• Journal of Photoscience
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• 제8권1호
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• pp.9-12
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• 2001

The photoisomerization behavior of benzylideneacetophenones, known as chalcones, was studied. We synthesized the chalcone derivatives that have ether groups at 4 and 4＇ positions. Due to the electron donating ability of the ether oxygen, the bond order of the single bond between two phenyl ring of the chalcone strengthened, which eventually increased the rotational barrier of the single bond. The rotational barrier of the single bond is about 20-22 kcal/mole. Thermal recovery of this process took about 1 min. The UV-visible spectra of these chromophores exhibit two characteristic absorption peaks at 276 nm and 340 nm. The relative intensity of the peaks varies depending on the alkyl chain length of the substituent. Photo-irradiation with the 365 nm light monotonously decreases the 340 nm peak. However, the photo-irradiation with 254 nm light induce two competing processes and produced rather complicated absorption profile.

• 대한치과보철학회지
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• 제37권1호
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• pp.42-50
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• 1999

This study investigated the effects of surface treatment for filling resins on the surface texture of denture resin teeth by the use of scanning electron microscope. This study also evaluated the bond strength of filling resins to denture resin teeth. The denture resin teeth in this study was Endura Posterio(Shofu Co., Japan). The ailing resins used were Coe-cure(Coe Co., USA), Vertex RS (Dentimax Ziest, Holland), and light cured resin Z-100(3M Co., USA). The test sample were divided into 3 parts. Group 1 : Sandblasted with $50{\mu}m$ Aluminum oxide. Group 2 : Treated with #60 silicone carbide paper Group 3 : Treated with monomer brush application. Control Group : No Treatment. The results were as follows ; 1. The bond strength of filling resins to denture resin teeth is increased by surface treatment. 2. Regardless of the filling resins, there was a significant difference with # 60 silicone carbide paper treated group. 3. Regardless of each group, the bond strength according to the filling resins were decreased in the following order: Vertex RS, Coe-cure and Z-100.

• Journal of Welding and Joining
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• 제20권5호
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• pp.120-126
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• 2002

Ni-5%Al alloy powder is widely used as the bond coating powder to improve the adhesive strength between the substrate and coating. The important properties in the bond coating are the deposition efficiency and surface roughness. In this study, it was tried to optimize the plasma spray parameters to maximize the deposition efficiency and surface roughness. In the first step, spray current and hydrogen gas flow rate were optimized in order to increase the deposition efficiency. In the next step, the seven plasma spray variables were selected and optimized to improve both the deposition efficiency and surface roughness using the Taguchi experimental method. By these optimization, the deposition efficiency was improved from about 10 % at the frist time to 51.2 % by the optimization of spray current and hydrogen gas flow rate and finally to 65.2 % by the Taguchi experimental method. The average surface roughness was increased from about $12.9\mu\textrm{m}$ to $15.4\mu\textrm{m}$.

• Bulletin of the Korean Chemical Society
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• 제7권5호
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• pp.391-395
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• 1986

MNDO calculations were carried out to determine reactant complexes and transition states of the $S_N2$ reactions of $CH_3X\;+\;Y^-\;{\to}\;CH_3Y\;+\;X^-$ where X = F, Cl, CN and Y = CN, OH, F, Cl. The leaving group ability was found to vary inversely with the activation barrier, which in turn was mainly ascribable to the deformation energies accompanied with bond stretching of C-X bond and inversion of $CH_3$ group. The nucleophilicity was shown to be in the order $Cl^->F^->OH^->CN^-$ but the effect on the activation barrier was relatively small compared with that of the leaving group. The bond breaking and bond formation indices and energy decomposition analysis showed that the TS for the reaction of $CH_3$Cl occurs in the early stage of the reaction coordinate relative to that of $CH_3$F. It has been shown that the potential energy surface (PES) diagrams approach can only accommodate thermodynamic effects but fails to correlate intrinsic kinetic effects on the TS structure.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권4호
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• pp.331-334
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• 2006

Original Support Vsctor Machines (SVMs) by Vapnik were used for binary classification problems. Some researchers have tried to extend original SVM to multiclass classification. However, their studies have only focused on classifying samples into nominal categories. This study proposes a novel multiclass SVM model in order to handle ordinal multiple classes. Our suggested model may use less classifiers but predict more accurately because it utilizes additional hidden information, the order of the classes. To validate our model, we apply it to the real-world bond rating case. In this study, we compare the results of the model to those of statistical and typical machine learning techniques, and another multi class SVM algorithm. The result shows that proposed model may improve classification performance in comparison to other typical multiclass classification algorithms.

• 구강회복응용과학지
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• 제21권1호
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• pp.59-67
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• 2005

The bond strength of denture base resin and resin teeth, is an important factor in the long term prognosis of dentures. The purpose of this study is to find an appropriate combination of commercial denture base resin and artificial resin teeth according to shear bond strength. In this study, the shear bond strength of various denture base resins (Vertex $RS^{(R)}$(Dentimax Ziest, Holland), $PERform^{(R)}$(Hedent GmbH., Germany), SR $IVOCAP^{(R)}$(Ivoclar AG, Schaan, Liechtenstein)) and resin teeth (SR Orthosit PE(Ivoclar AG, Schaan, Liechtenstein), $Trubyte^{(R)}$ $Biotone^{(R)}$(Dentsply, U.S.A.)) was evaluated. 1. In comparison of denture resin, the shear bond strength increased in the order of $IVOCAP^{(R)}$, $PERform^{(R)}$, Vertex $RS^{(R)}$. 2. In resin teeth, $Trubyte^{(R)}$ $Biotone^{(R)}$ showed higher strength, but there was no statistical difference between the groups. 3. According to loading direction, the lingual showed higher strength, but there was no statistical difference. 4. When using SR Orthosit PE, SR $IVOCAP^{(R)}$ showed significantly higher shear bond strength(p<0.05). 5. Fracture tendancy showed more cohesive fractures(59) than adhesive failures(13). $IVOCAP^{(R)}$ showed the most superior results statistically. $Trubyte^{(R)}Biotone^{(R)}$ showed the highest shear bond strength. When using the SR Orthosit PE, it is thought that $IVOCAP^{(R)}$ would present the most superior results.

• 콘크리트학회논문집
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• 제25권5호
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• pp.573-581
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• 2013

이 논문은 강섬유보강콘크리트와 GFRP (glass fiber reinforced polymer)사이의 부착 특성을 조사하기 위한 실험적 연구를 수행하였다. 실험 주요 변수로는 보강근 지름, 섬유혼입량, 피복두께 및 콘크리트의 압축강도를 설정하였다. 부착파괴는 주로 콘크리트 피복에서의 쪼갬으로 인하여 유발되며, 이러한 콘크리트의 쪼갬파괴는 보강근과 콘크리트 사이의 변형 차이로 유발되는 인장력때문에 발생한다. 따라서, 보강근과 콘크리트 사이의 부착파괴를 방지하기 위하여, 콘크리트 피복부위의 인장강도를 향상시켜야 한다. 실험결과를 살펴보면, 섬유혼입량 증가는 부착강도를 크게 향상시키고 있으며, 피복두께는 최종 파괴모드를 변화시킴을 확인할 수 있었다. 보강근의 지름 또한 최종 파괴모드를 변화시킴을 확인할 수 있었다. 일반적으로 보강근의 지름은 부착특성에 영향을 미치는 것으로 알려져 있으나, 섬유혼입량은 부착특성에 큰 영향이 없는 것으로 알려져 있다. 콘크리트 압축강도의 증가는 보강근과 콘크리트 사이의 부착강도를 증가시켰으며, 이는 압축강도의 증가가 직접적으로 인장강도의 증가를 유발하기 때문이라고 판단된다.

• 대한소아치과학회지
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• 제34권3호
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• pp.420-429
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• 2007

전통적인 3단계 total-etching 시스템인 제 4세대 상아질 접착제로부터 술식의 단순화를 이루며 진화한 제 5, 6세대 및 최근에 소개된 제 7세대 상아질 접착제를 상아질 표면처리방식과 적용단계별로 구분하여 bovine teeth 상아질에 대한 미세인장결합강도를 측정하여 그 효용성을 비교 평가하였다. Bovine incisor의 상아질 표면을 노출시키고, 적절한 표면처리 후 제조사의 지시에 따라 5종의 상아질 접착제; 제 4 세대로 Scotch $Bond^{TM}$ Multipurpose(3M ESPE, USA), $Adper^{TM}$ Single Bond 2(3M ESPE, USA), 제 5세대 $Clearfil^{(R)}$ SE Bond(KURARAY, JAPAN), 제 6세대 AQ $Bond^{TM}$(SUN MEDICAL, JAPAN), 제 7세대 $Clearfil^{(R)}$ tri-S Bond(KURARAY, JAPAN)를 각각 적용하여 미세인장결합강도를 측정하고 접착계면의 파절양상을 관찰하였다. 연구결과 미세인장결합강도는 $Clearfil^{(R)}$ SE Bond군에서 가장 높았으며 다음으로 Scotch $Bond^{TM}$ Multipurpose군, $Adper^{TM}$ Single Bond 2군, AQ $Bond^{TM}$군, $Clearfil^{(R)}$ tri-S Bond군의 순으로 나타났다. 계면의 파절양상은 상대적으로 미세인장강도가 높게 나타난 Scotch $Bond^{TM}$ Multipurpose, $Adper^{TM}$ Single Bond2, $Clearfil^{(R)}$ SE Bond군은 레진의 응집성 파절이 많이 발생하였고 상대적으로 미세인장강도가 낮은 AQ $Bond^{TM}$, $Clearfil^{(R)}$ tri-S Bond 군의 경우에는 대부분 접착성 파절이 관찰되었다. 이상의 결과를 종합하면 상아질 접착제의 미세인장결합강도는 각 접착시스템별로 다소의 차이를 보이며, 특히 제 6, 7세대 상아질 접착제가 이전 세대보다 낮은 것으로 나타났다.

• 대한치과보철학회지
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• 제32권2호
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• pp.212-224
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• 1994

The purpose of this study was to evaluate and compare film thickness of five kinds of resin luting cements [Comspan, Panavia Ex, Maryland bridge adhesive, All-bond C & B cementation kit, and Super-bond C & B]. Zinc-phosphate cement and glass-ionomer cement were used as the control group. In order to measure the film thickness the methods used were in broad compliance with ADA Specification No. 8, a tapered-die system that simulates clinical conditions more closely, and the connected tapered-die system that simulates bridge conditions. The inorganic filler size of resin cements was also examined with scanning electron micrographs. The results were obtained as follows ; 1. The film thickness of resin cements was increased in the order of Comspan, Panavia Ex, Super-bond C & B, Maryland bridge adhesive, and All-bond C & B cementation kit. Maryland bridge adhesive and All-bond C & B cementation kit showed significantly higher film thickness than the control group(p<0.01). 2. For all resin cements, there was a significant difference of film thickness between the ADA method and the tapered-die system. Generally, the tapered-die system demonstrated lower film thickness than the ADA method(p<0.01). 3. There was no significant difference in film thickness between the tapered-die system and the tapered-die bridge system in all resin cements(p<0.01). 4. The scanning electron microscope showed that the cement with larger filler had a tendency to be higher in film thickness.

• 대한소아치과학회지
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• 제32권2호
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• pp.191-199
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• 2005

본 연구는 매복된 치아를 교정력을 이용하여 견인할 때 견인의 대상이 되는 치아를 개창술로 노출시켜 브라켓을 부착하는 과정에서 혈액 오염이 일어날 수 있는 상황을 실험실 환경에서 재현한 다음, 이와 같은 오염의 유무와 접착제의 종류가 브라켓의 전단강도에 미치는 영향을 평가하기 위해 시행하였다. 본 연구의 결과 글래스 아이오노머의 전단 강도는 레진에 비해 모든 조건에서 낮은 수치를 보였으나 혈액 오염이 없거나 광조사 직전 오염된 경우 임상적으로 교정적 정출술에 적절한 전단 강도를 나타내었다. 두 재료 모두 접착제 적용 전에 치면이 혈액에 오염되었을 경우 다른 조건에 비해 현저하게 낮은 전단 강도를 보였으나 광조사 직전에 혈액에 오염되었을 경우에는 오염되지 않은 대조군과 유의한 차이가 없었다. 이상의 연구 결과, 개창술을 통해 브라켓을 부착할 경우 접착제 적용 직전 혈액 오염을 주의한다면 산부식 과정 이 생략되어 술식이 비교적 간단하고 접착 파절 후 치면에 접착제가 남아 있지 않은 장점을 지닌 글래스 아이오노머 접착제의 사용을 추천할 수 있을 것으로 사료된다.