• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.187-194
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• 2012

The strength of particle-reinforced metal matrix composites is, in general, known to be increased by the geometrically necessary dislocations punched around a particle that form during cooling after consolidation because of coefficient of thermal expansion (CTE) mismatch between the particle and the matrix. An additional strength increase may also be observed, since another type of geometrically necessary dislocation can be formed during extensive deformation as a result of the strain gradient plasticity due to the elastic-plastic mismatch between the particle and the matrix. In this paper, the magnitudes of these two types of dislocations are calculated based on the dislocation plasticity. The dislocations are then converted to the respective strengths and allocated hierarchically to the matrix around the particle in the axisymmetric finite-element unit cell model. The proposed method is shown to be very effective by performing finite-element strength analysis of $SiC_p$/Al2124-T4 composites that included ductile failure in the matrix and particlematrix decohesion. The predicted results for different particle sizes and volume fractions show that the length scale effect of the particle size obviously affects the strength and failure behavior of the particle-reinforced metal matrix composites.

• Clinics in Shoulder and Elbow
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• v.26 no.2
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• pp.205-207
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• 2023

A Monteggia fracture is a proximal ulnar fracture with proximal radioulnar ligamentous instability. While there is no precise definition, Monteggia-equivalent fractures are generally considered Monteggia fractures accompanied by radial head fractures. These are rare. In this study, we report a rare variation of a Bado type IV Monteggia-equivalent lesion (fracture of proximal ulnar shaft, proximal radial shaft, and radial head) and its management.

• Journal of dental hygiene science
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• v.9 no.1
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• pp.9-15
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• 2009

Aimed at office workers at their height of Temporomandibular joint disorder(TMD), organized self-filling questionnaires were distributed from January 7 to 26, 2008 to 216 workers in the fields of service, office work, and production in D metropolitan city, to get a proper recognition about prevention and treatment of TMD by observing how strongly occupational stress influence on them. The findings of the study were as follows: 1. For subjective symptoms of joint noise as TMD, occasional was 45.8% and often 12.0%, while for joint dislocation often was 12.0%. 41.2% said they feel pains while chewing, while 24.1% said they occasionally feel pains while not chewing. 2.8% said they often experience mouth-opening disorder. 2. For joint noise, answers were significantly different according to their ages, while 30's are at their height (P < 0.05). For joint dislocation, the shorter they worked the more they have it, so less than a year worker was 37.9%, while less than 3 years 31.0%, and less than 5 years 20.7%. For work type, daytime workers have more dislocation, 58.6%, than shift-workers 34.5% (P < 0.05, P < 0.01). For pains while chewing, the shorter they worked, the more they experienced, which is the same as mouth-opening disorder (P < 0.01). 3. Workers with mouth-opening disorder have much stress on occupational autonomy (P < 0.05) and workers with dislocation and pains while chewing have much stress on relation trouble (P < 0.05, P < 0.01). Workers with highly occupational insecurity has much trouble on dislocation and pains while chewing, while workers with dislocation have significantly much stress on unproper compensation (P < 0.05). 4. For who have joint dislocation, they have much stress on relation-trouble, occupational disorder, and un-proper compensation (P < 0.01, P < 0.05). Workers with pains while not chewing showed significant difference about occupational insecurity and relation troubles (P < 0.05, P < 0.01). Who have mouth-opening disorder showed significant difference about occupational autonomy (P < 0.05).

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.92-99
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• 2020

High-temperature mechanical behaviors of Type 316L stainless steel (SS), which is considered as one of the major structural materials of Generation-IV nuclear reactors, were investigated through the tension and creep tests at elevated temperatures. The tension tests were performed under the strain rate of 6.67×10^-4 (1/s) from room temperature to 650℃, and the creep tests were conducted under different applied stresses at 550℃, 600℃, 650℃, and 700℃. The tensile behavior was investigated, and the modeling equations for tensile strengths and elongation were proposed as a function of temperature. The creep behavior was analyzed in terms of various creep equations: Norton's power law, modified Monkman-Grant relation, damage tolerance factor(λ), and Z-parameter, and the creep constants were proposed. In addition, the tested tensile and creep strengths were compared with those of RCC-MRx. Results showed that creep exponent value decreased from n=13.55 to n=7.58 with increasing temperature, λ = 6.3, and Z-parameter obeyed well a power-law form of Z=5.79E52(σ/E)^9.12. RCC-MRx showed lower creep strength and marginally different in creep strain rate, compared to the tested results. Same creep deformation was operative for dislocation movement regardless of the temperatures.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.911-919
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• 2021

In this paper, the design stress intensity values for the plate-type fuel assembly for research reactor are presented. Through a tensile test, the material properties of the cladding (aluminum alloy 6061) and structural material (aluminum alloy 6061-T6), in this case the yield and ultimate tensile strengths, Young's modulus and the elongation, are measured with the temperatures. The empirical equations of the material properties with respect to the temperature are presented. The cladding undergoes several heat treatments and hardening processes during the fabrication process. Cladding strengths are reduced compared to those of the raw material during annealing. Up to a temperature of 150 ℃, the strengths of the cladding do not significantly decrease due to the dislocations generated from the cold work. However, over 150 ℃, the mechanical strengths begin to decrease, mainly due to recrystallization, dislocation recovery and precipitate growth. Taking into account the uncertainty of the 95% probability and 95% confidence level, the design stress intensities of the cladding and structural materials are established. The presented design stress intensity values become the basis of the stress design criteria for a safety analysis of plate-type fuels.

• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.20-26
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• 2011

Purpose: The purpose of this study is to investigate the accompanying lesions of humerus greater tuberosity fracture with anterior shoulder dislocation and to analyze its clinical results. Materials and Methods: From May 2005 to November 2008, arthroscopy was performed on a total of 30 selected patients who were diagnosed with humerus greater tuberosity fracture with anterior shoulder dislocation and who were also under the age of 40. The preoperative and postoperative Constant and Rowe scores were compared. Results: There was a total of 21 cases of anteroinferior labral lesions: 2 Bankart lesions, 4 bony Bankart lesions, 4 Perthes lesions, 2 free ALPSA lesions, 3 GLAD lesions and 6 capsular tears. For other lesions, 5 rotator cuff partial tears, 3 SLAP lesions and 1 biceps tendon rupture were found. The constant scores were increased from 56.3 to 94.43 points (p=0.034), and the Rowe scores were increased from 52.56 to 91.76 points (p=0.026). Conclusion: For humerus greater tuberosity fracture with anterior shoulder dislocation, the accompanying lesion was identified and the fracture was treated using arthroscopy. Good clinical results and bone union were achieved. According to the secondary arthroscopic findings, all of the Perthes lesion, the free ALPSA lesion, the GLAD lesion and the capsular tear spontaneously healed or they did not progress to extended rupture although arthroscopic suture was not performed. Any postoperative secondary instability was not observed.

• Clinics in Shoulder and Elbow
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• v.9 no.1
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• pp.50-59
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• 2006

Purpose: The nonoperative outcome of elbow dislocations with associated radial head and coronoid fractures are often unsatisfactory because of chronic instability and stiffness from proloned immobilization, Therefore we managed these injuries with well programed surgical appproaches. Method: Ten patients with this injury were evaluated retrospectively from May 1998 to June 2004 after a minimum of 12 months. These injuries include elbow dislocation and associated fractures of both the radial head and the coronoid process. All ten patients were treated by one clinic operatively with similar scheduled surgical methods which started on the lateral side and terminated on the medial side of the elbow. Radial head and neck fractures were classified Mason types, as two and three types respectively with six and four cases and six cases were fixated. Coronoid process were fixated with screws anteroposterior directly or anchor suture in all cases, each type was classified one, two and three. where were three type one, four type two, and three type three were according to Regan and Morrey classification. Results: The outcome was three resulting in excellent, four good, two normaland and the remaining case was one poor according to the Mayo Elbow Performance score. At a terminal follow up, the range of motion of the elbow averaged flection contracture, $6^{\circ}(0{\sim}20^{\circ})$ and further flection, $129^{\circ}(115{\sim}140^{\circ})$. Two patients had complications requiring additional care. One, displaced coronoid process which was repaired with capsule and the other patient experienced, palsy of ulnar nerve and contracted elbow joint. Conclusions: Usage of early operation as the minimum injury of medial ligaments complex and the rigid fixation of fractures to prompt motion with our scheduled management for elbow dislocations with associated radial head and coracoid fractures provided excellent results.

• Korean Journal of Materials Research
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• v.24 no.12
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• pp.645-651
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• 2014

GaN is most commonly used to make LED elements. But, due to differences of the thermal expansion coefficient and lattice mismatch with sapphire, dislocations have occurred at about $109{\sim}1010/cm^2$. Generally, a low temperature GaN buffer layer is used between the GaN layer and the sapphire substrate in order to reduce the dislocation density and improve the characteristics of the thin film, and thus to increase the efficiency of the LED. Further, patterned sapphire substrate (PSS) are applied to improve the light extraction efficiency. In this experiment, using an AlN buffer layer on PSS in place of the GaN buffer layer that is used mainly to improve the properties of the GaN film, light extraction efficiency and overall properties of the thin film are improved at the same time. The AlN buffer layer was deposited by using a sputter and the AlN buffer layer thickness was determined to be 25 nm through XRD analysis after growing the GaN film at $1070^{\circ}C$ on the AlN buffer CPSS (C-plane Patterned Sapphire Substrate, AlN buffer 25 nm, 100 nm, 200 nm, 300 nm). The GaN film layer formed by applying a 2 step epitaxial lateral overgrowth (ELOG) process, and by changing temperatures ($1020{\sim}1070^{\circ}C$) and pressures (85~300 Torr). To confirm the surface morphology, we used SEM, AFM, and optical microscopy. To analyze the properties (dislocation density and crystallinity) of a thin film, we used HR-XRD and Cathodoluminescence.

• Clinics in Shoulder and Elbow
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• v.25 no.3
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• pp.224-229
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• 2022

Background: Most acromioclavicular joint (ACJ) injuries are caused by direct trauma to the shoulders, and various methods and techniques are used to treat them; however, none of the options can be considered the gold standard. This study examines the horizontal stability of the ACJ after a complete dislocation was repaired using one of two Ethibond suture techniques, the loop technique and the two holes in the clavicle technique. Methods: In this single-blind, randomized clinical trial, 104 patients diagnosed with complete ACJ dislocation type V were treated using Ethibond sutures with either the loop technique or the two holes in the clavicle technique. Horizontal changes in the ACJ were radiographically assessed in the lateral axial view, and shoulder function was evaluated by the Constant (CS) and Taft (TS) scores at intervals of 3, 6, and 12 months after surgery. Results: The horizontal stability of the ACJ was better with the two-hole technique than the loop technique at all measurement times. CS and TS changes showed a significant upward trend over time with both techniques. The mean CS and TS at the final visit were 95.2 and 11.6 with the loop technique and 94.0 and 11.9 with the two-hole technique, respectively. The incidence of superficial infections caused by the subcutaneous pins was the same in the two groups. Conclusions: Due to the improved ACJ stability with the two-hole technique, it appears to be a more suitable option than the loop technique for AC joint reduction.

• Clinics in Shoulder and Elbow
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• v.19 no.4
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• pp.249-251
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• 2016

iepicondylar fracture of the humerus is very rare in adults. To date, there have been limited evidence of this injury in the English literature. We report a case of a 65-year-old female with a biepicondylar fracture of the left distal humerus without dislocation. Open reduction and internal fixation with K-wires, cannulated screw, and suture anchor were performed. We obtained stability of the elbow and a satisfactory functional outcome. Because this type of injury is associated with varus and valgus instability, operative reduction and fixation are essential in order to gain stability and early recovery of normal function.