• The Journal of Advanced Prosthodontics
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• v.10 no.5
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• pp.340-346
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• 2018

PURPOSE. In this study, the shear bond strengths (SBS) of luting cements to fixed superstructure metal surfaces under various seating forces were investigated. MATERIALS AND METHODS. Seven different cements [Polycarboxylate (PCC), Glass-Ionomer (GIC), Zinc phospahate (ZPC), Self-adhesive resin (RXU), Resin (C&B), and Temporary cements ((RXT) and (TCS))] were bonded to a total number of 224 square blocks ($5{\times}5{\times}3mm$) made of one pure metal [Titanium (CP Ti) and two metal alloys [Gold-Platinum (Au-Pt) and Cobalt-Chrome (Co-Cr)] under 10 N and 50 N seating forces. SBS values were determined and data were analyzed with 3-way ANOVA. Pairwise comparisons and interactions among groups were analyzed with Tukey's simultaneous confidence intervals. RESULTS. Overall mean scores indicated that Co-Cr showed the highest SBS values ($1.96{\pm}0.4$) (P<.00), while Au-Pt showed the lowest among all metals tested ($1.57{\pm}0.4$) (P<.00). Except for PCC/CP Ti, RXU/CP Ti, and GIC/Au-Pt factor level combinations (P<.00), the cements tested under 10 N seating force showed no significantly higher SBS values when compared to the values of those tested under 50 N seating force (P>.05). The PCC cement showed the highest mean SBS score ($3.59{\pm}0.07$) among all cements tested (P<.00), while the resin-based temporary luting cement RXT showed the lowest ($0.39{\pm}0.07$) (P<.00). CONCLUSION. Polycarboxylate cement provides reliable bonding performance to metal surfaces. Resin-based temporary luting cements can be used when retrievability is needed. GIC is not suitable for permanent cementation of fixed dental prostheses consisting of CP Ti or Au-Pt substructures.

• The korean journal of orthodontics
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• v.20 no.1
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• pp.169-179
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• 1990

Utilizing the repelling force of permanent magnet of find out weather it shows the findings of molar intrusion histologically and compares the result with the resin bite plane. As for the experimental animals, 10 cats of completion of permanent dentition with mean weight of 2.2kg which have flat occlusal plane of molar areas were used. I raised the cats under the condition of their being attached with manufactured appliance by direct bonding system and of their wearing vertical chin strap anesthetized for 12-14 hours per day through 5 days. Then, observing the root apex areas with lightmicroscope. The results were as follows; 1. In the group with resin bite plane, osteoblasts and osteoclasts could not find out but could find out periodontal ligment fiber obliquely angulated in the apical and lingual direction. 2. In the group with the permanent magnet, not only the obliquely angulated periodontal ligament fiber but also the osteoclasts at the apical areas were observed.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.871-876
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• 2001

Recent earthquakes in California and Japan caused extensive damage to highway bridge structures. It is also thought that during probable earthquakes bridge structures in Korea could be failed due to the structural deficiencies, which were nonseismically designed and constructed before 1992. In these regards, innovative strengthening methods have been developed to repair reinforced concrete bridge columns, especially by glassfiber sheet bonding methods which are widely used today. The primary objective of this research is to investigate the seismic behavior of RC bridge columns retrofitted with composite straps and to propose pertinent guidelines of repair and rehabilitation method for earthquake resistant design procedure of RC bridges which are located in low or moderate seismicity regions. Six scaled-down concrete test specimens were made with test variables such as lap splice ratio, axial force ratio, confinement ratio, composite straps in the plastic hinge region. Pertinent design guidelines could be developed for the earthquake resistant design of RC bridge piers retrofitted with glassfibers in low or moderate seismic region.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.8
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• pp.34-42
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• 2004

A new polishing technique for three dimensional micro/meso-scale parts is suggested using a micro quill and a magnetic chain structure. The principle of this method is to polish the target surface with the collected magnetic brushes at a micro tool by the non-uniform magnetic field generated around the tool. In a typical magnetic abrasive finishing process magnetic particles and abrasive particles are unbonded each other. But, to finish the three dimensional small parts bonded magnetic abrasive have to be used. Bonded magnetic abrasives are made from direct bonding, and their polishing characteristics are also examined. Alumina, silicon carbide and diamond micro powders are used as abrasives. Base metal matrix is carbonyl iron powder. It is found that bonded magnetic abrasives are superior to unbonded one by experiment. finally, the polished surface roughness is evaluated by atomic force microscope.

• Journal of the Korean Ceramic Society
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• v.31 no.9
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• pp.941-948
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• 1994

An underwater grout on material resistance against segregation in water were studied by water soluble polymer (methyl cellulose and acrylic acid ester and styrene). The mechanical properties of the grout agents were investigated through the observation of the microstructure and application of fracture mechanic. When the soluble polymer MC+AAES added with 0.6 wt% to the underwater grout agents the compressive strength, flexural strength and Young's modulus were about 58 MPa, 10 MPa and 3.2 GPa respectively, and critical stress intensity was about 0.8 MNm-1.5. It can be considered that the strength improvement and fracture toughness increase may be due to the pore decrease and bonding force by material resistance against segregation in water.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.2
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• pp.67-72
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• 2014

In this study, the viscosity of carbon black filled HTPB liner, mechanical properties and bonding force between propellant and liner were investigated. It is difficult to apply carbon black filled HTPB liner to the motor case in using a horizontal centrifugal casting because of its high viscosity. This problem is solved as a ageing premix at $60^{\circ}C$. The viscosity of premix is drastically decreased from 464 to 200 poise after 6days ageing.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.1
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• pp.35-41
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• 2003

With the understanding of tooth crown biomechanics and the progress of dentin adhesives, bonded porcelain restorations including a porcelain laminate veneer present an extended spectrum of indications for anterior teeth. Porcelain laminate veneer as a restoration offers the conservative solution that balances the functional and esthetic needs of the anterior dentition. Porcelain's stiffness, its surface characteristics, and the biomechanical strength achieved through bonding to tooth surface enable the restoration of the tooth as a whole supporting occlusal force and masticatory function. Namely, the optical effects inherent in the tooth and the lifelike features of the porcelain make that this restoration approaches the ultimate in esthetic satisfaction for both the dentist and the patient. A 49-year-old female patient with the incisal discoloration of upper central incisors and black triangle between the central incisors was referred to correct her esthetic problems with prosthodontic approach. The patient was satisfied with two porcelain laminate veneers that were made according to prof. Magne and Belser's recommendation.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1151-1158
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• 1997

Fracture of uni-directional carbon fiber reinforced carbon matrix composite is strongly dependent on the orientation of basal plane in graphite matrix when it is limited within matrix. The orientation of basal planes are vertically stacked to carbon fiber which results in the weakness for applied tensile or shear force in thermosetting resin derived-carbon matrix composite. Microtextural control of the matrix was tried through chemical interaction between metal carbides and furan resin derived-carbon matrix. SiC and TiO2 addition made the orientation disordered. However, porosity increased due to decomposition of SiC. Interfacial bonding could be controlled by TiO2 addition, but carbon fiber was considerably reacted with TiC during thermal treatment higher than 2$600^{\circ}C$. Therefore, it is desirable to control the thermal treatment temperature at which decomposition of SiC was not serious and TiC/C was not formed eutectoid.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1767-1776
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• 2001

For the stable operation of high speed air spindle, the low rotational inertia and high damping ratio of spindle shafts as well as high fundamental natural frequency are indispensable. Conventional steel spindles are net appropriate for very high speed operation because of their high rotational inertia and low damping ratio. In this study, a high speed spindle composed of carbon fiber epoxy composite shaft and steel flange was designed for maximum critical speed considering minimum static deflection and radial expansion due to bending load and centrifugal force during high speed relation. The stacking angle and the stacking thickness of the composite shaft and the adhesive bonding length of the 7teel flange were selected through vibrational analysis considering static and thermal loads due to temperature rise.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.6
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• pp.761-767
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• 2007

We have developed novel optical-fiber sensors based on strain-induced long-period fiber gratings for monitoring the deformation of a hull. They have no external pressure for sustaining the mechanical formed gratings. The pressure, which provides a force to form the periodic grating along the single mode fiber, was realized by the bonding strength of a photopolymer. To reduce the polarization dependency of the sensors caused by the asymmetry structure of gratings, a Faraday Rotator Mirror (FRM) was utilized in this experiment. We have realized the polarization-insensitive function of the proposed sensors. The change of an external strain are measured by an optical spectrum analyzer. When the external stain increases. the attenuation at the resonant wavelength decreases and the loss peak was slightly shifted to the shorter wavelength.