• 공업화학
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• 제30권3호
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• pp.352-357
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• 2019

본 연구에서는 3-butenoic acid와 폴리옥시에틸렌(20) 스테아릴 에테르를 사용하여 비닐기를 가진 반응성 유화제를 합성하였다. 합성 반응성 유화제는 FT-IR 및 $^1H-NMR$에 의해 확인되었다. 또한, 아크릴계 점착제의 제조에서 합성된 반응성 유화제와 통상적으로 사용되는 비이온성 유화제를 사용하여 각각의 점착제의 특성을 비교하였다. 고형분 함량은 56.8~57.4%의 범위에서 측정되었다. 초기 접착의 경우, 반응성 유화제로 제조된 S20BA는 $^{\sharp}13$으로 측정되었다. 제조된 접착제의 박리강도는 $0.66{\sim}1.05kg_f$의 범위에서 측정되었고 S20BA를 사용한 경우 가장 높은 박리 강도가 측정되었다. 내열성 시험 결과, S20BA의 내열성이 $840^{\circ}C$로 가장 높았다. 피부용 접착제에 대한 응용성을 평가하기 위하여 pH는 중성 7로 측정되었으며, 일차 피부 자극 시험의 결과로 비자극성으로 측정되었다.

• 한국항행학회논문지
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• 제24권6호
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• pp.465-470
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• 2020

복합 소재는 금속보다 가벼운 특성을 가져 경량화가 필수인 항공 산업에 널리 사용되고 있다. 하지만 복합소재는 생산 공정 중 내부 보이드 형성, 접착제 혼합 불량, 미접착 부분 발생 등 결함 요소가 발생할 수 있고, 저 에너지 충격에 의한 미세균열 및 층간분리가 발생할 위험이 있다. 그러므로 구조물 손상검사가 필수적으로 요구된다. 이에 FBG를 이용한 구조 건전성 모니터링이 주목받고 있다. FBG는 기존의 전기적 센서에 비해 전기적 노이즈 영향을 받지 않고 부식에 강하며 멀티플렉싱이 가능하다는 장점이 있다. 하지만 FBG를 계측하는 인터로게이터는 대형 구조물 계측을 전제로 만들었기 때문에 가격이 고가이며, 크기가 큰 단점이 있다. 이에 본 논문에서는 광 스위치와 WDM필터, LTF를 이용해 무인항공기나 소형항공기에 사용할 수 있도록 저가형 인터로게이터를 설계하여, 기존의 고가 인터로게이터와 비교를 진행하였다.

• Restorative Dentistry and Endodontics
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• 제47권2호
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• pp.21.1-21.11
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• 2022

Objectives: This study aimed to investigate the bonding effects of cleaning protocols on dentin impregnated with endodontic sealer residues using ethanol (E) or xylol (X). The effects of dentin acid etching immediately (I) or 7 days (P) after cleaning were also evaluated. For bonding to dentin, universal adhesive (Scotchbond Universal; 3M ESPE) was used. The persistence of sealer residues, hybrid layer formation and microshear bond strength were the performed analysis. Materials and Methods: One hundred and twenty bovine dentin specimens were allocated into 4 groups (n = 10): G1 (E+I); G2 (X+I); G3 (E+P); and G4 (X+P). The persistence of sealer residues was evaluated by SEM. Confocal laser scanning microscopy images were taken to measure the formed hybrid layer using the Image J program. For microshear bond strength, 4 resin composite cylinders were placed over the dentin after the cleaning protocols. ANOVA followed by Tukey test and Kruskal-Wallis followed by Dunn test were used for parametric and non-parametric data, respectively (α = 5%). Results: G2 and G4 groups showed a lower persistence of residues (p < 0.05) and thicker hybrid layer than the other groups (p < 0.05). No bond strength differences among all groups were observed (p > 0.05). Conclusions: Dentin cleaning using xylol, regardless of the time-point of acid etching, provided lower persistence of residues over the surface and thicker hybrid layer. However, the bond strength of the universal adhesive system in etch-and-rinse strategy was not influenced by the cleaning protocols or time-point of acid etching.

• Journal of Mechanical Science and Technology
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• 제17권3호
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• pp.343-349
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• 2003

The fuselage-wing intersection suffers from the cyclic bending moment of variable amplitude. Therefore, the influence of cyclic bending moment on the delamination and the fatigue crack propagation behavior in AFRP/Al laminate of fuselage-wing was investigated in this study. The cyclic bending moment fatigue test in AFRP/Al laminate was performed with five levels of bending moment. The shape and size of the delamination Lone formed along the fatigue crack between aluminum sheet and aramid fiber-adhesive layer were measured by an ultrasonic C-scan. The relationships between da/dN and ΔK, between the cyclic bending moment and the delamination zone size, and between the fiber bridging behavior and the delamination zone were studied. As results, fiber failures were not observed in the delamination zone in this study, the fiber bridging modification factor increases and the fatigue crack growth rate decrease and the shape of delamination zone is semi-elliptic with the contour decreasing non-linearly toward the crack tip.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.33-37
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• 2009

Finite-element methods are used to study non-adhesive, frictionless rough contact of elastic and plastic solids. Roughness on spherical surfaces is realized by self-affine fractal. True contact area between the rough surfaces and flat rigid surfaces increases with power law under external normal loads. The power exponent is sensitive to surface roughness as well as the curvature of spherical geometry. Surface contact pressures are analyzed and compared for the elastic and plastic solids. Distributions of local contact pressure are shown dependent on the surface roughness and the yield stress of plastic solids.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1061-1065
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• 1995

To improve dielectric and mechanical properties of insulating composite by plasma surface treatment, new plasma surface treatment process is designed with concentric and hemi-circle electrodes system, the plasma, which is generated between anode and cathode, is induced to the upper side of the electrode system and treats the surface of the insulators. The optimal surface treatment condition is that pressure : 0.5[torr], flux density 100[gauss], discharge current : 500[mA] and treatment time : 3 minutes. The composite filled with glass cloth surface-treated by plasma shows the improvement in electric and mechanical properties, comparing non- and coupling agent-treated samples.

• ALGAE
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• 제29권4호
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• pp.289-297
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• 2014

The taxonomic status and the distribution of Rosenvingea species need attention because of the difficulties in morphological identification in the laboratory as well as in the field. We analyzed mitochondrial cox3 and plastid psaA gene sequences from Rosenvingea species from Vietnam, Mexico and Panama in combination with morphological examinations. Our results confirmed the occurrence of R. intricata and R. orientalis in Vietnam. R. intricata formed dense decumbent mats with many flat branches, often inter-adhesive, and was up to 5 cm in diameter. R. orientalis thalli were up to 18 cm long with narrow (less than 2 mm in width) tubular to compressed fronds. Both cox3 and psaA phylogenies revealed the non-monophyly of the genus Rosenvingea, as reported previously for other scytosiphonacean genera.

• 한국식품저장유통학회지
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• 제6권1호
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• pp.81-86
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• 1999

The textural characteristics of nonxaxy rice flour gels and rice cake(Injolmi) with different water contents and additives were evaluated after freezing and microwave heating. As moisture content of rice flour gels increased from 45% to 55%, its hardness and gumminess decreased, but adhesive and cohesiveness had no significant difference. Microwave heating did not markedly affect the texture but frozen storage was very effective to prevent the hardening of products. Hardness of reheated rice gels increased more rapidly in non-packaged sample than in PE wrap film and affected by storage time of 24hrs at 20$^{\circ}C$. As sugar content of rice flour gels increased from 0% to 10%, its hardness, adhesiveness, and gumminess decreased, while cohesiveness did not change.

• Elastomers and Composites
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• 제11권2호
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• pp.113-121
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• 1976

Fundamental and specific properties of the tennis ball on rubber ball body are surveyed to match the quality of the tennis ball now on applied in the tennis game, 1. Much dose of filler of non-crystalline or flat form applied to rubber compounding than general procedure and over vulcanization is found excellent in the resistant to gas permeability. 2. Flat curing improved characteristics of the ball on the homogenous rebounds when applied on the specified concrete surface. 3. Satisfactory adhesive power is found with Desmodur R and standard rubber recipe in case of applying on the under-vulcanizate of half sphere. 4. The stable gas-generating compounds of sodiun nitrate, ammonium chloride, water and sodium carbonate, anhydorus help controlling of optimum internal over-pressure in the tall.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.343-348
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• 2007

Molecular dynamics study of thermal NIL (Nano Imprint Lithography) process is performed to examine stamp-resist interactions. A layered structure consists of Ni stamp, poly-(methylmethacrylate) thin film resist and Si substrate was constructed for isothermal ensemble simulations. Imposing confined periodicity to the layered unit-cell, sequential movement of stamp followed by NVT simulation was implemented in accordance with the real NIL process. Both vdW and electrostatic potentials were considered in all non-bond interactions and resultant interaction energy between stamp and PMMA resist was monitored during stamping and releasing procedures. As a result, the stamp-resist interaction energy shows repulsive and adhesive characteristics in indentation and release respectively and irregular atomic concentration near the patterned layer were observed. Also, the spring back and rearrangement of PMMA molecules were analyzed in releasing process.