• Elastomers and Composites
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• v.44 no.1
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• pp.76-83
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• 2009

The purpose of this study was to investigate the effects of combined use of several types of silicone polymers on the physical properties of the dental polyvinylsiloxane impression materials (PVS). Four types of silicone prepolymers having different molecular weight and vinyl group position, and two types of cross-linkers having differently located silyl hydride functional groups were used in various combinations for the formulation. The samples containing bimodal or trimodal prepolymers showed higher tensile strength, elongation at break, and elastic deformation than those containing only one type of prepolymer. The samples using CR210 cross-linker which has side- and terminal-silyl hydride groups showed higher elastic deformation and elongation at break than those using CR101 cross-liker which has side-only silyl hydride group. High vinyl content prepolymer having side vinyl group delayed setting even though it enhanced tensile strength. Further studies are needed to clarify the specific role of this component on setting time and to find appropriate controlling methods for making improved PVS with optimum workability.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.387-394
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• 2019

In this study, in order to evaluate the damage and deterioration of the track components of sleeper floating track (STEDEF), the field samples(specimens) were taken from the serviced line over 20 years old, and the track components were visually inspected, and investigated by laboratory tests and finite element analysis. As a result of visual inspection, the damage of the rail pad and fastener was slight, but the rubber boot was worn and torn at the edges of bottom. The resilience pads were clearly examined for thickness reduction and fatigue hardening layer. As a result of spring stiffness test of rail pad and resilience pad, the deterioration of rail pad was insignificant, but the deterioration of resilience pad exceeded design standard value. Therefore resilience pad was directly affected by train passing tonnage. As a result of comparing the deterioration state of the field sample and the numerical analysis result, the stress and displacement concentration position of the finite element model and the damage position of the field sample were coincident.

• Elastomers and Composites
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• v.38 no.3
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• pp.262-272
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• 2003

Maleic anhydride-grafted-polypropylene(PP-g-MA) were used as a blend component and a compatibilizer, respectively, for two reactive blends of polyamide 66(PA 66)PP-g-MA binary blends and PA 66/polypropylene(PP)/PP-g-MA ternary blends. The goal of this work was to investigate the property differences between binary and ternary blends. Tensile strength, flexural modulus, heat deflection temperature, impact strength, melt flow index, and the dependence of melt viscosity on the shear rate were examined. The impact strengths of binary blends were higher than those of ternary blends at all compositions, since the in situ synthesis of PP-g-PA 66 copolymer through the imide formation between the amine end group of PA 66 and the anhydride group of PP-g-MA gave the increase of molecular weight and was more popular in binary blends than in ternary blends. In case of ternary blends, most of the properties were superior to those of binary blends, owing to the better properties of PP compared with PP-g-MA. The toughened binary blends with 70/30(PA 66/PP-g-MA) and 80/20 ratios were not commercially applicable due to their poor processibility. So, the ternary blends which showed lower melt viscosities were recommended for the commercial applications.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.195-201
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• 2022

This study aims to evaluate the feasibility of the disinfection of clinical ultrasound probes using the vapor fumigation method, which can quickly achieve high-level disinfection. Upon the inspection of the microbial contamination level of clinically used ultrasound probes, nine different types of bacteria were detected. The disinfection efficacy of 7.5% and 35% hydrogen peroxide (H₂O₂) was comparatively tested for the detected microbes. The 35% H₂O₂ demonstrated superior efficacy per disinfection duration. No significant change was observed in the rubber component of the ultrasound probes as a result of the 35% H₂O₂ disinfection treatment. The probes were contaminated with the microbes detected in the microbial contamination level inspection and subsequently disinfected using the novel medical disinfector that utilizes the vapor fumigation method. As a result, the disinfection using the novel device achieved 100% eradication of the microbes from the probes.This study demonstrates that the novel vapor fumigation method-based disinfector provides a faster and more powerful means of disinfection than the conventional disinfection methods. Therefore, the novel disinfector has the potential to be used as a convenient ultrasound probe disinfector in clinical settings.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.561-568
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• 2021

In this study, in order to observe the change in the amount of Tire and Road Wear Particles and the ratio of tire components in it according to the tire wear resistance performance, carried out the evaluation by varying the vulcanization reaction design of the tire tread rubber. In addition, in order to improve the reliability of the evaluation of Tire and Road Wear Particles, the evaluation was performed indoor laboratory test equipment that simulates the condition on real driving to exclude various environmental influences including minerals, driver's habits, road surface, weather, tire structure and pattern designs. After the evaluation in closed space, it is estimated that the amount of collected Tire and Road Wear Particles is 84% compared to 100% of the tire and road wear loss weight, of which 96.4~97.7% was around the road and 2.3~3.6% was in the air. As a result of analy sis of the collected Tire and Road Wear particles, the tire component existed 63~75% in the Tire and Road Wear Particles depending on the wear resistance performance of the tire.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.77-83
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• 2022

This study was conducted to determine the optimal composition of sex attractant for monitoring adults of the tobacco cutworm, Spodoptera litura, in Korea. Lures of different compositions from the two sex pheromone components the female, (Z,E)-9,11-tetradecadienyl acetate (Z9E11-14:Ac) and (Z,E)-9,12-tetradecadienyl acetate (Z9E12-14:Ac), were compared for male attraction using synthetic chemicals, rubber septa, and funnel traps in soybean and peanut fields. After sequential tests were conducted using three sets of the two components different ranges from 5:5 to 10:1, from 9:1 to 99:1, and from 9:1 to 39:1, the 19:1 ratio was identified as the most efficient composition. However, S. litura males were barely caught in the trap of the Z9E11-14Ac single component lure. The results show that both the sex attractant compounds are necessary for monitoring adults S. litura males. The higher the pheromone amount in the dispenser in the range from 0.1 to 10 mg, the more males were attracted. Furthermore, the trap height of 1.5 m was optimal for male capture.