• Fire Science and Engineering
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• v.24 no.2
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• pp.82-88
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• 2010

In this study, we have performed several tests for composite plastic materials to be applied on interior materials of a vehicle to identify their combustion characteristics using cone calorimeter, smoke density chamber and toxicity index chamber. We have prepared a total of 12 samples for 4 major parts of a vehicle wherein each major part has 3 different materials. The results of cone calorimeter test showed ignition time of PVC sheet and PVC leather were 2s. The 8 samples showed under less than 10s of ignition time. The sample comprising Nylon and PE had the biggest maximum heat release rate of 635 $kW/m^2$. The sample comprising Rubber showed the smallest maximum heat release rate but with the biggest total heat release. The results of smoke density chamber test showed the sample that is made up with Rubber had the biggest specific optical smoke density. The sample comprising PVC leather and PUR showed the biggest VOF4 which enables the initial smoke production. The results of toxicity index test showed that all samples contained carbon dioxide content exceeding its lethal concentration. The sample comprising PVC showed high content of hydrogen chloride and hydrogen bromide. The PVC sheet showed the biggest toxicity index calculated by using lethal concentration and test results. Toxicity index of all sample wes over 1.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.587-592
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• 1994

To realize artificial device with sensing ability of the human skin, a mono-material tactile sensor with three sensing functions made of some elastic thin electro-conductive rubber sheet with eight latticed patch elements is proposed. This trial sensor provides the information of three kinds of model material characteristics such as thermal property, hardness property and the surface situation of materials by setting up three kinds of surface models as test materials. It can be finally expected to estimate unknown model materials by analyzing the data of the sensor.

• Journal of Powder Materials
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• v.20 no.2
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• pp.125-128
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• 2013

Magnetic and dielectric properties of rubber composites are controlled by using two kinds of high-permeability metal particles with different electrical conductivity (Sendust, Permalloy), and their effect on microwave absorbance has been investigated, focusing on the quasi-microwave frequency band (0.8-2 GHz). Noise absorbing sheets are composite materials of magnetic flake particles of high aspect ratio dispersed in polymer matrix with various filler amount of 80-90 wt.%. The frequency dispersion and magnitude of complex permeability is almost the same for Sendust and Permalloy composite specimens. However, the complex permittivity of the Permalloy composite (${{\varepsilon}_r}^{\prime}{\simeq}250$, ${{\varepsilon}_r}^{{\prime}{\prime}}{\simeq}50$) is much greater than that of Sendust composite (${{\varepsilon}_r}^{\prime}{\simeq}70$, ${{\varepsilon}_r}^{{\prime}{\prime}}{\simeq}0$). Due to the large dielectric permittivity of Permalloy composite, the absorbing band is shifted to lower frequency region. However, the investigation of impedance matching reveals that the magnetic permeability is still small to satisfy the zero-reflected condition at the quasi-microwave frequency band, resulting in a small microwave absorbance lower than 10 dB.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.207-210
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• 1998

Surface electrical conduction in insulator is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the widely used materials for outdoor insulator - porcelain, EPDM, Silicone rubber - were discussed by measuring properties of average leakage current and scintillation discharge pulses under artificial contamination conditions. The artificial contaminations used were deionized distilled water fog, 0.5wt% NaCl salt fog of light pollution and 2wt% NaCl salt fog of medium pollution. The average leakage current was appeared linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage was most different to that in case of dry and clean condition. In case of salt fog pollution condition. The leakage current was increased above critical voltage. The scintillation discharges were also activated at the level the leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.758-762
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• 1998

Electrical conduction property of insulator surface is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the materials to be used for outdoor insulator such as porcelain, EPDM, silicone rubber was discussed by measuring properties of average leakage current and scintillation discharge pulses under salt fog conditions. The fog was applied by nozzle in chamber and fogging fluids were deionized distilled water, 0.5wt% NaCI solution and 2wt% NaCl solution. The average leakage current showed linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage were much different to those in case of dry and clean condition with 2wt% salt fog. In case of slat fog pollution condition, the leakage current was increased above critical voltage. the scintillation discharges were also activated at the level. The leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.1
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• pp.62-80
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• 2013

This paper has been focused on developing a new hybrid mount for shipboard equipment used in naval surface ships and submarines. While the hybrid mount studied in our previous research was 100 kg-class series-type mount, the new hybrid mount has been designed as an inertia-type mount capable of supporting a static of 500 kg. The proposed mount consists of a commercial rubber resilient mount, a piezostack actuator and an inertial mass. The piezostack actuator connected with the inertial mass generates actively the control force. The performances of the proposed mount with a newly designed specific controller have been evaluated in accordance with US military specifications and compared with the passive mount. An isolation system consisting of four proposed mounts and auxiliary devices has been also tested. Through a series of experimental tests, it has been confirmed that the proposed mount provides better performance than the US Navy's standard passive mounts.

• Magazine of the Korea Concrete Institute
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• v.10 no.4
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• pp.171-182
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• 1998

Vibration-controlled concrete has been developed by using various concrete mixtures, such as latex, rubber powders, plastic resins and polystyrene(styrofoam). As part of the recycling research of obsolete aged tires and plastic materials, various vibration-reducing mixtures are used for 10 concrete panels having above 200 kg/cm$^2$ in uniaxial compressive strength. Plywood box with sand uniformly saturated by the raining device has been used for the analysis of the impact wave, of which data have been transfered by the FFT technique to comparatively investigate damping ratios of 10 concrete panels.According to wave propagation analysis on vibration-controlled concrete for this research, it can be concluded that Latex concrete has relatively larger damping ratios than those for noncontrolled normal concrete in a similar compressive strength

• International Journal of Precision Engineering and Manufacturing-Green Technology
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• v.5 no.5
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• pp.651-658
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• 2018

We comprehensively investigated the wrinkles of a stiff layer covering a spherical void embedded in a rubber matrix after the void experienced inflation or contraction. We developed an easy experimental way to realize the inflation and contraction of the voids. The inflation took place in a void right beneath the surface of the matrix and the contraction happened in a void at the bottom of the rubber matrix. In the inflation, the wrinkle at the center of the deformation was random, and the pattern propagated into rabyrinthine, herringbone, and then oriented parallel lines as the position was away from the center of the inflation to the edge. The cracks were concentric, which were perpendicular to the parallel wrinkled pattern. In the contraction, the wrinkle was simply concentric around the surface of the void without any crack. The cracks were found only near the center of the deformation. The strain distribution in the stiff layer after the inflation and contraction was theoretically analyzed with simulations that were in excellent agreement with the experimental results.

• Elastomers and Composites
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• v.54 no.3
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• pp.225-231
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• 2019

Bio-based polyester polyol was synthesized via esterification between azelaic acid and isosorbide. After esterification, bio-based polyurethanes were synthesized using polyester polyol, 1,3-propanediol as the chain extender, and 4,4'-diphenylmethane diisocyanate, in mixing ratios of 1:1:1.5, 1:1:1.8, 1:1:2, and 1:1:2.3. The bio TPU (Thermoplastic Polyurethane) samples were characterized by using FT-IR (Fourier Transform Infrared Spectroscopy), TGA (Thermal Gravimetric Analysis), DSC (Differential Scanning Calorimetry), and GPC (Gel Permeation Chromatography). The mechanical properties (tensile stress and hardness) were obtained by using UTM, a Shore A tester, and a Taber abrasion tester. The viscoelastic properties were tested by an Rubber Processing Analyzer in dynamic strain sweep and dynamic frequency test modes. The chemical resistance was tested with methanol by using the swelling test method. Based on these results, the bio TPU synthesized with the ratio of 1:1:2.3, referred to as TPU 4, showed the highest thermal decomposition temperature, the largest molecular weight, and most compact matrix structure due to the highest ratio of the hard segment in the molecular structure. It also presented the highest tensile strength, the largest elongation, and the best viscoelastic properties among the different bio TPUs synthesized herein.

• The korean journal of orthodontics
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• v.21 no.2 s.34
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• pp.433-446
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• 1991

The present study was performed to evaluate the relaxation patterns of rubber elastics, elastomeric modules and chains stored in the water bath. Initial loading profiles were established for extension of $100\%,\;200\%$ of their original length for elastomeric chains and of 21, 28, 35, 42, 49mm for rubber elastics and elastomeric modules. The tests were performed on materials stored in distilled water at $37^{\circ}C$ and extraoral elastics stored in dry state at room temperature, at 0 hour, 1 hour, 6 hours, 1 day, 1 week, 2 weeks, 3 weeks, and 4 weeks, respectively. The following results were drawn: 1. The relaxation of rubber elastics manifested no correlation with increments of the extension distances, but showed correlation with time lapse. Remaining forces of rubber elastics carne out $84.6-98.52\%$ after 1 day, $70.92-89.31\%$ after 3 weeks of period. 2. The relaxation of elastomers manifested no correlation with increments of the extension distances, however represented considerable relaxation with time lapse as rapid relaxation after 1 hour and then gradual relaxations with time lapse. Modules relaxed much more than chains. $60.58-67.05\%$ of remaining forces for chains and $37.77-65.17\%$ for modules after 1 hour were turned out, and $51.48-62.22\%$ for chains and $8.04-25.15\%$ for modules after 3 weeks as well. 3. Permanent deformation rates of rubber elastics could not be measured with present investigation, but elastomers underwent severe deformations. 4. $3-9\%$ of permanent deformations for chains, $3-10\%$ for modules at 0 hour were turned out, and $25-30\%$ for chains, $96-145\%$ for modules after 3 weeks as well.