• Journal of the Korean Wood Science and Technology
• /
• 제50권6호
• /
• pp.427-435
• /
• 2022

For effective applicability of reinforced cork, cork composites reinforced with metal, glass fiber, and carbon fiber were developed, and the effects of the reinforcing materials on the mechanical properties of cork composites were investigated. The bending moduli of elasticity (MOE) of cork composites were in the 32.7-35.9 MPa range, while the bending strength values were in the 1.62-1.73 MPa range. The strength performance decreased in the order cork-metal > cork-carbon fiber > cork-glass fiber. The bending MOEs were improved by 29%-41% compared with simple cork boards, while the bending strengths of reinforced cork were 35%-45% higher. The strength performance significantly improved following the incorporation of thin mesh materials into the middle layer of the studied cork composites. The bending strains of the cork composites were remarkably higher compared with oak wood, making them promising for applications that require bending processing, such as curved jointing. The internal bond strengths of the cork composites were 0.26-0.44 MPa, approximately 0.36-0.60 times lower compared with medium-density fiber boards.

• Nuclear Engineering and Technology
• /
• 제55권2호
• /
• pp.432-442
• /
• 2023

Characterizing the behavior of nuclear reactor plate fuels is vital to the progression of advanced fuel systems. The states of pre- and post-irradiation plates need to be determined effectively and efficiently prior to and following irradiation. Due to the hostile post-irradiation environment, characterization must be completed remotely. Laser-based characterization techniques enable the ability to make robust measurements inside a hot-cell environment. The Laser Shock (LS) technique generates high energy shockwaves that propagate through the plate and mechanically characterizes cladding-cladding interfaces. During an irradiation campaign, two Idaho National Laboratory (INL) fabricated MP-1 plates had a fuel breach in the cladding-cladding interface and trace amounts of fission products were released. The objective of this report is to characterize the cladding-cladding interface strengths in three plates fabricated using different fabrication processes. The goal is to assess the risk in irradiating future developmental and production fuel plates. Prior LS testing has shown weaker and more variability in bond strengths within INL MP-1 reference plates than in commercially produced vendor plates. Three fuel plates fabricated with different fabrication processes will be used to bound the bond strength threshold for plate irradiation insertion and assess the confidence of this threshold value.

• 대한소아치과학회지
• /
• 제29권4호
• /
• pp.632-640
• /
• 2002

초음파 진동을 치의학에 처음 이용한 것은 치석 제거기였으나, 최근에는 주조금속과 레진 인레이를 접착할 때, 인산아연시멘트나 레진시멘트의 점도를 낮추는데 이용되고 있다. 이러한 초음파 진동은 재료의 흐름성을 증가시킴으로써 피막도를 낮추고, 따라서 수복물 주위의 미제누출을 감소시킬 수 있는 장점이 있다. 그러나, 복합레진의 수복에 있어서 이러한 초음파 진동의 임상적 효과에 관한 연구가 아직까지 미흡한 실정이다. 이에 저자는 초음파 진동을 상아질 결합제에 적용하여 점도를 감소시킴으로써 상아세관으로의 레진 침투 정도의 변화와 결합력에 미치는 효과를 알아보고자 하였다. 발거 후 실온의 0.1% thymol 용액에 보관된 88개의 건전한 사람의 대구치를 치관부 법랑질을 제거하고 아크릴 레진을 이용하여 직경 1-inch의 PVC 관에 매몰하였다. 각 시편의 교합면이 아크릴봉과 동일한 높이가 되도록 220-, 500-grit의 연마지로 순차적으로 연마하였고, 무작위로 추출하여 각 군당 22개씩 네 군으로 분류하였다. 1군과 2군은 Single Bond(3M-ESPE, St. Paul, USA)를 3군과 4군은 One-Step(Bisco Inc., Schaumburg, USA)을 제조사의 지시에 따라 치면을 산부식, 수세, 건조한 후 연속하여 2번을 도포하였다. 2군과 4군은 초음파 치석제거기를 이용하여 치면에 대고 10 초간 진동을 가한 후 광중합하였다. 이후 직경 2.3mm, 높이 3.5mm의 Teflon mold(Ultradent Products Inc., South Jordan, USA)를 이용하여 복합레진을 충전한 후 40초씩 두 번에 나누어 광중합하였다. 모든 시편은 24시간 동안 실온의 수도물에 보관한 후 열순환을 시행하고, 만능측정기(Instron 4465, Canton, USA)로 전단결합강도를 측정하였으며 resin tag의 양상을 비교하기 위해 각 군의 시편의 치질을 탈회시킨 후에 표면을 주사전자 현미경으로 관찰하여 다음과 같은 결과를 얻었다. 1. 초음파 진동을 가하지 않은 1군, 3군에 비해 초음파 진동을 가한 2군과 4군에서 전단결합강도가 유의하게 높게 나타났다(p<0.05). 2. Single Bond와 One-Step의 전단결합강도는 유의한 차이를 보이지 않았다(p>0.05). 3. 전자현미경 관찰에서 초음파 진동을 가한 군에서 resin tag의 길이가 길었고, lateral branch의 수도 많이 관찰되었다.

• Journal of Korean Dental Science
• /
• 제2권2호
• /
• pp.5-11
• /
• 2009

Objectives : This study investigated the hypothesis that the dentin bond strength of self-etching adhesives (SEAs) may be improved by applying a coat of hydrophobic, neutral adhesive resin in addition to SEA. Method and Materials : The bond strengths of two SEAs - Experimental SEA (EX) and Adper Prompt (AP) - were measured with three bonding protocols. The D/E resin of All-Bond 2 was applied as the hydrophobic, neutral adhesive. Clearfil SE Bond (SE, self-etching primer system) and All-Bond 2 (AB, total etching system) were used as references. The following protocols were used: (1) EX1 (EX 1 coat); (2) EX2 (EX 2 coats); (3) EX+ (EX 1 coat + D/E resin); (4) AP1 (AP 1 coat); (5) AP2 (AP 2 coats); (6) AP+ (AP 1 coat + D/E resin); (7) SE (SE primer + SE bond); (8) SE+ (SE primer + D/E resin); (9) AB (etching + AB primer + D/E resin). Filtek Z250 composite resin was built up and the microtensile bond strength (MTBS) values of the specimens were compared. The fractured surfaces were observed using SEM. Results : When SEA was used as self-etching primer and hydrophobic, neutral adhesive was applied as well, MTBS was significantly higher than that when either one coat or two coats of SEA only were used (p < 0.05). Conclusion : The hydrophobic, neutral adhesive improved the integrity of the bonded interface obtained with SEA.

• Restorative Dentistry and Endodontics
• /
• 제20권1호
• /
• pp.351-361
• /
• 1995

The purpose of this study was to evaluate the shear bond strength of the composite resin bonded on the bleached enamel surface according to its surface treatment. 90 extracted human premolars were divided into six groups. : enamel unbleached (control group) and enamel bleached with 15% carbamide peroxide for 2 weeks (experimental groups: 1, 2, 3, 4 and 5). The surface of bleached enamel in all experimental groups was treated by following manners. Experimental group 1 : catalase immersion for 3 mimutes. Experimental group 2 : catalase immersion for 15 mimutes. Experimental group 3 : artificial saliva immersion for 1 hour. Experimental group 4 : artificial saliva immersion for 48 hours. Experimental group 5: surface reduction of the bleached enamel about 0.5mm-1mm with superfine diamond bur. Composite resin molds(3mm height, 3mm diameter) were bonded to the untreated enamel and treated. The shear bond strengths of composite resin bonded to enamel of each specimen were tested with universal testing machine at a crosshead speed of 5mm/min and 500Kg in full scale and analyzed statistically. The following results were obtained : 1. Control group had the highest shear bond strength with $19.92{\pm}5.14$ MPa and experimental group 5 had the lowest shear bond strength with $11.15{\pm}4.23$ MPa. 2. Control group showed significant differences in shear bond strength with experimental group 1(P<0.05). 3. Control group showed significant differences in shear bond strength with experimental group 5(P<0.05). 4. Experimental group 4 showed significant differences in shear bond strength with experimental group 5(P<0.05). 5. Experimental group 3 showed no significant differences in shear bond strength with experimental group 4(P<0.05).

• Restorative Dentistry and Endodontics
• /
• 제40권3호
• /
• pp.202-208
• /
• 2015

Objectives: This study determined the effect of the air-stream application time and the bonding technique on the dentin bond strength of adhesives with different solvents. Furthermore, the content and volatilization rate of the solvents contained in the adhesives were also evaluated. Materials and Methods:Three adhesive systems with different solvents (Stae, SDI, acetone; XP Bond, Dentsply De Trey, butanol; Ambar, FGM, ethanol) were evaluated. The concentrations and evaporation rates of each adhesive were measured using an analytical balance. After acid-etching and rinsing, medium occlusal dentin surfaces of human molars were kept moist (conventional) or were treated with 10% sodium hypochlorite for deproteinization. After applying adhesives over the dentin, slight air-stream was applied for 10, 30 or 60 sec. Composite cylinders were built up and submitted to shear testing. The data were submitted to ANOVA and Tukey's test (${\alpha}=0.05$). Results: Stae showed the highest solvent content and Ambar the lowest. Acetone presented the highest evaporation rate, followed by butanol. Shear bond strengths were significantly affected only by the factors of 'adhesive' and 'bonding technique' (p < 0.05), while the factor 'duration of air-stream' was not significant. Deproteinization of dentin increased the bond strength (p < 0.05). Stae showed the lowest bond strength values (p < 0.05), while no significant difference was observed between XP Bond and Ambar. Conclusions: Despite the differences in content and evaporation rate of the solvents, the duration of air-stream application did not affect the bond strength to dentin irrespective of the bonding technique.

• 대한치과보철학회지
• /
• 제47권2호
• /
• pp.174-181
• /
• 2009

연구목적: 본 연구에서는 35% 과산화수소를 사용하는 전문가 미백 술식에서 레진 접착제의 접착력 회복을 위한 유예 기간을 비교하고자 한다. 연구 재료 및 방법:3M사의 Single Bond와 Z350을 이용하여 미백 직 후, 1일후, 2일후, 일주일 후의 시간 차이를 두고 상아질에 접착된 복합 레진의 전단 결합 강도를 측정하여 다음과 같은 결과를 얻었다. 결과: 미백 처리 직 후의 상아질 전단 결합 강도는 다른 군에 비해 유의하게 낮았으며(P<.05), 미백 처리 전에 비해 약 78%의 결합력 감소를 보였다. 미백 처리 1일 후의 상아질 결합 강도는 미백 직 후 감소된 결합력의 51%에 이르는 회복을 보였으며, 2일 경과한 시편에서는 감소된 결합력의 63%가 회복되었다. 두 군은 미백 직 후에 비해 유의하게 큰 회복력을 보였으나, 두 군 간에는 유의한 차이가 없었다(P>.05). 미백 처리 후 결합력의 회복은 초기 24시간 이내에 급격히 일어나며 그 이후에는 서서히 일어나는 것으로 사료된다. 미백 일주일 후의 시편은 미백 처리 전에 비해97%에 이르는 결합력을 보이며 두 군 간에는 유의한 차이가 없었다(P>.05). 결론: 그러므로35% 과산화수소를 적용하는 전문가 미백 술식에서는 1주일간의 유예기간을 두고 복합 레진 접착술을 시행하는 것이 적절할 것으로 사료된다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
• /
• pp.945-948
• /
• 2008

본 연구는 초속경 아크릴 개질 폴리머 시멘트 콘크리트의 강도 특성에 미치는 폴리머-시멘트비의 영향을 검토한 것이다. 그 결과, 초속경 아크릴 개질 폴리머 시멘트 콘크리트의 윔 및 인장강도는 폴리머-시멘트비의 증가에 따라 증가하였다. 특히 폴리머-시멘트비 20%의 휨 및 인장강도는 폴리머를 혼입하지 않은 콘크리트보다 1.5배 이상의 강도발현을 나타냈다. 이와 같은 강도발현은 아크릴 에멀젼을 혼입함으로써 시멘트 수화물과 골재사이의 부착력이 증가되기 때문이라 판단된다.

• 대한치과기공학회지
• /
• 제35권1호
• /
• pp.19-27
• /
• 2013

Purpose: The aim of this research was to evaluate the shear bond strength of different zirconia veneering ceramics with and without liner glass materials to yttria partially-stabilized tetragonal zirconia polycrystalline(Y-TZP). Methods: Five co mmercial zirconia veneering ceramics were used in this study, E-Max(EM), Creation ZI(CR), Cercon ceram kiss(CE), Triceram(TR) and Zirkonzahn ICE(ZI). All samples were prepared according to manufacturer's instructions. Experimental industrially manufactured Y-TZP ceramic blocks(diameter: 2.7 mm; height: 13.5 mm) were used in this study. Shear bond strength between zirconia ceramic coping and zirconia veneering ceramics were evaluated by the push-shear bond test. The fracture load data were analyzed using ANOVA and Scheffe's test(${\alpha}$=0.05). The fractured surfaces of zirconia core ceraimc and zirconia veneering ceramics were observed using a scanning electron microscope(SEM). Results: The mean shear bond strengths ranged from 20 MPa ($20.12{\pm}6.34$ MPa) to 66.6 MPa ($66.62{\pm}10.01$ MPa). The Triceram(TRG) showed the highest value and Creation ZI(CR) showed the lowest value. In all groups, Zirconia liner and glass material groups was significantly higher shear bond strength than without liner(P<0.05), with the exception of Cercon ceram kiss(CE)groups. Conclusion: Zirconia bonding materials may have the advantage of improved bond strength between zirconia ceramic core and veneering ceramics.

• 대한토목학회논문집
• /
• 제34권1호
• /
• pp.87-94
• /
• 2014

이 연구에서는 형상기억합금과 강재로 구속된 콘크리트의 부착응력을 외부자켓의 구속비 및 강도비를 이용하여 분석하였다. 이를 위해서 직경 1.0 mm 형상기억합금 와이어와 두께 1.0 mm와 1.5 mm 강판을 사용하여, 구속비 및 강도비의 차이를 유발하여 각 변수의 차이에 따른 부착강도 및 부착거동을 분석하였다. 외부자켓 구속에 의해서 콘크리트의 부착강도는 증가하였으며, 파괴형태도 쪼갬파괴에서 뽑힘파괴로 전환되어 구속효과가 있음을 알 수 있었다. 콘크리트 부착강도는 구속비와 강도비가 증가함에 따라 증가하는 현상을 보이지만, 특정 시점부터는 부착강도가 거의 증가하지 않고 일정한 값을 나타내는 결과를 보였다. 그러나 강도비의 증가에 따라 발생하는 원주방향 최대 변형율은 거의 선형적으로 감소하는 결과를 보였다.