predict the wave energy efficiency of wave generators, which can reduce the development time and cost by preventing trial and error processes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.11
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• pp.1006-1015
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• 2016

This paper presents preliminary design and performance analysis of a fast and high precision Tracking Mount for 1m Satellite Laser Ranging(SLR) which is development by Korea Astronomy and Space science Institute(KASI). SLR is considered to be the most accurate technique currently available for the precise orbit determination of Earth satellites. The SLR technique measures the time of flight between pulses emitted from laser transmitter and pulses returned from satellites with laser retro-reflector array. It provides millimeter level precision of range measurements between SLR stations and satellites. A fast and high precision Tracking Mount for SLR which is proposed in this research should be capable of day and nighttime laser tracking about the satellites with laser reflectors from 200 km to 36,000 km altitude(geosynchronous orbit). In order to meet this requirement, we performed mechanical design and structural analysis for Tracking Mount. Also we designed the motion control system and conducted pre-performance analysis to obtain good performance results for a fast and high precision Tracking Mount.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.569-578
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• 2003

This paper presents a method in which the user produces a real-time facial animation by navigating in the space of facial expressions created from a great number of captured facial expressions. The core of the method is define the distance between each facial expressions and how to distribute into suitable intuitive space using it and user interface to generate realtime facial expression animation in this space. We created the search space from about 2,400 raptured facial expression frames. And, when the user free travels through the space, facial expressions located on the path are displayed in sequence. To visually distribute about 2,400 captured racial expressions in the space, we need to calculate distance between each frames. And we use Floyd's algorithm to get all-pairs shortest path between each frames, then get the manifold distance using it. The distribution of frames in intuitive space apply a multi-dimensional scaling using manifold distance of facial expression frames, and distributed in 2D space. We distributed into intuitive space with keep distance between facial expression frames in the original form. So, The method presented at this paper has large advantage that free navigate and not limited into intuitive space to generate facial expression animation because of always existing the facial expression frames to navigate by user. Also, It is very efficient that confirm and regenerate nth realtime generation using user interface easy to use for facial expression animation user want.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.1
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• pp.1-5
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• 2008

Purpose: We studied the diagnostic value of dynamic US in the extensor tendon dislocation at the metacarpophalangeal joint. Materials and Methods: From January 2007 to October, we studied 6 cases that had been diagnosed and followed over 5 months (2-10) in average. US examination using a 10-MHz linear transducer were performed in three cases. The causes of dislocations were traumatic in 5 cases and congenital in one case. Results: In only 3 cases which could not be diagnosed clinically, we performed US. In dynamic US, all three cases showed the extensor tendon dislocation evidently. Operative findings were sagittal band rupture in 4 cases, capsular loosening in one case and sagittal band thinning in one case. Sagittal band repair was performed in 4 cases and capsular augmentation in one case. In case of congenital dislocation showing 4 digital extensor tendon dislocations in right hand, we operated only the second extensor by sagittal band repair with augmentation by looping. At last follow-up, no case showed recurrence or limitation of motion. Conclusion: In case of extensor tendon dislocation without apparent clinical finding, US with dynamic study has so great value that it can detect the dislocation in real time, which is superior to MRI.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.705-713
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• 2018

An automotive ball joint connects the suspension system to the steering system and helps to enable rotational and linear motion between the two elements for steering. This study examines a ball joint used in medium and large-sized pickup trucks. Ball joints consist of a stud, socket, bearing, and plug. The main structural performance metrics of ball joints are the pull-out strength and push-out strength. These structural parameters must meet certain criteria to avoid serious accidents. Test and simulation methods are used to investigate the design requirements, but tests are time-consuming and costly. In this study, we modeled ball joints in SolidWorks and performed a finite element analysis in Abaqus to predict structural performance. The analysis was used to obtain the structural performance required for the static analysis of a 2D axisymmetric model. The uncertainties in the manufacturing of the ball joint were assumed to be the manufacturing tolerances, and the dimensional design variables were identified through case studies. The manufacturing tolerances at each level were defined, and the results were compared with experimental results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.794-801
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• 2017

When a radial wheel is placed so as to partially overlap a conductive plate and rotated, a lift force is generated on the wheel, a thrust force along the edge, and a lateral force which tends to reduce the overlap region. When several of these wheels are combined, it is possible to realize a system in which the stability of the remaining axes is ensured, except in the traveling direction. To validate the overall characteristics of the multi-wheel system, we propose a transfer system levitated magnetically using radial electrodynamic wheels. The proposed system is floated and propelled by four wheels and arranged in a structure that allows the thrusts generated by the front and rear wheels to offset each other. The dynamic stability of the wheel and the effect of the pole number on the three-axial forces are analyzed by the finite element method. At this time, the thrust and levitation force are strongly coupled, and the only factor affecting them is the wheel rotation speed. Therefore, in order to control these two forces independently, we make use of the fact that the ratio of the thrust to the levitation force is proportional to the velocity and is independent of the size of the gap. The in-plane and out-of-plane motion control of the system is achieved by this control method and compared with the simulation results. The experimental results show that the coupled degrees of freedom can be effectively controlled by the wheel speed alone.

• Clinical and Experimental Reproductive Medicine
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• v.21 no.1
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• pp.1-11
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• 1994

The occurrence and time course of capacitation, acrosomal loss, and hyperactivated motility require quantitative definition in order to characterize fertile human sperm. Recently the method has been developed to estimate the quality of spermatozoa by using kinematic parameters such as curvilinear velocity(VCL), average path velocity(VAP), linearity(LIN), straightness(STR), amplitude of lateral head displacement(ALH), and beat cross frequence(BCF) from Computer Assisted Sperm Analysis (CASA). In this study, using the Hamilton Thorn motility analyzer HTM 2030(Hamilton Thorn Research, Beverly, MA), we attempted to identify the spermatozoa with hyperactivated motility (HA) objectively and to monitor hyperactivation of human spermatozoa during incubation in capacitating media and after treatment of calcium ionophore as compared with acrosome status. And we examined whether HA are related to the result of SPA. Semen samples obtained from 16 healthy men were prepared by swim up technique and preincubated in a capacitating media(modified BWW medium) for 5 hours and treated with calcium ionophore solution. The acrosome reaction was detected with PSA-FITC labelling of the acrosome and in vitro sperm ferilizing capacity was assessed by the zona free hamster ovum penetration assay (SPA). The incidence of hyperactivated sperm was 2.6% in fresh semen, 14.3% of the swim up population, 13.7% after 5h of incubation. Significant increase of percentage of hyperactivated sperm was observed after the incubation (p<0.05) but after treatment, no significant changes of percentage of hyperactivated sperm(l1.8%) in contrast to significant rise in the percentage of acrosome reacted cells. Correlation analysis failed to show any significant relationship between the percentage of sperm with HA and SPA score. In conclusion, although no direct correlations were found between the results of SPA and HA, hyperactivation of sperm is associated with capacitation and monitoring hyperactivated sperm will be expected as a method of evaluating the functional quality of sperm such as SPA.

• Journal of Yeungnam Medical Science
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• v.3 no.1
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• pp.361-366
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• 1986

Fracture of the carpal scaphoid bone is the most common fracture of the carpus. Unfortunately. nonunion are common since the symptoms do not alert patients to seek early medical treatment and the diagnosis is easily missed. Fracture of the scaphoid is a common condition whose management remains controversial. The conservative treatment has many complications, these include inability to work while in plaster, stiffness of the wrist afterwards, muscle wasting, weakness and malunion. So various operative treatments of scaphoid fracture have been developed. Open reduction by use of screws suggested by Maclaughlin first in 1954. In 1984 a new and simple operative technique has been developed to provide rigid internal fixation for all types of fractures of the scaphoid by T.J. Herbert. This involves the use of a double-treaded bone screw which provides good fixation that, after operation, a plaster cast is rarely required and most patients are able to return to work within a few weeks. Authors have experienced 10 cases of scaphoid fracture and accomplished good result in all cases by internal fixation using Herbert screw. The results are as follows : Of these 10 fractures, 2 were fresh fractures and 8 were non unions of scaphoid fracture. In nonunion cases, the time interval between fracture and operation was from 5 months to 5 years. The postoperative immobilization period was average of 4 weeks. Short period of immobilization achieved early functional recovery of the wrist. The bony unions in roentgenogram were seen from 3 months to 9 months after operation. In 2 cases the fracture gap was seen after 9 months. But in these cases the symptoms such as pain and range of motion of wrist were improved.

• Journal of the Korean Arthroscopy Society
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• v.3 no.2
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• pp.102-108
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• 1999

Purpose : The purpose of this study was to evaluate the clinical results of bone-patellar tendon-bone(B-PTB) allograft for ACL reconstruction without mechanical tensioning device. Material and Method : Forty-six knees in 43 patients were reviewed and evaluated with subjective evaluation, objective evaluation, Telos stress arthrometer and modified Feagin Scoring System. The average age at the time of operation was 27 years(range, 18-42) and the average follow up period was 41 months(range, 22-79). Authors reconstructed ACL using B-PTB allograft which was prepared by rehydration preoperatively without tensioning by mechanical tensioning device. The tension for allograft was obtained by full flexion and extension intraoperatively. All operation were performed arthroscopically by two-tunnel method to avoid the mismatching of allograft tendon length. Result : The modified Feagin Scoring System revealed 39 cases(84.7%) with excellent or good results and 7 cases(15.3%) with fair or poor results. The mean follow-up Lysholm Knee Score was 84. Telos arthrometer revealed 41 cases had an injured-to-uninjured difference of 5 mm or less(mean 2.3mm). The range of motion of knee was nearly normal and there was no extension lag in any cases at last follow up. Conclusion : Clinical results using B-PTB allograft showed less morbidity than B-PTB autograft. The intraoperative tensioning method by full flexion and extension without mechanical tensioning device was not bad. Therefore, B-PTB allograft is a good substitute material in reconstruction of the ACL.