• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1775-1781
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• 2008

The effects of the type of curing agent on the swelling of the natural rubber(NR) sponge applicable to the self-sealing layer of a helicopter fuel tank were investigated. The curing systems employed were peroxide and mixed ones of sulfur and peroxide. The NR compounds were prepared in a kneader and a roll-mill. The compounds were partially cured in a press at high pressure and subsequently cured fully with expansion in another press at atmospheric pressure. The apparent density of the NR sponge was measured and the cell structure was observed with scanning electron microscopy. The swelling experiments were performed at room temperature using toluene, iso-octane, and an aircraft fuel as a solvent. More rapid volume swelling of the NR sponge cured by peroxide was achieved than cured by sulfur and peroxide with similar amount of curing agent added in rubber compounds. The apparent density and cell structure of the sponge were extremely sensitive to the amount of peroxide, which influences again the swelling behavior of the NR sponge. It is important to control properly two reactions of decomposition of foaming agent and crosslinking of NR in the mold to obtain rapid swelling of the NR sponge on contact of the fuel.

• Polymer(Korea)
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• v.37 no.5
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• pp.613-617
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• 2013

The effects of nano size kenaf cellulose fiber on mechanical property of polypropylene (PP) composite were investigated. The addition of nano-kenaf in place of natural kenaf showed higher tensile strength, flexural strength, impact strength, and heat deflection temperature compared to the natural kenaf filled PP composite, while it shows lower melt flow index, elongation%, and flexural modulus. These seemed to be due to the increased surface area of nano-kenaf fiber contacting PP matrix and reduced impurities such as volatile extractives on the fiber surface.

• KSBB Journal
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• v.19 no.2
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• pp.125-131
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• 2004

Various medicinal plants were examined as resources for antidiabetic biomaterials, using an oriental medicinal database. The prescription frequency and dosage of medicinal plants in 131 antidiabetic prescriptions were analyzed. Total prescription score of each medical plant was summed up from prescription table and score table. High-scored medicinal plants have been widely studied in the previous research on the diabetic treatment. Consequently, dangui, hwangryun, maekmoondong, ginseng, chick, saengjihwang, omija, bokryung, Jimo and cheonhwaboon were assumed to have high antidiabetic activities.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.930-935
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• 2005

In order to synthesis of the materials and modulus for floor impact sound reduction, we investigated effect on dynamic elastic modulus of floor impact sound reduction materials and module made by inorganic porous materials, EVA chips and so on. We find correlation property between dynamic elastic modulus and light-weight impact noise. And we measured the dynamic elastic modulus of materials and module for floor impact sound reduction. And we predicted reduction efficiency on floor Impact Noise of those. The dynamic elastic modulus is reduced by increase of filler contents and filler species. When the materials for floor impact sound reduction is consisted of l5wt% EVA Chip and l5wt% inorganic porous materials, its dynamic elastic material is the lowest. And when the module is consisted of PE (upper side), PS embossing board(lower side) and the materials for floor impact sound reduction(middle), its dynamic elastic material is the lowest.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.5
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• pp.391-398
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• 2016

Acoustic emission (AE) is one of the most powerful techniques for detecting damages and identify damage location during operations. However, in case of the source location technique, there is some limitation in conventional AE technology, because it strongly depends on wave speed in the corresponding structures having heterogeneous composite materials. A compressed natural gas(CNG) pressure vessel is usually made of carbon fiber composite outside of vessel for the purpose of strengthening. In this type of composite material, locating impact damage sources exactly using conventional time arrival method is difficult. To overcome this limitation, this study applied the previously developed Contour D/B map technique to four types of CNG storage tanks to identify the source location of damages caused by external shock. The results of the identification of the source location for different types were compared.

• Journal of Convergence for Information Technology
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• v.8 no.1
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• pp.227-233
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• 2018

The purpose of this study was to develop a warm cover for greenhouse with excellent thermal insulation and to propose ways of commercialization of the product. Feathers were used as filling materials because they formed the air layer to enhance insulation. Instead of downs for clothing or other textile products, we used disposed feathers. The developed product covers the outside of the greenhouse to keep the crops warm. It has multiple layers including feathers as filling materials, padding, inside fabric, heat insulation materials and outer fabric. It has proven to improve the insulation ratio. We developed other kinds of warm covers that are applicable to the inside of the greenhouse or the small houses in the greenhouse. Also, R&D system of educational industrial complex enables us to commercialize the products and building marketing strategies for them. This technology contributes to the expansion of energy-saving facilities for farmers, and it can serve the development and spread of various products utilizing feather.

• Culinary science and hospitality research
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• v.21 no.2
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• pp.41-51
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• 2015

The aim of this study was to investigate the applicability of Chinese mung bean as a natural antioxidant agent. This study evaluated the phenolic compounds content and antioxidative activity of methanol extract from Chinese mung bean. Antioxidative activities were measured by in vitro models such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid(ABTS) radical scavenging activity. The contents of total phenolics and total flavonoids of Chinese mung bean extract were $174.83{\pm}2.90GAE\;mg/g$ and $68.87{\pm}2.84QE\;mg/g$, respectively. The antioxidative activities of Chinese mung bean extract were significantly increased in a dose dependent manner on DPPH radical scavenging and ABTS radical scavenging(p<0.05). The concentration of Chinese mung bean extract that reduces the free radical ABTS about 50%($IC_{50}$) was 2.85 mg/mL. These results suggest that Chinese mung bean may have great potential as a natural antioxidant source linked with health benefits.

• Journal of the Korean Chemical Society
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• v.50 no.3
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• pp.224-231
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• 2006

agents used for enhancing mechanical properties of porous natural scaffolds, reduces biocompatability of the scaffolds, due to their inherent cytotoxicity. In this study, scaffolds which was composed of chitosan, alginate and gelatin were cross-linked by using heat treatment instead of cross-linking agent and mechanical properties of the cross-linked scaffold were investigated. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that cross-linking of heat-treated scaffold was formed via amide or ester linkage between the polymer chains. The heat-treated scaffold had interconnected pores with mean diameter of 100~200 m and showed more than two fold increase of water uptake in comparison with chemically cross-linked scaffold. Tensile strength of the heat-treated scaffold increased up to 130% compared to non cross-linked scaffold and average maximum elongation was 11.3%. The porous cross-linked scaffold with the improved mechanical property may be suitable as a biocompatable scaffold for tissue engineering.

• Elastomers and Composites
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• v.47 no.1
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• pp.23-29
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• 2012

The silica-silica interaction parameter (${\alpha}_F$) of the silane treated silica filled natural rubber (NR) compound was investigated. As silane (TESPT) concentration increased from 2 to 12% (2, 4, 6, 8, 10, 12%), the ${\alpha}_F$ value increased at the same silica concentration (10, 20, 30, and 40 phr). It seemed the sulfur atoms in TESPT acted as a crosslinking agent in the compound. As silica concentration increased from 10 to 40 phr, the ${\alpha}_F$ value increased at the same silane concentration due to increased silica-silica interaction.

• Elastomers and Composites
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• v.47 no.1
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• pp.18-22
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• 2012

The silica-silica interaction parameter (${\alpha}_F$) of the silane treated silica filled natural rubber (NR) compound was investigated. The measured ${\alpha}_F$ values using mass fraction method following Wolff's theory were compared with volume fraction method. As silica concentration increased, the ${\alpha}_F$ value increased for both methods. The value of ${\alpha}_F$ expressed as volume fraction was higher than that of mass fraction, which resulted in large gaps between ${\alpha}_F$ values. The effect of accelerator (MBT) concentration on ${\alpha}_F$ values was compared.