• Polymer(Korea)
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• v.30 no.2
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• pp.140-145
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• 2006

The mort commonly available substrate material is glass in the display fibrication process. However, glass is not desirable due to its heaviness and fragility. Recently, plastics such polysulfone (PSF), polyethesulfone (PES), polycarbonate (PC), polyethylene terephthalate (PET) and cyclic olefin polymers (COP) have been investigated to replace glass as a substrate material for display fibrication. Plastic substrates are advantageous in that they are lightweight, huh impart resistance, flexibility, and ability for roll to roll manufacturing process. But many plastics have poor chemical resistance in organic solvent. The chemica resistance is also lequired because they are exposed to solvents for various chemical treatments din the manufacturing process. So, we have an interest in the chemical modification of PSF to improve chemical resistance. We introduced crosslinkable imide moieties using chloromethylation method for the modification of PSF which could be overcome above shortcomings for display substrate based on plastic film. We prepared the cross-linked polysulfone films which were represented chemical resistance in HeOH, THF, DMSO and NMP. The thermal properties were measured by TGA, DSC and TMA. As the results, we have confirmed to enhance of the thermal property. They had low coefficient of thermal expansion (CTE) which decreased to 15% and had increased $T_g\;from\;180^{\circ}C\;to\;252^{\circ}C$. Cross-linked polysulfone films with imide side-chain had good optical properties and chemical resistance so that they could be used as flexible display substrate.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.466-472
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• 2013

The use of a concrete track is gradually growing in urban and high-speed railways in many part of the world. The resilient pad, which is essentially when concrete tracks are used, plays the important role of relieving the impact caused by train loads. The simple fatigue test[1] to estimate the variable stiffness of resilient pads is usually performed, but it differs depending on the practical conditions of different railways. In this study, the static stiffness levels of used resilient pads according to passing tonnages levels were measured in laboratory tests. Also, the simple fatigue test and the multi-stress accelerated degradation test for new resilient pads were performed in a laboratory. The static stiffness of the used pad was compared with the results of tests of usage times and cycles. The results of the comparison showed that the variable static stiffness levels of the used pad were similar to results of the multi-stress accelerated degradation test considering the fatigue and heat load. With a T-NT equation related to the degree of the multi-stress accelerated degradation, a model of multi-stress accelerated degradation for a resilient pad was devised. It was found through this effort that the total acceleration factor was approximately 2.62. Finally, this study proposes an equation for a multi-stress accelerated degradation model for polyurethane resilient pads.

• Korean Journal of Poultry Science
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• v.47 no.1
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• pp.29-37
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• 2020

This study was performed to investigate the effect of mixed rearing of male and female chickens on the stress response in Korean native chickens. To identify the degree of the stress response, heterophil-lymphocyte ratio (H/L ratio), heat shock protein genes (HSPs) expression, and intracellular nuclear DNA damage rate were analyzed before and after the mixed rearing of male and female chickens. The results showed that the H/L ratio of chickens after mixing males and females was more than thrice as higher than before mixing (P<0.001), but the differences between males and females were not significant. HSP-70, HSP90-α, and HSP90-β expression levels were 2.5 to 3.4 times higher after mixing male and female chickens, compared to before mixing (P<0.01). In the mixed rearing of male and female chickens, the increase in HSPs expression in females was higher than in males. Comet indicators in intracellular DNA damage rate analysis showed a significant increase after mixing male and female chickens compared to before mixing (P<0.001). However, there was no significant difference between males and females with respect to DNA damage rate. Taken together, these results suggest that male and female mixed rearing acts as a strong external stressor in both male and female chickens.

• Journal of Life Science
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• v.28 no.10
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• pp.1212-1219
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• 2018

The critical role of heat shock protein 90 (Hsp90) in tumorigenesis led to the development of several first- and second-generation Hsp90 inhibitors, which have demonstrated promising responses in cancers. In this study, we found second-generation Hsp90 inhibitor BIIB021-resistant multidrug-resistant (MDR) human cancer cells, although BIIB021 was shown to be active in first-generation Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG)-resistant MDR cells. MCF7-MDR and HeyA8- MDR cells were more resistant to BIIB021 than their parental counterparts, indicating that BIIB021 cannot be applicable to all cancer cells expressing MDR proteins. We revealed that dimethyl-celecoxib (DMC), one of the non-steroidal anti-inflammatory drugs (NSAIDs), potentiated cytotoxicity of BIIB021 against both BIIB021-resistant and BIIB021-sensitive MDR cells. The effectiveness of NSAIDs involving celecoxib and DMC in combination with BIIB021 led to the autophagic degradation/down-regulation of mutant p53 (mutp53) that overexpressed MDR cells and the suppression of Hsp70 induction. This resulted in sensitization of MDR cells to BIIB021. Moreover, autophagy induction by sulindac sulfide, another type of NSAID, and niclosamide, an FDA-approved anthelmintic drug, potentiated 17-AAG-mediated autophagic degradation/down-regulation of mutp53 and c-Myc, client proteins of Hsp90. Therefore, our results suggest that NSAIDs and niclosamide positively enhance the anticancer activity of Hsp90 inhibitors through an autophagic pathway. They may also be new candidates for sensitizing MDR cells to Hsp90 inhibitors.

• Journal of Navigation and Port Research
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• v.36 no.5
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• pp.339-347
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• 2012

After towing rope connecting a barge to a tug was subdivided into multiple finite elements, then those dynamic models was established using Newton's second law and considering the external force and moment such as tension, drag, Coriolis force, gravity, buoyancy, and impact due to free surface acting on each element. While the previous research on the model of towing rope considered only translation, five-degree-of-freedom equations of motion except roll based on the body-fixed frame were established in this paper. All elements are connected by a spring and a damper, and the stiffness of the spring was set as the equivalent value of the real rope. In order to confirm the established multiple finite element model, various scenarios such as freely falling of towing rope in the air and above the free surface, accelerating of a tug which tows a barge connected by towing rope, and sinusoidal moving of a tug were set up and simulated. As the results, the trajectories of the tug, the barge, and the towing rope showed good tendencies to the ones of real expected situations.

• Journal of Aquaculture
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• v.17 no.4
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• pp.268-274
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• 2004

Olive flounder was treated with oxytetracycline (OTC) and changes in blood physiology, antioxidant enzymes and heat shock protein (HSP) were recorded to obtain preliminary data for optimal OTC treatment. Blood parameters were measured 1 and 3 h after the OTC treatments at the concentration of 0 (control), 100, 300 and 500 ppm for I h. Hematocrit decreased with time, however the difference was not significant (P>0.05). Reduced number of red blood cell was observed with increasing OTC concentration. Serum glucose level increased as the OTC concentration increased. However, glucose level was similar to control after 3 h. Blood total protein decreased immediately after the OTC treatment but increased after 1 and 3 h. However, the increment in blood total protein was low. Activities of superoxide dismutase enzymes in 300 and 500 ppm groups increased by the OTC concentration. Catalase enzyme activity was negatively affected by the OTC concentration. However, the differences were not significant (P>0.05). High expression of HSP-70 protein was recorded for groups treated with 100 and 500 ppm compared to that of the control group. However HSP-70 mRNA showed a lower increment which was not significant (P>0.05).

• Fire Science and Engineering
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• v.23 no.6
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• pp.66-74
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• 2009

When a fire occurs, the concrete structure's strength decreases by the increasing temperature under the fire in certain condition of constant load. And, the ratio of the axial force is changed by such decreased strength so that the structure is deformed. In this research, considering such case, we have conducted an actual fire test for the concrete lining with constant loading condition and various fire conditions. The specimen adopts the shape condition for small practical specimen defined by the EFNARC and we used 24MPa, 40MPa and 50MPa to analyze the thermal properties by the strength. The ratio of loading is imposed by a certain loading condition based on 20% and 40% of the sectional stress in concrete and MHC Fire is selected to realize the thermal impact of the concrete by rapid increasing temperature. As the result of the experiment, in the same ratio of loading, the 50MPa specimen shows more cracks and spalling as time goes on. The area damaged by the fire, according to the functional criteria of the concrete lining under the fire in ITA, does not satisfy with the standard in lack of 50mm depth from the heating surface at total 200mm lining.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.27-33
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• 2016

Phenolic resin has excellent heat resistance and good mechanical properties as a thermosetting resin. However, its thermosetting characteristics cause it to produce a non-recyclable waste in the form of sprue and runner which is discarded and represents up to 15~20% of the overall products. Forty thousand tons of phenolic resin sprue and runner are disposed of (annually). The (annual) cost of such domestic waste disposal is calculated to be 20 billion won. In this study, discarded phenol resin scraps were pulverized and treated by silanes to improve their interfacial adhesion with HDPE. The sizes of the pulverized pulverulent bodies and fine particles were (100um~1000um) and (1~100um), respectively. The pulverized phenol resin was treated with 3-(methacryloyloxy) propyltrimethoxysilane and vinyltrimethoxy silane and the changes in its characteristics were evaluated. The thermal properties were evaluated by DSC and HDT. The mechanical properties were assessed by a notched Izod impact strength tester. When the silane treated phenol resin was added, the heat distortion temperature of HDPE increased from $77^{\circ}C$ to $96^{\circ}C$ and its crystallinity and crystallization temperature also increased. Finally, its impact strength and tensile strength increased by 20% and 50%, respectively, in comparison with the non-treated phenol resin.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.125-134
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• 2017

Unusual precipitation caused by typhoons and severe rain stormscan threaten human life and property. Thus, various organizations prepare emergency action plans (EAPs) to provide proper guidelines for operators, experts, and emergency response personnel to protect and enhance critical infrastructure. For example, FEMA and DHS have various types of EAPs for dams, levees, and other structures to protect people and property. FEMA defines EAPs as official documents to decrease the damage and impact in emergency situations and to reduce casualties. These documents should consider all possible situations in an emergency and can reduce problems in facility management. This study analyzes EAPs for infrastructure from the USA, Japan, and Korea in order to suggest an ideal EAP framework. EAPcontent can include how to guide experts and operators in disaster stages (mitigation, preparedness, response, and recovery), how to operate emergency equipment, and how to protect critical infrastructure and life. The suggested EAP framework performed very well in a test location. It can therefore be used for infrastructure organizations in Korea and to inform of the appropriate processes and methods for risk reduction in flood disasters.

• Journal of Marine Life Science
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• v.7 no.1
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• pp.29-36
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• 2022

Sea cucumber, Aposticopus japonicus, is a major invertebrate species in the coastal regions of Korea. To evaluate the short-term stress levels according to the releasing methods, this study investigated the gene expression profiles of heat shock protein 90 (HSP90) by real-time quantitative polymerase chain reaction. When the juvenile sea cucumbers were packed in the vinyl bag with oxygen followed by transportation for 30 min or air-exposed for 1 h, the HSP90 gene expression levels in the experimental groups were significantly increased compared to those of the control groups (transported group, p=0.001; air-exposed group, p=0.032). The experimental group at 6 h post-release by seed-spreading method and at 2~6 h post-release by underwater hose-releasing method on board a fishing boat showed that the levels of HSP90 gene expression were not statistically significant but decreased slightly compared to the control group (seed-spreading group, p=0.069; hose-releasing group, p=0.093). On the other hand, the HSP90 gene expression showed an increasing pattern as the time passed (~6 h) after underwater release of juvenile sea cucumbers by divers (p=0.061). These results suggest that HSP90 gene expression can be used to investigate short-term stress response and effective releasing methods of juvenile sea cucumbers.