• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.1
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• pp.51-62
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• 2014

The purpose of this experiment was to evaluate the apatite-formation abilities of low-modulus Ti-7.5Mo substrates treated with NaOH aqueous solutions and subsequent ethyl alcohol aging before soaking them in simulated body fluid. Specimens of Ti-7.5Mo were initially treated with 5 M NaOH at $60^{\circ}C$ for 24 h, resulting in the formation of a porous network structure composed of sodium hydrogen titanate. Afterwards, the specimens were aged in ethyl alcohol at $60^{\circ}C$ for 5 or 10 min, and subsequently immersed in simulated body fluid at $37^{\circ}C$ for 3, 7 and 14 days. Ethyl alcohol aging significantly increased the apatite-forming abilities of Ti-7.5Mo. The amount of apatite deposited on the Ti-7.5Mo after NaOH treatment and subsequent ethyl alcohol aging was much greater, especially after the Ti-7.5Mo specimens were aged for 5 min. Due to its excellent combination of bioactivity, low elastic modulus and low processing costs, the Ti-7.5Mo treated with NaOH aqueous solutions and subsequently aged in ethyl alcohol has promising heavy load-bearing applications.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.212-217
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• 2017

In case of the insufficient horizontal bone loss, a regular diameter implant is not possible without lateral bone augmentation. In this situation, narrow diameter implants (NDIs) could be the alternative to lateral bone augmentation procedures. However, complication generally expected with the NDI is implant fracture. Recently, the survival rate and success rate of NDI in the posterior region are similar to that of standard-diameter implants (SDIs). These 3 case reports demonstrate the incorporation of NDI to replace missing mandibular posterior teeth. So far, the follow-up examination period was maintained and no unusual complications were presented for more than four years. Long term follow-up clinical data are needed to confirm the excellent clinical performance of these implants.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.39-73
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• 1998

In the 60's to 70's, frame selection was a purely mechanical consideration almost entirely dominated by the optician and his subjective judgments. Toddy the cosmetic factor is predominant. The variety of frame color, materials, and style means that the main burden of selection has passed to the customer, leaving the optician control a subtle factor often difficult to exert. Common materials include nickel silver, Hi-nickel alloy, bronze, stainless steel, gold, gold plated, gold clad, copper beryllium, titanium and sometimes aluminium. In manufacturing of metal frames with the materials, even though fashion is the stimulant of consumer demand, all the metal frame for the prescription to refractive correction should be designed correctly styled eyewear which is cosmetically pleasing, functional correct, physically comfortable, mechanically and structurally perfectible, and temperamentally acceptable.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.5
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• pp.281-287
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• 2005

Titanium aluminium nitride((TiAl)N) film is anticipated as an advanced coating film with wear resistance used for drills, bites etc. and with corrosion resistance at a high temperature. In this study, (TiAl)N thin films were deposited both at room temperature and at elevated substrate temperatures of 573 to 773 K by using a two-facing-targets type DC sputtering system in a mixture Ar and $N_2$ gases. Atomic compositions of the binary Ti-Al alloy target is Al-rich (25Ti-75Al (atm%)). Process parameters such as precursor volume %, substrate temperature and Ar/$N_2$ gas ratio were optimized. The crystallization processes and phase transformations of (TiAl)N thin films were investigated by X-ray diffraction, field-emission scanning electron microscopy. The microhardness of (TiAl)N thin films were measured by a dynamic hardness tester. The films obtained with Ar/$N_2$ gas ratio of 1:3 and at 673 K substrate temperature showed the highest microhardness of $H_v$ 810. The crystallized and phase transformations of (TiAl)N thin films were $Ti_2AlN+AlN{\rightarrow}TiN+AlN$ for Ar/$N_2$ gas ratio of 1:3, $Ti_2AlN+AlN{\rightarrow}TiN+AlN{\rightarrow}Ti_2AlN+TiN+AlN$ for Ar/$N_2$ gas ratio of 1:1 and $TiN+AlN{\rightarrow}Ti_2AlN+TiN+AlN{\rightarrow}Ti_2AlN+AlN{\rightarrow}Ti_2AlN+TiN+AlN$ for Ar/$N_2$ gas ratio of 3:1. The above results are discussed in terms of crystallized phases and microhardness.

• Journal of Korean Neurosurgical Society
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• v.39 no.5
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• pp.360-365
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• 2006

Objective : This is a cadaver study to assess the accuracy of three cervical screw insertion techniques; the blind technique [Group I], the laminotomy technique [Group II], and the funnel technique [Group III]. Methods : Ten human cadavers embalmed with formaldehyde were prepared. After exposing the spinous processes, the laminas and the lateral masses, titanium alloy transpedicular screws were inserted from C3 to C7. A total of 100 pedicles were ramdomly assigned to one of three techniques [the blind technique : 31 screws, the laminotomy technique : 51 screws, the funnel technique: 18 screws]. Axial computed tomography with 1-mm slices, and sagittal and coronal reformation were performed to identify the accuracy of the screw insertion and the anatomic relationships. Results : In Group I, 9 screws [29%] were either contained within or penetrated less than 1mm, which were rated as successful. In Group II, 24 screws [47%] were successful. In Group III, 16 screws [89%] were successful. In the multiple comparison, there was a statistically significant difference between Groups I and III and between Groups II and III [$X^2$ test and Bonfenoni test]. Conclusion : The funnel technique can help a surgeon's understanding about the cervical pedicle more precisely than the other two techniques. The funnel technique is less dependent on lateral soft tissue retraction state.

• Journal of Veterinary Clinics
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• v.20 no.2
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• pp.207-211
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• 2003

This investigation aimed to determine the relative merit of osseointegration in immediate and delayed implantation in the dog mandible using radiography and bone scintigraphy. five adult mongrel dogs with a mean weight of 8.5 kg were used in this investigation. During the entire study period. all dogs were fed with a soft commercial diet and water ad libitum to minimize functional loading of the implant. Twenty titanium alloy systems 4 mm in diameter and 10 mm in length blasted with calcium phosphate were prepared for insertion. The second and third left mandibular premolars in each dog were extracted for the delayed implant insertion. Twelve weeks later, the second and third right mandibular premolars were extracted for the immediate implant insertion. Before the delayed and immediate implantation procedures and 0, 4, 8, and 12 weeks after the insertions, radiography and bone scintigraphy were conducted. Bone scans were obtained using a large field of view gamma camera equipped with a collimator about 3 hours after intravenous injection of Tc-99m-MDP to the dogs. All the dogs were evaluated weekly for inflammation, necrosis, and other of the bone or sort tissue. Significant macroscopic lesions were not detected. Radioisotope scintigraphy with Tc-99m-MDP hat proved to be a reliable method for measuring increased bone activity at specific skeleton tissue sites. In conclusion, osseointegration in peri-implant bone did not differ significantly between the immediate and delayed implant procedures during the experimental period. The immediate implant may be an alternative treatment of implant insertion in animals.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.11
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• pp.1121-1128
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• 2013

Ultrasonic grinding system is that the ultrasonic vibration by ultrasonic actuator is applied on conventional grinding system during grinding process. The Ultrasonic vibration with a frequency of over 20kHz can reduce grinding forces and increase surface quality, material removal rate (MRR) and grinding wheel life. In addition, ultrasonic vibration assisted grinding can be used for the materials that are difficult to cut. In this paper, methodology for ultrasonic tools is studied based on finite element method, and in turn the ultrasonic tools are designed and fabricated. It is found that the ultrasonic tool can vibrate with a frequency of 20kHz and amplitude of $25{\mu}m$. In order to verify the machining performance, the grinding experiment is performed on titanium alloy. By applying ultrasonic vibration, the grinding force and temperature are reduced and MRR is increased compared with the conventional grinding.

• Korean Journal of Veterinary Research
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• v.44 no.1
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• pp.131-136
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• 2004

Osseointegration involves anchoring dental implants to stable bone rather than to soft-tissue. Clinical osseointegration is currently defined as the process whereby alloplastic material is asymptomatically and rigidly fixed and maintained in bone during functional loading. Full osseointegration is necessary for the success of long-term dental implants. Recent developments in computer assisted measurement of bone formation have improved maxillofacial examination and osseointegration. Computer assisted examination has also proved effective in dental implantology. This investigation was aimed to determine osseointegration in immediate and delayed implantation in the dog mandible using dental computed tomography (CT) and bone scintigraphy. Five adult (mean age of 2 years) mongrel dogs with a mean weight of 9.1 kg were used in this investigation. Titanium alloy implant systems with 4 mm in diameter and 10 mm in length were chosen for insertion. The second and third left mandibular premolars in each dog were extracted for the delayed implant insertion. Twelve weeks later, the second and third right mandibular premolars were extracted for the immediate implant insertion. Before the delayed and immediate implantation procedures and 0, 4, 8, and 12 weeks after the insertions, dental CT and scintigraphy were conducted. The CT and scintigraphic images indicate that reconstruction of bone surrounding of the immediate implant can be as successful as reconstruction of bone surrounding of the delayed implant.

• 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.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.688-694
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• 1999

Ti-6Al-4V-N films have been grown onto glass substrates by dc reactive magnetron sputtering from a Ti-6Al-4V-N alloy target at different nitrogen partial pressure, input powers and sputtering times. The influence of various sputtering conditions on structural properties of Ti-6Al-4V-N films was investigated by measuring their X-ray diffraction. The quaternary Ti-6Al-4V-N film is crystallizing in a face centered cubic TiN structure, the lattice parameter is smaller than the TiN parameter as titanium atoms of the TiN lattice are replaced by aluminum and vanadium atoms. The films show the (111) preferred orientation and the (111) peak intensity decreases as the nitrogen partial pressure is increased, but the intensity increases as the sputtering time is increased. The deposition rate and the grain size are alto related with the variation of various sputtering conditions.