• The Journal of Advanced Prosthodontics
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• 제9권2호
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• pp.85-92
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• 2017

PURPOSE. The aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process. MATERIALS AND METHODS. Shear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one self-adhesive cement (Panavia SA plus) were included in this study. The interface of the cement and the tooth surface with the different pre-treatments was analyzed using SEM. pH values of the cements and primers were measured. RESULTS. The highest bond strength values for all cements were achieved with etching and primer on enamel ($25.6{\pm}5.3-32.3{\pm}10.4MPa$). On dentin, etching and priming produced the highest bond strength values for all cements ($8.6{\pm}2.9-11.7{\pm}3.5MPa$) except for Panavia V5, which achieved significantly higher bond strengths when pre-treated with primer only ($15.3{\pm}4.1MPa$). Shear bond strength values were correlated with the micro-retentive surface topography of enamel and the tag length on dentin except for Panavia V5, which revealed the highest bond strength with primer application only without etching, resulting in short but sturdy tags. CONCLUSION. The highest bond strength can be achieved for Panavia F 2.0, Permaflo DC, and Panavia SA plus when the tooth substrate is previously etched and the respective primer is applied. The new cement Panavia V5 displayed low technique-sensitivity and attained significantly higher adhesion of all tested cements to dentin when only primer was applied.

• Journal of Korean Dental Science
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• 제1권1호
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• pp.28-34
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• 2008

Objectives. The objectives of this study were: 1) to compare the effect of varying timing of light curing on shear bond strength, and; 2) to compare the shear bond strength of three self-adhesive cements. Materials and methods. A total of 72 extracted non-carious teeth were divided into 24 for Unicem tests, 24 for Maxcem tests, and 24 for Biscem tests; they were assigned 3 * 2 subgroups of 12 teeth each. The specimens were prepared as follows: 1) The calculus and periodontal ligament were removed from the teeth; 2) The teeth were stored in normal saline; 3) The occlusal enamel of each tooth was removed using high-speed coarse diamond burs under water cooling, and; 4) Finally, the teeth were flattened by 600-grit silicone carbide paper disks. Resin blocks were adhered using either Unicem, Maxcem, or Biscem. Light curing timing was divided into two groups: U10, M10, and B10 were exposed to light after 10 seconds, and; U150, M150, and B150 on the other side were exposed to light after 150 seconds. Shear bond strength was measured by a Universal testing machine with cross head speed of 1mm/min. T-test and One way ANOVA were used for the statistical analysis of data. Results. The shear bond strength of U150 was not significantly higher than that of U10 (U150: 20.55.7Mpa, U10: 18.73.80Mpa). On the other hand, the shear bond strength of M150 was significantly higher than that of M10. The shear bond strength of B150 was also significantly higher than that of B10 (M150:14.45.7Mpa, M10: 9.94.2Mpa, B150: 24.38.3Mpa, B10: 17.27.3Mpa). When the light curing timing was 10sec after bonding, the shear bond strength of Unicem was highest; the shear bond strength of Biscem was highest when the light curing timing was 150sec after bonding (U10: 18.73.80Mpa, B150: 24.38.3Mpa). Significance. Since Unicem is less sensitive based on light curing timing, dentists seem to use it without considering the light curing timing. Maxcem showed the lowest bonding strength (especially M10). Thus, when using Maxcem, dentists need to delay the light curing after adhesion.

• 접착 및 계면
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• 제3권2호
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• pp.17-29
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• 2002

Micromechanical 시험법과 표면 젖음성 측정을 이용한 implant용 생분해성 복합재료의 계면물성과 미세파괴 분해 메카니즘을 연구하였다. 분해시간이 경과함에 따라서 poly(ester-amide) (PEA)와 생활성 유리섬유의 인장강도와 탄성률 그리고 신율은 점차적으로 감소하는 경향을 보인 반면, chitosan 섬유는 거의 변화가 없었다. 생활성 유리섬유와 poly-L-lactide(PLLA) 사이의 계면전단강도는 PEA나 chitosan 섬유 시스템의 경우보다 더 큰 값을 보였으나, 계면전단강도 감소 속도는 가장 빨랐고 chitosan 섬유의 경우가 가장 느린 결과를 보였다. 접착일 ($W_a$)은 생활성 유리섬유와 PLLA 사이에서 가장 높은 값을 나타냈으며, 이러한 표면 젖음성 결과는 계면전단강도 결과와 잘 일치하였다. 계면물성과 미세파괴 분해 메카니즘은 생분해성 복합재료의 성능을 조절할 수 있는 가장 중요한 요인들이다.

• Carbon letters
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• 제19권
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• pp.47-56
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• 2016

In this study, the fracture behavior of a thermoplastic-modified epoxy resin reinforced with continuous carbon fibers for two levels of fiber-matrix adhesion was performed. A carbon fiber with commercial sizing was used and also treated with a known silane, (3-glycidoxy propyl trimethoxysilane) coupling agent. Toughness was determined using the double cantilever test, together with surface analysis after failure using scanning electron microscope. The presence of polysulfone particles improved the fracture behavior of the composite, but fiber-matrix adhesion seemed to play a very important role in the performance of the composite material. There appeared to be a synergy between the matrix modifier and the fiber-matrix adhesion coupling agent.

• Elastomers and Composites
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• 제50권4호
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• pp.304-313
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• 2015

In this study, the anionic emulsified asphalt was prepared by dispersing asphalt particles evenly into water with combination of anionic and nonionic surfactants. Effects of NaOH and $CaCl_2$ on the phase stability of the emulsified asphalt were also investigated through zeta potential value and rheology behavior; the emulsified asphalt added with NaOH and $CaCl_2$ showed higher zeta potential value than that the asphalt with addition of only anionic and nonionic surfactants. In addition, with regard to shear thinning behaviors, it was found that pH of the emulsified anionic asphalt and $Ca^{2+}$, counter ion, affected the phase stability. SBR (styrene-butadiene-rubber) latex, EPD (water dispersed Epoxy), PU (polyurethane) and RI-10S, SBS (styrene-butadiene-styrene)-based property improvement additive, were used and studied to enhance the adhesion properties with the aggregates. RI-10S, however, was found to be only compatible with the anionic emulsified asphalt; the coating rate, adhesion and compression strength were increased with the RI-10S content.

• 한국강구조학회 논문집
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• 제13권5호
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• pp.557-566
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• 2001

데크플레이트를 사용한 합성슬래브가 합성거동을 발휘하기 위해서는 데크플레이트와 콘크리트의 부착강도가 확보되어야한다. 합성슬래브에서 전단부착강도는 콘크리트와 데크플레이트의 화학적 부착력, 마찰저항 기계적 상호작용에 의해 발생한다. 또 기계적 상호작용은 길이 방향 전단력 전달 장치인 엠보싱 및 쉬어코넥터, 데크플레이트 형상 등에 의해서 확보되어 진다. 그리고 기계적 상호작용의 효과는 상호 접착부의 수직박리를 구속할 수 있는 데크의 형상과 쉬어코넥터 설치에 따른 단부정착 여부에 따라 크게 달라진다. 그러므로, 본 연구에서는 폐쇄형 데크플레이트에 대하여 기계적 전달장치인 엠보싱과 쉬어 코넥터로 사용되는 스터드 볼트에 대한 전단 보강장치의 부착효과를 Push-off 실험을 통하여 규명하였으며 이들 인자들에 대하여 제안식을 제시하였다. 이는 합성슬래브 설계방법의 기초자료로 이용될 수 있을 것으로 사료된다.

• 폴리머
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• 제26권6호
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• pp.718-727
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• 2002

본 연구에서는 최종 복합재료의 기계적 계면특성을 향상시키기 위하여 산소 분위기 하에서 반응성 기체를 사용하는 이온 보조 반응법에 의해 탄소섬유 표면에 Ar+ 이온 빔을 조사하였다. 그리고, 단일 섬유 pull-out 시험을 실시하여 가해진 이온 에너지 세기에 대한 수지 내의 섬유의 뽑힘 정도를 측정한 후 Greszczuk의 .기하학적 모델에 기초하여 섬유/매트릭스 간의 계면특성을 알아보고자 하였다. 그 결과, 탄소섬유를 이온 빔으로 처리함에 따라 섬유와 매트릭스 간의 부착력 증가의 원인이 되는 섬유축 방향으로의 표면 etching 및 반응성 그룹이 형성되어 계면 전단강도가 향상되었으며 0.8 keV 이온 빔 세기에서 최대값을 나타내었다.

• Journal of the Korean Wood Science and Technology
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• 제47권2호
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• pp.221-228
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• 2019

This study reports the performance of urea-formaldehyde (UF) resins prepared at two different low formaldehyde/urea (F/U) mole ratios with different numbers of urea addition during synthesis. The second or third urea was added during the synthesis of UF resins to obtain two different low molar ratios of 0.7 and 1.0, respectively. The molecular weights, cure kinetics, and adhesion performance of these resins were characterized by the gel permeation chromatography, differential scanning calorimetry, and tensile shear strength of plywood, respectively. When the number of urea additions and F/U molar ratio increased, the gelation time decreased, whereas the viscosity and molecular weight increased. Further, the UF resins prepared with the second urea and 1.0 molar ratio resulted in greater activation energy than those with third urea and 0.7 molar ratio. Tensile shear strength and formaldehyde emission (FE) of the plywood that bonded with these resins increased when the number of urea additions and molar ratio increased. These results suggest that the UF resins prepared with 0.7 molar ratio and third urea addition provide lower adhesion performance and FE than those resins with 1.0 mole ratio and the second urea addition.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.125-128
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• 2005

The dispersion of carbon nanofiber (CNF) was carried out by solution blending, mechanical mixing, and sonication. CNFs at levels of 5-50% fiber weight content were mixed with polypropylene (PP) powder, and then were melt-mixed using a twin-screw extruder. For the further alignment of fibers, extruded rods were stacked uni-directionally in the mold cavity for the compression molding. For the evaluation of mechanical properties of nanocomposites, tension, in-plane shear, and flexural tests were conducted. CNF/PP composites clearly showed reinforcing effect in the longitudinal direction. The tensile modulus and strength have improved by 100% and 40%, respectively for 50 % fiber weight content, and the flexural modulus and strength have increased by 120% and 25%, respectively for the same fiber weight content. The shear modulus showed 65% increase, but the strength dropped sharply by 40%. However, the property enhancement was not significant due to the poor adhesion between fiber and matrix. In the transverse direction, the tensile, flexural, and shear strength decreased as more fibers were added.

• 한국구조물진단유지관리공학회 논문집
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• 제27권5호
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• pp.139-146
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• 2023

In this study, compressive strength and adhesion strength were measured as repair materials to evaluate the mechanical and electrical properties of compression and shear specimens with self-sensing repair materials. As a result of the experiment, the strength improvement rate of the compression test specimen was higher than the section enlargement area ratio, but the shear test specimen did not show an improvement in strength as much as the section enlargement area ratio. Compression experiments under load showed high correlation between FCR-Strain and FCR-Stress, confirming self-sensing performance. However, the shear test did not show as much correlation as the compression test. Accordingly, it is judged that the self-sensing repair material is suitable for the compression member on which the compression load acts in the building.