• Restorative Dentistry and Endodontics
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• 제17권2호
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• pp.331-341
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• 1992

The purpose of this study was to measure the polymerization contraction stress of two types of composite resins; chemical cured type(Cliarfil F II, Kuraray, Japan) and photo-cured type(Photo-Clearfil Bright, Kuraray, Japan). The stresses of composite resin by contraction measured with specially designed measuring device(Fig. 1). The stresses caused by shrinkage during hardening of specimens were measured according to the type of composite resins, thickness of specimen(0.65, 1.30 and 1.95mm), and ratio of catalyst to base in case of only chemical cured composite resin(0.5, 1.0 and 1.5). As the composite resin specimen shrank on hardening, the load cell recorded force vs time automatically on pen-recorder(Toa, Japan) with a cross-head speed 60mm/hr at 0~10 voltages up to 2 hours. The experiments were conducted in a room maintained at $23{\pm}2^{\circ}C$ and relative humidity $50{\pm}10%$. The results were as follows. 1. The contraction stress during hardening was higher in photo cured composite resin than in chemical cured composite resin. 2. The contraction stress during hardening was increased with thickness of composite resin specimen. 3. In chemical cured composite resin, the polymerization contraction stress was decreased with ratio of catalyst and base. 4. The contraction stress during polymerization was higher in early time after insertion of photo cured composite resin and chemical cured composite resin.

• Restorative Dentistry and Endodontics
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• 제17권1호
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• pp.36-54
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• 1992

The purpose of this study was to compare the shear bond strengths to ground dentin surfaces of four dentinal bonding agents in 193 teeth. Various dentin surfaces treated with four dentin bonding agents were attached with two restorative composite resins. The effectiveness of the bonding were tested by the monitoring the shear bond strength. The shear bond strengths were measured after 2 hours and 24 hours after surface conditioning with four dentin bonding agents. Effects of EDTA, the additive illumination, and sealer treatments without primer on bond strength to dentin surfaces were assessed. In addition the effects of the thickness of specimens ranging from 0.65 mm to 1.95 mm and the ratio of catalyst and base paste on the bond strength of chemical cure composite resin were estimated. The shear bond strength was determined by testing specimens in the Instron universal testing machine (Model No. 1122) at a crosshead speed of 1.0 mm/min. Following condusions were drawn: 1. The highest mean shear bond strengths of chemical cure composite resin to dentin conditioning with dentin bonding agents aged 2 hours were obtained, and then that was decreased with time followed by EDTA treatment. 2. In light cure composite resin, the shear bond strength was increased following dentin conditioning with bonding agents with time, irradiation time and EDTA treatment except in SB group. 3. The thicker the composite resin specimen was, the less the shear bond strength in chemical cure composite resin was. 4. In light cure composite resin, there was a little change in shear bond strength following dentin conditioning with bonding agents. 5. In chemical cure composite resin, the shear bond strength was the highest in the ratio of 1/1 of catalyst and base part. 6. Without a dentin primer, shear bond strength to dentin conditioned only with UB sealer was the highest among four sealers in light cure composite resin.

• Journal of the Korean Wood Science and Technology
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• 제45권1호
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• pp.62-71
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• 2017

본 연구는 쌀의 도정과정에서 발생되는 농업부산물인 왕겨를 탄화시켜 만든 왕겨숯을 톱밥과 혼합하여 밀도별, 수지첨가율별 및 톱밥첨가율별로 보드를 제조하고 기초물성을 측정하여 보드 재료로서의 이용가능성을 검토하였다. 수분흡수율은 수지첨가량 25%일 때 80.09%로 가장 낮은 값을 나타냈고, 밀도가 증가하고 톱밥첨가량이 감소할 때 수분흡수율이 감소하는 경향을 나타냈다. 또한 측정된 두께팽윤율은 KSF 3104 파티클보드의 품질규정에 만족시키고 있어 치수안정성 부분에서 건축내장재로 활용가능성이 확인되었다. 박리강도는 수지첨가량 25%일 때 $0.244N/mm^2$으로 KSF 3104 파티클보드의 품질기준을 만족시켰지만, 나머지 조건에서는 현저하게 낮은 값을 나타내 조건을 충족시키지 못하였다. 밀도, 수지첨가율, 톱밥첨가율이 증가할수록 경도도 증가하는 경향을 나타냈다.

• 반도체디스플레이기술학회지
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• 제12권1호
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• pp.23-28
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• 2013

Epoxy resins are widely used in microelectronics packaging such as printed circuit board and encapsulating for semiconductor manufacturing. Water can diffuse into and through the epoxy matrix systems and moisture absorption at boarding interfaces of matrix resin systems can lead to a hydrolysis at the interfaces resulting in delamination of encapsulating materials. In the study, the changes of diffusion coefficient and moisture content ratio of epoxy resin systems with nano-sized fillers according to the change of liquid type epoxy resins were investigated. RE-304S, RE-310S, RE-810NM and HP-4032D as a epoxy resin, Kayahard AA as a hardener, and 1B2MI as a catalyst were used in these epoxy resin systems. After curing, moisture content ratios were measured with time under the 85 and 85% relative humidity condition using a thermo-hydrostat. The maximum moisture absorption ratio and diffusion coefficient of EMC decrease with the filler content. It can be seen that these decreases are due to the increase of filler surface area and the decrease of moisture through channel with the content of nano-sized filler.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.85-96
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• 1994

In this study, 24 curved resin blocks were prepared by one of the following four methods: 1) Conventional technique using K-flexo files 2) Step-back technique using K-flexo files 3) Crown-down technique using K-flexo files 4) Canal Master instrumentation using Canal Master Resin blocks were sectioned, photographed, and evaluated the mean centering ratio and the mean area of dentin removed before and after the instrumentation. The results were as follows : I. the mean centering ratio 1. In the level 1 and level 3, there was no significant difference in the mean centering ratio. 2. In the level 2, Step-back technique showed the worst mean centering ratio among the tested groups(p<0.001) and there was no significant difference between the other three groups. 3. In the level 4, Canal Master instrumentation and Step-back technique showed better mean centering ratio than the other two techniques(p<0.001) and there was no significant difference between the two techniques. II. the mean area of dentin removed 1. In the level l and level 3, there was no significant difference in the mean area of dentin removed. 2. In the level 2, Canal Master instrumentation removed less dentin than the other three techniques(P<0.01). 3. In the level 4, Crown-down technique removed less dentin than the other three techniques(P<0.05).

• 콘크리트학회지
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• 제5권4호
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• pp.156-166
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• 1993

본 연구는 산업폐기물인 플라이애쉬를 충전재로 사용한 강섬유보강 폴리에스터 수지 복합체의 워커빌리티 및 그 역학적 특성을 구명하고, 그 제조방법을 실험적으로 검토한 것이다. 동복합체는 강섬유, 충전재(플라이애쉬, 중질탄산칼슘), 불포화 폴리에스터수지(스티타이렌 모노머), 경화촉진제(코발트옥테이트), 촉매(MEKPO) 및 굵은 골재와 잔골재를 사용하여 제조하였고, 배합조건별로 그 특성을 검토하였다. 연구결과, 플라이애쉬$\cdot$폴리에스터 수지복합체의 경우, 플라이애쉬-결합재비의 증가에 따라 압축, 인장, 휨강도 및 경화수축은 현저히 개선되었고 강섬유 보강 플라이애쉬$\cdot$폴리에스터 수지복합체의 경우 워커빌리티는 플라이해쉬-결합재비 및 강섬유혼입율 증가에 따라 저하하였으나, 압축, 휨강도 및 휨인성은 섬유혼입율 증가에 따라 현저히 증가되었다.

• 반도체디스플레이기술학회지
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• 제9권2호
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• pp.33-39
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• 2010

The moisture absorption properties such as diffusion coefficient and moisture content ratio of liquid type epoxy resin systems with the filler were investigated. Bisphenol A type and Bisphenol F type epoxy resin, Kayahard MCD as hardener and 2-methylimidazole as catalyst were used in these epoxy resin systems. The nano-sized spherical type fused silica as filler were used in order to study the moisture absorption properties of these liquid type epoxy encapsulant according to the change of filler size. The temperature of glass transition (Tg) of these epoxy resin systems was measured using Dynamic Scanning Calorimeter (DSC), and the moisture absorption properties of these epoxy resin systems according to the change of time were observed at $85^{\circ}C$ and 85% relative humidity condition using a thermo-hygrostat. The diffusion coefficients in these systems were calculated in terms of modified Crank equation based on Ficks' law. An increase of Tg and diffusion coefficient with filler size in these systems can be observed, which are attributed to the increase of free volume with Tg. The change of maximum moisture absorption ratio according to the filler size and filler content cannot be observed; however, the diffusion coefficients of these systems decreased with filler content. The diffusion via free volume is dominant in the epoxy resin systems with low nano-sized filler content; however, the diffusion with the interaction of absorption according the increase of the filler surface area is dominant in the liquid type epoxy encapsulant with high nano-sized filler content.

• Journal of the Korean Wood Science and Technology
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• 제47권4호
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• pp.519-532
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• 2019

The objectives of this study were to evaluate the effects of shelling ratio and resin content on the properties of bamboo oriented strand board (BOSB) from betung (Dendrocalamus asper) and to determine the correlation between the results of dynamic and static bending tests. Strands were steam-treated at $126^{\circ}C$ for 1 h under 0.14 MPa pressure and followed by washing with 1% NaOH solution. Three-layer BOSB with the core layer perpendicular to the surface was formed with shelling ratios (face:core ratio) of 30:70; 40:60; 50:50; 60:40 and binded with 7% and 8% of phenol formaldehyde (PF) resin with the addition of 1% of wax. The evaluation of physical and mechanical properties of BOSB was conducted in accordance with the JIS A 5908:2003 standard and the results were compared with CSA 0437.0 standard for commercial OSB (Grade O-1). Non-destructive testing was conducted using Metriguard Model 239A Stress Wave Timer which has a wave propagation time from 1 to $9,999{\mu}s$ and a resolution of $1{\mu}s$. BOSB with 8% resin content showed better physical and mechanical properties than those with 7% resin content. The increase of the face layer ratio improved the strength of BOSB in parallel direction to the grain. The results suggested that shelling ratio of 50:50 could be used as a simple way to reduce PF resin requirements from 8% to 7% and to meet the requirements of CSA 0437.0 standard. The results of non-destructive and destructive tests showed a strong correlation, suggesting that non-destructive test can be used to estimate the bending properties of BOSB.

• 한국응용과학기술학회지
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• 제26권1호
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• pp.93-101
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• 2009

Antistatic acrylic resin is made from n-butyl methacrylate, methyl methacrylate, dimethyl amino ethyl methacrylate(DMAEMA), 2-ethyl hexyl methacrylate, hydroxy ethyl methacrylate, 2,2'-azobis iso-butyronitrile by synthesis. To achieve a lowest surface resistance of antistatic acrylic resin was applied to a variety of synthesis processes. The acrylic resin has been determined from the value of surface resistance and -then the antistatic acrylic resin including dimethyl amino ethyl methacrylate of the 10%, 20% and 30% is synthesized. Finally, dimethyl sulfate(DMS) on a variety of weight ratios is added to antistatic acrylic resin. When DMAEMA / DMS weight ratio is 1/1, antistatic acrylic resin isn't haze the lower the surface resistance. Compared to the traditional antistatic agent, all aspects of the physical properties is outstanding.

• 한국의류학회지
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• 제32권7호
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• pp.1095-1103
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• 2008

The effects of resin finish and dyeabilities of four kinds of Iyocell fabrics that were manufactured by four kinds of pulps were investigated. The dyeabilities of Iyocell fabrics were similar, but differed from cotton fabric. In early stage of 30 minutes, cotton fabric was shown higher dye exhaustion ratio than Iyocell fabrics, however after then cotton fabric did not increase dye exhaustion, Iyocell fabrics increased continuously. At last, the dye exhaustion ratio of Iyocell fabrics were about 75% and that of cotton fabric was 65%. Two kinds of experimental procedures were applied for Iyocell fabrics. One was what the fabrics were treated with resins and washed with cellulase, and then dyed with reactive dyes. The other procedure was the fabrics were dyed with reactive dyes, and then applied the resin treatments and cellulase washing. After fibrillation and washing the undyed Iyocell fabric and the Iyocell fabric that was dyed with C.I.Reactive Red 120, their weight loss ratios were 3.5% and 2.8%, respectively. Dyeing with reactive dyes caused the crosslinking between cellulose and dyes and the crosslinking decreased fibrillation. The weight loss by enzyme washing of Iyocell fabrics decreased by the glyoxal and melamine resin treatments. The reduction of weight loss can be caused by fibrillation decrease. Dyeing and resin treating can be showed the synergic effect on the reduction of fibrillation. The effect of glyoxal resin on the reduction of fibrillation was a little better than that of melamine resin.