• Advances in aircraft and spacecraft science
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• 제6권2호
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• pp.157-168
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• 2019

The production of nonwoven fabrics from natural fibers is already expanding at an industrial level for simple curvature semi-structural part in the automotive industry. To develop their use for technical applications, this paper provides an experimental study of the mechanical behavior of flax-fiber nonwoven preforms. A comparison between different sets of carded needle-punched nonwoven has been used to study the influence of manufacturing parameters such as fibers' directions, the area and the needle punching densities. We have found that the anisotropy observed between both directions can be reduced depending on these parameters. Furthermore, this work investigates the possibility to form double curvature parts such as a hemisphere as well as a more complex shape such as a square box which possesses four triple curvature points. We propose a forming process adapted to the features of the nonwoven structure. The purpose is to determine their behavior under high stress during various forming settings. The preforming tests allowed us to observe in real time the manufacturing defects as well as the high deformability potential of flax nonwoven.

• Structural Engineering and Mechanics
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• 제78권3호
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• pp.269-280
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• 2021

Reinforced concrete (RC) structural walls with L-shaped sections are commonly used in RC buildings. The walls are often expected to sustain biaxial load and Unsymmetrical bending in an earthquake event. However, there currently exists limited experimental evidence regarding their seismic behaviour in these lateral loading directions. This paper makes experimental and numerical investigations to these walls behaviours. Experimental evidences are presented for four L-shaped wall specimens which were tested under simulated seismic load from different lateral directions. The results highlighted some distinct behaviour of L-shaped walls sustaining Unsymmetrical bending relating to their seismic performance. First, due to the Unsymmetrical bending, out-of-plane reaction forces occur for these walls, which contribute to accumulation of the out-of-plane deformations of the wall, especially when out-of-plane stiffness of the section is reduced by horizontal cracks in the cyclic load. Secondly, cracking was found to affect shear centre of the specimens loaded in the Unsymmetrical bending direction. The shear centre of these specimens distinctly differs in the flange in the positive and negative loading direction. Cracking of the flange also causes significant warping in the bottom part of the wall, which eventually lead to out-of-plane buckling failure.

• International Journal of Computer Science & Network Security
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• 제21권6호
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• pp.161-168
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• 2021

Within the article, strategic guidelines for the modernization of microeconomic systems are identified. Modernization levels of the potential implementation are formalized for enterprises: contractile, extensive technical, technological, progressive, adaptive, steady, intensive, creative, absolute and leader modernization. This allowed to specify the directions and tasks of the enterprise modernization at different management levels. Accordingly, the conditions and criteria for selecting resource tools are set. It is proved that the strategies of the potential modernization of enterprises must be carried out at four main management levels: first, at the enterprise level; secondly, for a particular type of product / service; third, by functional directions of modernization of separate spheres of the enterprise activity or responsibility, fourth, at the level of structural units of the enterprise. It is substantiated that in the processes due to the activation of the potential modernization, the resources are transformed into the results of the innovation implementation and the investment strategies modernization. A system of tasks for the corporate strategies implementation in order to modernize microeconomic systems has been formed. Key vectors of the activation determine the nature and properties of investment resources and necessary innovations to enhance the modernization potential. Therefore, the system of innovation and investment strategies' modernization, based on the vector and resource provision of the modernization process, is specified:

• Steel and Composite Structures
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• 제45권5호
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• pp.665-682
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• 2022

In the current study, punching behavior of Reinforced concrete (RC) isolated footings was experimentally and numerically investigated. The experimental program consisted of four half-scale RC isolated footing specimens. The test matrix was proposed to show effect of footing area, reinforcement mesh ratio, adding internal longitudinal reinforcement bars and stirrups on the punching response of RC isolated footings. Footings area varied from 1200×1200 mm2 to 1500×1500 mm2 while the mesh reinforcement ratio was in the range from 0.36 to 0.45%. On the other hand, a 3D non-linear finite element model was constructed using ABAQUS/standard program and verified against the experimental program. The numerical results agreed well with the experimental records. The validated numerical model was used to study effect of concrete compressive strength; longitudinal reinforcement bars ratio and stirrups concentration along one or two directions on the ultimate load, deflection, stiffness and failure patterns of RC isolated footings. Results concluded that adding longitudinal reinforcement bars did not significantly affect the punching response of RC isolated footings even high steel ratios were used. On the contrary, as the stirrups ratio increased, the ultimate load of RC isolated footings increased. Footing with stirrups ratio of 1.5% had ultimate load equal to 1331 kN, 19.6% higher than the bare footing. Moreover, adding stirrups along two directions with lower ratio (0.5 and 0.7%) significantly enhanced the ultimate load of RC isolated footings compared to their counterparts with higher stirrups ratio (1.0 and 1.5%).

• Educational Technology International
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• 제20권2호
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• pp.169-194
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• 2019

This study aims to compare and analyze the trends of research on mobile learning conducted in Korea and China to suggest future directions and multifaceted subject areas in its study field. To achieve this purpose, 620 Chinese papers from CNKI (CSSCI and CSCD) database and 205 Korean papers from RISS database (KCI and KCI candidate) published between 2009 and 2018 were selected to be analyzed through applying the frequency analysis and visualized semantic network analysis. The criteria for analysis used in this study are four types: publication years, research subjects, research methods, and keywords. The results of this study are as follows. Firstly, in relation to the year of publication, Korea entered the peak of mobile learning research in 2016 (33 papers), and China reached high publications (94 papers) in 2017. Secondly, with regard to the research subjects, the most frequently studied subjects in Korea and China were targeted to college students, followed by general adult groups. Thirdly, in terms of research methods, quantitative research accounted for a high proportion in Korea, but in China, literature research showed a high frequency. Fourthly, the high frequency keywords appearing in mobile learning research of the two countries were mainly reflected in language learning. Based on the findings, several directions of future research for both countries were suggested.

• 한국전자통신학회논문지
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• 제18권5호
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• pp.945-952
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• 2023

본 논문에서는 안드로이드 플랫폼 기반의 GRS칩 구동 JNI 코드 응용 SW 설계 안드로이드 플랫폼 기반 동작 제스처 프레임 모듈 설계 제작하였다. 안드로이드 기반 모듈 설계, 안드로이드 기반 모듈 구현, 안드로이드 기반 기능 모듈 구현 설계로 응용애플리케이션 기반 네트워크 지원 API 기술 제안한 직렬 데이터 수신 모듈 설계를 하였다. 안드로이드 OS의 애플리케이션을 통해 무선 통신 디바이스로부터 데이터를 수신하기 위한 직렬 통신 드라이버, 라이브러리, 프레임워크의 클래스와 같은 안드로이드 애플리케이션을 통해 센서의 데이터 정보를 확인할 수 있었다. 또한 안드로이드에서의 어플리케이션들은 자바를 이용하여 좌우상하 4방향의 동작 제스처를 판단할 수 있는 응용 SW를 구현하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.3064-3082
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• 2023

During the last decade, several Electronic Orientation Aids devices have been proposed to solve the autonomy problems of visually impaired people. When hearing is considered the primary sense for Visually Impaired people (VI) and it is generally loaded with the environment, the use of tactile sense can be considered a solution to transmit directional information. This paper presents a new wearable haptic system based on four motors implemented in shoes, while six directions can be played. This study aims to introduce an interface design and investigate an appropriate means of spatial information delivery through haptic sense. The first experiment of the proposed system was performed with 15 users in an indoor environment. The results showed that the users were able to recognize, with high accuracy, the directions displayed on their feet. The second experiment was conducted in an outdoor environment with five blindfolded users who were guided along 120 meters. The users, guided only by the haptic system, successfully reached their destinations. The potential of tactile-foot stimulation to help VI understand Electronic Orientation Aids (EOA) instructions was discussed, and future challenges were defined.

• Geomechanics and Engineering
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• 제7권3호
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• pp.263-277
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• 2014

In the conventional design of retaining structures in a seismic zone, seismic inertia forces are commonly assumed to act upwards and towards the wall facing to cause a maximum active thrust or act upwards and towards the backfill to cause a minimum passive resistance. However, under certain circumstances this design approach might underestimate the dynamic active thrust or overestimate the dynamic passive resistance acting on a rigid retaining structure. In this study, a new analytical method for dynamic active and passive forces in c-${\phi}$ soils with an infinite slope was proposed based on the Rankine earth pressure theory and the Mohr-Coulomb yield criterion, to investigate the influence of seismic inertia force directions on the total active and passive forces. Four combinations of seismic acceleration with both vertical (upwards or downwards) and horizontal (towards the wall or backfill) directions, were considered. A series of dimensionless dynamic active and passive force charts were developed to evaluate the key influence factors, such as backfill inclination ${\beta}$, dimensionless cohesion $c/{\gamma}H$, friction angle ${\phi}$, horizontal and vertical seismic coefficients, $k _h$ and $k_v$. A comparative study shows that a combination of downward and towards-the-wall seismic inertia forces causes a maximum active thrust while a combination of upward and towards-the-wall seismic inertia forces causes a minimum passive resistance. This finding is recommended for use in the design of retaining structures in a seismic zone.

• 한국의상디자인학회지
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• 제21권4호
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• pp.17-26
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• 2019

This research aims to obtain useful data on the development of compression garment products with high-stretch knitted materials. Using nylon SCY, four specimens were knitted. Then, appearance (width, length, weight, thickness), stretch property (stretch, recovery) and clothing pressure were measured and their interrelation was analyzed. In the comparison of appearance features, yarn floating caused shrinkage in both course and wale directions of the specimens. Yarn overlapping by tucking caused a release in the course direction and shrinkage in the wale direction. Also, structural change was affected by the weight and thickness change of the knitted fabric. In the analysis of fabric stretch, yarn floating reduced the extension in course direction and increased that in wale direction of the knitted fabric. However, yarn overlapping reduced the elongation in both directions. In the analysis of recovery, yarn floating and overlapping raised fabric recovery in both directions, and tuck structure was superior to float in recovery. In the analysis of clothing pressure, 'Plain-Float' structured fabrics showed a higher clothing pressure than 'Plain' and the clothing pressure value of 'Plain-Tuck' was lower than that of 'Plain'. As for the correlation between fabric appearance, stretch property, and clothing pressure, the appearance change in course direction had a major influence on the clothing pressure. The shrinkage of appearance led to a decrease in stretch and an increase in clothing pressure.

• 한국전자통신학회논문지
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• 제5권5호
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• pp.477-486
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• 2010

본 논문은 스마트그리드 전력망과 정보통신망의 이원화된 별도의 망을 하나의 통신체제로 재구성하고 스마트그리드 융합 정보통신망을 구현하기 위한 보안 방향과 향후 사이버 공격으로부터 방어를 위한 네트워크를 3단계 주요 핵심 망으로 재구성 및 기존 정보통신망 구성 계층인 TCP/IP Layer 4계층과 전력망과의 계층적 분리를 통한 방어 방향을 제안하고 있다. 또한 현재 스마트그리드 전력망의 문제점과 취약성 그리고 3가지 보안 모델을 제안함으로써 연구와 실험을 위한 기반을 제안하고 있다. 미래지향적인 전력산업의 한 기술로써 발전 방향과 현황을 제시하고 본 논문을 통하여 TCP/IP Layer별 공격과 방어를 전력망과 융합하고 새로운 스마트그리드 전력통신망 기술과 시장의 발전방향 및 스마트그리드 향후 정보보안 과제를 알아보는데 의의가 있다.