• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.96-113
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• 1996

It has been found that the misfit dislocations in heavily boron-doped layers originate from wafer edges. Moreover, the propagation of the misfit dislocation into a heavily boron-doped region can be suppressed by placing a surrounding undoped region. Using a surrounding undoped region the disloction-free heavily boron-deoped silicon membranes have been fabricated. The measured surface roughness, fracture strength, and residual tensile stress of the membrane are 20.angs. peak-to-peak, 1.39${\times}$10$^{10}$ and 2.7${\times}$10$^{9}$dyn/cm$^{2}$, while those of the conventional heavily boron-doped silicon membrane with high density of misfit dislocations are 500 peak-to-peak, 8.27${\times}$10$^{9}$ and 9.3${\times}$10$^{8}$dyn/cm$^{2}$ respectively. The differences between these two membranes are due to the misfit dislocations. Young's modulus has been extracted as 1.45${\times}$10$^{12}$dyn/cm$^{2}$ for both membranes. Also, the effective lattice constant of heavily boron-doped silicon, the in-plane lattice constant of the conventional membrane, and the density of misfit dislocation contained in the conventional membrane have been extracted as density of misfit dislocation contained in the conventional membrane have been extracted as density of misfit dislocation contained in the conventional membrane have been extracted as 5.424.angs. 5.426.angs. and 2.3${\times}$10$^{4}$/cm for the average boron concentration of 1.3${\times}$10$^{20}$/cm$^{-23}$ cm$^{3}$/atom. Without any buffer layers, a disloction-free lightly boron-doped epitaxial layer with good crsytalline quality has been directly grown on the dislocation-free heavily boron-doped silicon layer. X-ray diffraction analysis revealed that the epitaxial silicon has good crystallinity, similar to that grown on lightly doped silicon substrate. The leakage current of the n+/p gated diode fabricated in the epitaxial silicon has been measured to be 0.6nA/cm$^{2}$ at the reverse bias of 5V.

• Journal of Korean Foot and Ankle Society
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• v.10 no.1
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• pp.42-47
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• 2006

Purpose: This study was performed to analyze the characteristics of calcaneocuboid joint involvement in intraarticular calcaneal fractures. Materials and Methods: Total number of 92 patients (111 cases) who underwent operation for intraarticular calcaneal fractures between Jan. 2000 and Oct. 2005 were included in this study. The preoperative computed tomographs of the subjects were retrospectively reviewed to analyze calcaneocuboid joint involvement. Results: It was revealed that 63 cases (56.8%) involved calcaneocuboid joint; 29cases (46.0%) showed type 1 (undisplaced or minimally displaced type, articular gap ${\le}1\;mm$), 16 cases (25.4%) exhibited type 2 (moderately displaced type, articular gap ${\ge}2\;mm$), 7 cases (11.1%) were included in type 3 (comminuted type) and 11 cases (17.5%) belonged to type 4 (fracture and dislocation). 48 out of 63 cases belonged to Sanders classification II and III that involved calcaneocuboid joint and included 25 cases (52.1%) of type 1 and 14 cases (29.2%) of type 2. Among 15 out of 63 cases included in Sanders classification IV, 4 (26.7%) showed type 1 and 6 (40.0%) belonged to type 4. According to our results, Sanders classification allowed to predict pattern of the involvement of calcaneocuboid joint (P<0.05). However, there was no statistically significant relationship between degree of posterior facet joint injuries and calcaneocuboid joint involvement (P>0.05). Conclusion: Calcaneocuboid joint involvement in intraarticular calcaneal fractures was common and more than half showed severe injuries. We concluded that further studies on the involvement of calcaneocuboid joint should be performed prior to surgical treatment of intraarticular calcaneal fractures.

• Journal of Korean Foot and Ankle Society
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• v.11 no.1
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• pp.45-50
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• 2007

Purpose: To evaluate the short-term clinical outcomes of total ankle arthroplasty for the post-traumatic osteoarthritis. Materials and Methods: Fourteen patients who had undergone total ankle arthroplasty from February 2005 to June 2006 were reviewed. Eleven patients were male and three patients were female. The mean age was 52.8 years (range, 33 to 69 years). The mean follow-up duration was 15.9 months (range, 12 to 24 months). Primary injuries were pilon fractures in eight cases, malleolar fractures in three, ankle syndesmotic injury in one, talus fracture and dislocation in one, and distal tibial physeal injury in one. Visual analogue scale (VAS), Range of motion (ROM), American Orthopaedic Foot and Ankle Society (AOFAS) score and complications were evaluated. Results: The mean VAS improved from 8.6 preoperatively to 2.6 at last follow-up. The mean ROM improved from 24.6 degrees preoperatively to 33.1 degrees postoperatively. The mean AOFAS score improved from 44.5 points preoperatively to 75.1 points postoperatively. Radiographically, all components were stable, but there were component malpositions in two cases, including one varus malposition of tibial component and one increased anterior translation of talar component. Complications were deep infection in one case, intraoperative malleolar fracture in three, marginal wound necrosis in two, and heterotopic ossification in one. One prosthesis was revised because of deep infection. Conclusion: Total ankle arthroplasty for the post-traumatic osteoarthritis is believed to be an useful method for preservation of the motion, relief of the pain and high satisfaction of patients in short-term results.

• 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.

• Journal of Korean Neurosurgical Society
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• v.30 no.12
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• pp.1388-1393
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• 2001

Objective : In the retrospective analyzing 19 consecutive patients with subaxial cervical spine(C3~T1) injury treated by posterior cervical fixation and fusion, clinical manifestation, radiologic finding, operative technique, and postoperative results following 6 months were analyzed. Materials and Methods : Most common fracture level was C4-5, mean age 41, and male to female ratio 13 : 6. The most common cause of injury was motor vehicle accident(17 cases). In 19 cervical procedures, interspinous triple wiring was done in 14 cases, lateral mass plating in 5 cases, and additional anterior fusion in 2 cases. Results : Twelve weeks after operation, all cases were reviewed by plain cervical radiogram. In 17 cases that treated by posterior fusion only, 14 cases(81%) had kyphotic angle change less than $5^{\circ}$, 2 cases(12%) $5-20^{\circ}$, and 1 case(6%) more than $20^{\circ}$. Overall fusion rate was 88%, and there was no significant difference of bone fusion rate between autogenous bone graft and allogenous bone graft. Conclusion : In the case of severe posterior column injury or displacement, posterior approach seems superior to anterior approach, but in the case of combined anterior column injury, anterior approach is considered necessary. In this study, posterior fixation and fusion might be acceptable procedure for subaxial cervical fracture and dislocation, owing to its high fusion rate, low kyphotic angulation and low operation related complication rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3048-3057
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• 1996

Analysis model containing two inclined surface cracks on semi-infinite elastic body is established and analyzed on the basis of linear fracture mechanics to examine mutual interference of two surface cracks. Muskhelishvili's complex stress functions are introduced and a set of singular integral equations is obtained for a dislocation density function. The stress intensity factors at crack tip are obtained by using the Gerasoulis'method. When two surface cracks are parallel and have the same length, the values of $K_1$and $\Delta K_11$(variation of $K_11$) for crack 1 and crack 2 decrease by the mutual interference of two surface cracks as the distance between the two surface cracks shortens. The effect of mutual interference is remarkable in high friction coefficient. In case that two surface cracks are parallel, the values of $K_1$and $\Delta K_11$for crack 2 decrease as the length ratio ot crack 2 to crack 1 becomes small. As the crack inclination angle rises, the value of $K_1$ and the mutual interference of $K_1$for crack 2 increase and the value of$\Delta K_11$ for crack 1 becomes smaller than that for crack 2.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.4
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• pp.25-33
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• 2001

Sn-3.5Ag-xBi alloys with five different levels of Bi (0, 2.5, 4.8, 7.5, 10 wt%) were prepared for evaluating creep properties. Cast alloys were roiled and heat treated to provide stable microstructures during the subsequent creep tests, which were conducted under constant load using dog-bone specimens. For the Bi containing alloys, creep strength showed the maximum around 2.5 wt%Bi and tended to decrease with increasing Bi content. The stress exponent of the alloy was around 4, suggesting typical dislocation creep, but the exponent was 2 for the 10 wt%Bi alloy, suggesting creep assisted by grain boundary Sliding. For the Bi containing alloys, the brittle fracture mode appeared showing small amount of reduction of area, while the ductile fracture mode was true for the Bi free alloy. Microstructural examination of ruptured specimens showed cavitations on grain boundaries normal to the load axis, and a significant of grain boundary sliding for the Bi containing alloys.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.4
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• pp.220-227
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• 2001

The static creep behaviors of dispersion strengthened copper GlidCop were investigated over the temperature range of $650{\sim}690^{\circ}C$ (0.7Tm) and the stress range of 40~55 MPa (4.077~5.61 $kg/mm^2$). The stress exponents for the static creep deformation of this alloy was 8.42, 9.01, 9.25, 9.66 at the temperature of 690, 677, 663, and $650^{\circ}C$, respectively. The stress exponent, (n) increased with decreasing the temperature and became dose to 10. The apparent activation energy for the static creep deformation, (Q) was 374.79, 368.06, 361.83, and 357.61 kg/mole for the stress of 40, 45, 50, and 55 MPa, respectively. The activation energy (Q) decreased with increasing the stress and was higher than that of self diffusion of Cu in the dispersion strengthened copper. In results, it can be concluded that the static creep deformation for dispersion strengthened copper was controlled by the dislocation climb over the ranges of the experimental conditions. Larson-Miller parameter (P) for the crept specimens for dispersion strengthened copper under the static creep conditions was obtained as P=(T+460)(logtr+23). The failure plane observed for SEM slightly showed up transgranular at that experimental range, however, universally it was dominated by characteristic of the intergranular fracture.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.2
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• pp.137-141
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• 2011

The extraction of an impacted third molar tooth is associated with many complications during the procedure and postoperative care. These complications include bleeding, swelling, pain, infection, as well as root fracture, proximal tooth injury, alveolar bone fracture, lingual nerve and inferior alveolar nerve injury etc. With the exception of a fractured root dislocation in the submandibular space, no direct submandibular gland injury related to extraction surgery has been reported until now. A 40 year old man visited the department of oromaxillofacial surgery at Yeouido St. Mary's Hospital for an extraction of the right mandible third molar. A partial third molar impaction was diagnosed by a clinical and radiographic examination. A surgical tooth extraction was practiced including buccal cortical bone osteotomy. During socket curettage, an encapsulated cyst-like lesion and a verified $3{\times}3\;cm$ neoplasm in the apically lingual direction were found during process of dissection. A biopsy confirmed that the neoplasm involved the submandibular gland and nerve trunk. This unusual anatomical organ injury during the surgical tooth extraction procedure is reported as a new complication during impacted third molar extraction.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.624-635
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• 1990

Analytical study based on linear fracture mechanics was conducted on propagation behavior of inclined surface crack in semi-infinite elastic body. The analytical model was assumed to be inclined surface crack under plane strain condition upon which Hertzian stress was superimposed. Supposing continuous distribution of dislocation and applying Erdogan-Gupta's method to this crack problem, the stress intensity factors $K_{I}$ and $K_{II}$) at the crack-tip were obtained for various Hertzian contact positions. Analytic results have shown that driving force for crack growth is $K_{I}$ for non-lubricated condition and $K_{II}$ for fluid and boundary lubricated condition. The coefficient of friction at the hertzian contact and crack surfaces plays an important role in predicting the direction of crack propagation. It is also found that the maximum effective stress intensity factor exists at cracks of a certain specific length depending on lubricated condition.ion.n.