• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.148-155
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• 2017

In this study, by using the international standards ISO TS 16774, Part 2 Test method for chemical resistance as a quality control method of injection type repair material used for leakage crack of underground concrete structure, the performance requirement against of chemical environment of underground concrete structures for repair materials was tested. For this testing 3 types for each of the 2 classes of repair materials(synthetic rubber, cement), with a total of 9 types repair materials, were selected and examined. As a result, the test results showed that the smallest performance deterioration by the change in the mass was with the synthetic rubber(RG) type as opposed to the cement type system, showing that the synthetic rubber type had the strongest relative resistance to chemical exposure. Furthermore, it is necessary to investigate the material with high resistance to chemical substances and to examine the material which can increase resistance to sodium hydroxide and sodium chloride in cement system. These results can be used as a basic index for the selection of repair materials with the strongest resistance to chemical environment found in concrete structures. In addition, it is expected that the test results derived in this study can be used as reference data that can be reflected in the quality improvement of the maintenance material to be developed later.

• Polymer(Korea)
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• v.31 no.1
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• pp.8-13
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• 2007

To overcome drawbacks of the nylon 6/poly (acrylonitrile-co-butadiene-co-styrene) (ABS) blend, nylon 6 blend with poly (acrylonitrile - co-styrene - co-acrylic rubber) (ASA) which containing poly (butyl acrylate) as a rubber phase in substitute of poly (butadiene) in ABS, was examined. Poly (styrene-co-maleic anhydride) (SMA) containing 25 wt% of maleic anhydride (MA) or poly (styrene- co-acrylo-nitrile-co-maleic anhydride) (SANMA) containing less than 3 wt% MA was used as a compatibilizer to fabricate blends having high impact strength. Changes in the mechanical properties of nylon 6/ASA blend with compatibilizer content were similar with those of nylon 6/ABS blend. Blends haying high impact strength was produced when blends contained more than about 20 wt% rubber. Blends containing SAM or SANMA as a compatibilizer were stayed in a injection molding machine at the molding temperature and afterwards specimens for the examination of the impact strength was prepared. Impact strength of blends containing SMA was decreased with retention time, while that of blends containing SANMA was not changed with retention time.

• Elastomers and Composites
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• v.39 no.3
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• pp.193-208
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• 2004

Morphology of injection molded polymer blend was investigated by experimental and theoretical approach. In experiments, the effects of injection speed and injection temperature on the morphology of injection molded MPPO/Nylon 6 blend were investigated. The morphology distribution across the part thickness was clearly observed in injection molded blend. We could observe several distinct regions across the thickness of molded part: skin layer, subskin layer and core region. The skin layer where the dispersed phase is fine and highly deformed to the flow direction is observed to be located near the part surface. The subskin layer located at inner region of the skin layer also observed. In the subskin layer, the dispersed phase is coarser than that of skin layer and deforms to the flow direction. Based on the experimental results, the calculation scheme to predict the morphology of injection molded polymer blend was suggested. The morphology of injection molded polymer blend could be predicted in corporation with the result of flow analysis obtained from commercial software for injection molding process and the theory of drop behavior under the flow. The suggested calculation scheme could predict the effect of injection conditions on the morphology of injection molded parts.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.179-182
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• 2007

In recent, recycling of plastic material has became a major issue due to the landfills and environmental problem. This study investigated fluidity of thermoplastic vulcanizate(TPV), which is for automobile component parts such as weather strip in order to replace ethylene propylene rubber (EPDM). So, using the spiral flow test mold and panel cover mold, we conducted an experiment on fluidity of TPV with injection molding. As results of injection molding experiment, the recycled TPV's flow length was a little bit longer than virgin TPV and a case of panel cover, the filled weight was almost same quantity.

• Journal of Korean Academy of Nursing
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• v.5 no.1
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• pp.87-92
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• 1975

This study was performed from July to December 1974 to investigate the rates of contamination of distilled water for injection and local anesthetics. 222 vials were sampled from 7 different places of St. Mary's Hospital The samples were cultured for isolation of microorganisms. The results were as follows; 1. Of 222 vials, 11 were Contaminated by 6 types: Staphylococcus epidermis, Bacillus subtilis, Mima polymorph a, Alcaligenes faecalis, Herellea vaginicala and pepto- streptococcus. 2. 5(9.1 %) of 55 vials from surgical wards, 2 (4.2 %) of 48 vials from surgical OPD, and 4 (12,l %) of 33 vials from pediatric wards were contaminated 3. Between rates of contamination of distilled water for injection and local anesthetics and the number of punctures, there was no significant relationship. (CR=1.42 P〉0.1) 4. There was no significant relationship (CR=1.02 P〉0.1) between the rates of contamination of vials and the duration of the first and the last punctures. 5. The ratios of contamination between 75% alcohol and 2% phenol used for disinfection of rubber lids of vials did not show significant difference.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.2
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• pp.154-159
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• 2004

A new microflow rate controller for medical injection was developed and evaluated. The flow rate was controlled by changing the friction depth as well as the friction length of the micro-channel. A precise micro-fabrication of the micro-channel was requested for an accurate flow control. The friction depth was inversely proportional to the friction length, which gives a linear flow control to the channel length. The channel groove was fabricated with a plastic material. A rubber containing silicone oil was covered over the groove, which satisfies both lubrication and leakage prevention. The flow controller was validated by performing the numerical simulation and experiment. A good agreement was shown between computation and experiment.

• Design & Manufacturing
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• v.1 no.1
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• pp.39-44
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• 2007

In recent, recycling of plastic material has became a major issue due to the landfills and environmental problem. This study investigated fluidity and hardness of thermoplastic vulcanizate(TPV), which is used for automobile component parts such as weather strip in order to replace ethylene propylene rubber (EPDM). So, using the spiral flow test mold, we conducted an experiment on fluidity and hardness of TPV according to injection molding conditions. As results of injection molding experiment, the recycled TPV's flow length was a little bit longer than virgin TPV and the hardness was decreased in case of using the recycled resin. Also, we investigated the morphology study by SEM photo.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.240-241
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• 2017

In this stduy, we will references to provide reasonable basis for the test environments applicable to the chemical resistance test covered by KS F 4935 『Injection-type Sealing Materials for Water Leakage Crack of Adhesive and Flexible Rubber Asphalt』, analyze the problems with the current test methods in consideration of the features of materials. As a result, we assured more objective data in improved chemical resistance test methods.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.271-275
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• 2007

These days, recycling of plastic material has become a major issue due to the landfills and environmental problem. This study investigates the fluidity of thermoplastic vulcanizate(TPV), which can be used for an automobile part such as a weather strip, in order to replace ethylene propylene rubber(EPDM). Injection molding experiments with the spiral flow test mold and panel cover mold are conducted to examine the fluidity of TPV during injection molding. It is found out that the recycled TPV's flow length is a little bit longer than the virgin TPV. However, the filling weight for a panel cover parts by a recycled TPV is almost the same as that by a virgin TPV.

• Elastomers and Composites
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• v.39 no.4
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• pp.324-329
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• 2004

The phase morphology, degree of craze and impact property in Polycarbonate (PC)/Acrylonitrile-Butadiene- styrene (ABS) blend containing the phosphate based flame retardant were studied in terms of injection molding temperatures. As the injection molding temperature increases, significant amount of coalescences and crazes were observed and impact strength decreased. It was also observed that the addition of compatibilizer into the blends suppresses the coalescence and craze.