• Journal of Mechanical Science and Technology
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• v.15 no.1
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• pp.35-43
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• 2001

Both tensile and tear properties of short-fiber reinforced Chloroprene rubber have been studied as functions of the fiber aspect ratio and fiber content. Both properties increased when both the fiber aspect ratio and fiber content were increased. The fiber reinforced rubbers exhibited maximum values of these properties at a fiber aspect ratio of about 300. When the fiber aspect ratio exceeds 400, the mechanical properties decreased with the fiber content because of the non-uniform dispersion of fibers. The tensile modulus was compared with the prediction by the Halpin-Tsai equations for randomly oriented cases. A bonding agent was used in the fiber treating process. It was found that the ultimate tensile strength, torque, tearing energy and tensile modulus of the rubbers with treated fibers were much higher than those with untreated ones.

• Corrosion Science and Technology
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• v.5 no.3
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• pp.94-98
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• 2006

The next generation nuclear power reactor will use Pb-Bi as the cooling material. The steel structure materials such as HT-9 used in the reactor suffer from corrosion when they are exposed to high temperature Pb-Bi. Therefore corrosion should be prevented to use Pb-Bi as the coolant material without any safety problem. One method is to control the oxygen content in Pb-Bi. An appropriate amount of oxygen in Pb-Bi can produce a thin oxide layer on steel, and this layer protects the steel from corrosion attack. Since the required oxygen content in Pb-Bi is in the range of $10^{-5}$ to $10^{-7}$ wt%, this small oxygen content can be controlled by flowing a mixture of hydrogen gas and water vapor. The stagnant corrosion test of HT-9 samples was performed by controlling the oxygen content up to 2,000 hours. The corrosion behavior of HT-9 was analyzed at the temperatures of $500^{\circ}C$ and $650^{\circ}C$ with a reduced condition and a oxygen content of $10^{-6}$ wt%.

• Elastomers and Composites
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• v.51 no.2
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• pp.93-98
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• 2016

The composites of EVA/EPDM including aluminum trioxide (ATH) as a fire retardant were manufactured for the purpose of improving low temperature property and flame resistance in the rubbery materials. The ratio of EVA to EPDM didn't affect the flame resistance of the rubber composites. The addition of ATH resulted in increase of the flame resistance. In the evaluation of the cold resistance, the increasing EPDM content showed enhancement of cold resistance in the composites due to increasing low Tg EPDM. It was found out that tensile strengths of the composites showed a maximum value at 100 phr of ATH by reinforcing effect, but a minimum value at 200 phr of ATH owing to slippage between the flame retardant by the external stress. In the measurement of solvent resistance in tetrahydrofuran, the increasing ATH content yielded enhancement of solvent resistance by reducing swelling of the composite, and increasing EPDM content also resulted from increase of the solvent resistance by reduction of polarizability as well as increase of crosslink in the composites.

• Horticulture, Environment, and Biotechnology : HEB
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• v.59 no.6
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• pp.835-845
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• 2018

We studied the role of ethylene control in regulating energy metabolism, antioxidant enzyme activity, and vase life of cut rose Rosa hybrida 'Carola'. Rose flowers at stage II were sprayed with one of the following solutions: water (control), $10{\mu}L\;L^{-1}$ 1-methylcyclopropene (1-MCP), or $0.5g\;L^{-1}$ 2-chloroethanephosphonic acid (ethephon). After harvest, ethylene production rate, respiration intensity, energy charge (EC), activities of energy metabolism-related and antioxidant enzymes, and malondialdehyde (MDA) content were measured. Results showed that 1-MCP enhanced the activities of superoxide dismutase, $H^+$-adenosine triphosphatase, $Ca^{2+}$-adenosine triphosphatase, succinic dehydrogenase, and cytochrome c oxidase, increased adenosine triphosphate (ATP) content, maintained high EC levels, inhibited respiration intensity, reduced peroxidase (POD) and polyphenol oxidase (PPO) activity and MDA accumulation, and prolonged vase life. Ethephon promoted ethylene production and respiration intensity, increased POD and PPO activity, reduced ATP content and EC levels, and accelerated senescence. Our results support a novel role for ethylene control in regulating senescence of 'Carola'.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.1
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• pp.86-91
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• 2021

In order to save the energy in vehicles using renewable energy, it is necessary to reduce the weight of parts with polymer matrix composites. Carbon nanotube (CNT) is the nano-scale reinforcement used to increase the interlaminar strength of fiber reinforced composites or enhance the fracture toughness of polymer. However, since the degree of improvement in mechanical properties varies according to the various experimental conditions such as shape of reinforcement, types of matrix and dispersion of reinforcement, research to find the optimal conditions is essentially needed. In this study, CNT/epoxy composites with different CNT concentration were fabricated under the same conditions, and the optimal CNT content (2 wt%) was found through Mode 1 fracture toughness test. Furthermore, through optical microscopy, it was confirmed that the fracture toughness was rather decreased due to the CNT aggregation when the CNT content exceeded 2 wt%.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.418.1-418
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• 2002

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.459-467
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• 2014

The catalytic steam reforming of toluene, a major component of biomass tar, was studied using several catalysts at various temperatures $400-800^{\circ}C$, kind of metal, and metal loading content. Ru and K promoted Ni-base catalyst were prepared, and used for steam reforming of toluene with steam/toluene molar ratio of 25. Concentration of toluene in reactant flow is $30g/Nm^3$ that is usual content of tar from biomass gasifier. The result from experiments showed that $H_2$ content in product gas and toluene conversion increased with temperature. Where in high temperature range, CO and $CO_2$ content in product gas were affected mainly by Boudouard reaction. Ni/Ru-K(3wt%)/$Al_2O_3$ catalyst showed best performance on steam reforming of toluene than used catalysts in this study at whole temperature. Catalysts have been characterized by XRD, TG. XRD analysis displayed that Ni particle size on Ni/Ru-K (3wt%)/$Al_2O_3$ catalyst was 29.4nm. Activation energy of Ni/Ru-K (3wt%)/$Al_2O_3$ catalyst was calculated 36.8kJ/mol by Arrhenius plot.

• Magazine of the Korea Concrete Institute
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• v.4 no.1
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• pp.81-87
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• 1992

In this thesis, the fatigue tests were performed on a series of SFRC(steel fiber reinforced concrete) to investigate the fatigue behavior of SFRC varying with the steel fiber contents and the steel fiber aspect ratios. The three point loading system is used in the fatigue tests. In tl1ese tests, relations between the repeated loading cycles and the mid-span deflections, number of repeated loadmg cycles when specimen was fractured were observed. On this basis, the mid-span deflections, the elastic strain energy and inelastic strain energy of SFRC were studied. A S - N curve \vas drawn to present the fatigue strength of SFRC beam. From che test results, by increasing the steel fiber content the energy lost on the permanent deformation decreases and the energy spent on crack growth increases. But in case of SFRC with the same steel fiber content the higher the steel fiber aspect ratio is, the less the elastic strain energy is. According to S - N curve drawn by the regression analysis on the fatugue test results, the fatigue strength with 2,000,000 repeated loading cycles in SFRC with the steel fiber content is 1.0% shows about 70% on the first crack static flexural strength.

• Journal of Radiation Industry
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• v.4 no.1
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• pp.53-57
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• 2010

Cooking drips which were obtained as by-product after seafood processing in the food industries, still contain lots of proteins, carbohydrates, and other functional materials. But, the seafood cooking drips are easily contaminated because of its rich nutrients, and their color are very dark. This study was conducted to investigate the effect of gamma irradiation on the quality of seafood cooking drips including Hizikia fusiformis, Enteroctopus dofleini, and Thunnus thynnus. The Hunter's color values (L, Brightness) of H. fusiformis, and T. thynnus were increased with increasing irradiation doses, showing becoming bright. The crude protein content and crude lipid content were increased by gamma irradiation. These results indicated that gamma irradiation increased extraction efficiency of available compounds in cooking drips.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.1
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• pp.38-46
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• 2022

Two different gas diffusion layers having noticeable differences in micro-porous layer's (MPL's) crack were studied as a substrate for the gas diffusion electrode (GDE) with different binder/carbon (B/C) ratios in high-temperature polymer electrolyte fuel cell (Ht-PEMFC). As a result, the performance defined as the voltage at 0.2 A/cm² and maximum power density from the single cells using GDEs from H23 C2 and SGL38 BC with different B/C ratios were compared. GDEs from H23 C2 showed a proportional increase of the voltage with the binder content on the other hand GDEs from SGL38 BC displayed a proportional decline of the voltage to the binder content. It was revealed that MPL crack influences the structure of catalyst layer in GDEs as well as affects the RC_athode which is in close connection with the Ht-PEMFC performance.