• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.79-87
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• 2012

Currently, The method to produce a brewing body for dentistry supplementation water produces a brewing body by fabrication, burying and it is heat wish in city gas and oxygen. It uses an original judgment found airplane the brewing body uses a spring of the back wait that melting temperature dissolved various alloys in by a blow pipe, and to generate centrifugal force and produces it. In addition, because it uses preheating to dissolve an alloy in general, it is hard to regulate the appropriate melting temperature of the alloy and brewing time and generates a brewing defect hereby same as gas industry and pinhole and shows the defect of the supplementation thing due to the super-heating. In this paper, We developed the high induction heating system which it could set brewing time,temperature and had durability and security,by the kind of the alloy to produce a high quality prosthetic thing brewing body.

• The korean journal of orthodontics
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• v.43 no.5
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• pp.235-241
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• 2013

Objective: The purpose of this study was to investigate whether extension of the custom base is necessary for enhancement of bond strength, by comparing the debonding forces and residual adhesives of 3 different lingual bracket systems. Methods: A total of 42 extracted upper premolars were randomly divided into 3 groups of 14 each for bonding with brackets having (1) a conventional limited resin custom base; (2) an extended gold alloy custom base: Incognito${TM}$; and (3) an extended resin custom base: KommonBase${TM}$. The bonding area was measured by scanning the bracket bases with a 3-dimensional digital scanner. The debonding force was measured with an Instron universal testing machine, which applied an occlusogingival shear force. Results: The mean debonding forces were 60.83 N (standard deviation [SD] 10.12), 69.29 N (SD 9.59), and 104.35 N (SD17.84) for the limited resin custom base, extended gold alloy custom base, and extended resin custom base, respectively. The debonding force observed with the extended resin custom base was significantly different from that observed with the other bases. In addition, the adhesive remnant index was significantly higher with the extended gold alloy custom base. Conclusions: All 3 custom-base lingual brackets can withstand occlusal and orthodontic forces. We conclude that effective bonding of lingual brackets can be obtained without extension of the custom base.

• Journal of Korea Foundry Society
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• v.20 no.3
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• pp.208-215
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• 2000

The mechanical properties and corrosion resistance of Ti alloys for medical implants have been investigated. Ti, Ti-15Sn-4Nb and Ti-15Sn-4Nb-2Zr alloys were melted in arc furnace and the corrosion resistance of Ti alloys was evaluated by anodic polarization test. The microstructure and mechanical properties of Ti alloys were analysed by optical microscope, hardness and tensile tester. The tensile strength of the pure-Ti improved by addition of Sn and Nb and Ti-15Sn-4Nb alloy showed better Rockwell hardness compared with pure Ti. However, there was no significant difference in corrosion resistance between thoseTi-alloys made of Pure-Ti and Ti-15Sn-4Nb alloy. The passive films on the Ti-15Sn-4Nb alloy in air atmosphere consisted of $TiO_2$, SnO and NbO as demonstrated by X-ray photoelectron spectroscopy(XPS)

• Korean Journal of Materials Research
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• v.14 no.12
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• pp.851-856
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• 2004

The aim of this study is to investigate the optimum drawing parameter for BAS121 welded tubes. The BAS121 aluminium alloy tubes with 25 mm in external diameter and 1.3 mm in thickness for heat-exchangers were manufactured by high frequency induction welding with the V shaped convergence angle $6.5^{\circ}$ and power input 55 kW. With increasing the reduction of area ($13,\;21\%$) by drawing, tensile strength was increased and elongation was decreased. With increasing the reduction of area by drawing, hardness in weld metal increased rapidly, while that of base metal increased slowly. In the specimen with the outer diameter smaller than 22 mm, hardness of weld metal was higher than that of base metal. The optimum drawing parameter of area reduction in BAS121 alloys was estimated about $13\%$ because of the work hardening of welds.

• Journal of the Korean institute of surface engineering
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• v.43 no.4
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• pp.199-204
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• 2010

The Co-Cr alloys have clinical histories as dental and orthopaedic implants, and recently as cardiovascular stent applications because they exhibit a high elastic modulus and radiopacity. In order to improve their mechanical and corrosion resistance, electropolishing is employed as the final process. Electropolishing, an anodic dissolution process in the transpassive state, is sensitively affected by process conditions such as current density, machining time, and electrode gap. In this study, the effect of the electropolishing conditions on surface roughness and corrosion resistance is investigated for Co-Cr alloys (L605). The most smooth surface is obtained when electropolishing is performed at 15-20 V for 15-30 sec with a electrode gap of 3.5 mm. It is found out that electropolishing reduces corrosion rate about one-tenth as much.

• Corrosion Science and Technology
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• v.8 no.4
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• pp.162-169
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• 2009

Pure titanium and its alloys are drastically used in implant materials due to their excellent mechanical properties, high corrosion resistance and good biocompatibility. However, the widely used Ti-6Al-4V is found to release toxic ions (Al and V) into the body, leading to undesirable long-term effects. Ti-6Al-4V has much higher elastic modulus than cortical bone. Therefore, titanium alloys with low elastic modulus have been developed as biomaterials to minimize stress shielding. For this reason, Ti-30Ta-xZr alloy systems have been studied in this study. The Ti-30Ta containing Zr(5, 10 and 15 wt%) were 10 times melted to improve chemical homogeneity by using a vacuum furnace and then homogenized for 24 hrs at $1000^{\circ}C$. The specimens were cut and polished for corrosion test and Ti coating and then coated with TiN, respectively, by using DC magnetron sputtering method. The analyses of coated surface were carried out by field emission scanning electron microscope(FE-SEM). The electrochemical characteristics were examined using potentiodynamic (- 1500 mV~+ 2000 mV) and AC impedance spectroscopy(100 kHz~10 mHz) in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The equiaxed structure was changed to needle-like structure with increasing Zr content. The surface defects and structures were covered with TiN/Ti coated layer. From the polarization behavior in 0.9% NaCl solution, The corrosion current density of Ti-30Ta-xZr alloys decreased as Zr content increased, whereas, the corrosion potential of Ti-30Ta-xZr alloys increased as Zr content increased. The corrosion resistance of TiN/Ti-coated Ti-30Ta-xZr alloys were higher than that of the TiN-coated Ti-30Ta-xZr alloys. From the AC impedance in 0.9% NaCl solution, polarization resistance($R_p$) value of TiN/Ti coated Ti-30Ta-xZr alloys showed higher than that of TiN-coated Ti-30Ta-xZr alloys.

• Journal of Technologic Dentistry
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• v.31 no.2
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• pp.45-52
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• 2009

Esthetic restorations have been widely used in dental practice, although many studies have focused on the development and improvement of all ceramic restorations. The success of esthetic restorations depends primarily on an optimal bond strength between various veneered ceramics and core materials for esthetic restorations. The purpose of this study was to compare the shear bond strength between various veneered ceramics and core materials for esthetic restorations. 30 metal cores and 20 zirconia cores were fabricated and divided into five groups according to veneered ceramic materials such as Creation porcelain powder, Cercon Ceram Kiss, and IPS e.max ZirPress. Thirty spacimens were prepared using Creation porcelain powder, veneered 3mm height and 3mm in diameter, over the metal cores (n=10). Twenty specimens were prepared using Cercon Ceram Kiss and Zirpress, veneered 3mm height and 3mm in diameter, over the zirconia cores (n=10). The shear bond strength test was performed in a universal testing machine with a crosshead speed of 1mm/min. Ultimate shear bond strength data were analyzed with One-way ANOVA and the Scheffe's test (p=.05). Within the limits of this study, the following conclusions were drawn: The mean shear bond strengths (MPa) were: 18.44 for Uni metal VH/Creation (NCUC); 18.72 for Heraenium/Creation (NCHC); 16.23 for Wirobond C/Creation (NCWC); 13.88 for Zirconia core/$110{\mu}m$ $Al_2O_3$ sandblasting/Cercon Ceram Kiss (ZS110P); 14.61 for Zirconia core/No surface treatment/IPS e.max ZirPress (ZNTH). The mean shear bond strength for NCUC (Uni metal VH/Creation), NCHC (Heraenium/Creation) and NCWC (Wirobond C/Creation) were significantly superior to ZS110P (Zirconia core/$110{\mu}m$ $Al_2O_3$ sandblasting/Cercon Ceram Kiss) and ZNTH(Zirconia core/No surface treatment/IPS e.max ZirPress) (p<0.05).

• Journal of dental hygiene science
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• v.13 no.3
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• pp.290-295
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• 2013

The purpose of this study was to investigate the shear bond strength between various commercial all-ceramic system core and veneering ceramics, and evaluate the clinical stability by comparing the conventional metal ceramic system. The test samples were divided into three groups: Ni-Cr alloy (metal bond), yttria-stabilized, tetragonal zirconia polycrystal (Y-TZP) (zirconia bond), lithium disilicate (lithium disilicate bond). The veneering porcelain recommended by the manufacturer for each type of material was fired to the core. After firing, the specimens were subjected to shear force in a universal testing machine. Load was applied at a crosshead speed of 0.50 mm/min until failure. Average shear strengths (mega pascal) were analyzed with a one-way analysis of variance and the Tukey test (${\alpha}$=0.05). The mean shear bond strength${\pm}$SD in MPa was $44.79{\pm}2.31$ in the Ni-Cr alloy group, $28.32{\pm}4.41$ in the Y-TZP group, $15.91{\pm}1.39$ in the Lithium disilicate group. The ANOVA showed a significant difference among groups (p<0.05). None of the all-ceramic system core and veneering ceramics could attain the high bond strength values of the metal ceramic combination.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.320-329
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• 2009

Objective: The aim of this study was to evaluate the effect of metal primers and thermocycling on shear bond strength between the orthodontic bracket and gold alloy. Methods: For this study, 80 specimens made of dental gold alloy were divided into 8 groups based on the combination of metal primers (none, Alloy primer, Metaltite, V-primer) and thermocycling (with and without thermocycling). Shear bond strength testing was performed with a universal testing machine. Bond failure sites were classified by a modified ARI (Adhesive Remnant Index) score. Results: All metal primer treated groups showed a significantly higher shear bond strength than the only sandblasting treated group without thermocycling (p < 0.05). There were no significant differences on shear bond strength in the groups with thermocycling (p > 0.05). Bond failure sites of the metal primer treated group without thermocycling occurred at gold alloy/adhesive interface, whereas there were no differences on bonding failure sites in the groups with thermocycling. Conclusions: These findings suggest that using metal primer on gold alloy enhances the initial bracket bond strength. But, this effect was not shown with thermocycling.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.194-201
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• 2016

Purpose: The purpose of this study was to evaluate of Zirconium Nitride (ZrN) coating on shear bond strength with denture base resin in Co-Cr and Ti-6Al-4V alloy. Materials and Methods: Co-Cr and Ti-6Al-4V alloy disks (10 mm in diameter, 2.5 mm in thickness; each other: n = 14) were prepared and divided with 2 groups each other by ZrN coating. After primer was applied to disks surface, denture base resin with diameter 6 mm, height 5 mm was bonded on metal disk surface. After surface roughness was measured by Profiler, shear bond strength was determined with Universal testing machine and analyzed with two-way ANOVA. The specimen surfaces and failure mode were examined using a scanning electron microscope. Results: ZrN coated groups showed significantly higher rough surface than non-coated groups (P < 0.05). Irrespective of alloy materials, shear bond strength of ZrN coated groups were lower than non-coated groups (P < 0.001). The scanning electron microscope (SEM) of ZrN coated groups showed mixed and adhesive fractures. Conclusion: ZrN coating weakened bonding strength between denture base resin and Co-Cr, Ti-6Al-4V alloy.