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Sterilization Effects of a TiO2 Photocatalytic Film against a Streptococcus mutans Culture
고영무,김도만,임성훈,조동련,국중기,옥승호,조용익,유소영,김병훈 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.2
Streptococcus mutans is one of the more significant pathogens involved in the development of dental caries in humans. The purpose of this research was to design a TiO2-coated dental instrument and to determine the bactericidal effects of the instrument on S. mutans. TiO2 photocatalytic films were prepared by the low-pressure metal-organic chemical vapor deposition (LPMOCVD) method using titanium tetraisopropoxide (TTIP) as precursor. The photocatalytic reaction was carried out on a TiO2-coated pyrex petri dish with an ultraviolet (UV) light emitting diode (LED) illuminator or a fluorescent lamp light source. Our data indicates that the relative survival ratio of S. mutans when plated onto TiO2 photocatalytic films and under exposure to UV-A light for 15 min was 0.01%. In addition, a fluorescent lamp light source also had bactericidal effects on the S. mutans plated TiO2 photocatalytic films. These results indicate that TiO2-coated dental materials or devices may be useful in dental treatments for the prevention of carious or enamel demineralization.
고영무 大韓齒科器材學會 2000 대한치과재료학회지 Vol.27 No.3
The high reactivity of fluoride agents used in topical fluoride treatments have raised important questions on their potential adverse effects on restorative materials. The purpose of this study was to evaluate the effect of various types of fluoride agents used for dental office and home treatments on the color change of some polyacid-modified resin composite(Compoglass and Dyract) and the resin-modified glass ionomer(Fuji Ⅱ LC). Each specimen was treated with 4 kinds of fluoride agents for 4 minutes every day until 8 weeks. The color change was measured using specimens aged up to two months with colorimeter. The resulted were as follows; 1. The color change of resin-modified glass ionomer cement Fuji Ⅱ LC was greater than any other material. 2. The color change of 3 kinds of materials were greatest in contact with 8% SnF₂solutions. 3. It showed greater color change in case of materials immersed in fluoride agents than materials immersed in water. In conclusion, Topically applied fluorides induced adverse effects on the color change characteristics of resin-modified glass ionomer cement and polyacid-modified composite resins suggesting that fluoride agents effective in limiting caries should be used with caution with patients who have aesthetic restoratives.
최과 교정용 스테인리스 강 선재의 신선 가공법이 내식성에 미치는 영향
고영무,모웅남,최한철 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.1
The dental orthodontic wire requires good mechanical properties, such as elastic strength, combined with a high resistance to corrosion. For increasing elastic strength and delaying onset of stress corrosion cracking, drawing methods(one-step and two-step drawing) have been used in this study to extend service life of metal components, However, there is no information on the electrochemical corrosion behavior of drawn wires for orthodontics. To increase elastic strength, good corrosion resistance, and biocompatibility, the electrochemical characteristics of drawn wire have been researched by field emission scanning microscope and potentiodynamic method in 0.9% NaCl solution. The one-step drawn wire showed the formation of rough surface. The hardness and tensile strength of two-step drawn wire increased. Electrochemical measurements showed that, in the case of two-step drawn wire, the corrosion resistance and pitting potential increased compared with two-step drawn wire due to the drawing induced small surface roughness, such as scratch, whereas passivation and active current density decreased as the reduction in area for drawing increased.
전자빔 진공증착을 이용한 치과용 임플란트재의 표면 전처리법에 따른 HA 코딩효과
고영무,최한철,최낙찬 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.4
The dental implant materials require good mechanical properties, such as fatigue strength, combined with a high resistance to corrosion. For increasing fatigue resistance and delaying onset of stress corrosion cracking, shot-peening has been used for over 50 years to extend service life of metal components, However, there is no information on the electrochemical behavior of shot-peened and hydroxyapatite(HA) coated Ti-6Al-4V alloys. To increase fatigue strength, good corrosion resistance, and biocompatibility, the electrochemical characteristics of Ti/TiN/HA coated and shot-peened Ti-6Al-4V alloys by EB-PVD have been researched by various electrochemical method in 0.9%NaCl The coated layer and surface showed the formation of dense and uniform surface in the case of TiN/HA and Ti/TiN/HA film coated samples. The hardness of shot-peened Ti-6Al-4V alloys(SPA) increased as SP treatment time increased. Electrochemical measurements showed that, in the case of shot-peened Ti-6Al-4V alloys, the corrosion and pitting potential increased due to the SP induced removal of defects, such as inclusion, scratch, and pore on the surface, whereas passivation and active current density decreased as the SP time increased. For the HA coated samples, pitting and repassivation potential increased in the order of Ti/TiN/Ha > TiN/HA > Ti/HA > HA coated SPA. Results suggest that the best pitting corrosion behavior is shown by Ti/TiN/HA coated SPA with a fatigue strength and biocompatibility.
고영무,황재혁,김종선,백승호 한국소음진동공학회 1995 소음 진동 Vol.5 No.4
In this study, an ROC(Reduced Order Controller) is designed to increase the flutter velocity of an aircraft wing, and the effect of ROC on the flight performance is also analyzed. The aircraft wing used in the paper is modelled as a 3 DOF two-dimensional rigid body. In the disign of controller, LQG and BACR(Balanced Augmented Controller Reduction) strategy is used as control algorithm and controller reduction method respectively. Simulation has been conducted to evaluate the effectiveness of ROC on the active flutter control, compared to FOC(Full Order Controller). It has been found that ROC using BACR is much effective than FOC in the sense of computation effort, without sacrificing the active flutter control performance.