• Korean Journal of Materials Research
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• v.26 no.4
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• pp.167-172
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• 2016

The high temperature deformation behavior of $Ni_3Al$ and $Ni_3(Al,Mo)$ single crystals that were oriented near <112> was investigated at low strain rates in the temperature range above the flow stress peak temperature. Three types of behavior were found under the present experimental conditions. In the relatively high strain rate region, the strain rate dependence of the flow stress is small, and the deformation may be controlled by the dislocation glide mainly on the {001} slip plane in both crystals. At low strain rates, the octahedral glide is still active in $Ni_3Al$ above the peak temperature, but the active slip system in $Ni_3(Al,Mo)$ changes from octahedral glide to cube glide at the peak temperature. These results suggest that the deformation rate controlling mechanism of $Ni_3Al$ is viscous glide of dislocations by the <110>{111} slip, whereas that of $Ni_3(Al,Mo)$ is a recovery process of dislocation climb in the substructures formed by the <110>{001} slip. The results of TEM observation show that the characteristics of dislocation structures are uniform distribution in $Ni_3Al$ and subboundary formation in $Ni_3(Al,Mo)$. Activation energies for deformation in $Ni_3Al$ and $Ni_3(Al,Mo)$ were obtained in the low strain rate region. The values of the activation energy are 360 kJ/mol for $Ni_3Al$ and 300 kJ/mol for $Ni_3(Al,Mo)$.

• Korean Journal of Materials Research
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• v.21 no.3
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• pp.161-167
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• 2011

The stress-strain responses and oxidation properties of cold-rolled Zr-1.5Nb-O and Zr-1.5Nb-O-S alloys were studied. The U.T.S. (ultimate tensile strength) of cold-rolled Zr-1.5Nb-O-S alloy with 160 ppm sulfur (765 MPa) were greater than that of Zr-1Nb-1Sn-0.1Fe alloy (750 MPa), achieving an excellent mechanical strength even after the elimination of Sn, an effective solution strengthening element. The addition of sulfur increased the strength at the expense of ductility. However, the ductile fracture behavior was observed both in Zr-Nb-O and Zr-Nb-O-S alloys. The beneficial effect of sulphur on the strengthening was observed in the cold rolled Zr-1.5Nb-O-S alloys. The activation volume of cold-rolled Zr-1.5Nb decreased with sulfur content in the temperature region of dynamic strain aging associated with oxygen atoms. Insensitivity of the activation volume to the dislocation density and the decrease of the activation volume at a higher temperature where the dynamic strain aging occurs support the suggestion linking the activation volume with the activated bulge of dislocations limited by segregation of oxygen and sulfur atoms. The addition of sulfur was also found to improve the oxidation resistance of Zr-Nb-O alloys.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.713-719
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• 2000

In order to Prepare the$Ge_xSi_{1-x}/Si$(111) heterosructure by solid phase epitaxy (SPE), about 1000A of Au and about 1000A Ge were sequentially deposited on the Si(111) substrate. The resulting Ge/Au/Si(111) samples were isochronically annealed in the high vacuum condition. The behaviors of Au and Ge during thermal annealing and the structural Properties of $Ge_xSi_{1-x}$ films were characterized by Auger electron spectroscopy (AES), X-ray diffraction (XRD) and high resolution transmission electron microscopy (TEM). The a-Ge/Au/Si(111) structure was converted to the Au/GeSi/Si(111) structure. Defects such as stacking faults, point defects and dislocations were found at the GeXSil-X(111) interface, but the film was grown epitaxially with the matching face relationship of $Ge_xSi_{1-x}/$(111)/Si(111). Twin crystals were also found in the $Ge_xSi_{1-x}/$(111) matrix.

• Journal of the Korean Arthroscopy Society
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• v.5 no.1
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• pp.41-44
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• 2001

The muscular button holing of vastus medialis is a very rare case of irreducible knee dislocations, and rapid reduction of this can diminish the complications which delayed reduction accompanies. We diagnosed a patient who appeared posterolateral dislocation of the knee and protrusion of the medial femoral condyle with MRI grossly. That was reduced by open arthrotomy, followed the reconstruction of both cruciate ligaments and repair of medial collateral ligament. Patient didn't show joint instability except minor posterior sagging and had full range of motion postoperatively after 10 months.

• Journal of Korean Foot and Ankle Society
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• v.13 no.2
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• pp.156-161
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• 2009

Purpose: The fracture of talus has critical complications and results in various clinical outcomes. The purpose of this study is to evaluate clinical outcome and influence on involvement of ankle and subtalar joint. Materials and Methods: From December 1999 to December 2008, a total of 66 fractures and dislocations of talus was treated with minimal 9 months follow up period. Ankle-hindfoot scale of the American Orthopedic Foot & Ankle Society (AOFAS) was used to evaluate the clinical outcome. The complications and sequential radiologic findings were also analyzed. Results: There were 28 neck fractures, 11 lateral process fractures, 10 body fractures, 7 osteochondral fractures, 4 posteromedial tubercle fractures and 4 medial process fractures. In 38 cases, there were concomitant injuries. Ipsilateral ankle fracture, which found in 19 cases, was most common. The surgical treatment was performed in 36 cases. Mean AOFAS score was 85.5 (range, 72 to 96). In 13 of 47 cases, one or more fracture lines involving weight bearing surface were confirmed. The involvement of ankle or subtalar joint had resulted in unsatisfied outcome. Complications were developed as follows, post-traumatic arthritis in 8 cases, avascular necrosis in 3 cases, and deep infection in 2 cases. Conclusion: The involvement of ankle or subtalar joint in fractures of talus seemed to be common and to impact the clinical outcome. Meticulous consideration about that will be positively necessary.

• Journal of Korean Orthopaedic Sports Medicine
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• v.8 no.1
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• pp.51-55
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• 2009

Volar rotatory dislocation of the proximal interphalangeal joint(PIP) of the finger is rare. We report a female judo player who had volar rotatory dislocation of the PIP joint of the middle finger. She had dislocation of PIP joint total 4 times. At operation, the central tendon was identified as being distension, with the ulnar collateral ligament ruptured. The ruptured ulnar collateral ligament was interposed within the joint. The ruptured ulnar collateral ligament was repaired and extensor expansion was repaired. At last follow-up, she didn't have recurrent dislocation during judo. Accurate diagnosis, early intervention and progressive rehabilitation of this injury are very important as other dislocations.

• Archives of Plastic Surgery
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• v.45 no.5
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• pp.458-465
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• 2018

Background Volar plate avulsion fracture of the proximal interphalangeal (PIP) joint is one of the most common hand injuries. In this study, we divided patients into two groups: patients with pure volar plate avulsion fracture, and patients with volar plate avulsion fracture concomitant with collateral ligament rupture. The purpose of this study was to compare long-term surgical outcomes between the two groups. As a secondary measure, the Mitek bone anchoring and polydioxanone (PDS) bone suturing techniques were compared. Methods A single-institutional retrospective review of the surgical treatment of volar plate avulsion fracture was performed. The cases were divided into those with pure volar plate avulsion fracture (group A, n=15) and those with volar plate avulsion fracture concomitant with collateral ligament rupture (group B, n=15). Both groups underwent volar plate reattachment using Mitek bone anchoring or PDS bone suturing followed by 2 weeks of immobilization in a dorsal protective splint. Results The average range of motion of the PIP joint and extension lag were significantly more favorable in group A (P<0.05). Differences in age; follow-up period; flexion function; visual analog scale scores; disabilities of the arm, shoulder, and hand scores; and the grip strength ratio between the two groups were non-significant. No significant differences were found in the surgical outcomes of Mitek bone anchoring and PDS bone suturing in group A. Conclusions Overall, the surgical outcomes of volar plate reattachment were successful irrespective of whether the collateral ligaments were torn. However, greater extension lag was observed in cases of collateral ligament injury.

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.141-150
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• 2011

Precise image-to-image registration is required to process multi-sensor data together. The purpose of this paper is to develop an algorithm that register between high-resolution optical and SAR images using linear features. As a pre-processing step, initial alignment was fulfilled using manually selected tie points to remove any dislocations caused by scale difference, rotation, and translation of images. Canny edge operator was applied to both images to extract linear features. These features were used to design a cost function that finds matching points based on their similarity. Outliers having larger geometric differences than general matching points were eliminated. The remaining points were used to construct a new transformation model, which was combined the piecewise linear function with the global affine transformation, and applied to increase the accuracy of geometric correction.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.3
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• pp.241-247
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• 2014

This study presents the ultrasonic nonlinearity of AISI316 austenitic stainless steels subjected to longterm isothermal aging. These steels are attractive materials for use in industrial mechanical structures because of their strength at high-temperatures and their chemical stability. The test materials were subjected to accelerated heat-treatment in an electrical furnace for a predetermined aging duration. The variations in the ultrasonic nonlinearity and microstructural damage were carefully evaluated through observation of the microstructure. The ultrasonic nonlinearity stiffly dropped after aging for up to 1000 h and, then, monotonously decreased. The polygonal shape of the initial grain structures changed to circular, especially as the annealing twins in the grains dissolved and disappeared. The delta ferrite on the grain boundaries could not be observed at 1000 h of aging, and these continuously transformed into their sigma phases. Consequently, in the intial aging period, the rapid decrease in the ultrasonic nonlinearity was caused by voids, dislocations, and twin annihilation. The continuous monotonic decrease in the ultrasonic nonlinearity after the first drop resulted from the generation of $Cr_{23}C_6$ precipitates and ${\sigma}$ phases.