• Journal of Microbiology and Biotechnology
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• v.33 no.4
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• pp.430-440
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• 2023

The type three secretion system (T3SS) is a major virulence system of Pseudomonas aeruginosa (P. aeruginosa). The effector protein Exotoxin S (ExoS) produced by P. aeruginosa is secreted into the host cells via the T3SS. For the purpose of an experiment on inhibitors with regard to ExoS secretion, we developed a sandwich-type enzyme-linked immunosorbent assay (ELISA) system. Quercetin was selected because it has a prominent ExoS inhibition effect and also is known to have anti-inflammatory and antioxidant effects on mammalian cells. In this study, we investigated the effects of quercetin on the expression and secretion of ExoS using ELISA and Western blot analysis methods. The results showed that the secretion of ExoS was significantly decreased by 10 and 20 µM of quercetin. Also, popB, popD, pscF, and pcrV which are composed of the T3SS needle, are reduced by quercetin at the mRNA level. We also confirmed the inhibitory effect of quercetin on cytokines (IL-6, IL-1β, and IL-18) in P. aeruginosa-infected H292 cells by real-time polymerase chain reaction (PCR) and ELISA. Collectively, quercetin inhibits the secretion of ExoS by reducing both ExoS production and the expression of the needle protein of T3SS. Furthermore, these results suggest that quercetin has the potential to be used as an anti-toxic treatment for the inflammatory disease caused by P. aeruginosa infection.

• Korean Journal of Veterinary Research
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• v.38 no.4
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• pp.745-750
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• 1998

A sensitive and rapid enzyme immunoassay(EIA) to detect Escherichia coli O157 in ground beef was developed by using a sandwich type assay with polyclonal antibodies to E coli O157. E coli O157 in ground beef could be detected within 15hr, including incubation for 12hr in enrichment broth and 3hr in immunoassay. The EIA could detect $1.3{\times}10^5$ cells of E coli O157/g of ground beef without enrichment. The lowest limit of detection was 0.23 E coli O157 per g of meat after enrichment. Confirmation was required in the positive specimens in the EIA by culture method even though the negative specimens were not. These results suggested that the immunoassay could be a very efficient method for the screening E coli O157 in meat.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.2
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• pp.78-81
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• 2020

Quantum dot efficiency was increased to evaluate reliability and optical characteristics using incidental materials. Quantum dot was manufactured by wrapping a sandwich type quantum layer using a product with a barrier property to prevent water and oxygen because it is vulnerable to oxygen and moisture. We used the three quantum dot films consisting of quantum dot only and quantum dot products consisting of film and barrier film combined with PET in the quantum dot product to evaluate the change over 650 hours under high temperature and high humidity conditions at 60℃ and 90 % humidity. As a result, the quantum dot product with Barrier Film has lowered luminance by 8 %, CIE x by 2 % and CIE y by 8 %. Quantum dot products exposed to moisture and oxygen were oxidized and measured low before measurement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.55-60
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• 2010

The honeycomb composite joint structure designed for application to a tilting KTX railroad car body is subjected to bending loads of a cantilever type. Honeycomb sandwich composite panel-joint attached in the real tilting car body was fabricated and sectioned as several beam-joint specimens for the bending test. The fracture behaviors of these specimens under static loads were different from those under cyclic loads. Static bending loads caused shear deformation and fracture in the honeycomb core region, while fatigue cyclic bend loading caused delamination along the interface between the composite skin and the honeycomb core, and/or caused a fracture in the welded part jointed with the steel under-frame. These fracture behaviors could occur in other industrial honeycomb composite joints with similar sub-structures, and be used for improving design parameters of a honeycomb composite joint structure.

• Fire Science and Engineering
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• v.32 no.2
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• pp.82-91
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• 2018

This study analyzed the working conditions and problems of screen fire shutters in the Goyang Bus Terminal fire based on the fire investigation results. At that time, screen fire shutters in the 1st basement, which was under construction, did not work because the power was shut off. Four screen fire shutters in the 1st and 3rd floor did not work despite the power not being shut off. The following problems related to a screen fire shutter were found: shutting off the power to screen fire shutters for the fire compartment on each floor, even when the fire compartments were changed in each area; installing an integral type screen fire shutter without any regulations, installing a two-stage screen fire shutter in a place not related to obstacles during evacuation; stopping the function of the screen fire shutters for a fire compartment on each floor after a combustible sandwich panel was comparted; installing a screen fire shutter over 10 meters in width, in which its performance was not verified; and no safety control standards for reinstalling or maintaining a screen fire shutter.

• The Journal of Internal Korean Medicine
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• v.27 no.1
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• pp.208-220
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• 2006

Objective: Eosinophils are typically characterized by a bilobar nucleus with highly condensed chromatin and cytoplasm containing two major types of granules, specific and primary granules, and lipid bodies. The role of inflammation in asthma and other allergic diseases of the airways is widely appreciated, and airway inflammation is now included as a defining feature of asthma. The importance of the presence of eosinophils in the airways of patients with fetal asthma has long been recognized, but the mechanism by which these cells are recruited and retained in the lungs are only now being elucidated. Eotaxin is a potent and specific eosinophil chemoattractant that is mobilized in the respiratory epithelium after allergic stimulation. Methods : Water extracts of Armeniacae Amarum Semen(AAS) and pulmonary epithelial cell lines A549(alveolar typeII epithelial cells) and human eosinophils were used. Cytotoxic effects of AAS and MIS assay were estimated, as well as the effects of AAS on chemokines from prestimulated A549 cells by sandwich ELISA and RI-PCR. Chemotaxis assay was conducted on prestimulated eosinophils treated with AAS. Results : In this study it is demonstrated that $TGF-{\alpha}$, IL-4 and $IL-1{\beta}$ induced the accumulation of chemokine mRNAs in the alveolar epithelial cell lines A549 in dose-dependent manner. Eotaxin and IL-8 were inhibited by AAS in dose-dependent manner(p<0.05). Eosinophil migration was inhibited at high concentrations of AAS(p<0.05). Conculusions : These findings are indicative of suppression of eotaxin and IL-8, and suggest that this is accomplished through AAS treatment. This raises the possibility that AAS is of therapeutic value in diseases such as asthma.

• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.359-368
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• 2013

This paper presents a simplified analysis method using the elastic equivalent modelling not using the global finite element modelling of deck for the basic design GFRP composites deck with cellular tubes or sandwich structural type. In order to verify the validation of the simplified method ANSYS software package is used and compared the results analyzed on the global finite element modelling and the elastic equivalent modelling. And the laboratory testing by 4-point bending is conducted to compare the results based on the simplified analysis method proposed in this paper. The comparison of the results based on the analysis and the testing are discussed. It is found that the presented simplified analysis is applicable to the use in the basic design GFRP composite deck.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.862-868
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• 2010

Development of a small scale aircraft has been carried out for the BASA(Bilateral Aviation Safety Agreement) program in Korea. This aircraft adopted all the composite structures for environmental friendly by low fuel consumption due to its lightness behavior. However the composite structure has s disadvantage which is very weak against impact due to foreign object damages. Therefore the aim of this study is focusing on the damage evaluation and repair techniques of the aircraft composite structure. The damages of composite laminates including the carbon/epoxy UD laminate and the carbon/epoxy fabric face sheets-honeycomb core sandwich laminate were simulated by a drop weight type impact test equipment and the damaged specimen were repaired using the external patch repair method after removing damaged area. The compressive strength test and analysis results after repairing the impact damaged specimens were compared with the compressive strength test and analysis results of undamaged specimens and impact damaged specimens. Finally, the strength recovery capability by repairing were investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.501-504
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• 2011

In this study, structural design of the propeller blade for turboprop aircraft was performed. The propeller shall have high strength to get the thrust to fly at high speed. The high stiffness and strength carbon/epoxy composite material was used for the major structure and skin-spar-foam sandwich structural type was adopted for improvement of lightness. As a design procedure for the present study, firstly the structural design load was estimated through investigation on aerodynamic load and then flanges of spars from major bending loads and the skin from shear loads were preliminarily sized using the netting rule. In order to investigate the structural safety and stability, stress analysis was performed by finite element analysis code MSC. NASTRAN. Finally, it is investigated that designed blade have high efficiency and structural safety to analyze of aerodynamic and structural design results.

• The Journal of Korean Oriental Chronic Disease
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• v.10 no.1
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• pp.1-20
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• 2005

Background and Objective: The importance of the presence of eosinophils in the airways of patients with fetal asthma has long been recognized, but the mechanism by which these cells are recruited and retained in the lung are only now being elucidated. Eotaxin is a potent and specific eosinophil chemoattractant that is mobilized in the respiratory epithelium after allergic stimulation. Material and Methods: We used water extracts of Liripois Tuber and pulmonary epithelial cell lines A549(human typeII-like epithelial cells) and human eosinophils. We estimated cytotoxic effects of Liripois Tuber via MTS assay, and estimated the effects of Liripois Tuber on chemokines from prestimulated A549 cells by sandwich ELISA and RT-PCR. We conducted chemotaxis assay on prestimulated eosinophils treated with Liripois Tuber. Result: In this study we demonstrated that $TNF-{\alpha}$, IL-4 and $IL-1{\beta}$ induced the accumulation of chemokines mRNA in the pulmonary epithelial cell lines A549 in dose-dependent manner. Chemokines were inhibited by Liripois Tuber in dose-dependent manner. The eosinophil migration was inhibited at high concentration of Liripois Tuber. Conculusion: These findings indicate that the supression of the expression of chemokines can be accomplished by Liripois Tuber treatment, raising the possibility that Liripois Tuber might be of therapeutic value in diseases such as asthma.