• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.1
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• pp.15-22
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• 2005

The purpose of this study is to find the effective dynamic characteristics of an improved pneumatic cushion cylinder with a spring type needle valve. The dynamic model represented the peak pressure control method when the pneumatic cushion cylinder is moving forward or backward in the horizontal direction. It was found from the simulation results that the peak pressure in the cushion chamber is affected by the spring, which helps to understand the performance of the pneumatic cushion cylinder and to improve or design a better cushion needle valve component. From the simulation results, the stability of pneumatic cushion cylinder with a spring type needle valve was superior and its cushion capability was also better than that without the spring.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.367-368
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• 2012

• Journal of the Korean Electrochemical Society
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• v.12 no.1
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• pp.34-39
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• 2009

In this study, a needle coke was oxidized in a mixture of dilute nitric acid and sodium chlorate ($NaClO_3$) solutions and followed by heat treatment. The samples were analyzed with using XRD, FESEM, elemental analyzer, BET, and Raman spectroscopy. Double layer capacitance was measured with the charge and discharge measurements. The consisting layers of the needle coke were expanded to single phase showing only (001) diffraction peak by the acid treatment for 24 hours. The oxidized coke returned to a graphite structure appearing (002) peak after heat treatment above $200^{\circ}C$. The structure returned could be more easily accessible to the ions by the first charge, and improve the double layer capacitance at the second charge. The two-electorde cell from acid treated coke and $300^{\circ}C$ heat treatment exhibited the maximum capacitances of 32.1 F/g and 29.5 F/ml at the potential of $0{\sim}2.5\;V$.

• Korean Journal of Plant Resources
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• v.13 no.3
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• pp.208-212
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• 2000

The effect of heat covering materials during cultivation of Shigyoku grape was examined on the effect of protection from freezing damage, labor reduction, and disease resistance during the wintering. This experimentwas accomplished using different combination of heat covering materials from the end of Nov as follows: straw and heat conservation cover B, kilding, color fabric A, and white needle punching fabric. Capacity of heat conservation was the least form white needle punching fabric, and the differences of other materials was slight. Early sprouting occurred by the treatment with heat conservation cover B, and the rate of sprouting was about 70.7% after 9 days of sprouting, showing 2.3-12.5% increase. Growth effect was not differ between heat conservation materials. Disease and insects occurred by the in dice 3.0-3.2 of crown gall from the heat conservation cover B treatment. Other damages were not observed or very little from other treatments. Demand of labor during steps of these treatments was more observed by 6% for kilding than heat conservation cover B, and those of color fabric A and white needle punching fabric were reduced by 6 and 15%, respectively.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.291-295
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• 2007

The oxidation treatment of needle cokes with 70 wt% of nitric acid and sodium chlorate ($NaClO_3$) was attempted to achieve an electrochemically active material with a large capacitance. The structure of needle cokes was changed to graphite oxide after oxidation treatment of needle cokes with acidic solution having the composition ratio, $NaClO_3$/needle cokes, of 7.5, and the inter-layer distance of the oxidized needle cokes was extended to $6.9{\AA}$with increasing oxygen content. On the other hand, the electrochemical performance of oxidized needle cokes as a polarized electrode for an Electric Double Layer Capacitor (EDLC) was examined with an electrolyte of 1.2 M $TEABF_4$ (tetraethylammonium tetrafluoroborate) and $TEABF_4$ (triethylmethylammonium tetrafluoroborate) in acetonitrile. The capacitor cell using 1.2 M $TEABF_4$/acetonitrile has exhibited smaller electric resistance of $0.05{\Omega}$, and larger capacitance per weight and volume of 32.0 F/g and 25.5 F/mL at the two-electrode system in the potential range 0~2.5 V than that of the capacitor cell using $TEABF_4$. The observed electrochemical performance was discussed with the correlation between the inter-layer distance in graphite oxide structure and the anionic size of electrolyte.

• Composites Research
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• v.12 no.5
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• pp.31-39
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• 1999

Glass-fiber reinforced polymeric composites provide the desitable properties of high stiffness and strength as well as specific weight. Hence, they have become some of the most important materials in several industries. These composites can be grouped into thermoplastic and thermoset composites, with thermoplastic composites having several advantages over thermoset composites in mechanical properties and processing. As a result, the study of the material behavior and forming techniques of such composites has attracted considerable attention in recent years. When the continuous fiber-reinforced polymeric composites are molded by flow molding, the molded parts leads to be nonhomogeneity and anisotropic because of the separation and orientation of fibers. As the characteristics of the products are greatly dependent on the separation, it is very important to clarify the separation in relarion to molding conditions, fiber mat structures and mold geometry. In this study, the effects of the mold geometry and the fiber mat structure on the compression moldability are studied using the cup-type molding.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.405-406
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.525-526
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• 2012

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.407-408
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• 2007

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• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.721-722
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• 2013