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클로르헥시딘의 접착성 수복재의 결합에 미치는 영향에 관한 비교 연구
염혜웅,김종수,권순원 大韓小兒齒科學會 2002 大韓小兒齒科學會誌 Vol.29 No.1
치아 수복 후 나타날 수 있는 술 후 동통과 치수 병변의 주원인은 수복재 자체의 독성보다는 박테리아의 침투에 의한 것으로 알려져 있으며, 와동내 항균제 처리는 잔존 박테리아를 제거하여 제 증상을 완화하는데 효과적이지만, 상아질면이나 상아세관에 잔유물을 남겨 상아질 결합제와 치질간의 긴밀한 결합을 방해하여, 미세누출을 증가시키고, 결합강도를 약화시킬 수 있다고 알려져 있다. 2% 클로르헥시딘 도포가 접착성 수복물과 치질과의 결합강도 및 미세누출에 미치는 영향을 평가하기 위하여, 건전한 소의 전치 상아질을 노출시키고 와동을 형성한 후, 클로르헥시딘을 도포하고 복합레진, 컴포머 그리고 글라스아이오노머를 각 제조사의 지시에 따라 각각 충전하고, 100회 열순환 처리 후 전단 결합 강도와 미세누출 양상을 비교 평가하였다. 상아질 전단 결합 강도와 수복재 변연 미세누출 양상에서 실험군과 대조군간에 통계학적 유의차를 보이지 않았다. Bacterialmicroleakage around restorations is considered the principal cause of pulpal inflammation associated with restorations. The rationale for using cavity disinefectant is based on its antimicrobial properties but the cavity disinfectant may leave debris on dentin surfaces. The purpose of this study was to evaluate the effect of 2% chlorhexidine on shear bond strength and microleakage of adhesive restoration. 45 sound bovine teeth were used for the shear bond strength test and 30 for the micorleakage. For the experimental groups, 2% chlorhexidine was applied before the restorations, and was not for the control groups. The result from the this study can be summarized as follows; 1. No significant difference could be found in shear bond strength of each group. 2. No significant difference could be found in microleakage of each group.
Effect of Grain Size and Die-Upset Temperature on Texture in Die-Upset Nd-Fe-B Magnet
Hae-woong Kwon,Kang, Y.S.,Choi, G.S.,Yu, J.H. IEEE 2009 IEEE transactions on magnetics Vol.45 No.6
<P>Hot-pressed Nd<SUB>13.5</SUB>Fe<SUB>77</SUB>Si<SUB>1</SUB>B<SUB>8</SUB> alloy compacts with various grain sizes ranging from approximately 50 nm to 200 nm were prepared using melt-spun material. The compacts were then subjected to die-upsetting. The effect of grain size in the hot-pressed compact on the texture in die-upset magnet was investigated. The effect of die-upset temperature on the texture in die-upset magnet was also investigated. Texture in the die-upset Nd<SUB>13.5</SUB>Fe<SUB>77</SUB>Si<SUB>1</SUB>B<SUB>8</SUB> alloy samples decreased with increasing the grain size in the hot-pressed compact before the die-upsetting. This dependence of texture on the initial grain size could be explained by the unique texture formation mechanism of a stress-induced preferential grain growth via dissolution and precipitation. Texture of the die-upset sample was also influenced by the die-upsetting temperature. The samples die-upset at 700degC and 900degC had poorer texture compared to the samples die-upset at the temperature range of 750degC-850degC. The poor texture in the sample die-upset at lower temperature of 700degC was attributed to the less dissolution of the unfavorable Nd<SUB>2</SUB>Fe<SUB>14</SUB>B grains and low fluidity of the liquid Nd-rich grain boundary phase. The poor texture in the sample die-upset at higher temperature of 900degC was explained by the reduced elastic modulus and the excessive grain growth of the Nd<SUB>2</SUB>Fe<SUB>14</SUB>B grains.</P>
Phase Relationships and Magnetic Properties of HDDR - treated Sm₃(Fe,Co,V)29 Alloy
Hae-Woong Kwon 한국자기학회 2001 Journal of Magnetics Vol.6 No.4
Phase relationships of the HDDR (hydrogenation, disproportionation, desorption and recombination)-treated Sm₃(Fe,M)_(29)-type alloy with chemical composition of Sm_9Fe_(65)Co_(20)V_6 were studied by X-ray diffraction (XRD) and by thermomagnetic analysis (TMA). The alloy was disproportionated into a mixture of SmHx and α-Fe at high temperature under hydrogen gas. The disproportionated material was recombined into a mixture of Sm(Fe,M) (M = Co and/or V) and α-Fe phases. The structure of the Sm-(Fe,M) phase was dependent upon the recombination conditions, and a detailed phase diagram showing the phase relationships in the HDDR-treated alloy has been established. The Sm-(Fe,M) phase in material recombined above 900℃ had the Sm₂Fe_(17)-type structure, and it exhibited the SmFe_7-type structure when recombined at temperatures ranging from 700℃ to 850℃. Recombination below 650℃ led to the SmFe₃-type structure of the Sm-(Fe,M) phase. Curie temperatures of the Sm-(Fe,M) phases in the recombined material were significantly higher than those of the corresponding stoichiometric phases. It was suggested that the chemical composition of the Sm-(Fe,M) phases may be significantly different from that of the corresponding stoichiometric phases. All the HDDR-treated Sm_9Fe_(65)Co_(20)V_6 materials showed the soft magnetic features regardless of the phase constitution.
공구수명과 표면거칠기 특성 분석을 통한 인코넬 718의 가공성 평가
권해웅(Hae-Woong Kwon),강익수(IK-Soo Kang),김정석(Jeong-Suk Kim),문성준(Sung-Jun Moon),김기태(Ki-Tae Kim) 한국기계가공학회 2008 한국기계가공학회 춘추계학술대회 논문집 Vol.2008 No.-
Inconel alloys have been widely used in the aerospace, heavy industry and automotive. Inconel 718 alloy has been applied in high temperature, high load and corrosion resistant environments due to its superior properties. However, This alloy is a difficult-to-cut nickel-based superalloy. In this study, the machinability of Inconel 718 is investigated to improve tool life under various cutting conditions with UT coated tungsten carbide(WC) end mills. . The tool life on the basis of flank wear(0.2㎜) has been investigated in side cutting. The cutting conditions can be suggested to improve both the tool life and machined surface quality in Inconel 718 maching.
고속 스핀들용 HSK 공구 클램핑 장치의 개발 및 성능평가
권해웅(Hae-Woong Kwon),박진효(Jin-Hyo Park),강익수(IK-Soo Kang),김정석(Jeong-Suk Kim),정수영(Su-Yong Kim),박성원(Sung-Won Park) 한국기계가공학회 2008 한국기계가공학회 춘추계학술대회 논문집 Vol.2008 No.-
As the rotational speed of spindles increases over ten thousands rpm, the HSK tooling system has been widely applied to the high-speed spindle of machining center. This paper presents the development and evaluation of HSK tool clamping system for a high-speed spindle. The HSK tool clamping system is comprised of a clamping unit, a power drawbar and a hydraulic pressure cylinder. These components are developed, and the performance evaluation is carried out. The clamping force transmitted by the drawbar is amplified by 2.7 times, and the number of clamping and unclamping is about 1.2 million.