• Polymer(Korea)
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• v.32 no.1
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• pp.1-6
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• 2008

The adhesion behaviors and processability of NBR as a sealing material were investigated. In order to find the optimum formulation, the adhesive properties and processability were observed as the change of the contents of acrylonitrile (ACN) in NBR. Effects of Mooney viscosity, filler, plasticizer and crosslinking agent on the adhesion behaviors were also studied. The contents of ACN in NBR have great effects on adhesion behaviors and processability in NBR sealing. To know the optimum condition of roll mixing, degree of dispersion was investigated. It was confirmed that degree of dispersion was influenced by various factors such as mixing order, time, and temperature. The crosslinking system was studied as the observation of sulfur system, peroxide system, crosslinking density, and structure. From the variation of the dry condition and hexamine contents, the relation between adhesive and NBR was studied. These results show the adhesion properties and processability are dependent on the contents of ACN and crosslinking system.

• Elastomers and Composites
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• v.36 no.3
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• pp.162-168
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• 2001

Low molecular weight polybutadiene (liquid BR) improves the filler dispersion in a silica-filled styrene-butadiene rubber (SBR) compound. In the present work, influence of molecular weight or the liquid BR on properties of a silica-filled SBR compound was studied. Minimum and maximum torques in the rheocurve for the compound containing the liquid BR with higher molecular weight (HLBR) are lower than those for the compound containing the liquid BR with lower one (LLBR) while the delta torques are nearly the same. Mooney scorch time of the compound containing HLBR is faster than that of the compound containing LLBR. Modulus or the compound containing HLBR is lower than that of the compound containing LLBR while tensile strength of the former is higher than that of the latter. The elongation at break of the former is also longer than that of the latter. Stability for the thermal aging at $90^{\circ}C$ for 3 days is less favorable for the former than for the latter.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1749-1755
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• 2010

The performance of power window system was decided by driving characteristics of the window regulator part and reaction by the glass run. The performance of power window system usually has been predicted by experimental methods. In this paper, an analytical method using the explicit code was suggested to overcome the limit of the experimental methods. The friction coefficient of glass run was obtained by the friction test at various conditions and the Mooney-Rivlin model was used. Also, a mechanism of window regulator consisted of the fast belt system and the slip ring elements. And, we conducted the analysis considering characteristic of a motor and obtained the lifting speed of automotive glass with high reliability

• Elastomers and Composites
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• v.15 no.3
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• pp.147-154
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• 1980

The cellular rubber products for industrial purpose have been applied in many fields such as auto-motive parts, ship-building, machinery, sports goods, diving suit or interior housings etc. The purpose of this dissertation is to study the physical properties of celluar rubber products particulary for those elastomers such as EPDM, CR and NBR with heat resistance property, weather proofness, and oil resistance characteristics respectively, aiming at improving their quality, and renovating the manufacturing know-how which is beyond our technical power at the present time in Korea. In order to meet this requirement an ideal recipe is being shown for the three elastomers, and also a practical recipe which is easily available in terms of compounding ingredients in domestic market has set up as shown in Table 1. for the investigation of vulcanization characteristics by means of Rheometer. The optimum Mooney viscosity of compounded rubber was found to be approximately $ML_{1+4}(100^{\circ}C)$ $30\sim45$. Excess mustication makes a dispersion of ingredients worse, consequently it causes deformation of shapes and heterogenous cell distribution. In other words the articles are rejected because of its insufficient workmanship. The results of physical properties of the products are indicated in Table 3. It has shown that the quality meet requirement when tested in accordance with ASTM D572, 573 and D 395. The test results o CR/IR blends in terms of hardness, volume change by blowing, tensile strength and elongation have been shown.

• Tribology and Lubricants
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• v.35 no.1
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• pp.52-58
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• 2019

In the case of high-voltage connectors applied to automobiles, waterproofing has become an important issue for the safety of automobiles. In this study, structural analysis is performed on silicone rubber-type waterproof seals used in the voltage connector. For the structural analysis, the tensile properties of the actual rubber seal are evaluated using a miniaturized tensile testing machine. The Mooney-Rivlin material constants of the rubber seal are determined as follows; $D_1=0$, $C_{01}=0.241$, $C_{10}=0.0142$. The analysis shows that the contact pressure at the top of the seal where the seal and male connector are in contact is approximately three times higher than that at the bottom of the seal where the seal and female connector are in contact. It is confirmed that the waterproofing performance of the rubber seal depends on the contact pressure of the seal bottom where the seal and female connector are in contact. The contact pressure for waterproofing is found to be 4.7 bar. The strain concentration of the curved part is attributed to excessive initial tension. Therefore, a redesign is recommended for uniform stress or strain distribution in the curved section of the seal in response to the stress relaxation problem due to permanent deformation.

• Textile Coloration and Finishing
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• v.35 no.4
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• pp.246-255
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• 2023

In this study, we investigated for natural rubber foam to replace petrochemical-based neoprene foam. Experiments were conducted on vulcanization system and 2-step foaming process of natural rubber. The vulcanization system were EV(Efficient Vulcanization Cure), Semi-EV(Semi-Efficient Vulcanization Cure) and CV(Conventional Vulcanization Cure). In the 2-step foaming process, first molding temperature was 140℃, times were 15, 20, 25, and 30minutes, and the second molding temperature was 160℃, the times 5, 10, 15, and 20minutes. The cure and viscosity characterization were evaluated by oscillating disc rheometer (ODR) and mooney viscosmeter. Various mechanical characteristics, including hardness, tensile strength, elongation at the point of rupture, and tear strength, were quantified. Subsequently, an assessment of alterations in these mechanical attributes was conducted post-immersion in a NaCl solution. In addition degree of volume change was measured after immersing the NR foam in NaCl solution and the low-temperature permanent compression set was evaluated at 4℃. And expansion ratio and shrinkage ratio of NR foam were evaluated for 28 days. As a result the EV vulcanization system showed the least change in physical properties before and after salt water immersion, and the lowest shrinkage ratio for 28 days. In addition it was confirmed that the 2-step foaming optimum condition differed depending on the appropriate vulcanization condition.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.841-845
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• 2003

In order for engineered tissues to find clinical utility, the engineered tissues must function appropriately. However, smooth muscle (SM) tissues engineered in vitro with a conventional tissue engineering technique may not exhibit contractile functions, because smooth muscle cells (SMCs) cultured in vitro typically revert from a contractile, differentiated phenotype to a synthetic, nondifferentiated phenotype and lose their ability to contract. SMCs in vivo typically reside in mechanically dynamic environments. We hypothesized that cyclic mechanical stretch induces the features of SMCs in in vitro engineered tissues to be similar to those of SMCs in native tissues. To test the hypothesis, aortic SMCs were seeded onto elastic, three-dimensional scaffolds and cultured in vitro under a cyclic mechanical stretching condition for 4 weeks. A significant cell alignment in a direction parallel to the cyclic stretching direction was found in the SM tissues exposed to cyclic stretching. The cellular alignment and alignment direction were consistent with those of native vascular SM tissues, in which SMCs in vivo align in the radial direction (parallel to stretching direction). In control tissues (SM tissues engineered without stretching), cells randomly aligned. The expression of SM ${\alpha}-actin$ and SM myosin heavy chain, phenotypic markers of SMCs in a contractile state, was upregulated in the stretched tissues by 2.5- and 2.0-fold, respectively, compared to SMCs in the control tissues. The cellular features of alignment and contractile phenotype of SMCs in the SM tissues engineered under a mechanically dynamic environment could allow the engineered SM tissues to exhibit contractile functions.

• Elastomers and Composites
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• v.48 no.2
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• pp.103-113
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• 2013

The properties of the rubber composites containing a silane and silica were evaluated by changing the mixing time and temperature, in order to find the optimum mixing conditions. Characteristics of the compounds were evaluated after mixing at $120^{\circ}C$, $140^{\circ}C$, and $160^{\circ}C$ with various mixing time. With increasing of mixing time, mooney viscosity decreased while the bound rubber contents of the compounds increased. Viscosity rise by increased mixing time was bigger at low temperature and the higher the mixing temperature the faster in the formation of bound rubber. With lower mixing temperature of $120^{\circ}C$, cross-linking rate was almost constant. Dynamic viscoelastic properties and dispersity of the compound showed that dispersion of ingredients and reaction was not sufficient with the mixing time of less than 10min. On the contrary, with high temperature, it was obvious that good dynamic and physical properties could be obtained due to sufficient coupling reaction, however it was thought this high temperature is not optimum because of sensitive cross-linking rate and physical properties and excessive formation of bound rubber. Consequently, it was confirmed that the mixing condition of 10min at $140^{\circ}C$ was optimum for the silane coupling reaction and dispersion of functionalized S-SBR containing silica and silane.

• Interdisciplinary Bio Central
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• v.4 no.3
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• pp.10.1-10.12
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• 2012

Introduction: We investigated frameshift suppressor tRNAs previously reported to use five-base anticodon-codon interactions in order to provide a collection of frameshift suppressor tRNAs to the synthetic biology community and to develop modular frameshift suppressor logic devices for use in synthetic biology applications. Results and Discussion: We adapted eleven previously described frameshift suppressor tRNAs to the BioBrick cloning format, and built three genetic logic circuits to detect frameshift suppression. The three circuits employed three different mechanisms: direct frameshift suppression of reporter gene mutations, frameshift suppression leading to positive feedback via quorum sensing, and enzymatic amplification of frameshift suppression signals. In the course of testing frameshift suppressor logic, we uncovered unexpected behavior in the frameshift suppressor tRNAs. The results led us to posit a four-base binding hypothesis for the frameshift suppressor tRNA interactions with mRNA as an alternative to the published five-base binding model. Conclusion and Prospects: The published five-base anticodon/codon rule explained only 17 of the 58 frameshift suppression experiments we conducted. Our deduced four-base binding rule successfully explained 56 out of our 58 frameshift suppression results. In the process of applying biological knowledge about frameshift suppressor tRNAs to the engineering application of frameshift suppressor logic, we discovered new biological knowledge. This knowledge leads to a redesign of the original engineering application and encourages new ones. Our study reinforces the concept that synthetic biology is often a winding path from science to engineering and back again; scientific investigations spark engineering applications, the implementation of which suggests new scientific investigations.