• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.156.1-156.1
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• 2016

Nickel sulfide (NiS) is one of the most promising candidates as an electrode material for supercapacitors due to its good capacitive properties, high electrical conductivity and low cost. In addition to the development of the new electrode materials, nanostructuring the electrode surface is one of the main issues in enhancing the capacitive performance of the supercapacitors because the increased surface area can improve the charge transfer and energy storage processes occurring at the electrode surface. However, most nanofabrication techniques require complicated and delicate nanoprocesses, and hence are not suitable for practical use. In this work, we developed a simple method to fabricate nanostructured NiS electrodes by depositing NiS onto $TiO_2$ nanoparticles. First, $TiO_2$ nanoparticles were spin-coated on a fluorine-doped tin oxide (FTO) substrate, and then NiS layers were deposited onto the $TiO_2$ nanoparticles by consecutive dip-coatings in the solutions containing nickel and sulfur precursors. This nanostructured NiS electrode showed significantly improved capacitive properties compared to the electrode of NiS films deposited without $TiO_2$ nanoparticles. The asymmetric full-cell supercapacitor with this nanostructured NiS electrode and activated carbon electrode was also fabricated and investigated.

• Journal of the Korean institute of surface engineering
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• v.46 no.5
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• pp.216-222
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• 2013

In order to improve the performance of electrodeposited diamond-nickel composite, surface modification of diamond particles was carried out using powder immersion reaction assisted coating (PIRAC). Titanium and chromium were selected as coating elements, which are known as carbide former. With respect to the powder elements, various phases were formed on diamond; metallic Ti and TiC for Ti powder, $Cr_3C_2$ for Cr powder, and TiC and $Cr_3C_2$ for Ti-Cr mixed powder. Surface modified diamond particle showed higher specific surface area, especially Ti coating induced considerable increase of specific surface area. The increase of specific surface area suggests increase of surface roughness, and that was confirmed by surface observation using FE-SEM. In addition, wear properties of diamond-nickel composite including surface modified diamonds were improved, and Ti coated diamond showed the highest performance. The wear property of diamond-nickel composite is dependent on adhesion strength between diamond particle and nickel layer. Therefore, surface modification of diamond particle by PIRAC increasing surface roughness is effective to improve the properties of diamond-nickel composite.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.124-128
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• 2018

Titanium doping is employed to enhance the structural strength of a high-Ni layered cathode material in lithium ion batteries during high temperature cycling. After Ti-doping, the external morphology remains similar, but the lattice parameters of the layered structure are slightly shifted toward larger values. With application of the prepared materials as cathodes in lithium-ion batteries, the initial capacities are similar but the cycling performance at $25^{\circ}C$ is enhanced by Ti-doping. During high temperature cycling at $60^{\circ}C$, furthermore, highly improved capacity retention is achieved with the Ti-doped material (95% of initial capacity at 50th cycles), while cycle fading is accelerated with the bare electrode. This enhancement is attributed to better retention of the compressive strength of the particles and retarded crack formation within the particles. In addition, impedance increase is reduced in the Ti-doped electrode, which is attributed to an improvement in the structural strength of the high-Ni cathode material with Ti-doping.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.599-599
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• 2003

Endodontic rotary NiTi(Nickel-Titanium) files have several advantages, but they also have some problems. Fracture of instrument is the one of the problems. Cyclic fatigue fracture may not give a previous sign(ex, bending or distortion of the files) before it happen. It is affected by various factors. This study investigated time which takes for cyclic fatigue fracture to happen and fracture patterns with regard to different NiTi files and pecking motion.(omitted)

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.580-580
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• 2003

I. Objectives This study investigated the quantity of debris which was extruded apically after canal instrumentation using different types of enlarging instrument in endodontic resin models. II. Materials and Methods Five groups of 9 endodontic resin model were instrumented using each different technique：hand instrumentation without early coronal flaring, hand instrumentation after early coronal flaring, and three nickel-titanium engine-driven instrumentations(Hero 642, Protaper, K3) after early coronal flaring.(omitted)

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.85-90
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• 2015

This report introduces a novel technique that allows a safe and predictable canal negotiation, creation of a glide path and canal preparation with reciprocating nickeltitanium or stainless steel engine-driven instruments in canals where the use of rotary and the newly developed reciprocating instruments is contraindicated. In this novel technique, the instruments are used in reciprocating motion with very small angles. Hand files are not used regardless of the complexity of the canal anatomy. It also allows achieving predictable results in canal negotiation and glide path creation in challenging canals without the risk of instrument fracture.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.271-281
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• 2001

The Purpose of this study was fourfold - to evaluate the general laws of friction applied to orthodontic conditions, to compare archwire materials under these controlled conditions, to compare ligation method, and to measure the effect of the artificial saliva on friction with these materials Three wire alloys (Cobalt-chromium, Nickel-titanium, Beta-titanium) in two size wires (.016" , .016" ${\times}$.022" ) were examined respect to the bracket (.018" ${\times}$.025" standard), and two ligature material (stainless steel, elastomeric) in dry and wet conditions The results were as follows, 1. The order of frictional force against alloy materials was Co-Cr (lowest), Ni-Ti, and ${\beta}$-Ti(highest) - with the exception of elastomeric ligation under wet conditions. 2. S.S. ligation gave rise to significantly greater friction than elastomeric ligation did. 3. Testing in the presence of saliva, rather than in dry conditions, decreased the frictional force for S.S. ligation with .016" Co-Cr, Ni-Ti, ${\beta}$-Ti. but, increased the frictional force for S.S. ligation with .016" ${\times}$ .022" Co-Cr, Ni-Ti, ${\beta}$-Ti. 4. .016" ${\times}$.022 " wire generated more friction than .016" wire.

• Restorative Dentistry and Endodontics
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• v.38 no.1
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• pp.21-25
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• 2013

Objectives: The aim of this study was to evaluate the shaping ability of newly marketed single-file instruments, Wave One (Dentsply-Maillefer) and Reciproc (VDW GmbH), in terms of maintaining the original root canal configuration and curvature, with or without a glide-path. Materials and Methods: According to the instruments used, the blocks were divided into 4 groups (n = 10): Group 1, no glide-path / Wave One; Group 2, no glide-path / Reciproc; Group 3, #15 K-file / Wave One; Group 4, #15 K-file / Reciproc. Pre- and post-instrumented images were scanned and the canal deviation was assessed. The cyclic fatigue stress was loaded to examine the cross-sectional shape of the fractured surface. The broken fragments were evaluated under the scanning electron microscope (SEM) for topographic features of the cross-section. Statistically analysis of the data was performed using one-way analysis of variance followed by Tukey's test (${\alpha}$ = 0.05). Results: The ability of instruments to remain centered in prepared canals at 1 and 2 mm levels was significantly lower in Group 1 (p < 0.05). The centering ratio at 3, 5, and 7 mm level were not significantly different. Conclusions: The Wave One file should be used following establishment of a glide-path larger than #15.

• Restorative Dentistry and Endodontics
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• v.42 no.4
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• pp.282-289
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• 2017

Objectives: It was aimed to compare the cyclic fatigue resistances of ProGlider (PG), One G (OG), and HyFlex EDM (HEDM) nickel titanium glide path files in single- and double-curved artificial canals. Materials and Methods: 40 PG (16/0.02), 40 OG (14/0.03), and 40 HEDM (10/0.05) single-file glide path files were used in the present study. Sixty files were subjected to cyclic fatigue test by using double-curved canals and 60 files by using single-curved canal (n = 20). The number of cycles to fracture (NCF) was calculated and the length of the fractured fragment (FL) was determined by a digital micro-caliper. Twelve pieces of fractured files were examined with scanning electron microscope to determine fracture types of the files (n = 2). The NCF and the FL data were analyzed using one-way analysis of variance and post hoc Tukey test using SPSS 21 software (p < 0.05). Results: In all of the groups, NCF values were significantly lower in double-curved canals when compared to single-curved canals (p < 0.05). For both of single- and double-curved canals, NCF values of HEDM group in apical and coronal curvatures were found to be significantly higher than NCF values of PG and OG groups (p < 0.05). In both of single- and double-curved canals, NCF value of PG group was found significantly higher than OG group (p < 0.05). Conclusions: Within the limitations of this study, HEDM glide path files were found to have the highest cyclic fatigue resistance in both of single- and double-curved canals.

• The korean journal of orthodontics
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• v.44 no.5
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• pp.236-245
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• 2014

Objective: To evaluate the therapeutic effects of a preformed assembly of nickel-titanium (NiTi) and stainless steel (SS) archwires (preformed C-wire) combined with temporary skeletal anchorage devices (TSADs) as the sole source of anchorage and to compare these effects with those of a SS version of C-wire (conventional C-wire) for en-masse retraction. Methods: Thirty-one adult female patients with skeletal Class I or II dentoalveolar protrusion, mild-to-moderate anterior crowding (3.0-6.0 mm), and stable Class I posterior occlusion were divided into conventional (n = 15) and preformed (n = 16) C-wire groups. All subjects underwent first premolar extractions and en-masse retraction with preadjusted edgewise anterior brackets, the assigned C-wire, and maxillary C-tubes or C-implants; bonded mesh-tube appliances were used in the mandibular dentition. Differences in pretreatment and post-retraction measurements of skeletal, dental, and soft-tissue cephalometric variables were statistically analyzed. Results: Both groups showed full retraction of the maxillary anterior teeth by controlled tipping and space closure without altered posterior occlusion. However, the preformed C-wire group had a shorter retraction period (by 3.2 months). Furthermore, the maxillary molars in this group showed no significant mesialization, mesial tipping, or extrusion; some mesialization and mesial tipping occurred in the conventional C-wire group. Conclusions: Preformed C-wires combined with maxillary TSADs enable simultaneous leveling and space closure from the beginning of the treatment without maxillary posterior bonding. This allows for faster treatment of dentoalveolar protrusion without unwanted side effects, when compared with conventional C-wire, evidencing its clinical expediency.