• 대한치과교정학회지
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• 제27권2호
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• pp.327-334
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• 1997

광중합형 글래스 아이오노머 시멘트(Fuji Ortho $LS^{(R)}$)와 화학중합형 레진 시멘트(Mono $Lok2^{(R)}$)을 선택하여 사람의 소구치를 대상으로 법랑질을 퍼미스 및 10% 폴리아크릴산, 38%인산으로 표면처리한 후 금속 및 프라스틱 브라켓을 부착하고 섭씨 $37^{\circ}C$의 생리 식염수에 24시간, 48시간 경과 시키고 만능강도시험기를 이용하여 전단결합강도를 측정하고 비교함으로써 교정용 접착제로서 광중합형 글래스 아이오노머 시멘트가 임상적 적용 가능성이 있는지 여부를 규명하고자 시행하여 다음과 같은 결론을 얻었다. 1. 퍼미스로 법랑질을 표면처리한 광중합형 글래스 아이오노머 시멘트군의 전단결합강도는 화학중합형 레진군의 결합 강도보다 유의성 있게 낮았다(P<0.01). 2. 10% 폴리아크릴산으로 법랑질을 표면처리한 광중합형 글래스 아이오노머 시멘트군의 전단 결합강도는 화학중합형 레진군보다 유의성이 낮았다(PC0.01). 3. 10% 폴리아크릴산으로 법랑질을 표면처리한 광중합형 글래스 아이오노머 시멘트군의 전단결합강도는 피미스로 법랑질을 표면처리한 광중합형 글래스 아이오노머 시멘트군보다 약간 높았으나 통계적으로 유의성이 없었다(P<0.05). 4. 메탈과 플라스틱군의 법랑질 표면처리에 관계없이 통계적으로 유의성이 없었다(P<0.05). 이상의 결과를 종합해볼 때 비록 광중합형 글래스 아이오노머 시멘트가 화학중합형 레진 시멘트보다 결합강도는 낮지만 이의 임상적 적용은 가능할 것으로 사료된다.

• 한국응용과학기술학회지
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• 제26권2호
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• pp.171-178
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• 2009

A comparative analysis of the hindered amine light stabilizers (HALS) and UV abosrber (UVA) and their respective photostabilizing effect on wood plastic composites (WPCs) are reported in this study. The influence of accelerated weathering on the mechanical properties of the composites and the microscopic morphology of a degraded layer on the cross section and the surface were studied. UV absorbers were more efficient at preventing composite lightening than was UV stabilizer. The amount of whitening decreased with the increase of photostabilizers. With the addition of a UV absorber (Tinuvin360), the tensile modulus and strength of the composites increased slightly. However, the addition of a light stabilizer (Tinuvin770) and a UV absorber decreased the tensile modulus and strength of the composites. After 250 and 500 hr exposure, tensile modulus and strength of the un stabilized and stabilized composites decreased. The tensile strength of UV absorber (Chimassorb81)-stabilized composites was significantly greater than that of control and light stabilizer (Tinuvin770)- and UV absorber (Tinuvin360)-stabilized composites. UV absorber-stabilized samples showed less whitening and photodegradation than control and light stabilizer-stabilized samples.

• 한국주조공학회지
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• 제24권3호
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• pp.138-144
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• 2004

Effects of alloying elements such as Si, Mn, Zn on the fluidity and mechanical properties of high ductility Al-Mg based alloys were investigated. The fluidity of alloys was evaluated using a vacuum suction fluidity test, and Si addition was observed to increase the fluidity of AI-Mg binary alloys substantially while Zn somewhat decreased the fluidity. However, both the strength and ductility were significantly deteriorated by the Si additions. It was observed that a small amount of Mn addition to Al-Mg alloy increased the tensile strength effectively without losing much ductility but the effect of Zn addition on the strength was relatively small.

• 한국건축시공학회지
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• 제17권5호
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• pp.393-401
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• 2017

본 논문에서는 발포폴리스티렌 비드 (EPB)와 폐 발포폴리스티렌 (WEP)의 대체율에 따른 경량 모르타르의 기초 특성을 평가였다. EPB 및 WEP를 이용한 경량 모르타르의 기초 특성으로서 단위용적중량, 압축 강도, 휨강도, 흡수율, 열전도율 및 폴리스티렌 (EPB 및 WEP) 분포를 분석하였다. 그 결과 경량 모르타르는 WEP의 대체율이 증가할수록 단위용적중량, 압축 강도, 휨강도, 흡수율 및 열전도율은 증가하고, 폴리스틸렌 면적 분포는 감소하였다.

• Restorative Dentistry and Endodontics
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• 제29권5호
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• pp.423-429
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• 2004

The purpose of this study was to evaluate the effect of multiple application of all-in-one dentin adhesive system on microtensile bond strength using confocal laser scanning microscope and microtensile bond strength test. Flat occlusal dentin surfaces were prepared using low-speed diamond saw. In group I, Scotchbond Multipurpose (SM) was applied by manufacturer's recommendation. In group II, after Adper Prompt L-Pop was applied for 15s and light cured for 10s. the second coat was re-applied and light-cured. In group III, after light-curing the second layer. the third coat was re-applied and light-cured. Specimens bonded with a resin-composite were sectioned into resin-dentin stick for measuring the adhesive layer thickness by confocal laser scanning microscope and evaluating micro-tensile bond strength. The adhesive layers of three-step dentin adhesive system. 3 coats of Adper Prompt L-Pop had significantly thicker than SM. 2 coats of Adper Prompt L-Pop (p < 0.05). However. there was no significant differences in bond strengths between SM and 3 coats of Adper Prompt L-Pop (p > 0.05). And SM. 3 coats of Adper Prompt L-Pop had significantly higher than 2 coats of Adper Prompt L-Pop in bond strengths (p < 0.05).

• 대한소아치과학회지
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• 제28권4호
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• pp.638-642
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• 2001

최근에 소개된 Plasma arc lamp를 이용한 고광도 광조사기는 조사되는 광도를 크게 증가시켜 필요한 조사시간을 단축시키고자하는 연구의 결과중 하나이다. 교정 임상에서 브라켓의 접착시 고광도 광조사기를 사용하여 시술시간을 줄인다면 환자뿐만 아니라, 술자에게도 시간적이나 경제적으로 많은 도움을 줄 것이다. 이 연구의 목적은 Plasma arc light를 사용하여 접착시킨 브라켓의 치면에 대한 전단강도를 측정하고 이를 기존의 할로겐 램프를 이용한 광중합 방법과 비교해보기 위함이다. I군은 할로겐 램프를 사용하는 $XL3000^{(R)}$을 이용하여 총 50초간 광중합하였고 II군은 plasma arc lamp를 사용하는 $Flipo^{(R)}$를 이용하여 2초간 광중합하였으며 III군도 $Flipo^{(R)}$를 이용하여 총 5초간 광중합하여 전단강도 측정을 시행한 결과는 다음과 같다. 1. 세 군의 전단강도의 평균은 비슷한 수치를 나타내었다. 2. 세 군간의 통계학적 유의 차가 없었다(p>0.05).

• 대한치과보철학회지
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• 제28권1호
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• pp.25-41
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• 1990

The purpose of this study was to evaluate and compare the dimensional changes of relined dentures with a light-curing resin, a heat-curing resin, and a direct, hard reline resin. And also to measure the transverse strength, impact strength, surface hardness of the three resins used in relining. The surface textures of three resins also of evaluated by using scanning electron microscope. Through analyses on the data from this study, the following conclusions were obtained. 1. Impact strength of heat-curing resin was highest, and direct, hard reline resin higher, light-curing resin lowest. 2. Transverse strength of heat-curing resin was highest, and direct, hard reline resin and light-curing resin was lower and not signiicantly different. 3. Surface hardness of light-curing resin was lighest, heat-curing resin higher, and direct, hard reline resin was lowest. 4. After storage of the relined dentures for 1 day and 1 week in water at room temperature, linear shrinkage of distance between the reference points in the maxillary base relined with direct, hard reline resin was lowest, and those relined with light-curing resin and heat-curing resin were lower and were not significantly different. 5. After storage for 4 weeks in orator at room tempeature, linear shrinkage of distance between ridge crests of dentures relined with heat-curing resin was highest and that of distance between denture borders was not significantly different. 6. The dimensional changes of relined dentures during storage in water was not significant except those of distance between denture borders relined with light-curing resin at 1 day and 1 week storage in water. 7. At low magnification (x40) of SEM examination, the surface textures of three resins were similar except light-curing resin which had some defects. At high magnification (x200), the surface textures of hard, direct reline resin were smooth with little defects, but those of heat-curing resin and light-curing resin w ere irregular.

• Restorative Dentistry and Endodontics
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• 제47권1호
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• pp.9.1-9.11
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• 2022

Objectives: This study investigated the microhardness, flexural strength, and color stability of bleach-shade resin composites cured with 3 different light-curing units. Materials and Methods: In this in vitro experimental study, 270 samples were fabricated of bleach and A2 shades of 3 commercial resin composites (Point 4, G-aenial Anterior, and Estelite Sigma Quick). Samples (n = 5 for each trial) were cured with Bluephase N, Woodpecker LED.D, and Optilux 501 units and underwent Vickers microhardness and flexural strength tests. The samples were tested after 24 hours of storage in distilled water. Color was assessed using a spectrophotometer immediately after preparation and 24 hours after curing. Data were analyzed using 3-way analysis of variance and the Tukey test (p ≤ 0.001). Results: Samples cured with Optilux exhibited the highest and those cured with LED.D exhibited the lowest microhardness (p = 0.023). The bleach shade of Point 4 composite cured with Optilux displayed the highest flexural strength, while the same composite and shade cured with Sigma Quick exhibited the lowest (p ≤ 0.001). The color change after 24 hours was greatest for the bleach shade of G-aenial cured with Bluephase N and least for the A2 shade of Sigma Quick cured with Optilux (p ≤ 0.001). Conclusions: Light curing with polywave light-emitting diode (LED) yielded results between or statistically similar to those of quartz-tungsten-halogen and monowave LED in the microhardness and flexural strength of both A2 and bleach shades of resin composites. However, the brands of light-curing devices showed significant differences in color stability.

• 대한치과기공학회지
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• 제35권4호
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• pp.333-341
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• 2013

Purpose: The purpose of this study was to evaluate the flexural strength of indirect composite resins with different polymerization conditions. Methods: Ten specimens ($2mm{\times}2mm{\times}25mm$) of each composite resins (Tescera (T), Gradia (S) and Sinfony (S)) were fabricated by two polymerization methods : manufacturers's and light heat pressure. Composite resins polymerized by manufacturers's method and light heat pressure served as control (TS, GS and SS) and experimental groups (TE, GE and SE), respectively. The composite resins were tested for flexural strength and the surface of composite resins were observed with scanning electron microscope (SEM) under X1,000 magnification. Results: The flexural strength values of cured composite resin decreased in the following order: TE (195.4MPa), TS (179.8MPa), GE (169.9MPa), SE (137.7MPa), SS (111.1MPa) and GS (100.9MPa) groups. Conclusion: The flexural strength values between the control and the experimental groups were not significantly different although experimental groups showed higher flexural strength values than control groups.

• 한국구조물진단유지관리공학회 논문집
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• 제2권4호
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• pp.186-193
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• 1998

The purpose of this research is to seek properties of flowing light-weight aggregate concrete and possibility of application. The experimental analysis results by using light-weight aggregate and industrial waste such flyash, furnace slag are as follow. 1) The research shows that flowing light-weight aggregate concrete of slump 23~27cm, slump flow 58~69 cm is possible, but material segregation is appeared above slump 26.5cm and slump flow 65 cm. 2) If mixing ratio of flyash is increase, strength deterioration is about 25 % in early age. It showed that effectiveness of long time strength improvement because strength manifestation ratio is above 95% in a long term. 3) This research showed possibility of substitution of blast furnace slag because strength deterioration by using mixing of furnace slag was appeared small deterioration range as below 10 %. 4) Each experimental compressive strength ratios were 77 %(1st week), 86 %(2nd week), 109 %(8th week), 115 %(13th week), 125 % (26th week) on the basis of 28 days. If mixing ratio of flyash is increase, long term strength increase ratio is improved.