• 대한치과보철학회지
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• 제39권2호
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• pp.157-170
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• 2001

The bond strength is the most important factor in establishing long-term success of resin-retained fixed prostheses. So, various surface treatment methods have been introduced to improve the bond strength of metal surface and bonding resin till now This study was performed to compare the effect of silicoating with that of metal primer and analyze the correlation between treatment time of sandblasting and the bond strength, so that meant to find more effective surface treatment method that could enhance the bond strength of resin-retained fixed prostheses. The surfaces of all specimens made of $Verabond^{(R)}$ alloys were air abraded with $250{\mu}m\;Al_2O_3$ according to treatment time of sandblasting and they were subdivided to be treated with only sandblasting(S group), silicoating following sandblasting(SS group) and metal primer application after sandblasting(SM group). Then pairs of metal specimens (${\phi}10mm{\times}h\;2mm,\;{\phi}6{\times}h\;2mm$) were bonded with Super bond $C&B^{(R)}$. The specimens were stored in $38^{\circ}C$ water for 48 hours and shear bond strength was measured using the universal testing machine. The results were as follows, 1. In the comparison of shear bond strength according to treatment time of sandblasting, bond strength was increased in the order of 0', 15', 30', 45', 60' group. 0' group had significantly lower value than any other, while 0', 15' group were significantly different with 30', 45', 60' group(p<0.05). 2. In the comparison of shear bond strength according surface treatment methods, bond strength was increased in the order of S group. SS group and SM group. S group was significantly different with SS group and SM group(p<0.05). 3. Observing the mode of bond failure. 0', 15' group showed only adhesive failure, and 30', 45', 60' group did mostly adhesive & cohesive failure in S group. In SS group and SM group, all other groups except 0', 15' group showed mostly cohesive failure. From the above results, it is considered that sandblasting should be treated for more than 30 seconds, and metal primer be more effective and available clinically than silicoater system which is complicate, technique-sensitive and time-consuming method, when nonprecious metal surface is planning be treated with in order enhance the bond strength of resin-retained fixed prostheses.

• Restorative Dentistry and Endodontics
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• 제29권5호
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• pp.423-429
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• 2004

The purpose of this study was to evaluate the effect of multiple application of all-in-one dentin adhesive system on microtensile bond strength using confocal laser scanning microscope and microtensile bond strength test. Flat occlusal dentin surfaces were prepared using low-speed diamond saw. In group I, Scotchbond Multipurpose (SM) was applied by manufacturer's recommendation. In group II, after Adper Prompt L-Pop was applied for 15s and light cured for 10s. the second coat was re-applied and light-cured. In group III, after light-curing the second layer. the third coat was re-applied and light-cured. Specimens bonded with a resin-composite were sectioned into resin-dentin stick for measuring the adhesive layer thickness by confocal laser scanning microscope and evaluating micro-tensile bond strength. The adhesive layers of three-step dentin adhesive system. 3 coats of Adper Prompt L-Pop had significantly thicker than SM. 2 coats of Adper Prompt L-Pop (p < 0.05). However. there was no significant differences in bond strengths between SM and 3 coats of Adper Prompt L-Pop (p > 0.05). And SM. 3 coats of Adper Prompt L-Pop had significantly higher than 2 coats of Adper Prompt L-Pop in bond strengths (p < 0.05).

• The Journal of Advanced Prosthodontics
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• 제7권6호
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• pp.446-453
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• 2015

PURPOSE. To compare the push-out bond strength of feldspar and zirconia-based ceramic inlays bonded to dentin with different resin cements following simulated aging. MATERIALS AND METHODS. Occlusal cavities in 80 extracted molars were restored in 2 groups (n=40) with CAD/CAM feldspar (Vitablocs Trilux forte) (FP) and zirconia-based (Ceramill Zi) (ZR) ceramic inlays. The fabricated inlays were luted in 2 subgroups (n=20) with either etch-and-bond (RelyX Ultimate Clicker) (EB) or self-adhesive (RelyX Unicem Aplicap) (SA) resin cement. Ten inlays in each subgroup were subjected to 3,500 thermal cycles and 24,000 loading cycles, while the other 10 served as control. Horizontal 3 mm thick specimens were cut out of the restored teeth for push out bond strength testing. Bond strength data were statistically analyzed using 1-way ANOVA and Tukey's comparisons at ${\alpha}=.05$. The mode of ceramic-cement-dentin bond failure for each specimen was also assessed. RESULTS. No statistically significant differences were noticed between FP and ZR bond strength to dentin in all subgroups (ANOVA, P=.05113). No differences were noticed between EB and SA (Tukey's, P>.05) bonded to either type of ceramics. Both adhesive and mixed modes of bond failure were dominant for non-aged inlays. Simulated aging had no significant effect on bond strength values (Tukey's, P>.05) of all ceramic-cement combinations although the adhesive mode of bond failure became more common (60-80%) in aged inlays. CONCLUSION. The suggested cement-ceramic combinations offer comparable bonding performance to dentin substrate either before or after simulated aging that seems to have no adverse effect on the achieved bond.

• Computers and Concrete
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• 제33권5호
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• pp.519-533
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• 2024

Many materials including cementitious concrete-type materials undergo material property changes during high-rate loading. There is a wealth of research regarding this phenomenon for concrete in compression and tension. However, there is minimal knowledge about how mortar material used in concrete masonry unit (CMU) construction behaves in high-rate shear loading. A series of experiments was conducted to examine the bond strength of mortar bonded to CMU units under high-rate shear loading. A novel experimental setup using a shock tube and dynamic ram were used to load specially constructed shear triplets in a double lap shear configuration with no pre-compression. The Finite Element Method was leveraged in conjunction with data from the experimental investigation to establish if the shear bond between concrete masonry units and mortar exhibits any rate dependency. An increase in shear bond strength was observed when loaded at a high strain rate. This data indicates that the CMU-mortar bond exhibits a rate dependent strength change and illustrates the need for further study of the CMU-mortar interface characteristics at high strain rates.

• 한국지반공학회논문집
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• 제27권10호
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• pp.13-23
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• 2011

동토기반 말뚝기초의 지지력은 말뚝구조물 표면과 주변 토사의 접촉면에서 발현되는 동착강도에 의해 산정되며, 이는 동착-강도가 동토지반 기초설계를 위한 가장 주요한 설계정수임을 의미한다. 동착강도는 토사종류, 동결온도, 말뚝표면에 수직방향으로 작용하는 지중응력, 재하속도, 말뚝구조물의 표면 거칠기 등 다양한 인자들에 동시다발적인 영향을 받는 것으로 보고되고 있다. 1960년대부터 동토지반 기초설계를 위한 동착강도 산정방법들이 제안되어 왔으나, 대부분 동결온도와 말뚝구조물 표면특성에 대한 영향은 고려하고 있는 반면 동착강도의 주요 영향인자 중 하나인 지중응력에 의한 영향을 고려하지 않고 있어 소정깊이 이상의 말뚝기초 설계를 위한 동착강도 산정방법으로 활용되기에는 한계가 있는 것으로 판단된다. 본 연구에서는 동결온도뿐 아니라 지중응력이 동착강도에 미치는 영향을 파악하기 위하여 직접전단시험기를 활용한 동결토 전단강도 및 동착강도 측정실험을 각각 수행하였다. 실험결과 전단강도와 동착강도는 모두 동결온도 조건이 낮아질수록, 혹은 수직응력 조건이 커질수록 증가하는 경향을 보였다. 전단강도와 동착강도의 정량적 관계분석을 위해 정의된 전단강도와 동착강도의 비 $r_s$는 초기 동결온도에서는 급격하게 감소하는 경향을 나타냈으나, 동결온도가 낮아질수록 증가하며 수렴구간을 형성해가는 경향을 보였다. 본 연구에서는 최종적인 연구결과로서 동결온도 및 수직응력 조건을 바탕으로 결정된 $r_s$값을 이용하여 동결토의 전단강도로부터 동착강도를 예측할 수 있는 방법을 제안하고 있다.

• 콘크리트학회논문집
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• 제24권4호
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• pp.415-422
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• 2012

이 연구에서는 FRP 부재를 이용한 표면매입 보강에서, FRP의 부착강도를 평가하기 위하여 총 78개의 기존실험 결과를 분석하고, 기존 연구자들에 의해 제안된 식들을 평가하였다. 그 결과 FRP부재의 형상계수(폭-두께비)와 강성을 반영한 Seracino의 식이 부착내력을 가장 근사하게 예측하는 것으로 나타났다. 그러나 Seracino의 식은 실험 결과를 다소 과소평가하는 양상을 보이고 특히 부착길이가 작을수록 그 경향이 두드러진 것으로 나타났다. 이는 부착길이 증가에 따른 영향이 Seracino의 식에는 전혀 반영되어있지 않기 때문으로 볼 수 있다. 기존 실험 결과의 분석을 통하여 부착길이와 강도와의 상관관계를 찾고 또한 여러 개의 FRP부재를 인접하여 배치시 발생하는 무리효과를 고려하여 Seracino 식을 수정 제안하였다. 이 제시된 식을 이용하여 기존 실험체에 대한 내력을 계산하고 평가한 결과, 제안된 식으로서 표면매입 보강된 FRP의 부착강도를 매우 근사하게 예측할 수 있는 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.559-566
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• 1999

Gas-phase alkylations of delocalized ambident anions, Y---CH---X- where X, Y=CH2, O, or S, have been investigated theoretically at the MP2/6-31+G*//MP2/6-31+G* and QCISD/6-31+G*//MP2/6-31+G* lev-els. O-and S-alkylations (X=O and S) are more favored kinetically by ΔE^≠ = 4.6 and 9.8 kcal mol-1 than the respective C-alkylations even though they are thermodynamically less favored by 22.4 and 6.0 kcal mol-1 respectively. It was found that the transition structures for the C-alkylations are imbalanced due to the endoergic rehybridi-zation of the carbon center from sp2 to sp3 which leads to premature bond contraction of the C-Y bond and delayed bond stretching of the C-X bond. In the O-, or S-alkylation, such endoergic process is not required since the σ-lone pair on O or S is involved in the initial stage of alkylation. The imbalanced TSs for the C-alkylation are accompanied by higher intrinsic barriers and deformation energies.

• Restorative Dentistry and Endodontics
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• 제32권5호
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• pp.426-436
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• 2007

본 연구에서는 접착레진의 부가적인 도포가 레진 시멘트의 결합강도에 미치는 영향을 연구하였다. One-Step Plus와 Choice, Single Bond와 Rely X ARC, One-Up Bond F와 Bistite II DC를 사용하였고 접착레진으로 D/E Bonding resin과 Pre-Bond Resin을 선택하였다. 적용 및 광중합 유무에 따라 12개의 군을 설정하였다. 제 3대구치의 건전한 상아질 면에 간접 복합레진 수복물을 제작하여 접착을 시행하고$1\;{\times}\;1\;mm^2$의 시편을 만들어 미세인장강도를 측정하였다. 또한 투과전자현미경으로 접착계면을 관찰하였다. 그리하여 다음과 같은 결론을 얻을 수 있었다. 1. Single Bond와 Rely X ARC, 그리고 One-Step Plus와 Choice를 조합하고 광중합을 시행한 군에서, 접착 레진을 부가적으로 도포할 경우 미세인장강도가 증가하였다. 2. One-Up Bond F와 Bistite II DC를 조합한 군에서 접착레진의 부가적인 도포에 의한 미세인장강도의 차이는 나타나지 않았다. 3. 광중합을 시행한 군들 중, One-Step Plus와 Choice를 조합한 군이 다른 군보다 높은 미세인장결합강도를 보였다. 4. 자가중합만을 시행한 군간에는 접착레진의 부가적인 도포에 의한 차이가 나타나지 않았다. 투과전자현미경 관찰을 시행하여 광중합을 시행하고 접착레진을 부가적으로 도포한 실험군에서 미세누출이 감소하고 접착층의 두께가 증가한 것을 확인할 수 있었다. 본 연구결과 완전산부식 상아질 접착제와 이중중합 레진 시멘트를 사용할 경우 부가적인 접착레진의 도포가 임상적으로 유용할 수 있다는 사실을 확인할 수 있었다.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.1-16
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• 1995

The purpose of this study was to investigate the effect of dentin bonding agents on the bond strength of composite resin restorations in case of applying the dentin bonding agents to acid etched enamel surfaces. Freshly extracted 364 bovine anterior teeth were selected as a adherents. 320 enamel specimens were divided into two groups(unetched group (1) and etched group (2) for testing the shear bond strength, 40 specimens were used for the hardness testing, and 4 specimens of rest were to observe the resin-tag formation into etched enamel surfaces. All surfaces of enamel specimens were polished with 320~1500 SiC paper under continuous running water. In Group (1), 100 enamel specimens were polished and unetched. 220 polished enamel specimens in Group (2) were etched with 37 % phosphoric acid solution for 60 seconds, washed with water for 20 seconds, and dried with a light air pressure for 60 seconds. Three kinds of dentin bonding agents(Gluma, Prisma, Scotchbond 2) were evaluated the effect on the bond strength to conditioned enamel surfaces. Shear bond strengths were measured on the three cases such as a coating of primer only, a coating of sealer only, and a sequential coating of primer and sealer to acid etched enamel surfaces were compared with the bond strengths measured by the coating of enamel bonding agent followed by the bonding of composite resin (Photo clearfil bright, Kuraray, Japan) to unetched and acid etched enamel surfaces. In addition, the hardness tested on the adhesive fractured surface between composite resin enamel as a mean of evaluation of a factor whether the mechanical bond strengths were affected and the penetration of dentin bonding agents into etched enamel surfaces was also observed. Bond strengths were measured using the method of shear bond strength by a universal testing machine (Instron-4467, USA), statistical test were applied to the results using a one way analysis variance(ANOVA), and hardness was measured by the Vicker's Hardness Tester(MHT-i, Matsuzawa, Japan) and the penetration of the resins were observed by the SEM (Hitachi, S-2300, Japan). The following conclusions were drawn; 1. Enamel bonding agent showed to affect the improvement of bond strength of composite resin to enamel surface both unetched and etched. 2. Dentin bonding agents could be resulted in increase of bond strength to unetched enamel surface, but there were no statistical significances. 3. Bond strengths to etched enamel surface were significantly decreased with a coating of dentin primer only. 4. Coating of sealer only and coating of primer and sealer noticed the similar bond strengths of composite resin to etched enamel using the enamel bonding agents. 5. The applying method proved to be more effective than the kinds of dentin bonding agents on the bond strength of composite resin to etched enamel than the kind of dentin. 6. Vicker's hardness numbers of dentin bonding agents were lower than that of composite resin, but the degree of penetration of dentin bonding agents into etched enamel surfaces was excellent.

• 한국시뮬레이션학회논문지
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• 제28권3호
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• pp.49-56
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• 2019

본 논문에서는 선도이자율 모형과 리보이자율 모형 사이의 관계를 이용하여 채권 옵션의 해석적인 해(Analytic Solution; AS)와 몬테 카르로 시뮬레이션(Monte Carlo Simulation; MCS)을 이용한 가격 결정을 다룬다. AS를 이용한 채권 옵션가격 결정은 Ritchken and Sankarasubramanian (RS)의 제한 조건을 이용하여 할인된 채권 가격을 구하는 공식을 유도하고, 선도이자율과 리보이자율 모형의 변동함수 사이의 관계를 활용한다. MCS을 이용한 채권 옵션 가격 결정은 MCS을 이용하여 제시된 조건으로부터 여러 가지 예정된 전개의 시뮬레이션을 활용한다. AS와 MCS을 이용한 가격 결정 방법을 실행하여 얻은 가격을 비교하면 AS와 MCS의 상대오차(Relative Error; RE)를 구할 수 있다. 이때 본 연구의 결과로부터 RE가 약 3.9%가 됨을 확인할 수 있다. 이것은 AS뿐만 아니라 MCS을 이용해도 채권 옵션의 가격을 매우 정확하게 예측할 수 있음을 의미한다.