• Structural Engineering and Mechanics
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• v.71 no.1
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• pp.89-98
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• 2019

In this study, the mechanical bending behaviors of functionally graded porous nanobeams are investigated. Four types of porosity which are, the classical power porosity function, the symmetric with mid-plane cosine function, bottom surface distribution and top surface distribution are proposed in analysis of nanobeam for the first time. A comparison between four types of porosity are illustrated. The effect of nano-scale is described by the differential nonlocal continuum theory of Eringen by adding the length scale into the constitutive equations as a material parameter comprising information about nanoscopic forces and its interactions. The graded material is designated by a power function through the thickness of nanobeam. The beam is simply-supported and is assumed to be thin, and hence, the kinematic assumptions of Euler-Bernoulli beam theory are held. The mathematical model is solved numerically using the finite element method. Numerical results show effects of porosity type, material graduation, and nanoscale parameters on the static deflection of nanobeam.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.223-232
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• 2019

Since the actuators with small- scale structures may be exposed to external reciprocal actions lead to create undesirable loads causing instability, the buckling behaviors of them are interested to make reliable or accurate actions. Therefore, the purpose of this paper is to analyze plastic buckling behavior of the micro beam structures by adopting a Conventional Mechanism-based Strain Gradient plasticity (CMSG) theory. The effect of length scale on critical force is considered for three types of boundary conditions, i.e. the simply supported, cantilever and clamped - simply supported micro beams. For each case, the stability equations of the buckling are calculated to obtain related critical forces. The constitutive equation involves work hardening phenomenon through defining an index of multiple plastic hardening exponent. In addition, the Euler-Bernoulli hypothesis is used for kinematic of deflection. Corresponding to each length scale and index of the plastic work hardening, the critical forces are determined to compare them together.

• ETRI Journal
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• v.41 no.1
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• pp.42-51
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• 2019

The rainbow hologram provides views of reconstruction with rainbow color within a large viewing zone. In our recent paper, a Fourier rainbow holographic display using diffraction grating and a white-light LED source was introduced. In this technique, the rainbow effect is realized by the dispersion of white-light source on diffraction grating, while the slit is implemented numerically by reducing the demands of the space-bandwidth product of the display. This paper presents a novel analysis on the visual perception of the Fourier rainbow holographic display using Wigner distribution. The view-dependent appearance of the image, including multispectral field of view and viewing zone, is investigated considering the observer and the display parameters. The resolution of the holographic view is also investigated. For this, a new quantitative assessment for image blur is introduced using Wigner distribution analysis. The analysis is supported with numerical simulations and experimentally captured optical reconstructions for the holograms of the computer model and real object generated with different slit size, reconstruction distance, and different observation conditions.

• Smart Structures and Systems
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• v.23 no.5
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• pp.429-447
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• 2019

The present study analyzed free vibration of the three-layered micro annular/circular plate which its core and face sheets are made of saturated porous materials and FG-CNTRCs, respectively. The structure is subjected to magneto-electric fields and magneto-electro-mechanical pre loads. Mechanical properties of the porous core and also FG-CNTRC face sheets are varied through the thickness direction. Using dynamic Hamilton's principle, the motion equations based on MCS and FSD theories are derived and solved via GDQ as an efficient numerical method. Effect of different parameters such as pores distributions, porosity coefficient, pores compressibility, CNTs distribution, elastic foundation, multi-physical pre loads, small scale parameter and aspect ratio of the plate are investigated. The findings of this study can be useful for designing smart structures such as sensor and actuator.

• International Journal of Computer Science & Network Security
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• v.22 no.4
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• pp.229-236
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• 2022

This study investigates the impact of flipped classroom strategy in developing students' achievement and acquisition of life skills. The study employed a quasi-experimental design where students were divided into two groups: an experimental (N=22) and a control (N=22). The randomly selected and assigned sample consisted of sixth-year elementary school students studying English as a basic course. The findings revealed statistically significant differences between the two group's means in both achievement and life skills tests in favor of the experimental group. Students of the experimental group who studied using the flipped classroom strategy outperformed the control group who studied in the standard way in achieving the English language and in the life situations test, where the effect size of the use of the strategy was large in both dependent variables. The study is concluded with some recommendations to facilitate the use of flipped classroom strategy for EFL teachers. This can be achieved by training teachers on using the strategy and providing technological resources at schools to implement the strategy efficiently.

• Advances in concrete construction
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• v.13 no.6
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• pp.451-459
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• 2022

In present study, the nonlocal Flügge shell model based is utilized to investigate the vibration characteristics of armchair and chiral single-walled carbon nanotubes with impact of small-scale effect subjected to two boundary supports. The wave propagation approach is employed to determine eigen frequencies for armchair and chiral tubes. The fundamental frequencies scrutinized with assorted aspect ratios by varying the bending rigidity. The raised in value of nonlocal parameter reduces the corresponding fundamental frequency. It is investigated with higher aspect ratio, the boundary conditions have a momentous influence on vibration of CNT. It is concluded that frequencies would increase by increasing of the bending rigidity. Solutions of the frequency equation have determined by writing in MATLAB coding.

• Advances in nano research
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• v.16 no.2
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• pp.175-186
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• 2024

Dynamical behaviors of one-dimensional (1D) nano-sized structures are of great importance in nanotechnology applications. Therefore, the torsional dynamic response of functionally graded nanorods which could be used to model the nano electromechanical systems or micro electromechanical systems with torsional motion about the center of twist is examined based on the theory of strain gradient nonlocal elasticity in this work. The mathematical background is constructed based on both strain gradient theory and Eringen's nonlocal elasticity theory. The equation of motions and boundary conditions of radially functionally graded nanorods are derived using Hamilton's principle and then transformed into the eigenvalue analysis by using Fourier sine series. A general coefficient matrix is obtained to assemble the Stokes' transformation. The case of a restrained functionally graded nanorod embedded in two elastic springs against torsional rotation is then deeply investigated. The effect of changing the functionally graded index, the stiffness of elastic boundary conditions, the length scale parameter and nonlocal parameter are investigated in detail.

• Korean Journal of Social Welfare Studies
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• v.49 no.4
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• pp.101-129
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• 2018

This study examined the overall effect size of the batterer intervention programs aimed at reducing violent behavior. This study calculated the 18 results and the 115 effect sizes of 11 theses published from 2000 to 2017 in Korea. It was demonstrated that the effect of an offender's program on the change in violent behavior was significant at both the practical and treatment level. The effect size was high in the order of control behavior, emotional violence, and physical violence. The effects of dependent variables other than violence were also researched. The batterer program positively changed the participant's attitudes in terms of sex-role and partner violence. Furthermore, it decreased the level of anger and depression, and enhanced self-esteem and communication skills thus increasing satisfaction in marital relationships. In addition, this study examined the factors that influence the effect of the offender's program in terms of the decrease of violent behavior. Upon analysis, it was examined that the moderating effect was great in the approach model and counsel form. More specifically, it was revealed that the feminist-cognitive behavioral models had a greater effect than the compromise model or single model. In terms of counsel forms, group counseling formed only of male offenders had greater effect than couples treatment group. Based on these findings, this study discussed the practical means for increasing the effect of batterer intervention programs.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.2
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• pp.103-118
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• 2012

In this study, the cellular protective effect of isoquercitrin against $H_2O_2$ and rose bengal-indued HaCaT cell damage was investigated. The ethosome and elastic liposome for enhanced transdermal delivery were prepared. Particle size, loading efficiency and cumulative permeated amounts of them were evaluated. Isoquercitrin didn't show any characteristic cytotoxicity at 50 ${\mu}M$. When HaCaT cells were treated with 5 mM $H_2O_2$ and 25 ${\mu}M$ rose bengal, isoquercitrin protected the cells against the oxidative damage in a concentration dependent manner (6.25 ~ 50 ${\mu}M$). The size of 0.03 % isoquercitrin loaded ethosome was 222.85 nm and the loading efficiency was 82.26 %. The ethosome loaded with 0.03 % isoquercitrin was stable and maintained the constant particle size for 2 weeks after being prepared. The ethosome exhibited more enhanced skin permeability than general liposome and ethanol solution. The optimal ratio of lipid to surfactant of 0.1 % isoquercitrin loaded elastic liposomes was observed to be 89 : 5 through evaluating particle size (341.2 nm), deformability index (59.89), loading efficiency (54.3 %), and skin permeability (54.4 %).

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.6
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• pp.95-114
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• 2020

This paper, a meta-analysis of the effect of the start-up support policy on the start-up performance was conducted to examine the effect of the start-up support policy on the start-up performance of beneficiary companies and to provide theoretical and practical implications to support organizations and practitioners. To this end, 35 papers containing the correlation coefficient, which is a positive statistical value, were selected from the previous studies in academic journals and dissertations published in Korea from 2007 to 2020. In the preceding study of the start-up support policy, the independent variables include funding, education support, facility/equipment support, network support, mentoring support, consulting support, marketing support, management support, technical support, manpower support, and finance as a dependent variable. The effect size of the impact on aptitude and non-financial performance was reviewed. The pattern of the effect size was presented as a forest plot for easy visual understanding, and outliers were verified through sensitivity analysis for small-study-effect data with publication convenience. As a result of analyzing the effect size of the government-supported policy, it was verified that the effect size was generally medium or higher, affecting the entrepreneurial performance. Among the independent variables, the factor that has the greatest effect on startup performance is manpower support, followed by technical support, marketing support, management support, facility/equipment support, education support, mentoring support, funding, network support, and consulting support. It was analyzed that the effect size was large in order. As the 「Small and Medium Business Startup Support Act」 was recently reorganized from the manufacturing industry to digital transformation and smartization on October 8, 2020, the start-up support policy should consider the start-up stage and verify the priorities to organize the budget.