• Corrosion Science and Technology
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• 제9권5호
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• pp.223-232
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• 2010

NiTi alloy has been used for orthodontic wire due to good mechanical properties, such as elastic strength, friction resistance, and high corrosion resistance. Recently, these wire were coated by polymer and ceramic materials for aesthetics. The purpose of this study was to investigate electrochemical characteristics of tooth colored NiTi wire using various instruments. Wires (round type and rectangular type) were used, respectively, for experiment. Polymer coating was carried out for wire. Specimen was investigated with optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDS). The corrosion properties of the specimens were examined using potentiodynamic tests (potential range of -1500 ~ 2000 mV) and electrochemical impedance spectroscopy (frequency range of 100 kHz ~ 10 mHz) in a 0.9 % NaCl solution by potentiostat. From the results of polarization behavior, the passive region of non-coated NiTi wire showed largely, whereas, the passive region of curved NiTi wire showed shortly in anodic polarization curve. In the case of coated NiTi wire, pitting and crevice corrosion occurred severely at interface between non-coated and coated region. From the results of EIS, polarization resistance(Rp) value of non-coated round and rectangular NiTi wire at curved part showed $5.10{\times}10^5{\Omega}cm^2$ and $4.43{\times}10^5{\Omega}cm^2$. lower than that of coated NiTi wire. $R_p$ of coated round and rectangular NiTi wire at curved part showed $1.31{\times}10^6{\Omega}cm^2$ and $1.19{\times}10^6{\Omega}cm^2$.

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.241-262
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• 2006

NiTi-wire shape memory alloy (SMA) dampers, that utilize NiTi SMA wires to simultaneously damp tension, compression and torsion, was developed for structural control implementation in this study. First, eight reduced-scale NiTi-wire SMA dampers were constructed. Then tension, compression and torsion experiments using the eight reduced-scale NiTi-wire SMA dampers of different specification were done. The experimental results revealed all of the eight reduced-scale NiTi-wire SMA dampers had the ability to simultaneously supply tension-compression damping and torsion damping. Finally, mechanics analysis of the NiTi-wire SMA dampers was done based on a model of the SMA-wire restoring force and on tension-compression and torsion damping analysis. The damping analytical results were found to be similar to the damping experimental results.

• 소성∙가공
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• 제22권8호
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• pp.470-476
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• 2013

The aim of the current study was to predict shape recovery behavior of Ni-Ti shape memory alloy (SMA) wire after loading-unloading and after wire drawing. The superelasticity of SMA was analyzed by a hyper-elastic model for the Mullins effect using ABAQUS. Firstly, tensile tests and loading-unloading tests of the Ni-Ti SMA wire with a diameter 1.0 mm were performed using an MTS servo-hydraulic tester. The parameters for the Mullins effect were computed by ABAQUS based on curve-fitting of the loading-unloading test data. The proposed FE-model predicted the shape recovery of Ni-Ti SMA after wire drawing. Finally, the effectiveness of the model was verified by drawing experiments. The wire drawing experiments using the Ni-Ti SMA were conducted on a drawing machine(1ton, 50mm/s). In order to evaluate the shape recovery of Ni-Ti SMA, the drawn wires are annealed for 30min at $450^{\circ}C$.

• 한국표면공학회지
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• 제43권3호
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• pp.132-141
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• 2010

NiTi alloy has been used for orthodontic wire due to good mechanical properties, such as elastic strength and frictional resistance, combined with a high resistance to corrosion. Recently, these wire were coated by polymer and ceramic materials for aesthetics. The purpose of this study was to investigate surface characteristics of polymer coated NiTi alloy wire for orthodontics using various instruments. Wires (round type and rectangular type) were used, respectively, for experiment. Polymer coating was carried out for wire. Specimen was investigated with field emission scanning electron microscopy(FE-SEM), energy dispersive x-ray spectroscopy(EDS) and atomic force microscopy(AFM). The phase transformation of non-coated NiTi wire from martensite to austenite occurred at the range of $14{\sim}15^{\circ}C$, in the case of coated wire, it occurred at the range of $16{\sim}18^{\circ}C$. Polymer coating on NiTi wire surface decreased the surface defects such as scratch which was formed at severe machined surface. From the AFM results, the average surface roughness of non-coated and coated NiTi wire was 13.1 nm, and 224.5 nm, respectively. From convetional surface roughness test, the average surface roughness of non-coated and coated NiTi wire was $0.046{\mu}m$, and $0.718{\mu}m$, respectively.

• 한국재료학회지
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• 제9권4호
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• pp.419-427
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• 1999

TiNi shape memory alloy was shape memory heat-treated and investigated its mechanical properties with the variation of prestrain. Also 6061 Al matrix composites with TiNi shape memory alloy fiber as reinforcement have been fabricated by Permanent Mold Casting to investigate the microstructures and interface properties. Yield stress of TiNi wire was the most high in the case of before heat-treatment and then decreased as increasing heat-treatment time. In each heat-treatment condition, the yield stress of TiNi wire was not changed with increasing the amount of prestrain. The interface bonding of TiNi/6061Al composite was fine. There was a 2$\mu\textrm{m}$ thickness of diffusion reaction layer at the interface. We could find out that this diffusion reaction layer was made by the mutual diffusion. The diffusion rate from Al base to TiNi wire was faster than that of reverse diffusion and the amount of the diffusion was also a little more than that of reverse.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.465-469
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• 1997

In this paper, shape memory compsites are made by powder metallurgy. And then, an self-strengthening effect of the composites by shape memory effect above inverse transformation temperature A/sab f/ of TiNi alloy discussed. Moreover, TiNiCo/Al composite is made by using TiNiCo alloy as fiber. And it is discused aboutaffection of Co in the shape memory composite. The results of the intelligent properties of TiNi/Ai-radical shape memory composite, using SMA, by powder metallurgy are the tensile strength of TiNiCo wire is much higher than that of TiNi wire. and the strength of TiNiCo/Al composite is generally higher than that TiNi/Al composite.

• 대한치과교정학회지
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• 제25권2호
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• pp.187-200
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• 1995

국산 Ni-Ti합금 교정용 선재(ORTHOLLOY)의 특성을 평가하기 위하여 성분, 인장특성, 굽힘특성, 열처리성, 내식성, 이온용출 등에 대해 조사하고 외국산 Ni-Ti합금 선재(SENTALLOY)의 특성과 비교 분석한 결과는 다음과 같았다. ORTHOLLOY는 초탄성 효과를 나타내는 범위내에서의 Ni과Ti 함량을 포함하고 있었다. 인장실험에서 ORTHOLLOY는 연신율 $2\%$에서 $8\%$정도 범위내에서 하중의 변화가 거의 없는 초탄성 효과를 나타내었다. 3점 굴곡실험에서 ORTHOLLOY는 SENTALLOY 보다 같은 변위량에서 높은 하중값을 나타내었고, 초탄성을 나타내는 변위영역에서의 하중 범위는 ORTHOLLOY의 경우 0.014" 에서 80-100g, 0.016"에서 140-180g, 0.018" 에서 150-200g의 값을 나타내었다. $400^{\circ}C,\;500^{\circ}C$의 열처리에 의해 초탄성을 나타내는 하중범 위가 낮아졌고, 각 열처리 온도에서는 시간이 증가함에 따라 초탄성을 나타내는 하중값의 범위가 낮아졌으며 $600^{\circ}C$에서는 10분간의 열처리로 초탄성 효과가 소실되었다. 용출되어 나온 Ni 이온의 양은 SENTALLOY의 0.01ppm미만의 극소량에 비해 ORTHOLLOY에서는 0.3ppm 전후로 높게 나타났다. 침적 실험후 주사전자현미경 관찰을 통한 표면조직 소견은 SENTALLOY에서는 침적 전후 및 침적 시간의 경과에 관계없이 전체적으로 비교적 균일한 양상을 보였으나 ORTHOLLOY에서는 pitting corrosion양상을 보였다.

• 대한소아치과학회지
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• 제49권4호
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• pp.505-513
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• 2022

고탄성의 가는 강선을 이용한 부분교정은 약한 힘의 적용으로 고정원에 대한 부담을 줄이면서 치료기간을 단축시킬 수 있다. 기공실 과정 없이 즉시 적용이 가능하고 환자의 협조를 필요로 하지 않기 때문에 임상적으로 유용하게 사용될 수 있다. 본 증례들은 직선형의 0.012 인치 NiTi 분절 강선과 유동성 레진만을 이용하여 전치, 소구치, 대구치 등 구강 내 다양한 위치에 존재하는 문제들에 적용하여 단기간에 양호한 결과를 얻었기에 보고하는 바이다.

• 대한치과교정학회지
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• 제41권5호
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• pp.337-345
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• 2011

본 연구는 초탄성 니켈-타이타늄 wire로 수직적 높이 차이가 있는 치아의 leveling 과정을 재현하여 wire의 size와 결찰방법에 따른 force system의 변화를 알아보고 여기에 마찰력의 영향에 대해서 알아보고자 하였다. 브라켓은 0.018" slot의 standard twin bracket을 사용하였으며 교정용 wire는 0.014", 0.016" 그리고 0.016" ${\times}$ 0.022" NiTi를 이용하였고 수직적인 높이는 0에서 5 mm까지 1 mm 간격으로 부하와 탈부하 과정을 실험하여 다음과 같은 결론을 얻었다. 마찰력은 loading 시 wire의 stiffness를 증가시켰으며, 0.014" NiTi를 O-ring 결찰을 한 경우에 현저한 stiffness의 증가를 나타내었다. Light wire (0.014)는 수직적으로 5 mm 변위된 치아의 이동 시 2 mm, 0.016"는 3 mm, 0.016" ${\times}$ 0.022"는 4 mm까지의 이동에 유용한 것으로 분석되었다. 본 연구결과는 수직적 변위가 큰 경우에 light wire조차도 적절한 힘을 발휘하지 않은 것으로 나타났다.

• 대한치과교정학회지
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• 제41권4호
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• pp.297-306
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• 2011

경미한 III급 부정교합의 비발치 치료는 하악 치열의 원심이동과 상악 치열의 근심이동을 통하여 절충 치료를 하게 된다. 지금까지 하악 구치의 원심경사 및 후방이동을 시키기 위해서 다양한 치료 방법이 소개되어 왔다. 골성 고정원을 이용한 치료는 총생이 심한 경우와 같이 하악치열의 후방이동이 요구될 때 적용되는데 환자의 협조도와 무관하게 사용할 수 있지만, 하악 치열의 후방 이동 시 치근 접촉가능성이 있으며 골성 고정원의 탈락 가능성을 배제할 수 없다. Multiloop edgewise arch wire (MEAW)와 악간 고무줄을 이용한 치료는 효율적으로 하악 치아를 원심 경사할 수 있지만, 장치의 복잡성 때문에 제작이 어렵고 환자의 불편감이 증가하는 단점을 가지고 있다. 최근에 향상된 초탄성 Ni-Ti alloy wire는 교정력을 좀 더 효과적으로 전달할 수 있고, improved superelastic wire (ISW)를 이용한 tip-back은 디자인이 간단하기 때문에 간단한 조작으로 와이어를 제작할 수 있으며, 환자의 불편감이 감소할 수 있다. 본고에서는 향상된 초탄성 Ni-Ti alloy wire와 악간 고무줄을 이용하여 하악 구치부를 원심 경사이동한 증례를 소개하고, 효과적인 임상 적용을 위한 고려사항을 살펴보고자 한다.