• Polymer(Korea)
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• v.27 no.1
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• pp.40-45
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• 2003

In this work, the effect of different contents of $Fe_3O_4$ and temperature variation on the electrical conductivity ($\sigma$) in the polar acrylonitrile butadiene rubber (NBR)/$Fe_3O_4$ (magnetite) mixture system was investigated. It was found that the percolation threshold concept holds true for the conductive particle-filled composites where $\sigma$ indicates a nearly sharp increase when the concentration of magnetite in the mixture exceeds 22%. The temperature dependence of $\sigma$ was thermally activated below and at the percolation threshold ($P_c$). Magnetite acted as reinforcing and conductive filler for NBR. At room temperature and higher voltages, the electrical current was proportional to the square of voltage ($I{\propto}V^2$) for the composites which contain 30 phr of magnetite. Moreover, it was shown that the composites with magnetite of 50 phr showed the highest tensile strength and elongation at break, which was due to the formation of optimal physical interlock and crosslinking. The results of 100%, 200%, and 300% Young moduli said that the moduli are largely correlated with reinforcement effect of magnetite and viscosity of the blends from torque curve.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.62-73
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• 2004

The current status and problems of UST management in gas stations were reviewed, and suggestions were made for possible improvement of UST management. Regulations and programs relevant through the whole life cycle of the UST, such as construction, installation, operation, and disclosure are insufficient to prevent oil release. The UST requirements are less stringent compared to those of the U.S. and EU members. Current soil test does not seem to be practically effective in detecting soil contamination caused by oil release. The potential for subsurface contamination due to oil release from the UST is estimated from available data other than soil test results. Much higher following future directions and suggestions are made to improve current unsatisfactory UST management: Firstly, increasing the UST requirements - establishing more stringent standards for new UST facilities, and adding new regulatory requirements for existing UST facilities; secondly, replacing current soil test with the tank and piping tests; thirdly, reinforcing programs for supervising the tank construction and installation; fourthly, constructing a system in which independent gas stations can properly manage the USTs; and lastly, educating UST owners and operators, and constructing DB of UST facilities.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.786-795
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• 1996

The fiber reinforced thermoplastics(FRTP) were prepared with polypropylene fiber(PP) as matrix and polyvinyl alchol(VF), aramid(KF) or polyamide fiber(PAF) as the reinforcing materials using the integrated fiber mixing apparatus. The reinforced thermoplastic sheets were prepared by com¬pression molding and their morphology, rheological and mechanical properties were characterized. In the morphological properties of composites, the wettability of the reinforced thermoplastics were decreased in proportion to the content of fibers. At low angular frequency, the viscosity of PAF /PP and VF/PP composite was increased with the content of reinforced fiber. However at high frequency the viscosity of composite reinforced with 5~20wt% fiber, was shown the reduced values which approaches that of the neat matrix. The mechanical properties of the composite were changed with the content of reinforecd fiber, and VF/PP and KF/PP composite had better properties than PAF/PP system.

• Elastomers and Composites
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• v.33 no.4
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• pp.274-280
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• 1998

Order of reaction, rate constant, activation energy for vulcanization reaction, crosslinking density, and elastic constant of the network produced by sulfur curing were investigated on the SBR/BR blends containing silica and carbon black under same cure system. The reaction order was shown to be first order regardless of filler types. The carbon black filled rubber compounds showed higher rate constant compared to silica filled compounds. But activation energy appeared to be same regardless of filler type and rubber blend ratio. The crosslinking density and elastic constant is higher in the carbon black filled compound compared to silica filled compounds because of strong interaction between rubber and carbon black. On the other hand, crosslinking density and elastic constant were decreased with increasing the butadine rubber content in rubber blends. From the comparison of combined sulfur content in the vulcanized rubber, sulfur content in the silica filled compound become constant 20min later after reaction initiates but sulfur content in the carbon black filled compound become constant 10min later after reaction starts. The silica compound has a longer induction time ($t_2$) and optimum cure time($t_{90}$) compared to those of the carbon black filled compound.

• Journal of the Korean GEO-environmental Society
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• v.20 no.8
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• pp.13-20
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• 2019

In order to ground reinforcement, the chemical grouting, the anchor, the soil nailing system, the micropile, etc. can be mentioned by the methods widely used in domestic. The above ground reinforcement methods are developed by various methods depending on the type of reinforcement, installation method, presence of prestress, grouting method, etc. However, in common, the strength of reinforcement, the friction force of grout and reinforcement and the friction force of grout and ground are the main design variables. Therefore, the optimized ground reinforcement is a material with a high tensile strength of the reinforcement itself, the friction force between the reinforcement and the grout is high, and the application of an optimal grouting method is necessary to improve the friction force between the grout and the ground. In this study, a total of 20 model tests were conducted to analyze the reinforcement effects according to the shape of the reinforcement and the grouting method. As a result of the test, As a result of the experiment, it is judged that the reinforcing effect is superior to the perforated + wing type reinforcement and post grouting method.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.85-89
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• 2019

Cell-free protein synthesis utilizes the translational machinery in a cell extract. Unlike the conventional cell-based expression methods, not being affected by the conditions for cell growth, cell-free protein synthesis enables flexible manipulation of individual factors affecting the efficiency protein biosynthesis. However, the high cost and low stability of the energy sources to regenerate ATP have limited the use of cell-free synthesis for large-scale production of recombinant proteins. One of the approaches to address this problem is to use glucose as an alternative energy source to regenerate ATP through the glucose-metabolizing pathways in a cell extract. In this study, in an attempt to improve the efficiency of ATP regeneration by reinforcing oxidative phosphorylation process, we supplemented with cellular lipids to a glucose-fueled reaction mixture for cell-free protein synthesis. As a result of the lipid supplementation, the productivity of chloramphenicol acetyltransferase in a cell-free synthesis system using glucose increased more than 6 fold compared to when the lipid was not supplemented.

• Food Science and Industry
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• v.54 no.2
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• pp.62-72
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• 2021

It is necessary to improve the self-management ability of Hazard Analysis Critical Control Point (HACCP) certified companies and intensive management for companies with insufficient management. In addition, the efficiency and convenience of HACCP operation should be improved by expanding and distributing smart HACCP. In this way, it is the direction that HACCP in Korea should go forward to continuously discover and expand the field of application with the improving and smartening the HACCP system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.67-74
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• 2011

In this paper, we presented a dynamic cyber attack tree which can describe an attack scenario flexibly for an active cyber attack model could be detected complex and transformed attack method. An attack tree provides a formal and methodical route of describing the security safeguard on varying attacks against network system. The existent attack tree can describe attack scenario as using vertex, edge and composition. But an attack tree has the limitations to express complex and new attack due to the restriction of attack tree's attributes. We solved the limitations of the existent attack tree as adding an threat occurrence probability and 2 components of composition in the attributes. Firstly, we improved the flexibility to describe complex and transformed attack method, and reduced the ambiguity of attack sequence, as reinforcing composition. And we can identify the risk level of attack at each attack phase from child node to parent node as adding an threat occurrence probability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.103-111
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• 2021

Naju Seokdanggan, Treasure No. 49, was dismantled and reconstructed due to poor performance. During construction, the crack area was reinforced and the inclination was improved. It is necessary to analyze the stiffness changes before and after the reconstruction of these cultural properties, and to establish a database of related information. In addition, there is a need for research on a scientific non-destructive testing method capable of predicting or evaluating the reinforcing effect. In this study, a simple equation for estimating the overall stiffness of the structural system was derived from information on the elasticity coefficient and the natural frequency measured by vibration tests before and after reconstruction work, and the applicability of the equation was examined. If the stiffness of important cultural properties is regularly investigated by the suggested method, it is judged that it can be used as data to estimate the time when structural safety diagnosis is necessary or when repair or reinforcement is necessary.

• Textile Coloration and Finishing
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• v.34 no.2
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• pp.109-116
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• 2022

Tire codes are made of materials such as hemp, cotton, rayon, nylon, steel, polyester, glass, and aramid are fiber reinforcement materials that go inside rubber to increase durability, driveability, and stability of vehicle tires. The reinforcement of the tire cord may construct a composite material using tires such as automobiles, trucks, aircraft, bicycles, and fibrous materials such as electric belts and hoses as reinforcement materials. Therefore, it is essential to ensure that the adhesive force between the rubber and the reinforced fiber exhibits the desired physical properties in the rubber composite material made of a rubber matrix with reinforced fibers. This study is a study on the heat treatment conditions for improving the adhesion strength of the tire cord and the reinforced fiber for tires. The core technology of the drying process is a uniform drying technology, which has a great influence on the quality of the reinforcement. Therefore, the uniform airflow distribution is determined by the geometry and operating conditions of the dryer. Therefore, this study carried out a numerical analysis of the shape of a drying nozzle for improving the performance of hot air drying in a dryer used for drying the coated reinforced fibers. In addition, the flow characteristics were examined through numerical analysis of the study on the change in the shape of the chamber affecting drying.