• Journal of the Computational Structural Engineering Institute of Korea
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• 제35권5호
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• pp.299-308
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• 2022

This study was conducted to predict the tendency for heat exchange and boil-off gas (BOG) in a liquefied hydrogen tank under sloshing excitation. First, athe fluid domain excited by sloshing was modeled using a multiphase-thermal flow domain in which liquid hydrogen and hydrogen gas are in the saturated state. Both the the volume of fluid (VOF) and Eulerian-based multi-phase flow methods were applied to validate the accuracy of the pressure prediction. Second, it was indirectly shown that the fluid velocity prediction could be accurate by comparing the free surface and impact pressure from the computational fluid dynamics with those from the experimental results. Thereafter, the heat ingress from the external convective heat flux was reflected on the outer surfaces of the hydrogen tank. Eulerian-based multiphase-heat flow analysis was performed for a two-dimensional Type-C cylindrical hydrogen tank under rotational sloshing motion, and an inflation technique was applied to transform the fluid domain into a computational grid model. The heat exchange and heat flux in the hydrogen liquid-gas mixture were calculated throughout the analysis,, whereas the mass transfer and vaporization models were excluded to account for the pure heat exchange between the liquid and gas in the saturated state. In addition, forced convective heat transfer by sloshing on the inner wall of the tank was not reflected so that the heat exchange in the multiphase flow of liquid and gas could only be considered. Finally, the effect of sloshing on the amount of heat exchange between liquid and gas hydrogen was discussed. Considering the heat ingress into liquid hydrogen according to the presence/absence of a sloshing excitation, the amount of heat flux and BOG were discussed for each filling ratio.

• 한국체육학회지인문사회과학편
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• 제51권3호
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• pp.363-372
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• 2012

One of the major ocular complications of diabetes mellitus(DM) is retinopathy, which is characterized by increased neovascularization and neural degeneration in the retina. In the present study, we investigated the effects of treadmill exercise on retinopathy in the rats with DM. Thirty-two male Sprague-Dawley rats were divided into four groups(n = 8 in each group): control group, exercise group, DM-induction group, and DM-induction and exercise group. DM was induced by intraperitoneal injection of streptozotocin. The rats in the exercise groups were made to run on the treadmill for 30 min five times per a week, during 12 weeks. The expressions of phosphoinositide 3-kinase(PI3K), phospho-protein kinase B(pAkt), hypoxia inducible factor-1α(HIF-1α), and vascular endothelial growth factor(VEGF) in the retina were determined using western blot analysis and immunohistochemistry. In the present results, the expressions of PI3K, pAkt, HIF-1α, and VEGF in the retina of the diabetic rats were increased. Treadmill exercise suppressed HIF-1α and VEGF expressions through inhibition of PI3K/pAkt pathway in the diabetic rats. These results suggest that treadmill exercise may ameliorate the progression of diabetes-induced retinopathy by inhibiting neovascularization in the retina.

• Journal of International Area Studies (JIAS)
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• 제13권1호
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• pp.345-368
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• 2009

Our research task have goal to describe a treaty rhetoric known as 『La Rhétorique ou L'Art de Parler』(1688) which corresponds to a very wide field of which the step is not yet dubious in our country. Thus to study the rhetoric of Lamy borrowed from the thought of Descartes, we left the concept d' origin of language in traditional rhetoric in connection with logic and grammar (in first part). Also the second part is devoted to the tropes and the figures that are modified and deteriorated by the language of passion called 'rhetoric of passion or psychological of figure', etc. And the third part interests in the body of the speech being the character of l' heart. Under the influence of the rhetoric of Lamy, French rhetoric at the 17th century is held for an essential text when one interests in the history of the ideas and rhetoric, marked in its specificity (passion). The project of Lamy registered in the concept of passion like 'manners of speaking'. To close this study, which does one have to retain? The first remark to note is that Lamy founds his rhetoric in opposition to traditional designs dating from the beginning of Aristote. Second remark is the idea that one finds based in famous the books of Dumarsais at the 18th century and Fontanier at the 19th century. Admittedly, Lamy is a true rhetorician, grammairien which interests in the question of passions in the speech forces to reconsider the idea spread since Mr. Foucault, and makes it possible to understand the passage of the Great century at the Century of Lumuères. Even if this opinion is not shared, it will be agreed that the work of Lamy on passions or the phenomena sensory and psychological in the center of the language deserves reflexion.

• Journal of the Korean Geotechnical Society
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• 제22권8호
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• pp.129-136
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• 2006

Engineered mixtures, which consist of rigid sand particles and soft fine-grained rubber particles, are tested to characterize their small and large-strain responses. Engineered soils are prepared with different volumetric sand fraction, sf, to identify the transition from a rigid to a soft granular skeleton using wave propagation, $K_{o}-loading$, and triaxial testing. Deformation moduli at small, middle and large-strain do not change linearly with the volume fraction of rigid particles; instead, deformation moduli increase dramatically when the sand fraction exceeds a threshold value between sf=0.6 to 0.8 that marks the formation of a percolating network of stiff particles. The friction angle increases with the volume fraction of rigid particles. Conversely, the axial strain at peak strength increases with the content of soft particles, and no apparent peak strength is observed in specimens when sand fraction is less than 60%. The presence of soft particles alters the formation of force chains. While soft particles are not part of high-load carrying chains, they play the important role of preventing the buckling of stiff particle chains.

• Journal of the Korean Geotechnical Society
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• 제38권2호
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• pp.29-38
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• 2022

The friction anisotropy of shear resistance can be selectively used in geo-structures. For example, larger axially loaded deep foundation, soil nails, and tiebacks increase load carrying capacity due to induced large shear resistance while pile penetration and soil sampling produce minimal shear resistance. Previous studies confirmed direction-dependent shear resistance induced by interface between soil and surface asperity of plate inspired by geometrical shape of snake scale. The aim of this paper is to quantitatively evaluate interface friction angle with different surface asperities. Using the modified direct shear test, a total of 51 cases, which sand are prepared at the relative density of 40%, are conduced including 9 plates, two shear direction (shearing direction against the height of surface asperity is increased or decreased during shearing test), and three initial vertical stress (100 kPa, 200 kPa, 300 kPa). Experimental results show that shear stress is increased with higher height of surface asperity, shorter length of surface asperity, and the shearing direction that the height of surface asperity increases. Also, interface friction angle is decreased with larger surface asperity ratio, and shearing direction with increasing height of surface asperity produces larger interface friction angle regardless of the surface asperity ratio.

• Journal of Practical Agriculture & Fisheries Research
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• 제18권1호
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• pp.101-112
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• 2016

Monitoring and control of the greenhouse environment play a decisive role in greenhouse crop production processes. The network system for greenhouse control was developed by using recent technologies of networking and wireless communications. In this paper, a remote monitoring and control system for greenhouse using a smartphone and a computer with internet has been developed. The system provides real-time remote greenhouse integrated management service which collects greenhouse environment information and controls greenhouse facilities based on sensors and equipments network. Graphical user interface for an integrated management system was designed with bases on the HMI and the experimental results showed that a sensor data and device status were collected by integrated management in real-time. Because the sensor data and device status can be displayed on a web page, transmitted using the server program to remote computer and mobile smartphone at the same time. The monitored-data can be downloaded, analyzed and saved from server program in real-time via mobile phone or internet at a remote place. Performance test results of the greenhouse control system has confirmed that all work successfully in accordance with the operating conditions. And data collections and display conditions, event actions, crops and equipments monitoring showed reliable results.

• Korean Journal of Remote Sensing
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• 제39권6_1호
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• pp.1517-1522
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• 2023

This study evaluates the impact of Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) expected error (EE) on the accuracy of surface reflectance (SR) derived from the KOMPSAT-3A satellite, utilizing the Second Simulation of the Satellite Signal in the Solar Spectrum Vector radiative transfer model. By considering a range of ground-based AOD and the resultant MODIS AOD EE, the research identifies significant influences on SR accuracy, particularly under high solar zenith angles(SZA) and shorter wavelengths. The study's simulations reveal that SR errors increase with shorter wavelengths and higher SZAs, highlighting the necessity for further research to improve atmospheric correction algorithms by incorporating wavelength and SZA considerations. Additionally, the study provides foundational data for better understanding the use of AOD data from other satellites in atmospheric correction processes and contributes to advancing atmospheric correction technologies.

• The Journal of the Convergence on Culture Technology
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• 제9권6호
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• pp.525-530
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• 2023

Digital drawing subjects require the subdivision of evaluation elements and the graduality of evaluation according to the recent movement of the innovative curriculum. The purpose of this paper is to present the criteria for evaluating the drawing and to propose it as a rubric evaluation. In the text, criteria for beginner evaluation were technical skills such as the accuracy and consistency of the line, the ratio and balance of the picture, and the ability to effectively utilize various brushes and tools at the intermediate levels. In the advanced evaluation section, it is a part of a new perspective or originality centered on creativity and originality, and a unique perspective or interpretation of a given subject. In addition, as an understanding of design principles, the evaluation of completeness was derived focusing on the ability to actively utilize various functions of digital drawing software through design principles such as placement, color, and shape. The importance of introducing rubric evaluation is to allow instructors to make objective and consistent evaluations, and the key to research in rubric evaluation in these art subjects is to help learners clearly grasp their strengths and weaknesses, and learners can identify what needs to be improved and develop better drawing skills accordingly through feedback on each item.

• The Journal of the Korea institute of electronic communication sciences
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• 제18권6호
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• pp.1015-1022
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• 2023

In this paper, we propose DLP(Dual Linear Polarization) antenna with aperture coupled feeding structure for private network. The proposed antenna has general aperture coupled structure and design two port between top and bottom layer to obtain the enhanced isolation. Also, The size of each substrate(top and bottom layer) is 34.0 mm(W)×34.0 mm(L), which is designed on the FR-4 substrate which thickness (h) is 1.0 mm, and the dielectric constant is 4.4. Also, the size of patch antenna is 12.70 mm(W2)×14.60 mm(L3), and it is located on the top layer. The size of feeding line is 24.0 mm(W2)×1.6 mm(L3), and is located at the bottom layer Also, rectangular slot is located on the ground plane between top layer and bottom layer. From the fabrication and measurement results, bandwidths of 300 MHz (4.52 to 4.82 GHz) for feeding port 1, and 170 MHz (4.65 to 4.82 GHz) for feeding port 2 are obtained on the basis of -10 dB return loss and transmission coefficient S21 is got under the -30 dB. Also, cross polarization isolation between each feeding port obtained

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• 제17권4호
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• pp.127-142
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• 2022

According to social change, entrepreneurship education at university is drawing attention as a means to cultivate convergent creative competency required by the times. Currently, the number of entrepreneurship education at university is increasing every year, and quantitative expansion is taking place, but quality advancement of education remains a task. In this context, this study conducted an action research with the aim of revitalizing entrepreneurship education and upgrading quality, and developing a entrepreneurship education program suitable for general elective courses operated by universities. In the process of the study, first, through literature analysis related to entrepreneurship education at university, educational contents and teaching methods of entrepreneurship education were confirmed. Based on this, the IPA analysis was used to analyze the educational needs of students for entrepreneurship education contents and design a program that reflects this. The designed program was applied and operated to the entrepreneurship education of A University, and improvements were derived and improved by analyzing the opinions of learners in the action research process. The entrepreneurship education program developed through this study was composed as follows. The necessity of entrepreneurship education at the beginning of the lecture is sufficiently presented, and the knowledge necessary for start-up, including idea discovery and business model design, is delivered through theoretical lectures by teacher-centered method. In the second half of the lecture, students with similar interests are gathered into teams and learner-centered practical activities are operated. The contents of the activities include information on idea discovery, business model design, business plan and pitching. Practical activities for each team are conducted during class hours, and the professor advice on difficulties for each team.