• Laboraroty Animal Research
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• v.33 no.2
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• pp.76-83
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• 2017

Chronic obstructive pulmonary diseases (COPD) is an important disease featured as intense inflammation, protease imbalance, and air flow limitation and mainly induced by cigarette smoke (CS). In present study, we explored the effects of $Pycnogenol^{(R)}$ (PYC, pine bark extract) on pulmonary fibrosis caused by CS+lipopolysaccharide (LPS) exposure. Mice were treated with LPS intranasally on day 12 and 26, followed by CS exposure for 1 h/day (8 cigarettes per day) for 4 weeks. One hour before CS exposure, 10 and 20 mg/kg of PYC were administered by oral gavage for 4 weeks. PYC effectively reduced the number of inflammatory cells and proinflammatory mediators caused by CS+LPS exposure in bronchoalveolar lavage fluid. PYC inhibited the collagen deposition on lung tissue caused by CS+LPS exposure, as evidenced by Masson's trichrome stain. Furthermore, transforming growth $factor-{\beta}1$ ($TGF-{\beta}1$) expression and Smad family member 2/3 (Smad 2/3) phosphorylation were effectively suppressed by PYC treatment. PYC markedly reduced the collagen deposition caused by CS+LPS exposure, which was closely involved in $TGF-{\beta}1$/Smad 2/3 signaling, which is associated with pulmonary fibrotic change. These findings suggest that treatment with PYC could be a therapeutic strategy for controlling COPD progression.

• Wind and Structures
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• v.32 no.2
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• pp.127-142
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• 2021

Wind load acting on a standalone structure is different from that acting on a similar structure which is surrounded by other structures in close proximity. The presence of other structures in the surrounding can change the wind flow regime around the principal structure and thus causing variation in wind loads compared to a standalone case. This variation on wind loads termed as interference effect depends on several factors like terrain category, geometry of the structure, orientation, wind incident angle, interfering distances etc., In the present study, a three building configuration is considered and the mean pressure coefficients on each face of principle building are determined in presence of two interfering buildings. Generally, wind loads on interfering buildings are determined from wind tunnel experiments. Computational fluid dynamic studies are being increasingly used to determine the wind loads recently. Whereas, wind tunnel tests are very expensive, the CFD simulation requires high computational cost and time. In this scenario, Artificial Neural Network (ANN) technique and Support Vector Regression (SVR) can be explored as alternative tools to study wind loads on structures. The present study uses these data-driven approaches to predict mean pressure coefficients on each face of principle building. Three typical arrangements of three building configuration viz. L shape, V shape and mirror of L shape arrangement are considered with varying interfering distances and wind incidence angles. Mean pressure coefficients (Cp mean) are predicted for 45 degrees wind incidence angle through ANN and SVR. Further, the critical faces of principal building, critical interfering distances and building arrangement which are more prone to wind loads are identified through this study. Among three types of building arrangements considered, a maximum of 3.9 times reduction in Cp mean values are noticed under Case B (V shape) building arrangement with 2.5B interfering distance. Effect of interfering distance and building arrangement on suction pressure on building faces has also been studied. Accordingly, Case C (mirror of L shape) building arrangement at a wind angle of 45º shows less suction pressure. Through this study, it was also observed that the increase of interfering distance may increase the suction pressure for all the cases of building configurations considered.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.6
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• pp.375-382
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• 2020

Owing to the rapid development of infrared guided weapon systems, the threat to aircraft survivability is constantly increasing, and research on infrared stealth technologies are being conducted to ensure aircraft survival. In this study, we analyze the minimum infrared signature of an aircraft according to its flight altitude by considering the characteristics of infrared guided missiles, which detect the contrast signature between the aircraft and background. We conducted computational fluid dynamics simulations for the convective coefficient, and heat transfer simulations were performed considering convection, conduction, and radiation for flight conditions. Thus, we obtained the surface temperature distribution of the aircraft and analyzed the aircraft infrared signature based on the flow characteristics around it. Furthermore, the optimum emissivity for the minimum infrared signature was derived, and the effect of the infrared signature was analyzed when this optimum emissivity was applied to the fuselage surface for each flight condition.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.65-76
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• 2020

On the initial design process of a scramjet vehicle such as the trajectory prediction, it is inevitable to estimate the aerodynamic performance of a three-dimensional effect. Despite the necessity of intensive computing for the three-dimensional model, it is inefficient in predicting a wide range of aerodynamic performance. In this study, an engineering model for aerodynamic performance was developed based on two-dimensional computational fluid analysis and linearized supersonic inviscid flow theory. Correspondingly, the three-dimension aerodynamic performance relations are presented based on the two-dimensional results. And the additional three-dimensional computation was performed to evaluate the adequacy for the extended relations.

• Journal of English Language & Literature
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• v.57 no.1
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• pp.147-170
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• 2011

This paper elucidates the characteristics of transnational adoption, estimates the possibility of beyond-borders identity of transnational adoptees, and tries to analyze Jane Jeong Trenka's The Language of Blood in its context. Though it has been regarded as one of the most humanitarian ways of helping orphans and poor children of the world, transnational adoption, a one-way flow of children from poor Asian countries to rich white countries, has been operated under the market logic between countries. Transnational adoptees, who had been abandoned and forced to be taken away from their birth mother, and later, to fulfill the desire of white parents for a perfect family, perform an ideological labor, serving to make the heterogeneous nuclear family complete. Korean transnational adoptees, forced to transcend the borders of nation, culture, and ethnicity, experience racial conflict and alienation in white adoptive family and society. Their diaspora experience of violent dislocation creates frustration and confusion in establishing their identity as a whole being. When they return to Korea to find their birth mother and their true identity, Korean adoptees, however, are faced with other obstructing issues, such as language problem, culture conflict, and maternal nationalism. Finally, Korean transnational adoptees reject Korean nationalism discourse based on blood, and try to redefine themselves as beyond-borders subjectivities with new and fluid identities. Jane Jeong Trenka's The Language of Blood, an autobiographical novel based on her experiences as a transnational adoptee, represents a Korean adopted girl's personal, cultural, and racial conflict within her white adoptive family, and questions the image of benevolent white mother and the myth of multiculturalism. The novel further represents Jane's return to Korea to find out her true identity, and shows Jane's disappointment and alienation in her birth country due to her ignorance of language and culture. Returning to USA again, and trying to be reconciled with her American mother, Jane shows the promise of accepting her new identity capable of transcending the borders, and thus, the possibility of enlarging the category of belonging.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.538-549
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• 2021

In this study, a trim tab on the stern hull of a small high-speed vessel of approximately 10 m length sailing at a Froude number of 1.0 was designed for energy efficiency. The running attitude and resistance performance of the bare hull and trim tab hull at several angles to the base line were analyzed for model and full scale ships using computational fluid dynamics, and compared to investigate the scale effect. The analysis results for the bare hull were quite similar, but a difference in the attitude control under same conditions of the trim tab was observed, resulting in the total resistance error. However, there was no significant difference in tendency of the variation in the resistance with the attitude. Thus, the optimum running attitude could be determined from the tendency despite the scale effect, but a full scale analysis is required to analyze the control of the attitude by the trim tab and flow characteristics near the full scale ship.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.420-433
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• 2020

In order to increase the stability of existing breakwater, new caissons are installed on the back or the front of existing caissons. It is very important to evaluate wave force and wave run-up according to the change of porosity among caissons and the energy loss due to separation effects. In this study, we use the eigenfunction expansion method with Darcy's law, which describes the flow of a fluid through a porous plate, to analyze the characteristics of wave on circular breakwater of double array for various porous coefficients. To verify the numerical method, the comparison between present results and Sankarbabu et al. (2008) is made. The wave force and the wave run-up acting on each dual cylindrical caisson are calculated for various parameters by considering the energy loss and the change of porosity.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.5
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• pp.10-17
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• 2021

In this study, cold-flow test of simulant gel is conducted using a pressure swirl injector to identify spray characteristics according to gellant weight percent. Experiment results show the aircore is developed locally at the nozzle and expanded to the entire swirl chamber as the supply pressure increases. The aircore formation of simulant gel showed no significant difference compared to Newtonian fluid. The spray pattern was classified into four distinct shapes where relationship between the breakup regimes and dimensionless numbers were investigated. In the future, additional study is necessary to understand the aircore formation mechanism, stability and spray characteristics at different configuration of the swirl chamber shape.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.1
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• pp.121-129
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• 2022

With the recent increase in international trade volume the trade volume through ships is also continuously increasing. The treatment of ballast water goes through the following five steps, samples are taken and analyzed at each step, and samples are obtained using a suction pump. These suction pumps have low efficiency and thus need to be improved. In this study, it is to optimize the form of the impeller which affects directly improvements of performance to determine the capacity of suction pump and to fulfill the purpose of this research. To do it, we have carried out parametric design as an input variable, geometric form for the impeller. By conducting the flow analysis for the optimum form, it has confirmed the value of improved results and achieved the purpose to study in this paper. It has selected the necessary parameter for optimizing the form of the pump impeller and analyzed the property using experiment design. And it can reduce the factor of parameter for local optimization from findings to analyze the property of form parameter. To perform MOGA(Multi-Objective Genetic Algorithm) it has generated response surface using parameters for local optimization and conducts the optimization using multi-objective genetic algorithm. with created experiment cases, it has performed the computational fluid dynamics with model applying the optimized impeller form and checked that the capacity of the pump was improved. It could verify the validity concerning the improvement of pump efficiency, via optimization of pump impeller form which is suggested in this study.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.3
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• pp.122-127
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• 2021

Flow features near the ship bow such as wave breaking, small scale phenomena have been studied using numerical methods. In this study, the bow shaped wedge was adopted which is from previous paper [1, 2] and the conditions of simulation were Re = 1.64 × 10⁵) and Fr = 2.93. Star CCM+, one of the commercial CFD programs has been used for the simulations. Simulation results such as wave profiles near the ship bow, shape of plunging jet, air entrainment, and wave breaking process have been compared with previous experimental and numerical studies. Overall results showed good agreements with previous studies. Profiles of bow waves showed that overturning jet has been created and broken along the wedge. Plunging wave breaking has been observed along the wedge and four components of plunging wave breaking process were shown. It is confirmed that velocity near the overturing jet significantly increased during plunging wave breaking.