• Journal of Periodontal and Implant Science
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• v.35 no.1
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• pp.235-250
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• 2005

The current interest in periodontal tissue regeneration has lead to research in bone graft, root surface treatments, guided-tissue regeneration, administration of growth factors, and the use of enamel matrix protein as possible means of regenerating lost periodontal tissue. Several studies have shown that a strong correlation between platelet-rich plasma and the stimulation of remodeling and remineralization of grafted bone exits, resulting in a possible increase of 15-30% in the density of bone trabeculae. The purpose of this study was to study the histopathological results and differences between the use of platelet-rich plasma and the use of enamel matrix $protein(Emdogain^?)$ about bone regeneration at the implant. Implant fixtures were inserted and graft materials placed into the left femur in the experimental group, while the only implant fixtures placed in the control group. In the first experimental group, platelet-rich plasma and xenograft were placed at the supracrestally placed implant site, and in the second experimental group, $Emdogain^{(R)}$ and xenograft placed at the supracrestally placed fixture site. The degree of bone regeneration adjacent to the implant fixture was observed and compared histopathologically at 2, 4, and 8 weeks after implant fixture insertion. The results of the experiment are as follows: 1. The rate of osseointegration to the fixture threads was found to be greater in the experimental group compared to in the control group. 2. The histopathological findings showed that the bone regeneration, the partial osseointegration existed at 4 weeks, and that osseointegration and bone density increaced in the experimental groups at 8 weeks. 3. The results showed that new bone formation and bone remodeling increased in the area near to the fixture in the first and second experimental groups at 8 weeks than at 4 weeks. The results showed that in the area distant from the fixture, new bone formation did not increase and bone remodeling decreased in the first experimental group at 4, 8 weeks, and that new bone formation increased in the second experimental group. 4. The histopathological findings showed that AZ deposition in the first experimental group was remarkable at 2, 8 weeks, and in the second experimental group at 2, 4, 8 weeks in the area distant from the fixture threads.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.5
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• pp.297-302
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• 2022

Objectives: This retrospective study aimed to analyze data on nerve damage in patients who complained of sensory changes after dental implant surgery, the clinical results according to proximity of the implant fixture to the inferior alveolar nerve (IAN) canal, and the factors affecting recovery of sensation. Materials and Methods: The electronic medical records of 64 patients who had experienced sensory change after implant surgery were reviewed. Patients were classified by sex, age, implant installation sites, recovery rate and the distance between the implant fixture and IAN canal on computed tomography (CT). The distance was classified into Group I (D>2 mm), Group II (2 mm≥D>0 mm), and Group III (D≤0 mm). Results: The 64 patients were included and the mean age was 57.3±7.3 years. Among the 36 patients who visited our clinic more than two times, 21 patients (58.3%) reported improvement in sensation, 13 patients (36.1%) had no change in sensation, and 2 patients (5.6%) reported worsening sensation. In Group II, symptom improvement was achieved in all patients regardless of the removal of the implant fixture. In Group III, 8 patients (40.0%) had reported symptom improvement with removal of the implant fixture, and 2 patients (33.3%) of recovered patients showed improvement without removal. Removal of the implant fixture in Group III did not result in any significant difference in recovery (P=0.337), although there was a higher possibility of improvement in sensation in removal cases. Conclusion: Clinicians first should consider removing the fixture when it directly invades the IAN canal. However, in cases of sensory change after dental implant surgery where the drill or implant fixture did not invade the IAN canal, other indirect factors such as flap elevation and damage due to anesthesia should be considered as causes of sensory change. Removal of the implant should be considered with caution in these situations.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.2
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• pp.113-132
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• 2005

The purpose of this study was to assess the stress-induced pattern at the supporting bone, the implant fixture, the abutment and the abutment screw according to a friction-fit joint (Astra; Model 1) or slip- fit joint (Frialit-2; Model 2) in the internal connection system under vertical and inclined loading using finite element analysis. In conclusion, in the internal connection system of the implant and the abutment connection methods, the stress-induced pattern at the supporting bone, the implant fixture, the abutment and the abutment screw according to the abutment connection form had difference among them, and the stress distribution pattern usually had a widely distributed tendency along the inner surface of the implant fixture contacting the abutment post. The magnitude of the stress distributed in the supporting bone, the implant fixture, the abutment and the abutment screw was higher in the friction-fit joint than in the slip-fit joint. But it is considered that the further study is necessary about how this difference in the magnitude of the stress have an effect on the practical clinic.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.541-545
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• 2009

This study evaluated the contact resistance, insulation resistance, withstand voltage characteristics and insertion force, etc., of the wire connector used inside an integrated LITE WAY lighting fixture developed for efficient installation. Since the connector connecting the lighting fixture's internal wires is housed, it is easily connected and separated and has a structure enabling a close-fitting connection. The temperature and time applied to the high temperature characteristics test of the connector are $105^{\circ}C$ and 16 hours, respectively. The measured contact resistance of the high temperature tested connector was 3.258 mV/A, and its measured insulation resistance was greater than $10\;G{\Omega}$ All specimens demonstrated uniform insulation characteristics, which could be seen to be in good condition. From the withstand voltage test results found before and after performing the high temperature operation test on the connector for cable connection, it was confirmed that the withstand voltage characteristics between all terminals were good. The insertion force of the connector connecting the internal wiring averaged 9.67 kgf. It was observed that the insertion force between the plug housing and the female terminal, and that between the plug housing and the male terminal, were 0.680 kgf and 1.27 kgf on average, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.730-733
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• 2010

The Green Lamp Fixture (GLF) of LED prepared with thin panel structure was investigated for illumination of street lamps and other lighting system uses, which was also very useful to aquaculture and aquafarm lighting uses, or fish luring lights and marine aquanautics of aquamarinautics (aquamarine+aquanautics) uses, etc. In the case of fish luring lights, it was verified that the fish luring of Green Lamp Fixture of LED was very effective for phototaxis movement and ecological community promotion to the micro-living things of organisms and the small fries and fishes, like as 'crowding together'. For the aquaculture lightings, it was also very excellent in waterproof and heat-sink properties, photosynthetic growing of algae and micro-organisms, water-weeds and seaweeds living underwater.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.79-83
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• 2018

An accurate method to measure shielding effectiveness(SE) of EMI spray coating film is presented. After high frequency simulating, Circular coaxial standard test fixture is fabricated. A sample of EMI spray coating film was fabricated for insertion into a circular coaxial standard test fixture. The measuring instrument used an Agilent 8722ES vector network analyzer for the SE measurement. The exact SE of copper and silver mixed spray coating sample was measured by the composition of the measuring instrument and the measuring sample. The SE of copper sample was measured at 70 dB and the SE of copper and silver mixed spray coating sample was measured at 60 dB. As a result of the measurement, the reliability of the circular coaxial standard test fixture was confirmed.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.13.1-13.6
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• 2020

Background: The aim of this study was to evaluate the factors that may affect implant fixture fractures. Methods: Patients who experienced implant fixture removal at Seoul National University Bundang Hospital from 2007 to 2015 due to implant fixture fracture were included. Implant/crown ratio, time of implant fracture, clinical symptoms before implant fracture, treatment of fractured implants, and the success and survival rate of the replaced implants were evaluated retrospectively. Results: Thirteen implants were fractured in 12 patients. Patient mean age at the time of fracture was 59.3 years. Of the 13 implants, 7 implants were placed at our hospital, and 6 were placed at a local clinic. The mean crown/implant ratio was 0.83:1. The clinical symptoms before fracture were screw loosening in five implants, marginal bone loss in five implants, and the presence of peri-implant diseases in five implants. All the fractured implants were removed, and 12 out of the 13 sites were re-implanted. Parafunctions were observed in two patients: one with bruxism and one with attrition due to a strong chewing habit. Conclusions: Several clinical symptoms before the fracture of an implant can predict implant fixture failure. Therefore, if these clinical symptoms are observed, appropriate treatments can be taken before more serious complications result.

• Advances in Computational Design
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• v.7 no.4
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• pp.281-295
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• 2022

Tensile property is one of the excellent properties of ultra-high performance concrete (UHPC), and uniaxial tensile test is an important and challenging mechanical performance test of UHPC. Traditional uniaxial tensile tests of concrete materials have inherent defects such as initial eccentricity, which often lead to cracks and failure in non-test zone, and affect the testing accuracy of tensile properties of materials. In this paper, an original integrated design scheme of mould and end fixture is proposed, which achieves seamless matching between the tension end of specimen and the test fixture, and minimizes the cumulative eccentricity caused by the difference in the matching between the tension end of specimen and the local stress concentration at the end. The stress analysis and optimization design are carried out by finite element method. The curve transition in the end of specimen is preferred compared to straight line transition. The rationality of the new integrated design is verified by uniaxial tensile test of strain hardening UHPC, in which the whole stress-strain curve was measured, including the elastic behavior before cracking,strain hardening behavior after cracking and strain softening behavior.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.148-155
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• 2008

The aim of the study is to interpret the distribution of occlusal force by 3-dimensional finite element analysis of ISP(Implant Supported Prosthesis) supported by minimum number of implant to restore the edentulous patients. For this study, the Astra Tech implant system is used. Geometric modeling for 6 and 4 fixture ISP group is performed with respect to the bone, implant and one piece superstructure, respectively. Implants are arbitrarily placed according to the anatomical limit of lower jaw and for the favorable distribution of occlusal force, which is applied at the end of cantilever extension of ISP with 30mm. Element type is tetrahedral for finite element model and the typical mechanical properties, Young's modulus and Poisson's ratio of each material, cortical, cancellous bone and implant material are utilized for the finite element analysis. From this study, we can see the distribution of equivalent stress equal to real situation and speculate the difference in the stress distribution in the whole model and at each implant fixture, From the analysis, the area of maximum stress is distributed on distal contact area between bone and fixture in the crestal bone. The maximum stress is 53MPa at the 0.2mm area from the bone-implant interface in the maximum side for 300N load condition for 4 fixture case, which is slightly less than the stress calculated from allowable strain. This stress has not been deduced to directly cause the loss of crestal bone around implant fixture, but the stress can be much reduced as the old peoples may have lower chewing force. Thus, clinical trial may be performed with this treatment protocol to use 4 fixtured ISP for old patients.

• Journal of Biomedical Engineering Research
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• v.31 no.1
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• pp.56-66
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• 2010

The various total replacement artificial discs have developed because spinal fusion has shown a lesser mobility of an operated segment and an accelerated degeneration at adjacent discs. But almost artificial discs have not yet been reached on the substitute surgery of fusion because many problems such as those clinical success rates were not more than them of fusion have not solved. In this paper, vertically inserted assemble-screw fixture in vertebrae was proposed to improve the fixed capability of artificial disc. And also, to evaluate the design suitability of newly designed screw-type, including fixtures of commercial discs such as wedge and plate type, the 1/4 finite element model with a vertebra and various implanted fixtures were generated, and next, 3 bending motions such as flexion, bending and twisting under the moment of 10Nm and compression under the force of 1000N were considered, respectively and finally, FE analyses were performed. Results of three fixture types were compared, such as Range of Motion and maximal stress, and so on. For ROM, the screw type was average 58% less than the wedge type and was average 42% less than the plate type under all loading conditions. For average stress ratio at closer nodes between vertebra and each fixture, the wedge type was the lowest as minimum 0.02 in twisting, screw types were the highest as maximum 0.28 in compression. As the results of using cement material, it was predicted that the instability problem of the wedge type was better solved. The screw type which could be increased by implanting depth according to the number of assembling mid screws, showed that the decreased tendency of ROMs and maximal cancellous bone stresses. In further study, controlling the number of assembling screws that was suitable for a patient's bone quality, development of surgical tools and keeping on design supplementations, which will be able to develop the competitive artificial disc.