• 대한치과보철학회지
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• 제25권1호
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• pp.137-154
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• 1987

The purpose of this investigation was to determine the surface characteristics and the fittness of the resilienct denture lines. Firstly, 50 samples ($2.0{\times}4.0{\times}0.3cm$) of 4 resilient lining materials (Molloplast B, Coe Super Soft, Mollosil, Coe Soft) and one conventional acrylic resin (K-33) were processed according to manufacture's direction and examined the surface characteristics by use of surface profilometer and scanning electron microscopy. Secondly, 50 identical maxillary casts were made and 50 denture bases were pro cessed of 4 resilient liners and one conventional acrylic resin and they were stored in the room temperature water bath of 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks and 6 weeks after processing. The original casts were cut away 1 cm from the posterior border, the dentures were seated, and the existing space was measured at seven regions according to the storage time by use of the modified thickness guage. The results were as follows. 1. Surface roughness (Rz) were $4.00{\pm}1.60{\mu}m$ in Mollosil, $4.47{\pm}2.21{\mu}m$ in Molloplast B, $7.46{\pm}1.70{\mu}m$ in Coe Super Soft, $12.70{\pm}2.39{\mu}m$ in Coe Soft and $13.03{\pm}2.74{\mu}m$ in K-33. 2. The generation of porosity was far more active in cold-cured resilient liners (Coe Soft and Mollosil) than in heat cured resilient liners (Molloplast B, and Coe Super Soft) and conventional heat cured resin (K-33). 3. Denture bases showed the greatest discrepancy at the central portion of the posterior palatal border and the intimate contact in the buccal flange regardless of denture base materials. 4. When the denture bases were stored in the water for 1 day and 6 weeks after processing, the sum of average discrepancies in the seven regions of the denture base was the greatest in K-33 followed by Molloplast B, Mollosil, Coe Soft and Coe Super Soft but followed by Coe Soft, Molloplast B, Mollosil, Coe Super Soft in that order respectively. 5. There was not a significant difference (p>0.05) in Coe Super Soft, K-33 but there was a significant difference (P<0.01) in Molloplast B, Mollosil, Coe Soft at the amount of dimensional changes according to the storage time.

• Journal of the Korean Wood Science and Technology
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• 제42권3호
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• pp.339-345
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• 2014

집성재의 생산성 향상을 위한 고주파 가열 경화기술에 대해 연구하였다. 고주파가 유전체에 가해지면 내부에서 에너지 손실에 의한 발열이 발생한다. 집성재를 구성하는 라미나와 접착제는 유전체이므로 집성재에 고주파를 주사하면 내부에서 발열이 발생한다. 집성재 제조에 이용되는 대부분의 상온 경화형 접착제는 고온에서 빠른 경화가 이루어지므로 고주파 가열 기술을 이용하면 집성재 내부 접착층의 온도를 상승시킴으로써 빠른 경화를 유도할 수 있다. 본 연구에서는 낙엽송재와 phenol-resorcinol-formaldehyde (PRF) 접착제의 유전 특성을 평가하고, 집성재 내부의 접착층의 빠른 경화를 유도하는 고주파 가열 경화 기작을 이론적으로 분석하였다. 연구 결과, 온도상승인자인 PRF 접착제의 상대손실계수가 낙엽송재의 상대손실계수에 비해 높았으나, 온도상승저해인자인 밀도와 비열도 높았다. 그러나 상대손실계수의 비율이 온도상승저해인자의 비율보다 높기 때문에 고주파 가열에 의한 발열량은 접착제에서 더 높을 것으로 예상된다. 이러한 실험 결과를 이용한 이론적 접근을 바탕으로, 접착층이 목표온도까지 상승하기 위한 ISM 영역의 고주파 주파수 별 전기장의 상대 세기를 추정하였다.

• 접착 및 계면
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• 제7권1호
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• pp.16-22
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• 2006

본 연구에서는 페놀수지 SMC 제조에 사용되는 수용성 레졸형 페놀-포름알데히드 수지의 열안정성과 경화 발열반응 피크의 변화에 미치는 경화온도 및 경화시간의 영향을 열중량분석기와 시차주사열량계를 사용하여 조사하였다. 수용성 페놀-포름알데히드 수지의 중량감소는 주로 $200^{\circ}C,\;400^{\circ}C$ 그리고 $500^{\circ}C$ 부근에서 세 단계로 발생하였다. 경화된 수지의 $750^{\circ}C$에서 탄화수율은 약 62%~65%이었다. 수용성 페놀수지의 열안정성은 경화온도와 경화시간이 증가할수록 증가하였다. 경화시 발열반응은 약 $120^{\circ}C{\sim}190^{\circ}C$ 사이에서 진행되며, 발열피크의 최대점은 약 $165^{\circ}C{\sim}170^{\circ}C$ 사이에서 관찰되었다. 발열반응 곡선의 형태와 발열피크의 최대점은 주어진 경화온도와 경화시간에 의존하였다. 경화되지 않은 수지에 포함되어 있는 $H_2O$ 및 휘발성분을 제거하기 위하여 경화 또는 성형 전에 적어도 $100^{\circ}C$ 이상에서 약 60분 이상의 열처리가 요구되었다. $130^{\circ}C$에서 120분 동안의 경화는 수용성 페놀-포름알데히드 수지의 발열피크를 사라지게 하며, $180^{\circ}C$에서 60분 동안이 후경화는 수지의 열안정성을 더욱 향상시켜 주었다.

• 한국응용과학기술학회지
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• 제21권4호
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• pp.300-305
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• 2004

High-solid coatings were prepared by blending of previosly synthesized acrylic resins and hexamethylene diisocyanate-trimer and curing it at room temperature. The characterization of the films of the prepared coatings was performed. The impact resistance, cross-hatch adhesion, $60^{\circ}$specular gloss, and heat resistance of the films proved to be good, and the pencil hardness and drying time proved to be slightly poor. Especially, there was a remarkable improvement in the heat resistance. This improvement may stem from the regular arrangement of ethyl groups introduced into the acrylic resin. As a result of Rigid-body pendulum visco-elasticity measurement, dynamic $T_g$ values of cured films increased with dynamic $T_g$ values.

• Composites Research
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• 제14권2호
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• pp.33-42
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• 2001

DSC(differential scanning calorimetry)를 이용하여 S2-유리섬유/폴리에스터 프리프레그 복합재료의 경화반응식을 구성하였다. 구성된 경화식과 블리더의 수지 함침에 의한 열전달 조건의 변화를 고려하여, 두꺼운 복합재료의 두께 방향 위치에 따른 온도분포를 계산하였다. 유래섬유 복합재료의 경화중 온도과승을 줄이기 위한 방법으로 냉각 및 재가열 구간을 도입하여 경화 사이클을 개선하였다. 냉각-재가열 구간이 없는 기존의 경화 사이클과 개선된 경화 사이클로 두꺼운 복합재료를 각각 제조하여 short beam shear 시험 및 Barcol 경도시험을 실시하고, 그 결과를 비교하였다.

• 대한치과보철학회지
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• 제39권1호
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• pp.58-70
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• 2001

For the successful treatment of complete denture, obtaining a good retention is essential. There are lots of factors affecting denture retention. Denture material, one of those factors affecting denture retention, was the subject of this study, and internal surface treatment also considered for the method of enhancing denture retention. Two resin(Lucitone $199^{(R)}$(heat cured resin) Vertex $CP^{(R)}$(self cured resin)) and two metal($Biosil^{(R)}$(Co-Cr alloy), $Vitallium^{(R)}$(Co-Cr alloy)) denture base materials were used for making test denture base. Newly developed device was used for measuring denture retention. After the retention was measured. We treated internal surface of test denture base with $50{\mu}m\;Al_2O_3$ powder, under 90psi, for 1 minute. Then the retention was measured again. The result was analyzed with K-S test, one-way ANOVA test and independent t-test to deter mine the significant differences as the 95% level of confidence. The results are as follows : In cases of without internal surface treatment, the retention was increased in order of $Vitallium^{(R)},\;Biosil^{(R)},\;Vertex CP^{(R)}$ and Lucitone $199^{(R)}$. Except between Vertex $CP^{(R)}$ and $Biosil^{(R)}$, retention of the other materials was significantly different (p<0.05). After the treatment of internal surface, the retention was increased in order of $Vitallium^{(R)},\;Biosil^{(R)},\;Lucno\;199^{(R)},\;Vertex\;CP^{(R)}$. Except between Lucitone $199^{(R)}$ and Vertex $CP^{(R)}$, $Vitallium^{(R)}$ and $Biosil^{(R)}$ the retention of remaining groups was significantly different each other (p<0.05). In the matter of each material, after the internal surface treatment the retention was increased with Vertex $CP^{(R)},\;Biosil^{(R)}\;and\;Vitallium^{(R)}$ and the value of differences were statistically significant. When we compare the retention of resin and metal denture base, the retention of both denture bases increased significantly with internal surface treatment, and resin denture base showed better retention. As the results show, selecting denture base material could be an important choice of complete denture treatment. To increase denture retention, internal surface treatment can be considered as a possible method.

• 치과방사선
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• 제26권2호
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• pp.133-145
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• 1996

Aspirating or swallowing foreign bodies is a common occurrence. If they are wholly or partly radiopaque, their localization in and progress through the gastrointestinal tract can be more effective. Of the dental origin foreign materials swallowed, the most common things are fragments of anterior maxillary partial denture. But the radiopacity of denture base resins is not sufficient to determine the location of the objects. The purpose of this study was to develop a radiopaque dental acrylic resin, which has clinically detectible radiopacity with minimal change of mechanical properties and color. The radiopacity, color change(CIE 6..E) and microhardness of acrylic resins were determined after mixing barium sulfate or iodide compound. Thermocycling course was conducted to determine the change of characteristic of resins after using for a long time in the mouth. Five or ten percent of barium sulfate to total weight of cured material was mixed with heat curing dental acrylic resin or chemically curing orthodontic resin. In the case of iodide compound, the mixing ratio was two or three percent. After mixing the high radiopaque materials, resin was cured to 20×20×2 mm plate, polished with #600 sand paper and finally polished with Microcloth(Buehler). The specimens were thermocycled in 5 and 55 t distilled water for 2,000 times, and the measurement of radiopacity, color and Vickers hardness was repeated every 500 times thcrmocycling. The radiopacity of specimens on the X -ray films was measured with densitometer(X-rite). The color change was detennined with differential colorimeter(Model TC-6FX, Tokyo Denshoku), and the Vickers hardness number was measured with microhardness tester(Mitsuzawa). The following results were obtained : 1. All the three variables, the kinds of acrylic resins, the mixing or the kinds of high radiopaque materials and thermocycling, had combined effect on the radiopacity of the dental acrylic resins(p<0.0l). 2. The two variables, the mixing or the kinds of high radiopaque materials and thermocycling, influenced on the radiopacity of the dental acrylic resins(p<0.01). But the kinds of acrylic resins did not influence on the color change of mixed dental acrylic resins(p>0.05). 3. Each of the three variables, the kinds of acrylic resins, the mixing or the kinds of high radiopaque materials and thermocycling, influenced on the radiopacity of dental acrylic resins(p<0.0l). 4. The high radiopaque materials used in this study did not yield clinically usable radiopacity, and the color change was great after mixing those materials.

• 대한소아치과학회지
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• 제26권2호
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• pp.296-309
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• 1999

가철성 상교정 장치에 많이 사용되는 자가중합형 상교정용 레진의 미반응 단량체는 레진의 물성과 생물학적인 면에 많은 영향을 끼친다. 따라서 미반응 단량체를 최소화하고 중합률을 최대로 하는 중합방법에 대한 연구는 중요한 의의를 갖는다. 저자는 자가중합형 상교정용 레진의 중합시간과 중합방법에 따른 중합률을 비교해보기 위해 시편을 다음과 같이 5군으로 나누어 연구를 진행하였다. 상교정용 레진의 분말과 용액을 혼합하여 제 1군은 $28^{\circ}C$의 공기중에 보관하였고, 제 2군은 $28^{\circ}C$의 물에, 제 3군은 $28^{\circ}C$의 물과 30psi의 압력에, 제 4군은 $43^{\circ}C$의 물에, 제 5군은 $43^{\circ}C$의 물과 30psi의 압력하에 각각 보관하였고, 10분, 1시간, 12시간, 1일, 3일 경과 후에 각 시편을 Fourier 변환적외선분광법을 이용하여 중합률을 측정하여 다음과 같은 결론을 얻었다. 1. 모든 군에서 중합시간이 경과함에 따라 중합률도 지속적으로 증가하는 양상을 보였다. 10분 경과 후의 결과와 비교하여 볼 때, 제 1군은 12시간 경과 후부터 중합률의 증가가 유의성이 있었고, 제 2군과 3군, 4군, 5군은 1시간 경과 후부터 유의성이 있었다(p<0.05). 2. 10분과 1일, 3일 경과 후에 제 5군, 제 4군, 제 3군, 제 2군, 제 1군의 순서대로 중합률이 높았다. 3. 중합시 온도에 따른 비교에서, 1일 경과 후를 제외하고는 모든 시간에서 $43^{\circ}C$에서 중합시킨 군의 중합률이 $28^{\circ}C$에서 중합시킨 군의 중합률 보다 유의성 있게 높았다(p<0.05). 4. 압력은 12시간 경과 후를(p<0.05) 제외하고는 중합률에 영향을 주지 못했다. 5. 보관방법은 1시간 경과 후를(p<0.05) 제외하고는 중합률에 영향을 주지 못했다.

• 대한치과보철학회지
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• 제45권4호
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• pp.457-468
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• 2007

Statements of problem: The fracture of acrylic resin dentures remains an unsolved problem. Therefore, many investigations have been performed and various approaches to strengthening acrylic resin, for example, the reinforcement of heat-cured acrylic resin using glass fibers, have been suggested over the years. Silane is important for bonding between glass fiber and resin. Purpose: The aim of the present study was to investigate the effect of various silane on the strength of PMMA resin and roughness of resin-glass fiber complex after abrasion test. Material and methods: 3mm glass fiber (Chopped strand, Hankuk fiber Co., Milyang, Korea) was treated with 3 kinds of silane (MPS, EPS, APS) (Sila-ace, Chisso chemical, Tokyo, Japan) and mixed with PMMA resin(Vertex RS, Vertex Dental B.V., Zeist, Netherlands). Transverse strength and Young's modulus was measured using Instron (Instron model 4466, Instron, Massachusetts, USA). After abrasion test (The 858 Mini Bionix II Test System, MTS System Co., Minnesota, USA) surface roughness was evaluated using tester (Form Talysurf plus, Taylor Hopson Ltd., Leicester England). Examination of scanning electron microscope was also performed. Results: Within this study, the following conclusions were drawn. 1. Surface treatment of glass fiber with MPS and APS increased transverse strength of PMMA resin complex, but surface treatment with EPS decreased transverse strength of PMMA resin complex (p<0.05). 2. Silane treated glass fiber increased Young's modulus of PMMA resin complex compared to desized glass fiber (p<0.05). 3. Roughness increased after abrasion test in case of PMMA resin reinforced with desized glass fiber (p<0.05). 4. Roughness change was not observed after abrasion test in case of PMMA resin reinforced with silane treated glass fiber (p>0.05).

• The Journal of Advanced Prosthodontics
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• 제7권1호
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• pp.47-50
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• 2015

PURPOSE. This study aimed to discover a way to increase the bond strength between bis-acryl resins, using a comparison of the shear bond strengths attained from bis-acryl resins treated with light curing, pressure, oxygen inhibition, and heat. MATERIALS AND METHODS. Self-cured bis-acryl resin was used as both a base material and as a repair material. Seventy specimens were distributed into seven groups according to treatment methods: pressure - stored in a pressure cooker at 0.2 Mpa; oxygen inhibition- applied an oxygen inhibitor around the repaired material,; heat treatment - performed heat treatment in a dry oven at $60^{\circ}C$, $100^{\circ}C$, or $140^{\circ}C$. The shear bond strength was measured with a universal testing machine, and the shear bond strength (MPa) was calculated from the peak load of failure. A comparison of the bond strength between the repaired specimens was conducted using one-way ANOVA and Tukey multiple comparison tests (${\alpha}$=.05). RESULTS. There were no statistically significant differences in the shear bond strength between the control group and the light curing, pressure, and oxygen inhibition groups. However, the heat treatment groups showed statistically higher bond strengths than the groups treated without heat, and the groups treated at a higher temperature resulted in higher bond strengths. Statistically significant differences were seen between groups after different degrees of heat treatment, except in groups heated at $100^{\circ}C$ and $140^{\circ}C$. CONCLUSION. Strong bonding can be achieved between a bis-acryl base and bis-acryl repair material after heat treatment.