• Title/Summary/Keyword: 경사부착구간

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An Aerosol CVD Method Using Internal Jet for Optical Fiber Synthesis (내부제트 분사를 이용한 새로운 광섬유제조 화학증착 방법에 관한 연구)

  • Hong, Choon-Keun;Choi, Man-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.4
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    • pp.608-613
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    • 2000
  • The present study has proposed a novel aerosol CVD utilizing an internal jet in the conventional MCVD reactor for the purpose of enhancing the deposition efficiency(and rate) and the uniformity of deposited film. The use of impingement of high temperature jet through a thin inner tube ensures the reduction of non-uniform particle deposition zone as well as higher thermophoretic particle deposition. It is shown that significant improvements have been achieved for both aspects of deposition efficiency and uniformity. As jet temperatures increase, the tapered length is reduced and deposition efficiency is significantly increased.

Evaluation of friction of ceramic brackets in various bracket-wire combinations (브라켓 각도 변화에 따른 세라믹 브라켓의 마찰력 측정)

  • Cha, Jung-Yul;Kim, Kyung-Suk;Kim, Dong-Choon;Hwang, Chung-Ju
    • The korean journal of orthodontics
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    • v.36 no.2 s.115
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    • pp.125-135
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    • 2006
  • The purpose of this study was to measure and compare the level of frictional resistance generated from three currently used ceramic brackets; 1, Crystaline $V^{(R)}$, Tomy International Inc., Tokyo, Japan; 2, $Clarity^{(R)}$, 3M Unitek, Monrovia, CA, USA; 3, $Inspire^{(R)}$, Ormco, Orange, CA, USA; with composite resin brackets, Spirit, Ormco, Orange, CA, USA; and conventional stainless steel brackets, Kosaka, Tomy International Inc., Tokyo, Japan used as controls. In this experiment, the resistance to sliding was studied as a function of four angulations $(0^{\circ},\;5^{\circ},\;10^{\circ}\;and\;15^{\circ})$ using 2 different orthodontic wire alloys: stainless steel (stainless steel, SDS Ormco, Orange, CA, USA), and beta-titanium (TMA, SDS Ormco, Orange, CA, USA). After mounting the 22 mil brackets to the fixture and $.019{\times}.025$ wires ligated with elastic ligatures, the arch wires were slid through the brackets at 5mm/min in the dry state at $34^{\circ}C$. Silica-insert ceramic brackets generated a significantly lower frictional force than did other ceramic brackets, similar to that of stainless steel brackets. Beta-titanium archwires had higher frictional resistance than did stainless steel, and all the brackets showed higher static and kinetic frictional force as the angulation increased. When the angulation exceeded $5^{\circ}$, the active configuration emerged and frictional force quickly increased by 2.5 to 4.5-fold. The order of frictional force of the different wire-bracket couples transposed as the angle increased. The silica-insert ceramic bracket is a valuable alternative to conventional stainless steel brackets for patients with esthetic demands.