• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.116-126
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• 1998

Numerous chemical agents have been developed to reduce the activity of cariogenic bacteria. Of these, chlorhexidine is acknowledged as the most effective. Gel and mouthrinse have been the traditional method of its application in the mouth. It has been reported that chlorhexidine varnish has prolonged inhibitory effect on the number of streptococcus mutans in saliva and plaque. Recently, chlorhexidine varnish and polyurethane sealant have been developed to promote prolonged anticariogenic effect of chlorhexidine. Products containing 10% chlorhexidine varnish and polyurethane sealant have been developed to prevent caries by reducing the number of streptococcus mutans in the oral cavity. The purpose of this study is to investigate the inhibitory effect of chlorhexidine varnish and polyurethane sealant on streptococcus mutans in the primary dentition. Children with primary dentition containing no active carious lesion were divided into two groups. To the experimental group (n=11), chlorhexidine varnish and polyurethane sealant ($Chlorzoin^{(R)}$, Knowell Therapeutic Technologies, Inc. Canada.) was applied once a week for four weeks according to the manufacturer's instruction. Only oral prophylaxis was performed on the control group(n=7). Caries activity was measured after using $Cariescreen^{(R)}$SM (Knowell Therapeutic Technologies, Inc. Canada,) to incubate streptococcus mutans before and 5, 12, 24 weeks after initial varnish application. The following results were observed.; 1. There was statistically significant decrease in the number of streptococcus mutans in the experimental group for 5 weeks(P<0.01), 12 weeks(P<0.05) after the initial application. but, by 24 weeks significant difference had disappeared. 2. As the inhibitory effect of chlorhexidine varnish and polyurethane sealant application is not everlasting, reapplication at 12-24 weeks should be needed.

• Polymer(Korea)
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• v.35 no.5
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• pp.488-492
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• 2011

Three isocyanatopropyldimethoxysilylpolydimethylsiloxanes(IDMSi-PDMS) were synthesised from the reaction of isocyanatopropyltrimethoxysilane with monohydroxyl group termainated PDMS having different molecular weight($M_n$=5000, 10000, and 20000). Then PDMS modified polyurethane hybrid elastomer(PSMPH) were prepared from the reaction of IDMSi-PDMS with ${\alpha}$, ${\omega}$-hydroxyl group terminated polyurethane. PSMPH sealant was prepared by compounding PSMPH elastomer with additives such as plasticizer, adhesion promoter, crosslinking agent, vicosity increasing agent, inorganic filler, and catalyst at room temperature under nitrogen atmosphere. The methoxy group in the PSMPH sealant should be crosslinked with the hydroxyl group in the building stone or moisture by typical sol-gel reaction. The adhesive strength of the sealant having PDMS of $M_n$=5000 showed 40.28 kg of maxium load and 20.14 kg of break load. The shrinkage rate of the sealant having PDMS of $M_n$=20000 was 5.7% as the best result. Also, their skin over time, slump, oil content after 8 days under oil soaked paper and alkaline resistance characteristics show good results.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.75-77
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• 2014

Using sealant for window installation is sealing the gap between the window frame and outer wall (such as concrete). A sealant serves to prevent external environmental impacts such as moisture, rain, sand, and dust entering inside of the building and make the building durable. In order to fulfill basic jointing function of sealing, at least 6 mm joint gap between two bonding surfaces are required. Also, adhesion performance between sealant and surfaces and the compatibility with other building materials are required to check before installation. In general, 2 part polyurethane sealant and 1 part silicone sealant are most common materials for sealing the joint of window. In this study, adhesion performances of those two generic sealants reflecting actual application conditions and the compatibility evaluations with other building materials are conducted to propose proper window installation procedures.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.220-221
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• 2014

The various type of polymer such as silicone, modified silicone, polyurethane, etc are being used in domestic construction sealant market. Once sealant is installed in building, it should maintain their specific performances such as preventing moisture, rain, air, etc against environment conditions for several decades. In this study, weather resistance as per polymer type of sealant has been evaluated using QUV accelerated weathering tester. As a result, weather resistance of silicone is highest and modified silicone is lowest in the comparison of other type of polymer.

• Polymer(Korea)
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• v.26 no.5
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• pp.607-614
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• 2002

Polyorganosiloxane(HBPS) modified polyurethane (UMPS) was synthesized to improve weatherability in the polyurethane (ITPU) sealant and its rheological propoerty was investigated. It was found that the viscosity increased with increasing HBPS content in polyurethane and maximum viscosity was observed in UMPS having 70/30 ITPU/HBPS ratio. This was understood that the segregation of HBPS segment in UMPS chain has been developed. Further increasing of the content of HBPS resulted in the lowering of viscosity because of the flexibility of HBPS block segment in UMPS chain. It was also found that UMPS has more sensitive environmental dependency of viscosity than ITPU such as shear rate, humidity and temperature. In additions, UMPS having Si(O$CH_3$)$_3$ end group (TUMPS) by adding coupling agent up to 0.3 wt% resulted in the increase of viscosity by the acceleration of curing. But introducing more than 0.5wt% curing agent to TUMPS caused the lowering of viscosity because of less NCO group in TUMPS for the curing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4D
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• pp.587-592
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• 2006

The joint sealants used in the airside should resist the high temperature of the jet blast and the jet fuel oil spilled when the aircraft is maintained and filled. The material of joint sealant for the airside should be different from that for the road due to these characteristics. Three different kinds of the joint sealant materials were tested in this paper. The materials include the polysulfide, the polyurethane and the silicon. The test results show that the physical properties and the performance of the polysulfide show the high resistance to the jet blast and the jet fuel oil. When the characteristics of the airside considered, the polysulfide may apply in the both of the runway and the apron area, the polyuretane can be applied the taxiway. The use of the silicon sealant is not recommended for the airside.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.133-139
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• 2009

Joints on concrete road prevent failure and crack securing the moderate space when concrete slab expands and contracts as a function of varying temperature throughout all seasons. Filling joint sealants in joints can prevent the interruption of slab movement and failure due to the infiltration of alien substances, and also can prevent crack caused by freezing and thawing and Dowel bar corrosion resulted from water - rainfall and snowfall infiltration through the inside the pavement. They lead to the improvement of the commonality of road. This paper evaluates physical strength, weatherability and deicer resistance of a two-year aged sample from joint on concrete road and its virgin sample. It was found that there are significant differences in aspects of weatherability and adhesive force between the tested sample and silicon materials.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.513-524
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• 1998

The purpose of this study was to compare the staining ratio on the enamel surface following the use of chlorhexidine mouthwash and the chlorhexidine varnish application. Labial and lingual surfaces of maxillary and mandibular incisors of adults were selected to evaluate the staining ratio. The control group was consisted of 8 individuals, the experimental group 1 and 2 were consisted of 50 each. Prophylaxis with pumice was performed to remove the stain already established on the enamel surface of all groups. The group 1 was asked to use chlorhexidine mouthwash(Hexadent, chlorhexidine gluconate 1ml/100ml) for a minute twice a day. The chlorhexidine $varnish^{(R)}$($Chlorzoin^{(R)}$, consisted of solution 1(10% chlorhexidine acetate) and solution 2(polyurethane sealant)) was applied on the enamel surfaces of the group 2. After 4 weeks of experiment, intraoral photogragh of tooth surfaces were taken in order to record the stained area on the enamel of the control and the experimental groups. Outline of teeth and the stained area in the photographs was traced on the OHP film. Scanner and computer processor were used to calculate stained surface ratio.