• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.130-131
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• 2017

The combined waterproofing technique, which forms the waterproofing layer of two or more substances, is characterized by forming a waterproof layer, which is characterized by the formation of waterproof layers and the thickness of the waterproofing layer is inherently formed. In this study, it is intended to verify the integrity of the material through the manufacture of materials for special purpose waterproofing methods, primarily for the manufacture of composite waterproofing materials and composite waterproofing methods using cement materials and materials.

• 보존과학연구
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• 통권19호
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• pp.179-191
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• 1998

The Dumu of casted iron objects which is the big vessel for the prevention of fire to wood building is conserved in Kyongpok Palace(Dumu sizes：diameter 97cm, height 42cm, thickness 2cm, weight 250kg). The treated objects which some parts were lost, were not corroded, but cracted and broken by an external power, and strongly attached an cement layer on inside surface. First of all cement layer was mechanically removed by pneumatic needle scaler, welded to electric method for broken and cracked pieces, and then the lost sections were restored to use a epoxy resin and glass fiber. In order to prevent a damage during the handling, the restoration section of the inside surface was treated different colour in comparison with original part.

• 대한치과보철학회지
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• 제53권4호
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• pp.325-329
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• 2015

목적: 본 연구에서는 임상에서 사용되는 몇 가지 레진 시멘트의 혼합 후 부하를 가하기까지의 시간에 따른 피막도의 변화를 비교하고, 혼합 후 작업 시간과 레진 시멘트의 피막도의 관계를 알아 보고자 하였다. 재료 및 방법: 네 종류의 레진 시멘트(Panavia F2.0, Clearfil SA Luting, Zirconite, RelyX U200)를 제조사의 지시대로 혼합한 후 두 장의 투명한 Mylar matrix strip 사이에 소량의 시멘트를 넣고 다양한 시간 간격(20, 40, 60, 80, 100, 120, 140, 160, 180, 200초) 후에 50 N의 부하를 가하고 광중합을 시행하였다. 각 시점에서의 피막도는 $1{\mu}m$ 단위까지 측정 가능한 디지털 피막도 측정기를 이용하여 각 시편 당 세 번씩 측정하여 평균값을 구하였으며, 선형회귀분석을 통하여 시간에 따른 측정값의 변화를 알아 보았다. 또한 Wilcoxon 검정을 사용하여 각 측정값과 제조사에서 제시한 작업 시간을 유의수준 0.05로 비교 분석하였다 ($\alpha$=.05). 결과: 본 연구에 사용된 모든 레진 시멘트에서 혼합 후 부하를 가하기까지 걸린 시간과 피막도는 선형회귀분석 결과 양의 상관관계를 갖는 일차함수적 패턴을 보였다. ISO기준에 따라 피막도가 $50{\mu}m$가 되는 시점까지의 시간은 각 레진 시멘트의 제조사가 제시한 작업 시간과 차이가 있었으나 통계적인 유의성은 없었다. 결론: 레진 시멘트의 피막도는 작업 시간의 증가에 따라 증가한다. 임상에서의 레진 시멘트의 작업 시간은 제조사에서 제시한 작업 시간과 차이가 있을 수 있다.

• 대한치과의사협회지
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• 제48권9호
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• pp.680-687
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• 2010

The purpose of this study was to compare post cementation efficacy according to the different adhesive systems and cement delivery methods. A total of 40 extracted human single-rooted premolar teeth were randomly divided in four groups according to the two luting agents of Unicem applicap (3M ESPE, St. Paul, MN, USA) or Variolink II (Ivoclar Vivadent, Liechtenstein) and cement delivery methods of direct cement application or lentulo spiral application. After restoration using glass?fiber posts, the samples were embedded in acrylic resin. Three sections of 2 mm thickness were prepared from each specimen, and the post in each section was subjected to a push-out test. The data were analysed statistically at significant level of 95%. The Unicem had significantly higher push-out bond strength than Variolink and the lentulo spiral application made higher bond strength (p<0.05). Adhesive failure between cement and dentin was predominant in all groups. The Unicem of self-etch system and cement delivery using lentulo spiral showed clinically acceptable and comparable bonding strength for the fiber post.

• The Journal of Advanced Prosthodontics
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• 제13권5호
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• pp.269-280
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• 2021

PURPOSE. The objective of this study was to evaluate the effect of thickness reduction and fatigue on the failure load of monolithic zirconia crowns. MATERIALS AND METHODS. 140 CAD-CAM fabricated crowns (3Y-TZP, inCorisTZI, Dentsply-Sirona) with different ceramic thicknesses (2.0, 1.5, 1.0, 0.8, 0.5 mm, respectively, named G2, G1.5, G1, G0.8, and G0.5) were investigated. Dies of a mandibular first molar were made of composite resin. The zirconia crowns were luted with a resin composite cement (RelyX Unicem 2 Automix, 3M ESPE). Half of the specimens (n = 14 per group) were mouth-motion-fatigued (1.2 million cycles, 1.6 Hz, 200 N/ 5 - 55℃, groups named G2-F, G1.5-F, G1-F, G0.8-F, and G0.5-F). Single-load to failure was performed using a universal testing-machine. Fracture modes were analyzed. Data were statistically analyzed using a Weibull 2-parameter distribution (90% CI) to determine the characteristic strength and Weibull modulus differences among the groups. RESULTS. Three crowns (21%) of G0.8 and five crowns (36%) of G0.5 showed cracks after fatigue. Characteristic strength was the highest for G2, followed by G1.5. Intermediate values were observed for G1 and G1-F, followed by significantly lower values for G0.8, G0.8-F, and G0.5, and the lowest for G0.5-F. Weibull modulus was the lowest for G0.8, intermediate for G0.8-F and G0.5, and significantly higher for the remaining groups. Fatigue only affected G0.5-F. CONCLUSION. Reduced crown thickness lead to reduced characteristic strength, even under failure loads that exceed physiological chewing forces. Fatigue significantly reduced the failure load of 0.5 mm monolithic 3Y-TZP crowns.

• Restorative Dentistry and Endodontics
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• 제35권6호
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• pp.445-452
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• 2010

연구목적: 이 연구의 목적은 새로운 근단 역충전 재료를 개발하기 위해 MTA, MTA와 AH-plus 혼합물 (AMTA), 그리고 실험적 개발재료인 Portland cement-Epoxy resin composite (EPPC)의 미세 누출 및 물리적인 성질을 비교하는 것이다. 연구 재료 및 방법: 발거 치아 49개를 근관 성형하고 gutta-percha와 sealer로 충전하였다. 각 치아의 치근을 근단부 3 mm에서 절단하고 3 mm 깊이의 역충전 와동을 형성하였다. 15개씩 무작위로 분류한 치근을 세 군으로 나누어 각각 MTA, AMTA, EPPC로 충전하였고 네 개의 치근은 대조군으로 사용하였다. 각 군의 재료로 역충전이 완료된 모든 실험군을 젖은거즈로 덮고 24시간 동안 경화시켰다. 경화 후 72시간 동안 1% methylene blue 염색액에 담근 후, 치근단을 수직 절단하여 사진을 촬영하고 미세 누출을 평가하였다. Vicat apparatus를 사용하여 실험군 별로 경화시간을 측정하였으며, aluminum step wedge를 사용한 디지털 방사선 사진을 촬영하여 각 군의 방사선 불투과도를 평가하였다. 미세누출과 경화시간에 대해 각 군간의 차이를 일원배치분산분석 및 Scheffe 사후 검증으로 유의수준 95%에서 평가하였다. 결과: AMTA와 EPPC는 MTA군에 비해 적은 미세누출량을 보였다 (p < 0.05). AMTA는 가장 높은 방사선 불투과도를 보였으며 개발 재료인 EPPC군은 5 mm aluminum 두께의 방사선 불투과도를 보였다. MTA가 가장 긴 경화시간을 나타낸반면 EPPC군은 다른 군에 비해 초기경화와 최종경화 모두 가장 짧은 경화시간을 나타냈다 (p < 0.05). 결론: 이 연구 조건하에서, 신개발 재료인 EPPC는 치근단 역충전 재료로서 기존의 MTA보다 양호한 밀폐능력과 방사선 불투과성 및 짧은 경화시간 등의 역충전 재료로서 적절한 물리적 성질을 가진 것으로 보인다.

• 대한치과보철학회지
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• 제25권1호
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• pp.303-316
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• 1987

The purpose f this study was to evaluate the effect of resin film thickness on the tensile bond strength and to compare the tensile bond strengths of 4 differently treated metal surfaces. For the experiment, seventy metal specimens were cast with Verabond and divided into I, II, III, groups. The metal specimens in group I were electrolytically etched and cemented with Panavia under finger pressure. Cement film thickness was regulated with metal spacers. The metal specimens in Group II were treated by 4 methods, such as electrolytic etching method, salt-roughened method, EZ-oxisor method , chemical etching method and cemented with Panavia. In group III, electrolytically etched metal specimens were cemented with Hy-Bond. The etched surface of metal specimens and the cement film thickness were examined under the scanning electron microscope. Results were as follows; 1. The tensile bond strength showed no significant difference between $30{\mu}m,\;80{\mu}m,\;130{\mu}m$ film thicknessspecimens. 2. There was no significant difference in the tensile bond strength between the 4 differently treated metal specimens. 3. The tensile bond strength showed significant difference between Panavia and Hy-Bond. 4. Scanning electron microscope photograph revealed that tile interdendritic eutectic was removed in electrolytically etched metal surfaces hilt even dendritic arm was removed in Chemically etched metal surfaces. 5. The metal surfaces which were air-abraded with $50{\mu}m$ aluminum oxide showed roughness and small crack on scanning electron microscope photograph.

• Restorative Dentistry and Endodontics
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• 제40권3호
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• pp.209-215
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• 2015

Objectives: The aim of this study was to evaluate the fluoride release of conventional glass ionomer cements (GICs) and resin-modified GICs. Materials and Methods: The cements were grouped as follows: G1 (Vidrion R, SS White), G2 (Vitro Fil, DFL), G3 (Vitro Molar, DFL), G4 (Bioglass R, Biodinamica), and G5 (Ketac Fil, 3M ESPE), as conventional GICs, and G6 (Vitremer, 3M ESPE), G7 (Vitro Fil LC, DFL), and G8 (Resiglass, Biodinamica) as resin-modified GICs. Six specimens (8.60 mm in diameter; 1.65 mm in thickness) of each material were prepared using a stainless steel mold. The specimens were immersed in a demineralizing solution (pH 4.3) for 6 hr and a remineralizing solution (pH 7.0) for 18 hr a day. The fluoride ions were measured for 15 days. Analysis of variance (ANOVA) and Tukey's test with 5% significance were applied. Results: The highest amounts of fluoride release were found during the first 24 hr for all cements, decreasing abruptly on day 2, and reaching gradually decreasing levels on day 7. Based on these results, the decreasing scale of fluoride release was as follows: G2 > G3 > G8 = G4 = G7 > G6 = G1 > G5 (p < 0.05). Conclusions: There were wide variations among the materials in terms of the cumulative amount of fluoride ion released, and the amount of fluoride release could not be attributed to the category of cement, that is, conventional GICs or resin-modified GICs.

• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.45.1-45.11
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• 2018

Objectives: This study was conducted to evaluate fluoride release and the micro-shear bond strength of resin-modified glass ionomer cement (RMGIC) in casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-remineralized caries-affected dentin (CAD). Materials and Methods: Exposed dentin surfaces of 30 human third molar teeth were divided into 2 equal groups for evaluating fluoride release and the micro-shear bond strength of RMGIC to CAD. Each group was subdivided into 3 equal subgroups: 1) control (sound dentin); 2) artificially demineralized dentin (CAD); 3) CPP-ACP remineralized dentin (remineralized CAD). To measure fluoride release, 15 disc-shaped specimens of RMGIC (4 mm in diameter and 2 mm in thickness) were bonded on one flat surface of the dentin discs of each group. Fluoride release was tested using ion chromatography at different intervals; 24 hours, 3, 5, 7 days. RMGIC micro-cylinders were built on the flat dentin surface of the 15 discs, which were prepared according to the assigned group. Micro-shear bond strength was measured after 24 hours water storage. Data were analyzed using 1- and 2-way analysis of variance and the post hoc least significant difference test (${\alpha}=0.05$). Results: Fluoride detected in solutions (at all intervals) and the micro-shear bond strength of RMGIC bonded to CPP-ACP-remineralized dentin were significantly higher than those bonded to artificial CAD (p < 0.05). Conclusions: Demineralized CAD consumes more fluoride released from RMGIC into the solution for remineralization than CPP-ACP mineralized dentin does. CPP-ACP increases the micro-shear bond strength of RMGIC to CAD.

• 한국농공학회지
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• 제45권7호
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• pp.20-26
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• 2003

The ultra-lightweight high strength polymer concrete could be used for the drain structures under severe condition. In this study, materials used were unsaturated polyester resin, heavy calcium carbonate, artificial lightweight coarse aggregate and perlite. In the test results, the unit weight of the ultra-lightweight high strength polymer concrete was 946 kg f/$\textrm{m}^3$ and the compressive strength was appeared in 34.5 MPa. The compressive strength, splitting tensile strength, flexural strength, acid resistance and weather resistance were shown in excellently than that of the normal cement concrete. The draining trench had 1m length, 0.24 m width, 0.02 m thickness and 0.07 m height. The developed trench could be effectively used at the draining structures.