• 구강회복응용과학지
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• 제23권4호
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• pp.269-281
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• 2007

Fluoric acid etching is an essential procedure in cementation of reinforced ceramics to tooth surface. But there have been few studies about the changes of surface structure and flexural strength of IPS $Empress^{(R)}$ 2 ceramic according to the etching time. The objectives of this study were to examine the surface structure changes and the difference in biaxial flexural strength of IPS $Empress^{(R)}$ 2 ceramic according to various etching times. Sixty one disk-shaped specimens of IPS $Empress^{(R)}$ 2 ceramic($14mm{\times}1.2mm$) were fabricated for the biaxial flexural strength test and SEM analysis according to the manufacturer's recommendations. Sixty specimens were divided into 6 groups(n=10) according to the time of HF acid etching(0, 20, 180 and 300s)and silane/resin cement application. Each disk was loaded using a piston-on-3 ball biaxial configuration in a universal testing machine. The failure loads(N) were recorded, and the biaxial flexural strength for each disk was calculated. A one-way analysis of variance and independent t-test on transformed fracture strength data were used to determine significant differences between groups. The groups of no cementation showed a trend toward progressive weakening with increasing the etching time. However, this was not statistically significant at p=0.05 level. The groups of resin cementation exhibited no apparent trend in their mean strength values. SEM photomicrographs showed very different results of etching. Within the conditions of this study, alteration of surface topography by acid etching does not have a deleterious effect on the biaxial flexural strength of IPS $Empress^{(R)}$ 2 ceramic.

• 대한화학회지
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• 제55권6호
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• pp.1007-1011
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• 2011

숙신산을 시작물질로 Amberlite IR-120을 이용하여 다이옥틸숙시네이트와 무수숙신산을 합성했다. 양이온 교환 수지를 촉매로 사용했을 때, 숙신산과 옥탄올을 이용한 다이옥틸숙시네이트의 합성은 환류조건에서 18시간의 반응 시간이 요구되었고, 무수숙신산의 합성도 숙신산, Amberlite IR-120, isopropenyl acetate의 존재하에 반응을 진행하였을 때, 18 시간이상의 긴 반응 시간이 요구되었다. 그러나, 마이크로파를 이용하게 되면 반응시간은 10분 이내로 획기적으로 줄어 들었다. 80% 이상의 높은 수득률을 유지하는 상태로 촉매는 최소 4회 이상 재사용 할 수 있었다.

• 대한소아치과학회지
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• 제38권4호
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• pp.348-354
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• 2011

침식 법랑질의 표층은 건전 법랑질과는 물리화학적 성상이 다르므로 침식 법랑질면에 대한 복합레진의 결합력을 증가시키기 위한 대안으로, 법랑질 내층으로의 침투력이 탁월한 infiltrant resin을 응용하는 방법을 생각하게 되었다. 본 연구는 다양한 정도로 인공 침식이 유발된 법랑질면을 대상으로, infiltrant resin과/또는 기존의 접착제를 적용한 경우의 복합레진 결합강도를 비교 분석할 목적으로 시도되었다. 건전한 순면을 가진 발거된 상악 유전치를 대상으로, 인공침식 유발 횟수 및 infiltrant resin과/또는 기존의 접착제를 적용한 방법에 따라 각 20개씩의 시료를 제작하였으며, 각 군의 미세인장 결합강도를 측정하고, 파절면의 파절 양상을 평가하여 다음과 같은 결과를 얻었다. 법랑질 표면의 침식 유발 횟수가 늘어날수록 결합강도가 낮았다(p<0.05). 기존의 접착제 상부에 infiltrant resin을 추가 적용한 군, infiltrant resin만 적용한 군, 접착제만 적용한 군의 순으로 미세인장결합강도가 높게 나타났다(p<0.05). 파절 양상의 관찰에서는 인공 침식 유발 횟수가 적은 군 및 infiltrant resin을 적용한 군에서 응집파절의 비율이 높게 나타났다. 결론적으로, 법랑질의 침식도가 클수록 복합레진 수복물과의 결합 강도는 감소하였으며, infiltrant resin으로 기존의 적찹제를 대체하거나 첨가함으로써 결합강도를 보완시킬 수 있을 것으로 판단되었다.

• Restorative Dentistry and Endodontics
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• 제22권2호
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• pp.505-518
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• 1997

The objective of this investigation was to compare the effects of water storage on the aspect of hardness and diametral tensile strengths of four hybrid glass ionomer cements(two compomers and two resin-reinforced glass ionomers) with a resin composite material. One composite resin(Degufill Ultra), two compomers(Dyract, Compoglass Cavifil), and two resin-reinforced glass ionomers(Fuji Duet, Vitremer) were used in this study. Cylindrical specimens were prepared and stored at $36{\pm}1^{\circ}C$ in distilled water for 10 minutes after set, and then tested on an Instron testing machine(No.4467) at 1.0 mm/min displacement rate. Vicker's hardness and diametral tensile strengths as time elapsed were measured after aging in water for 10 minutes, 1 hour, 3 hours, 1 day, 3 days, 5 days and 7 days at $36{\pm}1^{\circ}C$. During the test of diametral tensile strength, stress-strain curves were obtained, from which the compressive modulus were calculated and compared. The structure of four set glass ionomer cement mass was observed on SEM(Hitachi, S-2300) after being etched with 9.6% hydrofluoric acid for 1 minute. The results were as follows; 1. The hardness of the experimental group(compomer and the resin reinforced glass ionomer cement) did not exceed the value of control group(Degufill Ultra). 2. Vicker's hardness of the Fuji Duet tended to increase succeedingly, Dyract was decreased after 3 hours in water, and Vitremer was the lowest. 3. The control group(Degufill Ultra) presented progressively on increased diametral tensile strength with time, Fuji Duet were decreased after 3 days, Compoglass Cavifil and Vitremer were decreased after 5 days in water storage. 4. Compressive modulus of the control group(Degufill Ultra) and Dyract were increased sharply timely, Fuji Duet and Vitremer were increased smoothly by lapse of time in water. Fuji Duet were stronger than Vitremer. On the other hand, Vitremer exhibited the lowest toughness. 5. The microstructure of compomer was similar with that of the composite resin(Degufill Ultra), and the fillers in resin-reinforced glass ionomer cements were noticed. It can be concluded that mechanical properties of hybrid glass ionomer cements is weaker than composite resin, and that the compomers or the resin-reinforced glass ionomers can not substitute the composite resins. A plenty of considerations should be done on the application of them to the area under the loading and high wear has a little adverse effect on the mechanical properties on the water storage for 7 days. The further research should be needed to confirm the advantage of the compomer.

• 환경생물
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• 제22권4호
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• pp.494-500
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• 2004

In order to investigate the effect on morphology of Rhizopus oryzae and production of lactic acid, various interface materials were used. Morphology of fungal showed sheet and flock when resin was added. The production of lactic acid was increased dramatically when interface materials were added. Furthermore, the effect of resin was more significant than that of others. It was assumed that interface materials could absorb substrate and microorganism together, so microorganism was not inhibited by substrate. The effect of static electric field on the interface culture was studied. When the exerting potential was 6.78 voltage, the biomass y was obviously higher than that of zero voltage. A simulated gas-solid interface system was developed to study the growth and two phases model for the growth of Rhizopus oryzae was build up that depended on the symmetric branching theory. An important parameter F was researched. The results indicated that the value of F had obvious difference at exponential and deceleration period, respectively.

• 대한치과기공학회지
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• 제29권2호
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• pp.141-150
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• 2007

The purpose of this study was to ascertain the bonding durability of self-etching dentin bonding agents to dentin by means of shear bonding strength. Several acid-etching dentin bonding system (ESPE Z100) and self-etching dentin bonding systems (DEN-FIL, GRADIA DIRET) were used. The occlusion surface of human molars were ground flat to expose dentin and treated with the etch bonding system according to manufactures instruction and followed by composite resin application. After 24hours of storage at 37$^{\circ}C$, the shear bonding strength of the specimens was measured in a universal testing machine with a 1mm/min crosshead speed. An one-way analysis of variance and the scheffe test were performed to identify significant differences (p<0.05). The bonded interfacial surfaces and treated dentin surfaces were examined using a SEM. Through the analysis of shear bond strength data and micro-structures of dentin-resin interfaces, following results are obtained. In dentin group, the shear bond strength of DEN-FIL showed statistical superiority in comparison to the other groups and followed by ESPE Z100 and GRADIA DIRECT (p<0.05).

• 대한화학회지
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• 제34권1호
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• pp.69-75
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• 1990

모자나이트 광물 중에 포함된 각각 희토류 원소를 이온회합 크로마토그래피 방법으로 분리 및 정량하였다. 정량하기 전에 양이온교환수지(Dowex 5OW-X8) 칼럼으로 희토류 원소를 집단 분리하였다. 이 때 수지 칼럼에 의하여 희토류 원소가 정량적으로 회수되며, 시료 중의 공존이온으로부터 깨끗이 분리됨을 방사성 추적자 및 유도쌍 결합 분광-질량분석법(ICP-MS)으로 각각 확인 하였다. 역상 칼럼($\mu$-Bondapak $C_{18}$)에 의하여 미량(ppm)의 희토류 원소를 pH 4.6의 $\alpha$-hydroxyisobutyric acid으로 0.05M부터 0.3M까지 기울기 용출하여 각각 분리하였다. 희토류 원소와 PAR (4-(2-pyridylazo)-resorcinol monosodium salt)과의 포스터 칼럼 착색반응을 통하여 각각의 희토류 원소를 검출하였다.

• Korean Chemical Engineering Research
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• 제56권1호
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• pp.14-23
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• 2018

The effect of dodecylbenzene sulfonic acid (DBSA) with different addition amount of DBSA ($M_{DBSA}$), temperatures and solvent-to-oil ratio (SOR, v/v) on asphaltene aggregation in a solvent deasphalting system was investigated. Increasing the $M_{DBSA}$ at SOR 10 and $55^{\circ}C$ caused the asphaltene removal ratio (ARR) to increase first, then maximize at 1 wt% of $M_{DBSA}$ and then decrease continuously. Based on the SARA (saturate, aromatic, resin, asphaltene) composition, the adsorption amount of DBSA on the asphaltene surface and the self-aggregation of the DBSA, the reason for the change in ARR with $M_{DBSA}$ was found due to the adsorption mechanism. In addition, the asphaltene-resin-DBSA colloidal size confirmed the change of adsorption behavior between the asphaltene and DBSA. Based on the results of this study, a hypothetical adsorption mechanism of DBSA on asphaltene aggregation in the solvent deasphalting system was conceived of and proposed.

• Nuclear Engineering and Technology
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• 제15권2호
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• pp.142-148
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• 1983

핵급물질에 함유된 미량 희토류윈소인 Sm, Eu, Gd, Dy를 개별 분리하기 위해 Dowex50W$\times$8 양이온교환수지와 $\alpha$-hydroxyisobutyric acid ($\alpha$-HIBA) 사이에서 분배계수를 측정하였다. 양이온교환수지를 이용하여 우라늄매질로부터 미량희토류원소를 군분리한 후 0.40M$\alpha$-HIBA용리액의 pH를 3.40에서 3.60까지 변화시키면서 개별분리하였다. Sm, Eu, Dy은 형광분석법으로 Gd은 비색법으로 정량하였으며 실험결과를 토대로하여 magnesium diuranate(yellow cake) 중의 Sm, Eu, Gd, Dy를 각각 정량하였다

• 대한치과의사협회지
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• 제23권12호통권199호
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• pp.1031-1037
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• 1985

The purpose of this study was to evaluate the marginal sealing ability of 'vivadent.' Using freshly extracted human teeth and 2% aqueous methylene blue, the marginal leakage of dye in restorative materials such as vivadent with acid etching technique, Durafill with acid etching technique, silar with acid etching technique, Adaptic, and Amalgam were investigated at 37℃ and under temperature cycling in range of 4℃-60℃. The results were as follows; 1. All filling materials showed some degree of marginal penetration by 2% methylene blue dye. 2. Vivadent with acid etching technique revealed effective marginal sealing ability, but under temperature cycling it showed increased marginal leakage. 3. All resins showed greater marginal leakage than amalgam restoration. 4. Vivadent had the most effective marginal sealing ability in experimented resins.