• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.4
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• pp.278-286
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• 2011

Introduction: This study examined the predictability of new bone formation in the pneumatized maxillary sinus using only fibrin-rich blocks with concentrated growth factors as an alternative to bone grafts. Materials and Methods: Maxillary sinus augmentation was performed in thirty-three patients with a deficient alveolar bone height (mean 3.9 mm). All patients were treated consecutively with sinus membrane elevation via the lateral window approach and panoramic radiograms and cone-beam computed tomograms were taken to evaluate the remaining bone height and the new bone formation in the maxillary sinus, before and after surgery. Four biopsy specimens were taken at the time of implant consolidation (after an average of five months healing) and were stained by H & E and Trichrome staining. Results: None of the patients had postoperative complications during implant consolidation. After an average of 5 months since sinus augmentation, newly formed bone was observed in all cases by a radiographic evaluation. In 4 biopsy samples, newly formed bone was observed along the floor of the replaced bony window. The osteoblast lining and well distinguished Osteocytes in the lacunas were observed in the newly formed bone. Of the 74 implants (4 different surfaced implants - resorbable blast media-surfaced (RBM), Hydroxyapatite (HA) coated, acid-etched, sintered porous-surfaced implant) placed, one RBM implant failed. The success rate was 98.6% after a mean of 15 months. Discussion: These results suggest that maxillary sinus augmentation using fibrin rich block with concentrated growth factors is a successful and predictable technique.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.671-679
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• 2007

Background: $TiUnite^{TM}$ is a highly crystalline and phosphate enriched titanium oxide surface which has a unique porous surface structure. This improved implant surface enhances bone response and reduces healing period. It also assures early stability of implant. These help to increase the success of implant. The aim of this study is to evaluate the survival rate of $TiUnite^{TM}$ surfaced single implant. Materials and methods: A retrospective analysis of 89 $TiUnite^{TM}$ surfaced implants replacing a single tooth was assessed according to their dental record. The age of the patients ranged from 17 to 82 years (mean age: $45.8{\pm}14.6)$. Data were recorded regarding the survival rate of these implants. Results: Fifty-two implants (57%) were placed in the maxilla, and 37 (43%) in the mandible. Over 75% were placed in the posterior area. Of the placed implants, 67% were the wide type. while 25% were the regular type and only 8% were of the narrow type. The single implants produced an overall clinical survival rate of 96.6% over the observation period (mean 17.9 months). Among 89 implants, only 2 implants were removed and one implant was submerged. Conclusion: According to these data, $TiUnite^{TM}$ surfaced implant in a single tooth restoration showed favorable survival rate although this study was done in a short term period.

• Journal of Powder Materials
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• v.12 no.5 s.52
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• pp.325-331
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• 2005

Implant prototypes with various porosities were fabricated by electro-discharge-sintering of atomized spherical Ti-6Al-4V powders. Single pulse of 0.75 to 2.0 kJ/0.7 g-powder, using 150, 300, and $450{\mu}F$ capacitors was applied to produce a fully porous and porous surfaced implant compact. The solid core formed in the center of the compact after discharge was composed of acicular ${\alpha}+{\beta}$ grains and porous layer consisted of particles connected in three dimensions by necks. The solid core and neck sizes increased with an increase in input energy and capacitance. On the other hand, pore volume decreased with increased capacitance and input energy due to the formation of solid core. Capacitance and input energy are the only controllable discharge parameters even though the heat generated during a discharge is the unique parameter that determines the porosity of compact. It is known that electro-discharge-sintering of spherical Ti-6Al-4V powders can efficiently produce fully-porous and porous surfaced Ti-6Al-4V implants with various porosities in a short time less then 400 isec by manipulating the discharging condition such as input energy and capacitance including powder size.

• The Korean Journal of Zoology
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• v.22 no.3
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• pp.103-114
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• 1979

The authors observed the ultrastructure of the granular glands in the amphibian skin with an electron microscope. The specimens from the experimental animals (Bombina orientalis, Bufo bufo gargarizans, Rana nigromaculata and Rana rugosa) were fixed in 2.5% glutaraldehyde-paraformaldehyde fixative in phosphate buffer at pH 7.2 prior to fixation in 1% osmium tetroxide, dehydrated in graded ethanol and acetone, embedded in Epon 812 mixture, and sectioned with a LKB-ultramicrotome. the ultrathin sections were contrasted with uranyl acetate and lead citrate and observed with a JEOL-100B electron microscope. The results were as follws: 1. The granular gland in the amphibian skin consisted of the glandular epithelial and the myoepithelial cells. 2. The epithelial cells of the granular gland in the amphibian skin consisted of the dark cells but the light cells were also observed in that of Bombina orientalis. 3. The granular glands of the amphibian skin were in holocrine fashion. 4. The nuclei of the epithelial cells of the amphibian cutaneous granular glands were round or oval and showed small and large inforldings of nuclear envelope. Heterochromatins were mainly distributed near the nuclear envelope. Mitochondria were mainly distributed in the perinuclear portion and rough-surfaced endoplasmic reticulums were developed in the cytoplasm but smooth-surfaced endoplasmic reticulums were not well developed. 5. Secretory granules were round or oval and electron-dense and less electron-dense granules were observed. 6. The authors infer that the differences in electron density of the secretory granules in the granular glands of the amphibian skin are due to difference in the concentrations of secretory substances as related to the processes of its formation, and that those chemical components are identical.

• 대한치주과학회:학술대회논문집
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• 2007.11a
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• pp.150-151
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• 2007

• Journal of Ocean Engineering and Technology
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• v.31 no.1
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• pp.28-35
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• 2017

This paper introduces a GPS-aided dead reckoning algorithm that asymptotically estimates the heading bias error of a magnetic compass based on geodetic north, improves the position error accumulated by dead reckoning, and helps the estimated position of an AUV to represent a position in the NED coordinate system, by receiving GPS position information when surfaced. Based on the results of a simulation, the locational error was bounded with a modest distance, after estimating the AUV position and heading bias error of the magnetic compass when surfaced. In other words, it was verified that proposed algorithm improves the position error in the NED coordinate system.

• The Korean Journal of Zoology
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• v.26 no.2
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• pp.107-123
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• 1983

The globus pallidus of normal cats were prepared for electron microscopic study following perfusion with a mixture of 1% paraformaldehyde and 1% glutaraldehyde solution. Neurons of two size categories were identified in 1 $\\mu$m araldite sections and their ultrastructural characteristics were studied in adjacent thin section. 1. Large neurons ($30 \\mum \\times 45 \\mum$ in diameter) had extensive areas of rough surfaced endoplasmic reticulm, abundant perinuclear Golgi complex, numerous mitochondria and lipofusin granule, and had a large spherical nucleus with shallow indentation of nuclear manbrane. Small neurons ($17 \\mum \\times 27 \\mum$ in diameter) had poorly rough surfaced endoplasmic reticulum, moderate number of mitochondria and randomly distributed Golgi complex. The nuclear envelope of this cell frequently showed multiple deep invagination. 2. Three types of axo-somatic synapses were identified on the basis of the size and shape of vesicle in the axon terminal and the symmetrical or asymmetrical thickening at the synaptic site. Type I synaptic terminal shows an even distribution of round and oval synaptic vesicles, and has a symmetrical synaptic thickening. Type II axon terminals reveal mostly round and pleomorphic vesicles and a few vesicles were localized near the presynaptic membrane in pale axoplasm and its synaptic thickening were symmetric. Type III axon terminals contain round vesicles, which were aggregated in the axoplasm, and has a asymmetrical synaptic thickening. 3. The majority of axo-somatic contact with the large and small neurons were type I, and type II and III synapes were rare.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.1
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• pp.62-71
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• 2001

Prediction of ship's signature of RCS(Radar Cross Section) and TES(Target Echo Strength) is mostly required in the initial design stage of naval craft, because RCS is directly related to the radar detection while TES to the sonar detection. In this research, a numerical scheme using a curved-patch physical optics method is proposed to evaluate signature of a perfectly reflecting curved object. The scheme is validated by comparing numerical RCS values of circular cylinder, sphere and NACA3317 airfoil with available data. It is also further applied to predict RCS of a surfaced submarine and TES of fully submerged one. Major reflectors of the surfaced or submerged submarine for the various incident angles of radar and sonar waves are investigated as well.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.3
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• pp.325-340
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• 2008

The purpose of this study was to evaluate the artificial dental plaque by Streptococcus mutans on 4 different implant surfaces. In this study, the specimens were divided into 4 groups according to implant surface treatment. Uncoated implant group(n=5) which has an uncoated, smooth surfaced implant(Osstem, Korea), SLA implant group(n=5) which has an sandblasted large grit and acid-etched surface implant(Bicon, USA). Oxidized implant group(n=5) which has an oxidized surfaced implant (Osstem, Korea), and RBM implant group(n=5) which has resorbable blasting media(RBM) surfaced implant(Osstem, Korea). Acquired pellicle by human saliva and dental plaque by Streptococcus mutans were made on each implant surface. To analyze the plaque condition on implants surfaces, cell count and optical density were taken as a microbiologic method, and SEM(Scanning Electronic Microscope) findings was also taken for evaluation of surface condition. The following results were obtained. 1. Cell counting results of artificial dental plaque were Uncoated group($658.0{\pm}102.0$), RBM group($878.0{\pm}170.0$), SLA group ($946.0{\pm}42.0$), Oxidized group($992.0{\pm}40.0$), and there was difference between Oxidized group and Uncoated implant group(p<0.05). In case of modified cell counting results by v/w% were RBM group($197.8{\pm}45.2$), Oxidized group($207.04{\pm}8.34$), Uncoated group($261.6{\pm}40.6$), SLA group($315.4{\pm}14.0$), and there was difference between RBM group and SLA group(p<0.05). 2. Optical density results of artificial dental plaque after ultrasonic treatment was that there was difference among groups, and optical density of RBM group was higher than that of Uncoated group(p<0.05). In case of modified optical density results by v/w%, there was difference among groups, and the modified optical density of Uncoated group and SLA group was higher than those of Oxidized group and RBM group(P>0.05). 3. SEM findings of artificial dental plaque on the surfaces of implant as follows; there were artificial dental plaque on the surfaces of all test implants. Streptococcus mutans and by-product were observed at 10,000 times magnified condition on all test implants. Adhesion area of artificial dental plaque was about 1/2 of total surface after 24 hours incubate at $37^{\circ}C$. These results showed that there were differences among implant surfaces on the growth of Streptococcus mutans, and bacteria and by-product were covered about 1/2 area of total implant surfaces at 24 hours incubate at $37^{\circ}C$.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.1
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• pp.52-59
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• 2008

The geometric design of an implant surface may play an important role in affecting early osseointegration. It is well known that the porous surfaced implant had much benefits for the osseointegration and the early stability of implant. However, the porous surfaced implant had weakness from the transgingival contamitants, and it resulted in alveolar bone loss. The other problem identified with porous surface implant is the loss of physical properties resulting from the bead sintering process. In this study, we developed the new bead coating implant to overcome the disadvantages of porous surfaced implant. Ti-6Al-4V beads were supplied from STARMET (USA). The beads were prepared by a plasma rotating electrode process (PREP) and had a nearly spherical shape with a diameter of 75-150 ${\mu}m$. Two types of titanium implants were supplied by KJ Meditech (Korea). One is an external hexa system (External type) and the other is an internal system with threads (Internal type). The implants were pasted with beads using polyvinylalcohol solution as a binder, and then sintered at 1250 $^{\circ}C$ for 2 hours in vacuum of $10^{-5}$ torr. The resulting porous structure was 400-500 ${\mu}m$ thick and consisted of three to four bead layers bonded to each other and the implant. The pore size was in the range of 50-150 ${\mu}m$ and the porosity was 30-40 % in volume. The aim of this study was to evaluate the osseointegration of the newly developed dental implant. The experimental implants (n=16) were inserted in the unilateral femur of 4 mongrel dogs. All animals were killed at 8 weeks after implantation, and samples were harvested for hitological examination. All bead coated porous implants were successfully osseointegrated with peripheral bone. The average bone-implant contact ratios were 84.6 % (External type) and 81.5 % (Internal type). In the modified Goldner's trichrome staining, new generated mature bones were observed at the implant interface at 8 weeks after implantation. Although, further studies are required, we could conclude that the newly developed vacuum sintered Ti-6Al-4V bead coating implant was strong enough to resist the implant insertion force, and it was easily osseointegrated with peripheral bone.