• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.774-780
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• 1999

The study of bond behavior between concrete and rebar has been performed for a long time. On this study, we tried to analysed variation of bond behaviors quantitatively with varying the strength of concrete. Bond stress which observed below the neutral surface of beam and at connecting part of beam and column is affected by various bond parameters. Resistance of deformed bars which embedded in concrete to the pullout force is divided 1) chemical adhesive force 2) frictional force 3) mechanical resistance of ribs to the concrete and these horizontal components of resistance is being bond strength. We selected the most common and typical variable which is concrete strength among various variables. So we used two kinds of concrete strength like as 25MPa(NSC) and 65MPa(HSC). Tension Test was performed to verify how bond behavior varied with two kinds of concrete strength. Concentration of bond stress was observed at load-end commonly in Tension Test of the initial load stage. At this stage stress distribution was almost coincident at each strength. As tension load added, this stress distribution had difference gradually and movement of pick point of bond stress to free-end and central section was observed. This tendency was observed at first and moving speed was more fast in NSC. At the preceeding result the reason of this phenomenon is considered to discretion of chemical adhesion and local failure of concrete around rebar in load-end direction. Especially, when concrete strength was increased 2.6 times in tension test, ultimate bond strength was increased 1.45 times. In most recent used building codes, bond strength is proportioned to sqare root of concrete compressive strength but comparison of normalized ultimate bond strength was considered that the higher concrete strength is, the lower safety factor of bond strength is in each strength if we use existing building codes. In Tension Test, in case of initial tensile force state, steel tensile stress of central cross section is not different greatly at each strength but tensile force increasing, that of central cross section in NSC was increased remarkably. Namely, tensile force which was shared in concrete in HSC was far greater than that of concrete in NSC at central section.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.234-237
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• 2003

Previous researches about headed reinforcement have not been concerned about bond failure which is quite important is some cases. In this paper, failure mechanism including bond failure was presented in order to define the contribution of bond stress at the time failure occurs. Examined with design codes and test results, it is proved to be rational to consider the contribution of bond stress in determining the ultimate pull-out capacity of headed reinforcement. Direct adaptation of design code for anchor bolt without modification for the contribution of bond stress will lead to underestimate the capacity of headed reinforcement.

• 대한치과기공학회지
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• 제24권1호
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• pp.33-41
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• 2002

In dental prosthetics, the application of metal-ceramic restorations has steadily increased since their introduction. This is due to excellent esthetics in combination with high mechanical stability. In order to optimum bond strength between metal and ceramics, controlled oxidation of metal substructure is essential factor. Beryllium containing and beryllium free Ni-Cr alloys for metal-ceramic restorations were evaluated for the metal-ceramic bond strength by changing heat treatment for oxide formation. A mechanical three-point bending test was employed to evaluate the interfacial bond strength of metal-ceramic. In each metal, plate type specimens were used for mechanical three-point bending test. With Ni-Cr alloys for metal ceramics, mechanical three-point bending test showed that double degassing was more available preheat treatment method than another. It was found that beryllium containing Ni-Cr alloys are more effective than beryllium-free for metal-ceramic bond strength.

• 한국구조물진단유지관리공학회 논문집
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• 제14권3호
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• pp.100-107
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• 2010

본 연구에서는 순환 굵은 골재를 사용한 철근콘크리트 (RC) 보의 부착거동을 평가하였다. 총 4개 실험체를 제작하였으며, 실험변수는 굵은 골재의 종류(천연 및 순환골재)와 순환골재의 흡수율로 하였다. 본 실험에서는 흡수율이 3%와 6%인 순환 굵은 골재를 사용하였으며, 실험체는 단순지지 형태로 집중하중을 받도록 계획하였다. 실험체의 부착특성을 효과적으로 평가하기 위하여 Ichinose가 제안한 실험방법을 채택하였다. 본 실험결과, 순환 굵은 골재의 흡수율에 따른 부착 특성의 차이는 발견되지 않았다.

• 대한토목학회논문집
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• 제28권3A호
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• pp.401-406
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• 2008

본 연구에서는 폐 PET병을 사용하여 구조적으로 효과가 있는 재생 PET섬유를 생산하였고 세 가지 형상의 재생 PET섬유와 시멘트 매트릭스와의 부착성능을 평가하였다. 또한 세 가지 형상의 재생 PET섬유로 보강된 콘크리트의 휨성능 시험을 실시하였다. 시험결과 재생 PET섬유는 우수한 부착성능의 증가를 보여주었다. 휨시험 결과 재생 PET섬유는 콘크리트의 휨인성을 증가시킨다는 것을 증명하였다. 부착 및 휨시험 결과를 기본으로 요철형 재생 PET섬유의 부착 및 휨성능이 다른 형상의 섬유와 비교하여 가장 우수하였다.

• The Journal of Advanced Prosthodontics
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• 제10권1호
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• pp.25-31
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• 2018

PURPOSE. The aim of the present study was to record the metal-ceramic bond strength of a feldspathic dental porcelain and a Co-Cr alloy, using the Direct Metal Laser Sintering technique (DMLS) for the fabrication of metal substrates. MATERIALS AND METHODS. Ten metal substrates were fabricated with powder of a dental Co-Cr alloy using DMLS technique (test group) in dimensions according to ISO 9693. Another ten substrates were fabricated with a casing dental Co-Cr alloy using classic casting technique (control group) for comparison. Another three substrates were fabricated using each technique to record the Modulus of Elasticity (E) of the used alloys. All substrates were examined to record external and internal porosity. Feldspathic porcelain was applied on the substrates. Specimens were tested using the three-point bending test. The failure mode was determined using optical and scanning electron microscopy. The statistical analysis was performed using t-test. RESULTS. Substrates prepared using DMLS technique did not show internal porosity as compared to those produced using the casting technique. The E of control and test group was $222{\pm}5.13GPa$ and $227{\pm}3GPa$, respectively. The bond strength was $51.87{\pm}7.50MPa$ for test group and $54.60{\pm}6.20MPa$ for control group. No statistically significant differences between the two groups were recorded. The mode of failure was mainly cohesive for all specimens. CONCLUSION. Specimens produced by the DMLS technique cover the lowest acceptable metal-ceramic bond strength of 25 MPa specified in ISO 9693 and present satisfactory bond strength for clinical use.

• 대한치과교정학회지
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• 제27권5호
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• pp.781-789
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• 1997

본 연구는 교정치료를 위해 최근에 발거된 소구치 65개를 대상으로 발거직후 부착된 이물질을 제거하고 생리식염수에 담구어 보관한 후 법랑질을 퍼미스 및 $38\%$ 인산으로 표면 처리하고 불소가 유리되는 교정용 전색제로는 광중합형 FluoroBond, 광중합 접착제로는 Transbond, 화학중합 접착제로는 Mono-Lok 2를 선정하여 1차 부착 및 재부착시의 전단결합강도를 만능강도시험기로 측정함으로서, 치아우식 예방 및 진행 억제효과를 지닌 불소가 유리되는 교정용 전색제가 광중합형 및 화학중합형 교정용 접착제의 전단결합강도에 미치는 영향과 재부착에 의한 전단결합강도의 변화를 규명하고, 광중합형 접착제와 화학중합형 접착제 사이의 전단결합강도를 비교하여 다음의 결론을 얻었다. 1. 1차부착에 의한 전단결합강도의 크기는 Mono-Lok2군(11.84MPa), Trans bond군(10.75MPa), Light cured FluoroBond+Mono-Lok 2군(9.69MPa), Light cured FluoroBond+Transbond군(9.39MPa)순이었다. 2. 재부착에 의한 전단결합강도의 크기는 Transbond군(7.40MPa), Light cured FluoroBond+Transbond군(6.48MPa), Mono-Lok 2군(5.89MPa), Light cured FluoroBond+Mono-Lok 2군(5.15MPa)순이었다. 3. 불소가 유리되는 교정용 전색제를 적용한군과 적용하지 않은 군 모두에서 화학중합형 접착제가 광중합형 접착제보다 높은 전단결합강도를 보였으나 통계학적으로 유의한 차이는 없었다(p>0.05). 4. 불소가 유리되는 교정용 전색제를 적용한군과 적용하지 않은 군 모두에서 재부착된 광중합형 접착제가 재부착된 화학중합형 접착제보다 높은 전단결합강도를 보였으나 통계학적으로 유의한 차이는없었다(p>0.05). 5. 1차 부착된 군에 비해 재부착된 모든 군에서 전단결합강도가 현저하게 감소되었으며, 통계학적으로 유의한 차이를 보였다(p<0.05 p<0.001). 이상의 결론을 종합해볼 때 임상적으로 브라켓의 전단결합강도에 경향을 미치지 않는 불소가 유리되는 교정용 전색제를 치아 협면에 적용하여 불소의 유리에 의한 치아우식 예방 및 억제효과를 기대하는 것이 필요할 것으로 생각된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.621-626
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• 1998

An experimental investigation on the reinforcing bar corrosion and relationshid of reinforcing bar and concrete bond strength has been conducted to establish the allowable limit of rust in the construction field. The reinforcing bars used in this study were rusted before embedding in concrete. The first component of this experiment is to make rust of reinforcing bar rust artificially based on Faraday's theory at certain rates such as 2, 4, 6, 8 and 10% of reinforcing bar weight. For estimation of the amount of rust by weight, Clarke's solution and Shot blasting were adopted and compared. Parameters include 240 and 450kg/㎠ of compressive strengths and diameter of reinforcing bar (16, 19 and 25mm) corresponding development length for pull-ort test. And, pull-out tests were carried. out according to KSF 2441 and ASTMC 234 to investigate the effect of the corrosion rate on reinforcing bar-concrete bond behavior. It is found from the test results that the test techniques for corrosion of bar used in this study is relatively effective and correct test method. Results shows that up to 2% of rust increases the bond strength regardless of concrete strength and diameter of reinforcing bar like the existing data. It might be because of the roughness from rust. As expected, the bond strength increases as compressive strength of concrete increases and the diameter of bar decreases.

• Restorative Dentistry and Endodontics
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• 제29권3호
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• pp.273-280
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• 2004

The purpose of this study was to evaluate the etching effects and bond strength of total etching and self-etching adhesive system on unground enamel using scanning electron microscopy and microtensile bond strength test. The buccal coronal unground enamel from human extracted molars were prepared using low-speed diamond saw. Scotchbond Multi-Purpose (group SM). Clearfil SE Bond (group SE), or Adper Prompt L-Pop (group LP) were applied to the prepared teeth. and the blocks of resin composite (Filtek Z250) were built up incrementally. Resin tag formation was evaluated by scanning electron microscopy. after removal of enamel surface by acid dissolution and dehydration. For microtensile bond strength test. resin-bonded teeth were sectioned to give a bonded surface area of $1\textrm{mm}^2$. Microtensile bond strength test was perfomed. The results of this study were as follows. 1. A definite etching pattern was observed in Scotchbond Multi-Purpose group. 2. Self-etching groups were characterized as shallow and irregular etching patterns. 3. The results (mean) of microtensile bond strength were SM: 26.55 MPa, SE: 18.15 MPa, LP: 15.57 MPa. SM had significantly higher microtensile bond strength than 8E and PL (p < 0.05). but there was no significant differance between SE and PL.

• 대한치과의사협회지
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• 제53권12호
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• pp.958-966
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• 2015

Objective: Sodium hypochlorite (NaOCl) decreases the bond strength of resin composite. The purpose of this study was to compare the effect of antioxidant and superficial dentin surface removal on the microtensile bond strength of NaOCl-treated dentin. Materials and Methods: Twenty non-carious human third molars were used in this study. The dentin surfaces were treated with 5.25% NaOCl for 10 min, followed either by treatment with 10% ascorbic acid or superficial dentin surface removal. Two-step self-etch adhesive and resin composite were used for restoration. The bonded specimens were subjected to the microtensile bond strength test. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey's test (p < 0.05). Results: The bond strength after removal of the superficial dentin surface following NaOCl irrigation was similar to that in the control group. The group treated with 10% ascorbic acid demonstrated significantly higher bond strength than the other groups. Conclusion: NaOCl irrigation-induced reduction in dentin bond strength could be recovered by either treatment with 10% ascorbic acid or simple removal of the superficial dentin surface.