• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.258-272
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• 1998

This investigation evaluated patients who received Steri-Oss implants from the Dental Hospital of Chosun University during the period from March 1989 to August 1997. 346 fixtures of 127 patients were included in this study. The results were as follows ; 1.The follow-up period was defined as the period between the surgical placement of the implants and the last follow-up examination. The mean follow-up period was $2.17{\pm}1.21$ years. 2.The period between fixture installation and second surgery was $0.71{\pm}0.44$ years in the maxilla and $0.46{\pm}0.21$ years in the mandible. 3.The number of fixtures which were installed in the upper jaw(112) was less than that in the lower jaw(234) and in the posterior region(260) was more than in the anterior region(86). 4.The length of fixture which was most frequently used was 12 mm and least was 8mm. Screw implants were installed more than cylindrical implants. 3.8mm implant was the most common implans, followed by 4.5mm and 3.25mm. 5.The number of augmentation cases was more than that of non-augmentation cases and the rate of augmentation cases in the maxilla was more than that in the mandible. 6.Implant restorations for partial edentulos patients(94cases) were more than single- tooth implant restorations(33cases) or implant restorations for complete edentulos patients(10cases). 7.Free-standing prostheses for partially edentulous patients were more commom than any other type of connection between implants and natural teeth. 8.Plaque Index($0.95{\pm}0.74$) and Gingival Index($0.31{\pm}0.52$) were very similar around the natural teeth and reflected an acceptable level of plaque and gingivitis control. Mean value for keratinized mucosa index($1.93{\pm}1.20$) remained fairly constant around level 2(1-2 mm keratinized epithelium). 9.Patients were generally satisfied with implant in terms of comfort, function, speech and esthetics. 10.There was not a statistically significant differences in overall survial rate between implants placed in the maxilla (91.5%) and those placed in the mandible (93.8%). Fourteen implants lost before the prosthetic rehabilitation and eleven implants lost following variable periods in function after the prosthetic phase of the treatment. 11.Cause of implant failures was exfoliation or removal of fixture due to non-osseointegration before the prosthetic rehabilitation or due to fracture of fixture, masticatory pain after the prosthetic rehabilitation. 12.The survival rate of Steri-Oss implants using the Kaplan-Meier statistical analysis was 93.8% at 2 year and 86.6% at 5 year, In all cases, implant losses occured predominantly in the healing period. There was a steep decline in the rate of implant loss after the first year. 13.The survival rate of Steri-Oss implants in the anterior region was 94.8% at 2 year and 94.8% at 5 year and that in the posterior region was 92.8% at 2 year and 75.9% at 5 year. In conclusion, this study revealed a number of parameters and guidelines for achieving an optimal success rate in osseointegration.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.5
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• pp.381-389
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• 2000

Metal matrix composite(MMCs) have been rapidly becoming one of the strongest candidates for structural materials for high temperature application. It is well recognized that MMCs always experience at least one large cool-down from processing temperature before my significant applied service loading. Due to the large difference in thermal expansion coefficient between the fiber and matrix, large thermal residual stresses generally develop in composites. It was reported from many previous studies that the effects of thermal residual stress on mechanical properties and fracture behavior were much more complex and dramatic than conventional engineering materials. Therefore it is crucial to evaluate the effect of heat treatment which changes the characteristic of distribution of thermal residual stress in MMCs. Single fiber composite(SFC) test based on the balance in a micromechanical model is a quite convenient method to evaluate interfacial shear strength(IFSS) and the failure mode of composite. In this study the effect of heat treatment on IFSS and the microscopic failure mechanism of MMC is investigated by combining acoustic emission(AE) technique with SFC test. The characteristic of AE signal, IFSS and microscopic failure mechanism due to heat treatment condition is discussed.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.261-273
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• 1998

Multiple well log analysis technique consisting of geophysical well log and geological core log has been made to analysis the discontinuities of a test borehole-PABH1 located in Pungam sedimentary basin, Sosok, Hongchon-gun, Kangwon Province. Well log methods consist of normal resistivity log, focussed log, single point resistance log, SP log, gamma log, natural gamma log as well as acoustic televiewer log and borehole television log. Core scanning technique was used as an aid for geological core log. The analysis was made by comparing firstly the televiewer and core discontinuities, and then the results from conventional geophysical log analysis were compared to those from core log and acoustic televiewer log. Fractures deduced from the acoustic televiewer log coincide well with discontinuities shown on the core and conventional geophysical logs. Particularly close coincidence could be observed between fractures derived from acoustic televiewer and conventional geophysical log analysis. It has been noted that the geophysical logs such as, caliper, resistivity, density and high resolution gamma gamma curves are effective in delineating the fractures. For example the ratio between density and resistivity (BRD/SHN) provides also an alternative indicator for discerning the fracture condition in the study area.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.4 s.74
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• pp.429-440
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• 2006

This paper comprises two specific objectives. The first is to examine the applicability of ordinary kriging interpolation(OK) to the p-adaptivity of the finite element method that is based on variogram modeling. The second objective Is to present the adaptive procedure by the hierarchical p-refinement in conjunction with a posteriori error estimator using the modified S.P.R. (superconvergent patch recovery) method. The ordinary kriging method that is one of weighted interpolation techniques is applied to obtain the estimated exact solution from the stress data at the Gauss points. The weight factor is determined by experimental and theoretical variograms for interpolation of stress data apart from the conventional interpolation methods that use an equal weight factor. In the p-refinement, the analytical domain has to be refined automatically to obtain an acceptable level of accuracy by increasing the p-level non-uniformly or selectively. To verify the performance of the modified S.P.R. method, the new error estimator based on limit value has been proposed. The validity of the proposed approach has been tested with the help of some benchmark problems of linear elastic fracture mechanics such as a centrally cracked panel, a single edged crack, and a double edged crack.

• The Journal of Korean Physical Therapy
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• v.12 no.2
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• pp.255-265
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• 2000

The term 'myositis ossificans' encompasses four categories of clinicopathological disorders. The first, myositis ossificans progressive(fibrodysplasia ossificans progressive), is a rare genetic disease characterized by progressive heterotopic ossification involving skeletal muscle, tendon, ligaments, and fascia, with congenital malformation of the great toes, and usually microdactyly, monophalangism, and mal formed proximal phalanges. with valgus deformity of metatarsophalangeal joint. The ossification begins shortly after birth and may contribute to the patient's death. The second, heterotopic ossificans, can occur in patients with neuromuscular and chronic diseases such as paraplegia, poliomyelitis, polymyositis, bum, tetanus, and infection. But the lesions in these cases often lack the typical histologic features of myositis ossificans. The third, myositis ossificans traumatica, is the most common; it develops in response to soft tissue trauma such as a single severe injury, minor repetitive injures, fracture, joint dislocation, stab wound, or surgical incision. The forth, nontraumatic myositis ossificans, also designated :pseudomalignant osseous tumors of extraskeletal soft tissues' and 'psedomalignant myositis ossificans', occurs in persons repeated small mechanical injures or nonmechanical soft tissue injuries due to local ischemia, inflammation. or other factors cannot be ruled out in such cases.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.289-299
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• 2002

The bond strength is one of the most important factor in establishing long-term success of esthetic restorative dentistry. So, various restorative materials have been introduced to improve the esthetic and physical properties. Ormocer (organically modified ceramic) was developed as a result of such efforts. This study was performed to compare the shear bond strength of ormocer based adhesive with that of existing dentin adhesive. In this study $Admira^{(R)}$ and $Admira^{(R)}$ bond of the ormocer system are grouped together for ADM, Single $Bond^{(R)}$ which is an one-bottle adhesive and Z-250TM which is hybrid composite resin of BIS-GMA system for SIN, and $Definite^{(R)}$ of ormocer and Etch & $Prime^{(R)}$ 3.0 which is a self etching priming/ bonding agent for ETC. The results of this study were as follows. : (1) In the comparison of shear bond strength according to different adhesive system, shear bond strength was increased in the order of ETC group, SIN group, ADM group. There was no significant difference between ADM group and SIN group. However, there was a significant level of difference between ADM and ETC groups as well as SIN and ETC groups( p<0.05). (2) Examination by a scanning electron microscope showed a well established hybrid layer and resin tag in both ADM group and SIN group, while ETC group showed a minimal formation of the hybrid layer when compared with ADM and SIN groups. From the above results, it may be reasonable to start the clinical application of ormocer system, and it is recommended that ormocer system should be used along with an ormocer based adhesive because ormocer system showed the lower shear bond strength when it used with other existing self etching priming/bonding agent. The self etching priming/bonding agent showed relatively low shear bond strength, and it is considered that the further study should be needed.

• Resources Recycling
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• v.29 no.3
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• pp.11-23
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• 2020

This study aims to investigate breakage and liberation characteristics of iron ore from Shinyemi mine, Jeongseon by ball mill. Parameters of breakage functions for three grade samples of iron ore were obtained using single-sized-feed breakage test and back-calculation based on nonlinear programming. The results showed that with the increase in the grade of iron ore, the breakage rate factor decrease whereas the particle size sensitivity decreases. This results from retardation of microcrack-propagation by magnetite grain in the ore. Breakage distribution analysis showed that the breakage mechanism appear to be impact fracture dominant with the increase of grade owing to the stress distribution effect by magnetite grain. Degree of liberation (DOL) increased with the increase in grade and decrease in particle size, respectively. Using the breakage function and size-DOL relationship, a model that can predict time-dependent-DOL is established. When scale-up factors from operating condition are available, the model is expected to be capable of predicting size and DOL with time in actual mining process.

• Archives of Plastic Surgery
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• v.36 no.5
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• pp.623-628
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• 2009

Purpose: In cases where nasal fractures involve frontal process of maxilla or perpendicular plate of ethmoid, 4 - 5 days of nasal packing may not provide sufficient support for avoiding displacement after packing removal. Therefore a single Kirschner - wire(K - wire) is used as an internal splint when nasal fractures involve the above two areas. Methods: Thirty five patients during the last 3 practical years were treated with a K -wire pinning according to the anatomic locations of nasal fractures. We performed a retrospective study using 13 nasal fractures out of total 35 patients. Among 13 cases, 10 patients involved frontal process of maxilla, and 3 patients were diagnosed as bilateral nasal side wall fractures accompanied with fractures of perpendicular plate of ethmoid. One patient of the last three cases had been augmented with dorsal silicone implant long before the trauma. We analyzed the anteroposterior displacement of key stone area and the width between both lateral walls by comparing immediate postoperative radiographs with 2 month follow - ups. To reduce the errors, the same measurements were taken by two different inspectors, and the mean of each inspector's measurements was compared. Patient satisfaction was analyzed using a questionnaire regarding the esthetic and functional outcomes. Results: Ten patients underwent a longitudinal K - wire fixation in submucoperiosteal plane underneath the frontal process of maxilla. And three patients underwent a transverse K - wire fixation from the one side of lateral wall to the perpendicular plate of ethmoid and to the other side of lateral wall. The mean postoperative anteroposterior displacement of the key stone area measured by two inspectors were 1.84% and 3.06%; mean narrowing of bony pyramid were 1.33% and 1.48%, respectively. Subjective satisfaction scores regarding the esthetic appearance and the maintenance of nasal shape compared with immediate post - operative state with the long term ones were not different (p>0.05). Conclusion: K - wire pinning after closed reduction is a reliable and useful method for the treatment of nasal fractures involving frontal process of maxilla or perpendicular plate of ethmoid. This is because it achieves longer intranasal support after reduction. This method also leaves conspicuous external scar, and minimal soft - tissue injury.

• Journal of Trauma and Injury
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• v.27 no.3
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• pp.50-56
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• 2014

Purpose: Rollover motor vehicle crashes have a higher injury severity and fatality than other motor vehicle crash types. From a left-quarter turn rollover accident of 25-passenger bus, we intend to assess the injury of the occupant and the injury severities according to the occupants' position. Methods: We carried out the 3 steps investigation of occupants' interview, visiting the repair shop and using the police report. We analyzed injuries sustained by occupants, and compared injury severities considering column, row in occupant's position and passenger interaction Results: The rollover involved 14 passengers in the bus who were all old women except a man driver. The most common injury was in the upper extremity, with six occurrences being a left clavicle fracture. Major injuries including hemothorax and pneumothorax were diagnosed at left side of the occupant. In the comparison of injury severity among driver's column (left side), mid column and passengercolumn, ISS of passenger column was the highest ($9.9{\pm}7.4$, $8.8{\pm}5.5$, and $10.3{\pm}4.0$, respectively, p>0.05). The injury severity of multiple occupants by row was higher than that of single occupant (10.8 vs. 3, p<0.05). Conclusion: An occupant must fasten their seat belt to prevent an injury by passenger interaction in the left-quarter turn rollover accident of a bus.

• Korean Journal of Materials Research
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• v.3 no.3
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• pp.282-291
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• 1993

Joining ${Al}_{2}{O}_{3}$ and STS 304 stainless steel by active metal brazing method with using CuI Owt % Ti and Cu -7 .5wt % Zr insert metal, their interfaces were analyzed and strength of the joint brazed with Cu-7.5wt % Zr insert metal also investigated with shear strength testing method. In brazing with Cu-lOwt% Ti insert metal, the single reaction layer was formed by the reaction with Ti and ${Al}_{2}{O}_{3}$ at the interface between ${Al}_{2}{O}_{3}$ and insert metal, but the double reaction layer was found in brazing with Cu-7.5wt % Zr insert metal because of the difference of their wettability on the surface of ${Al}_{2}{O}_{3}$. Fracture shear strength about 86MPa was obtained from ${Al}_{2}{O}_{3}$/Cu-7.5wt% Zr/STS 304 stainless steel joint and reasonable strength of the joints is attributed to the formation of double reaction layer at the interface.