• Nuclear Engineering and Technology
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• 제31권3호
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• pp.267-275
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• 1999

This paper deals with the industrial problem of thermal striping damage on the French prototype fast breeder reactor, Phenix and it was studied in coordination with the research program of IAEA. The thermomechanical and fracture mechanics evaluation procedure of thermal striping damage on the tee-junction of the secondary piping using Green's function method and standard FEM is presented. The thermohydraulic(T/H) loading condition used in the present analysis is the random type thermal loads computed by T/H analysis on the turbulent mixing of the two flows with different temperatures. The thermomechanical fatigue damage was evaluated according to ASME code section 111 subsection NH. The results of the fatigue analysis showed that fatigue failure would occur at the welded joint within 90,000 hours of operation. The assessment for the fracture behavior of the welded joint showed that the crack would be initiated at an early stage in the operation. It took 42,698.9 hours for the crack to propagate up to 5 mm along the thickness direction. After then, however, the instability analysis, using tearing modulus, showed that the crack would be arrested, which was in agreement with the actual observation of the crack. An efficient analysis procedure using Green's function approach for the crack propagation problem under random type load was proposed in this study. The analysis results showed good agreement with those of the practical observations.

• 한국생산제조학회지
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• 제25권6호
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• pp.492-497
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• 2016

Teaching an industrial robot is still a dangerous and time-consuming process. It is expected that a robot can track a trajectory that is repeatedly taught by a human operator. Teaching a robot in joint space is easier than that in Cartesian space or a work space because the robot will never lose its stability when it is taught and operated in a joint space. However, it is very easy for a robot to lose its stability when it is taught in a work space. This is because of the singular points problem in kinematics for manipulators. Thus, experts should teach a given task to a robot in a careful manner. A new algorithm that avoids the problem of singular points is proposed. Using this proposed method, a user can freely teach a robot without the chance of instability in an entire work space.

• 한국정밀공학회지
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• 제23권7호
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• pp.84-92
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• 2006

This paper deals with determination of motions of a humanoid robot using genetic algorithm. A humanoid robot has some problems of the structural instability basically. So, we have to consider the stable walking gait in gait planning. Besides, it is important to make the smoothly optimal gait for saving the electric power. A mobile robot has battery to move autonomously. But a humanoid robot needs more electric power in order to drive many joints. So, if movements of walking joint don't maintain optimally, it is hard to sustain the battery power during the working period. Also, if a gait trajectory doesn't have optimal state, the expected lift span of joints tends to be decreased. Also, if a gait trajectory doesn't have optimal state, the expected lift span of joints tends to be decreased. To solve these problems, the genetic algorithm is employed to guarantee the optimal gait trajectory. The fitness functions in a genetic algorithm are introduced to find out optimal trajectory, which enables the robot to have the less reduced jerk of joints and get smooth movement. With these all process accomplished by PC-based program, the optimal solution could be obtained from the simulation. In addition, we discuss the design consideration fur the joint motion and distributed computation of tile humanoid, ISHURO, and suggest its result such as structure of the network and a disturbance observer.

• 근관절건강학회지
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• 제14권1호
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• pp.5-12
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• 2007

Purpose: The purpose of the study was to identify the relationship between low back pain and job stress in hospital nurses. Method: A descriptive correlation research design was employed. The participants were 355 nurses who worked in a general hospital in W city Kangwon-do and consented to participate in this study. The Visual Analog Scale and job stress scale were used in this study. Analysis included descriptive statistics, t-test, ANOVA, and partial correlation coefficients. Results: Experience of low back pain for nurse in the past was 86.5% and in the present was 67.5% for low back pain which measured an average of 4.4 points for the level of low back pain. The mean score for job stress was relatively low(M=47.2). Job demand, organization system, job instability and conflict in relationships contributed to high stress scores, instead inappropriate compensation, job culture, and job autonomy contributed to low stress. There was a significant relationship between low back pain and job stress. Conclusion: These results suggest that further research is needed to develop programs to prevention and management of low back pain for nurses.

• 대한족부족관절학회지
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• 제23권4호
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• pp.201-207
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• 2019

An osteochondral fracture is considered to be an injury involving the cartilage and subchondral bone. Acute traumatic osteochondral fractures can be related to joint instability because abnormal joint motion causes shearing and rotatory stress. Acute osteochondral fractures are frequently missed or misdiagnosed as a pure soft tissue injury. Thus, surgeons' proactive attention is highly required as articular cartilage has limited potential for self-repair and these lesions may develop osteoarthritis. In order to minimize the progression of post-traumatic osteoarthritis, it is important to properly identify and treat osteochondral fractures. Yet, little is known about the operative management of acute osteochondral fractures of the talus. We report here on a case of a middle-aged male with acute osteochondral fractures of the bilateral lateral talar dome. We applied different operative methods on each side with regard to fragment size and stability. A favorable clinical outcome was obtained at 18 months follow-up.

• 한국운동역학회지
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• 제28권4호
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• pp.219-225
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• 2018

Objective: Epidemiological research shows that 47 to 73% of athletes suffer from recurrent ankle sprains. Joint mobilization techniques (JMT) implemented in correcting may be beneficial in the management of ankle injuries. The purpose of this study is to examine the immediate JM on ankle complex as clinical measures in individuals with chronic ankle instability (CAI) through intervention. Method: Thirteen subjects with CAI (8 males and 5 females) participated in this study. Each subject tried total four alignments (Navicular drop test: NDT, Standing rearfoot angle: SRA, Tibia torsion: TT, and dorsiflexion range of motion: DFROM). The participants were performed the 10 meter shuttle run after JMT for post-task. Finally, it was tried to compare between pre-post tasks after shuttle run. Results: SRA and DFROM after intervention showed significant differences. SRA (p=.026), and DFROM (p=.034). Conclusion: We concluded that the JMT has resulted in improvement in SRA, DFROM. Increased DFROM and varus shapes of foot would be closed kinetic chain, indicating that reduce the risk factors of ankle sprain. Future study needs to be conducted in order to measure the effects of prolonged intervention of JMT.

• 대한족부족관절학회지
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• 제25권4호
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• pp.177-180
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• 2021

Pediatric ankle fractures can cause physeal injuries which can lead to the shortening of the fibula. This induces a lateral shift of the talus, valgus tilt, and instability of the ankle joint, which can result in an arthritic change in this joint. Patients with a shortening of the fibula may complain of constant pain and restricted movements in their daily lives and during sports activities. Ankle reconstruction with fibula lengthening Z-osteotomy can provide excellent results if arthritis is absent or minimal, especially in young and active patients. To the best of the authors' knowledge, this is the first report in South Korea regarding the treatment of fibula shortening following a growth arrest due to injury.

• Hip & pelvis
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• 제35권1호
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• pp.15-23
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• 2023

Purpose: Hip microinstability is defined as hip pain with a snapping and/or blocking sensation accompanied by fine anatomical anomalies. Arthroscopic capsular plication has been proposed as a treatment modality for patients without major anatomic anomalies and after failure of properly administered conservative treatment. The purpose of this study was to determine the efficacy of this procedure and to evaluate potential predictors of poor outcome. Materials and Methods: A review of 26 capsular plications in 25 patients was conducted. The mean postoperative follow-up period for the remaining patients was 29 months. Analysis of data included demographic, radiological, and interventional data. Calculation of pre- and postoperative WOMAC (Western Ontario and McMaster Universities Osteoarthritis) index was performed. Pre- and postoperative sports activities and satisfaction were also documented. A P<0.05 was considered significant. Results: No major complications were identified in this series. The mean pre- and postoperative WOMAC scores were 62.6 and 24.2, respectively. The WOMAC index showed statistically significant postoperative improvement (P=0.0009). The mean satisfaction rate was 7.7/10. Four patients with persistent pain underwent a periacetabular osteotomy. A lateral center edge angle ≤21° was detected in all hips at presentation. We were not able to demonstrate any difference in postoperative evolution with regard to the presence of hip dysplasia (P>0.05), probably because the sample size was too small. Conclusion: Capsular plication can result in significant clinical and functional improvement in carefully selected cases of hip microinstability.

• Clinics in Shoulder and Elbow
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• 제26권3호
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• pp.302-305
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• 2023

The authors present a case of transient postoperative inferior subluxation of the shoulder after arthroscopic surgical stabilization for recurrent anterior dislocation. The patient was a 61-year-old woman with myasthenia gravis (MG). The first anterior shoulder dislocation occurred because of a fall to the ground. Despite a successful closed reduction, two more dislocations occurred in 3 weeks. Magnetic resonance imaging revealed an anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion, an engaging Hill-Sachs lesion, and large tears of the supraspinatus and infraspinatus tendons. The patient underwent arthroscopic rotator cuff repair and ALPSA repair with a remplissage procedure. Intraoperatively, no tendency for instability was found; however, a widened glenohumeral joint space and inferior subluxation of the humeral head without functional compromise was observed on the day after surgery and disappeared spontaneously on radiographs 2 weeks later. To the authors' knowledge, this is the first report documenting the occurrence of transient postoperative inferior subluxation of the shoulder in a patient with MG.

• 대한치과보철학회지
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• 제39권3호
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• pp.297-305
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• 2001

Statement of problem. There have been previous studies about instability according to screw material by means of calculating preload in tightening screw or recording of the torque necessary to loosen screw after tightening screw. Purpose. The purpose of this study was to evaluate screw joint stability through the analysis of fitness at the mating thread surfaces between implant and screw after tightening screws made of different materials. Material and methods. In this study, screws were respectively used to secure a cemented abutment to a hexlock implant fixture; teflon coated titanium alloy screw and titanium alloy screw(Steri-Oss), gold-plated gold-palladium alloy screw and titanium alloy screw(Implant Innovation), gold screw and titanium screw(AVANA Dental Implant System). Each abutment screw was secured to the implant with recommended torque value using a digital torque controller. Each screw was again tightened after 10minutes. All samples were cross sectioned with sandpaper and polished. Then samples were evaluated with an scanning electron microscope analysis. Results. In titanium alloy screw, irregular contact and relatively large gap was present at mating thread surface. Also in teflon-coated titanium screw, incomplete seating and only partially contact was present at the mating thread surface. In gold-plated gold-palladium alloy screw, relatively close and tight contact without the presence of large gap was present by existing of gold coating at the mating thread surfaces. In gold alloy screw, relatively small gap between the mating components was seen. Conclusions. This result suggested that gold plated gold-palladium alloy screw and gold alloy screw achieved a greater degree of contact at the mating thread surfaces compared to titanium alloy screw and teflon-coated titanium alloy screw.