• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.183-192
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• 1995

The purpose of this study was to evaluate the effect of smear layer management on the interfacial morphology between dentin bonding system and dentin. Clearfil New Bond, Scotchbond Multipurpose, Prisma Universal Bond 3 and X-R Bond were used on the cervical dentinal surfaces of bovine incisor teeth. All of the dentin bonding systems were labeled with fluorescene in primer and rhodamine B in adhesive. Specimens of 2~3mm thichness were prepared by longitudinal and labiolingual sectioning. The interface between dentin bonding system and dentin was observed by flouresence imaging with a confocal laser scanning microscope. Following results were obtained. 1. In the specimen of Clearfil New Bond, dentinal tubules were widened by destruction of peritubular dentin in the course of treatment with phosphoric acid of high concentration. 2. Hybrid layer was observed in the specimen of Scotchbond Multipurpose and X-R Bond. 3. In the specimen of Prisma Universal Bond 3, the penetraton of adhesive was not observed clearly.

• 한국막학회:학술대회논문집
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• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
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• pp.79-82
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• 1999

Using Small Angle Light Scattering (SALS), the effect of quench depth on the kinetics of phase separation for ternary solution blends was investigated. The system was composed of two polymers (polystyrene and polybutadiene) and a solvent (toluene). The analyses of the early stage of phase separation were based of the Cahn-Hilliard theory [1,5]. Apparent diffusion coefficients and the fastest mode of fluctuations were evaluated, when quench depth of the system were varied near the critical composition of polymer. In the late stage of phase separation, the domain growth showed a power law with the 1/3 exponent, i.e. $q_m(t)~t^{-1/3}$. For comparison between real images and scattering profiles with time, the image of phase domains with time were obtained by using Laser Confocal Scanning Microscopy (LSCM).

• 대한치과보철학회지
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• 제45권3호
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• pp.303-309
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• 2007

Statement of problem. The effect of gold electroforming on gold alloy was not studied. Purpose. This in vitro study investigate the effect of gold electroforming on gold-silver-palladium alloy. Material and methods. Three pieces of gold strips had undergone the electroforming procedures on one side and then half of the side again electroformed. The set mode for this study was program 1 ($200{\mu}m$). And the processing time was 15min (1/20 time to form $200{\mu}m$ coping). The confocal laser scanning microscope (PASCAL 5, Carl Zeiss, Bernried, Germany) was used to measure the thickness of the pure gold layer electroformed on the gold strips. Half of the gold strip was coated two times with electroformed gold, and the other half one time. The data from the cone focal laser system was processed to get the vertical profile of the strips and the difference of the vertical height between the double coated and single coated layer was regarded as the thickness of the gold coating. The layer thickness value to built 3D image of the cone-focal laser was set $0.5{\mu}m$. Next to the measurement of the thickness of the coating, the Vicker's hardness test was done. It was performed on the double coated surface, single coated surface and non-coated surface (back side) three times each. Results. The mean thickness value gained from gold electroforming technique was measured to be $22{\mu}m$ for sample 1, $23{\mu}m$ for sample 2, $21{\mu}m$ for sample 3. In the same condition of time, power and the amount of electrolyte, the data showed no difference between samples. According to the results of variance analysis, the differences among the variations in number of coating were statistically insignificant (p>0.05), meaning that the two times of gold electroforming coating did not change the hardness of gold-silver-palladium alloy. Conclusion. The test of thickness of gold coating proved the coherency of the gold electroforming procedure, in other words, when the power, the exposed surface area, processing time and the amount of electrolytes were set same, the same thickness of gold would be coated on. The hardness test showed that the electroformed gold coating did not change the hardness of the gold-silver-palladium alloy when it is coated not more than $45{\mu}m$.

• Restorative Dentistry and Endodontics
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• 제24권2호
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• pp.310-321
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• 1999

In this in vitro study, confocal laser scanning microscopic morphology of dentin-resin interface and its relationship to shear bond strength were investigated after the exposed dentin surfaces were treated with 3 different kinds of dentin adhesive systems[three-step; Scotchbond Multi-Purpose Plus(SMPP), self-priming bonding resin; Single Bond(SB), self-etching primer; Clearfil Liner Bond 2(LB2)]. 52 extracted human molar teeth without caries and/or restorations. The experimental teeth were randomly divided into three groups of seventeen teeth each. In five teeth of each group, class V cavities(depth: 1.5mm) with 900 cavosurface angles were prepared at the cementoenamel junction on buccal and lingual surfaces. Bonding resins of each dentin adhesive system were mixed with rhodamine B. Primer of SMPP was mixed with fluorescein. In group 1. the exposed dentin was conditioned with etchant, applied with above primer and bonding resin of SMPP. In group 2, with etchant and self-priming bonding agent of SB. In group 3, with self-etching primer and bonding agent of LB2. After treatment with dentin adhesive systems, composite resin were applied and photocured. The experimental teeth were cut longitudinally through the center line of restoration and grounded so that about $90{\mu}m$-thick wafers of buccolingually orientated dentin were obtained. And, $70{\sim}80{\mu}m$-thick wafers sectioned horizontally, thus presenting a dentinal tubules at 900 to the cut surface of a remaining tooth, were obtained. Primer of SMPP mixed with rhodamine B was applied to these wafers. Confocal laser scanning microscopic investigations of these wafers were done within of 24 hours after treatment. To measure shear bond strength, the remaining twelve teeth of each group were grounded horizontally below the dentinoenamel junction, so that no enamel remained. After applying dentin adhesive systems on the dentin surface, composite was applied in the shape of cylinder. The cylinder was 5mm in diameter, and 2mm in thickness. Shear bond strength was measured using Instron with a cross-head speed of 0.5mm/min. It was concluded as follows ; 1. Hybrid layer of SMPP(mean: $4.56{\mu}m$) was thicker than that of any other groups. This value was not statistically significant thicker than that of SB(mean: $3.41{\mu}m$, p>0.05), and significant thicker than that of LB2(mean: $1.56{\mu}m$, p<0.05). There was a statistical difference between SB and LB2(p<0.05). 2. Although there were variations in the length of resin tag even in a sample, and in a group, most samples in SMPP and SB showed resin tags extending above $20{\mu}m$. But samples in LB2 showed resin tags of $10{\mu}m$ at best. 3. Besides primer's infiltration into demineralized peritubular dentin and dentinal tubules, fluorophore of primer was detected in the lateral branches of dentinal tubules. 4. All groups demonstrated statistically significant differences from one another(p<0.05), with shear bond strengths given in descending order as follows: SMPP(18.3MPa), SB(16.0MPa) and LB2(12.4MPa). 5. LB2 having thinnest hybrid layer($1.56{\mu}m$) showed the lowest shear bond strength(12.4MPa).

• 대한소아치과학회지
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• 제33권2호
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• pp.207-220
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• 2006

새로 개발된 조기 진단 장비들로는 laser fluorescence device(LFD), 초음파 진단 시스템, confocal laser scanning microscopy(CLSM), quantitative light-induced fluorescence(QLF) 시스템 그리고 digital imaging fiber-optic trans-illumination(DIFOTI) 시스템 등이 있다. 본 연구는 임상에서 사용되고 있는 DIFOTI시스템과 LFD를 이용하여 유치 교환 시기에 있는 환아 21명, 25개의 유치를 대상으로 각 치아당 $1{\sim}3$점을 선정하여 구강내에서 초기 우식법랑질에 대한 DIFOTI 이미지 촬영 결과와 LFD 계측값을 3회 측정하고 그 평균을 대표값으로 한 결과를 CLSM과 비교하여 진단 능력을 평가하였다. 실험실 연구에서는 인공우식 용액을 이용하여 수거된 40개의 유치를 협설면에 $2{\times}3mm$ 크기의 창을 형성하고 4, 8, 12, 16일간 탈회시키면서 그 변화를 DIFOTI 시스템과 LFD를 이용하여 측정하고 이를 CLSM과 비교 분석하여 다음과 같은 결론을 얻었다. 1. 구강내에서 촬영된 DIFOTI의 민감도는 88.2%이었고, 특이도는 76.9%이었다. 2. 구강내에서 측정된 LDD의 민감도는 76.5%이었고, 특이도는 69.2%이었다. 3. 실험실 연구에서 유치 법랑질의 탈회 기간에 따른 DIFOTI 광투과율의 회귀 분석한 결과, 탈회 시간에 따라 광투과율은 감소하였다(r=-0.96, p<0.05). 4. 실험실에서 탈회 기간에 따른 LFD의 측정값의 회귀 분석 결과 통계적 유의성을 보이지 않았다(p>0.05). 5. DIFOTI 이미지의 광투과율과 CLMS의 병소 깊이에 대한 상관 계수는 -0.688이었으나(p<0.05), LFD의 측정값은 유의성을 보이지 않았다.

• 한국광학회지
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• 제9권2호
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• pp.96-99
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• 1998

본 연구에서는 새로운 광피드백 장기 안정화법을 제안하고 실험적으로 그 가능성을 입증하였다. 제안한 방법은 광로장을 제어하는 방법으로써 지금까지와는 다른 고감도의 광피드백 위상 변별 기법을 도입하였다. 이는 외부 반사체로 사용한 공초점 패브리-페로 공진기의 반사모드의 편광 분광법에 의하여 위상 변별 신호를 얻어내는 것이다. 실험 결과 약 20시간 정도의 안정된 제어 상태를 유지하였다. 이 실험에서 사용한 광학계가 각각의 분리된 광학 요소를 광학 테이블에 배열한 불안정한 상태였으므로 광학계의 크기를 줄이고 각 광학적 요소를 하나의 판 위에 고정시킴으로서 일체화시킨다면 안정된 제어의 유지시간을 대폭 늘일 수 있을 것이다.

• 한국광학회지
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• 제24권2호
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• pp.71-76
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• 2013

형광상관분광법을 이용하여 광세기에 따른 공초점 시스템의 유효 초점 부피의 변화를 분석하였다. 형광상관분광장치는 632.8 nm 파장의 He-Ne 레이저에 맞춰서 실험실에서 자체 제작하였고, 시료 또한 레이저 파장에 적합한 두 종류의 시료 AlexaFluor647과 quantum dot 655를 사용하였다. 각 시료에 대해 광원의 세기를 1~50 ${\mu}W$ 범위내에서 변화시켜가며 얻어진 상관함수를 비교 분석하였다. 10 ${\mu}W$ 이하의 약한 광 세기에서는 세기 변화에 따라 입자수와 확산시간이 증가하는 것을 통해 초점 영역의 반지름이 선형적으로 증가하는 결과를 보였다. 반면 10~15 ${\mu}W$ 이상에서는 입자의 수와 확산 시간의 증가율은 감소하였지만 미세하게 계속해서 증가하는 결과를 보였고, 이 결과를 통해 초점영역의 반지름 역시 증가율은 감소하였지만 미세하게 증가한 것을 알 수 있었다.

• 새물리
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• 제69권10호
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• pp.1107-1114
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• 2019

다양한 기능의 새로운 물질을 합성하고 정적 및 동적 특성을 조사하기 위해서는 매우 안정된 고온 및 고압 조건을 만드는 것이 중요하다. 새로운 물질을 제조하는 데 필요한 다이아몬드 엔빌 셀 (DAC)을 사용하여 Mbar 범위의 고압 조건은 이미 확보되었다. 이 연구에서는 DAC와 결합된 레이저 가열 시스템을 설계하였으며, DAC의 양쪽 방향에서 시료를 가열하기 위해 2 대의 1064 nm, 100 W 파이버 레이저를 사용했을 뿐만 아니라 3 대의 분광기를 사용하여 온도, 압력 및 라만 스펙트럼을 측정하였다. 고압 실험에서 시료를 가두는 구멍으로 일반적으로 사용되는 스테인리스 강 개스킷을 가열하여 열 방사선원을 만들고, 이 방사선원으로부터 방출되는 복사 스펙트럼을 획득하여 가열된 개스킷의 온도를 측정하였다. 이 기술을 적용하여 다양한 물질들을 만들고 극한 조건에서 물리적 특성을 조사 할 수 있다.

• 한국광학회지
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• 제10권1호
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• pp.1-4
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• 1999

공초점 현미경 시스템을 사용하여 반복률이 17MHz이며, 중심파장이 638nm인 극초단 펄스 다이오드 레이저에 의해서 여기된 단분자의 형광폭발신호를 게측하였다. 에칠렌글리콜 용액에 있는 적색 색소 분자(JA22)를 시료로 사용하였다. 시상관 단광자 계수기응 사용하여 단분자들의 현광소멸곡선을 수집하였으며, maximum likelihood estimator로 그것들을 분석하였다. 색소 분자당 40개 이상의 광자수를 가지고 분석하였을 때, 21%의 오차 확률로 형광소멸시간을 계측하는 것이 가능하였다.

• International Journal of Precision Engineering and Manufacturing
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• 제1권1호
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• pp.152-159
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• 2000

In piercing operation for small hole in very thin plate, micro burrs are formed. The micro burr is very difficult to remove because the thin plate is to be deformed during deburring and deteriorate accuracy. As a first step to remove the micro burrs effectively, the burr must be measured accurately as much as possible. For most micro burrs are so small as less than 10$\mu\textrm{m}$, it is very difficult to measure. Several methods are reviewed to measure the micro burr formed in piercing operation from very thin plate with thickness less than 0.1mm. Also the effective deburring methods are reviewed. Barreling ultrasonic and chemical deburring methods are performed and the results are compared.