• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.406-413
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• 2001

Up to this day, reinforced spun concrete pipes have been widely used as drain pipes. However, many reinforced spun concrete pipes are exposed to the deteriorated environment such as freezing-thawing damage and chemical attack by the growth of a sulfur-oxidizing bacterium isolated from corroded concrete. The purpose of this study is to evaluate the effects of lining by polymer-modified mortar using polymer dispersions as cement modifier on the development in durability of reinforced spun concrete pipe. The polymer-modified mortars were prepared with various polymer types and polymer-cement ratios, and tested for compressive and flexural strengths, acid, freezing-thawing, and heat resistances. And then, the reinforced spun concrete pipe product lined by polymer-modified mortars was tested for adhesion in tension and surface conditions according to curing temperatures in the field. From the test results, it is apparent that the polymer-modified mortars have good mechanical properties and durability as a lining material. In practice, all polymers can be used as lining the materials for reinforced spun concrete pipe, and types of polymer, and polymer-cement ratio and curing conditions are controlled for a good lining product.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.341-349
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• 2017

Blood decontamination is an important factor in success of the orthodontic bracket. The purpose of this study is to evaluate the shear bond strength affected by blood decontamination. The shear bond strength was measured on blood decontamination before and after primer photopolymerization. And the adhesive remnants type and surface patterns was evaluated under scanning electron microscopy. A total of 50 human premolars were prepared. Group I was attached using conventional resin-acid etching method as control group. Group II and III were blood contaminated before curing primer and groups IV and V were blood contaminated after curing primer. Group II and IV were treated only with cotton pellet and Groups III and V were treated with cotton pellet after water washing. The mean shear bond strengths were in the order of groups I, V, III, II, and IV. In scanning electron micrographs group III and V showed more uniform surface than group II and IV. The ARI was significantly different between the control group and the experimental groups (p <0.05).

• Journal of Adhesion and Interface
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• v.10 no.3
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• pp.148-153
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• 2009

An atmospheric plasma pre-treatment method was applied to PU foam, Leather (Action), Rubber to improve its adhesion using solvent and water soluble type pressure sensitive adhesion in atmospheric plate type reactor. In order to investigate the optimum reaction condition of plasma treatment, type of reaction gas (nitrogen), rate of gas flow (30~100 mL/min), and reaction time (0~30 s) were examined in a plate plasma reactor. The result of the surface modification with respect to the treatment procedure was characterized by using SEM. Due to a de-crease of the contact angle of various materials, the greatest adhesion strength was achieved at optimum condition such as flow rate of 100 mL/min, reaction time of 10 second for an atmospheric plasma treatment of the PU foam, EVA foam, Leather (Action) and Rubber also resulted in the improvement of the adhesion.

• Journal of Adhesion and Interface
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• v.8 no.4
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• pp.23-31
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• 2007

An atmospheric plasma pre-treatment method was applied to EVA foam, Leather (Action), Rubber and Unwoven to improve its contact angle and adhesion using atmospheric plate type reactor. In order to investigate the optimum reaction condition of plasma treatment, type of reaction gas (nitrogen), rate of gas flow (30~100 mL/min), and reaction time (0~30 sec) were examined in a plate plasma reactor. The result of the surface modification with respect to the treatment procedure was characterized by using SEM. Due to a decrease of the contact angle of various materials, the greatest adhesion strength was achieved at optimum condition such as flow rate of 100 mL/min, reaction time of 10 second for an atmosphere nitrogen gas. Consequently, the atmospheric plasma treatment reduced the contact angle of the EVA foam, Leather (Action) and Rubber also resulted in the improvement of the adhesion.

• Journal of Adhesion and Interface
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• v.7 no.3
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• pp.1-9
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• 2006

To improve the poor mechanical and thermal properties of conventional PMMA bone cement, we impregnated three types of polyethylenes (PE) (200, 3,800, and 8,000 kg/mol). MMA/xylene solution was used to modify the surfaces of PEs and new composite PMMA bone cements were manufactured by impregnating 3 wt% of the surface-modified PEs into conventional PMMA bone cement. As molecuar weigth of PE increased, tensile strengths of the manufactured composite PMMA bone cements were improved. Also, we confirmed that the curing temperatures of the composite PMMA bone cements decreased from near $100^{\circ}C$ to $40^{\circ}C{\sim}80^{\circ}C$.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.1-8
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• 2007

This study compared the microshear bond strength (${\mu}SBS$) of light-cured and dual-cured composites to enamel bonded with three self-etching adhesives. Crown segments of extracted human molars were cut mesiodistally, and 1 mm thickness of specimen was made. They were assigned to three groups by used adhesives: Xeno group (Xeno III), Adper group (Adper Prompt L-Pop), and AQ group (AQ Bond). Each adhesive was applied to cut enamel surface as per manufacturer's instruction. Light-cured (Filtek Z 250) or dual-cured composite (Luxacore) was bonded to enamel of each specimen using Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to ${\mu}SBS$ testing with a crosshead speed of 1 mm/minute. The mean ${\mu}SBS$ (n = 20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at the 0.05 probability level, The results of this study were as follows ; 1. The ${\mu}SBS$ of light-cured composite was significantly higher than that of dual-cured composite when same adhesive was applied to enamel. 2. For Z 250, the ${\mu}SBS$ of AQ group ($9.95{\pm}2.51 MPa$) to enamel was significantly higher than that of Adper soup ($6.74{\pm}1.80 MPa$), but not significantly different with Xeno group ($7.73{\pm}2.01 MPa$). 3. For Luxacore, the ${\mu}SBS$ of Xeno group ($5.19{\pm}1.32\;MPa$) to enamel was significantly higher than that of Adper group ($3.41{\pm}1.19\;MPa$), but not significantly different with AQ group ($4.50{\pm}0.96\;MPa$).

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.685-698
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• 1995

This study was conducted to the effect of temporary cement on the adhesiveness of dentin bonding agent to dentin surface. One hundred freshly extracted bovine mandibular incisors were grinded to expose flat labial dentin surface. The dentin surfaces were temporarized with either eugenol-containing temporary cement(TemBond and Zinc Oxide Eugenol cement) or non-eugenol temporary cement(Nogenol and TempBond NE) for 7days, and then the temporarization was removed with surgical currette and the exposed dentin surfaces were water-rinsed. Bonding specimens were made by use of All-Bond 2 and Super-Bond C&B dentin bonding agent, and stored in $37^{\circ}C$ distilled water for 24hours. The tensile bond strenth and the cohesive failure rate were measured, and then the pretreated dentin surfaces which the temporary cement had been applied to and removed from and the fractured dentin surfaces after bonding test were examined under scanning electron microscope. The results were as follows : In case of bonding with All-Bond 2, tensile bond strength of each experimental group was lower than that of the control group(p<0.05), but there was no significant difference between the bond strengths of the control group and each experimental group in case of bonding with Super-Bond C&B(p>0.05). No significant difference between tensile bond strength of experimental group, whether temporary cement contains eugenol or not, was seen(p>0.05). In case of bonding with All-Bond 2, the control group showed cohesive-adhesive mixed failure mode and the experimental groups mainly showed adhesive failure mode, but in case of bonding with Super-Bond C&B, almost of the control and the experimental groups mainly showed cohesive failure mode. On SEM examination, all of the dentin specimens pretreated with either 10 % phosphoric acid or 10% citric acid after application of the temporary cements demonstrated remnants of temporary cement attached to dentin surface.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.420-429
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• 2007

The purpose of this study was to compare the micro ensile bond strength to bovine dentin of several adhesives (SM, Scotch $Bond^{TM}$ Multipurpose; SB, $Adper^{TM}$ Single Bond 2; SE, $Clearfil^{(R)}$ SE Bond; AQ, AQ $Bond^{TM}$; TS, $Clearfil^{(R)}$ tri-S Bond). Except SM and SB, they have a simplified one- or two-step application protocols in compare with the dentin adhesives conventional three-step protocols. For the microtensile bond strength test, the labial surfaces of bovine incisors were used. Following exposure of dentin layer, according to their manufacturer's directions, each dentin adhesives were applied and composite resin blocks were constructed. The teeth were sectioned for specimen and tested microtensile bond strength. Also observed the fracture mode of interface. The obtained results were as follows : 1. The microtensile bond strength values ranged from 51.34 to 24.04 MPa on dentin(in decreasing order, SE, SM, SB, AQ and TS). 2. The highest microtensile bond strength was by SE and SM on bovine dentin, and the lowest by AQ and TS. 3. SM, SB and SE showed cohesive failures and adhesive failure but AQ, TS presented almost adhesive failures. In summary, microtensile bond strengths of single-step adhesives (AQ and TS) on bovine dentin were significantly lower than those of multi-step adhesives (SM, SB and SE) (p<0.05).

• Polymer(Korea)
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• v.32 no.3
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• pp.276-283
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• 2008

Kind of monomer(MMA, EA, BA, St)and the monomer ratio(80/20 to 20/80) where changed in the preparation of the core shell binder, and property was improved the plasma processing. Each material changed by plasma treatment time($1{\sim}10\;s$) to change to measure the tensile strength, contact angle and adhesion peel strength for the core shell binder optimal conditions for handling the output of the surface treatment. The type of polymerization and composition of the binder is a regardless initiator of APS, the reaction temperature of $85^{\circ}C$ to 0.3 wt% of the surfactant used to indicate when the conversion rate was the highest, core shell composite particle binder got two glass temperature curves. Core shell binder after the plasma processing contact angle change is the PEA/PSt 38 percent of cases within five seconds to indicate slight decrease was a decline rapidly if not handled $0^{\circ}$ to reach. Tensile strength PSt/PMMA varies $46.71{\sim}46.27\;kg_f$/2.5 cm and adhesion strength PEA/PMMA varies $7.89{\sim}14.44\;kg_f$/2.5 cm increases. Overall, adhesion strength of core shell composite particle is in the order of order PEA>PBA>PSt for shell monomer MMA.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.17-17
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• 2000

탄소섬유/에폭시 적충복합재는 경량성 및 비강도, 비강성이 우수해 최근 들어 항공기, 자동차, 우주선 등에 대한 적용이 급속도로 증가하고 있다. 그러나 적충복합재 구조물에 있어 최대 약점 중 하나는 적충된 면이 서로 떨어지는 충간분리가 발생 할 수 있다는 것이다. 본 논문에서는 탄소섬유/에폭시 적충복합재의 파괴특성을 향상시키기 위해 프리프레그 (prepreg)를 이온빔으로 표면처리하는 방법에 대해 연구하였다. 즉 프리프레그를 $Ar^+$ 이온도 움반응법에 의해 표면처리 하였으며 이를 적용, 열림모드 파괴특성을 검토하였다. 즉 표준 프리프레그와 표면처리 된 프리프레그를 이용 $0^{\circ}$ 단일방향 DCB(Double Cantilever Beam) 시편을 제작하였으며, 각각의 경우에 대하여 파괴시험을 수행하였다. 파괴시험으로부터 파괴 저항곡선(R-곡선)을 결정하여 이를 비교 검토함으로서 프리프레그의 표면처리가 파괴특성에 미치는 영향을 해석하였다. 본 연구를 통해 얻어진 결과를 요약하면 다음과 같다. 첫째, 층간분리 길이가 동일한 경우 표면처리한 경우의 컴플라이언스가 표면처리 하지 않은 경우에 비해 작게 나타남을 알 수 있었다. 둘째, 파괴하중 값은 컴플라이언스와 반대현상을 나타낸다. 즉 표면처리한 경우의 파괴하중 이 표면처리 하지 않은 경우에 비해 크게 나타남을 알 수 있었다. 셋째, 표면처리 한 시편의 경우 R-곡선이 향상됨을 알 수 있었다. 즉 표면처리 한 경우의 열림모드 파괴이성, $G_{Ic}$ 값은 표준 시편의 값보다 24% 높았다. 이는 프리프레그의 표면처리 가 충과 충간의 접착강도를 증가시키고 또한 탄소섬유와 에폭시 간의 계면력을 증가시킨데 기인하는 것으로 사려된다.되었으며, duty-on 시간의 증가에 따라 $Cr_2N$ 상의 형성이 점점 많아져 80% duty-on 시간 경우에는 거의 CrN과 $Cr_2N$ 상이 공존하는 것으로 나타났다. 또한 duty-on 시간이 증가할수록 회절피크의 세기가 증가하여 결정화가 더 많이 진행되어짐을 알 수 있었다. 마찬가지로 바이어스 펄스이 주파수에 다른 결정성의 변화도 펄스의 주파수가 증가할수록 박막이 결정성이 좋아지고 $Cr_2N$ 상이 쉽게 형성되었다. 증착 진공도에 따른 결정성은 상대적으로 질소의 농도가 높은 낮은 진공도에서는 CrN 상이 주로 형성되었으며, 반대로 높은 진공도에서는 $Cr_2N$ 상이 많이 만들어졌다. 즉 $1.3{\times}10^{-2}Torr$의 증착 진공도에서는 CrN 상만이 보이는 반면 $9.0{\tiems}1-^{-2}Torr$ 진공도에서부터 $Cr_2N$ 상이 형성되기 시작하여 $5.0{\tiems}10^{-2}Torr$ 진공도에서는 두개의 상이 혼재되어 있음을 알 수 있었다. 박막의 내마모성을 조사한 결과 CrN 박막의 마찰 계수는 초기에 급격하게 증가한 후 0.5에서 0.6 사이의 값으로 큰 변화를 보이지 않았으며, $Cr_2N$ 박막도 비슷한 거동을 보였다.차 이, 목적의 차이, 그리고 환경의 의미의 차이에 따라 경관의 미학적 평가가 달라진 것으로 나타났다.corner$적 의도에 의한 경관구성의 일면을 확인할수 있지만 엄밀히 생각하여 보면 이러한 예의 경우도 최락의 총체적인 외형은 마찬가지로 $\ulcorner$순응$\lr