• Smart Structures and Systems
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• v.16 no.1
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• pp.27-46
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• 2015

Active surface adjustment of cable net structures is becoming significant when large-size cable net structures are widely applied in various fields, especially in satellite antennas. A general-duty adjustment method based on active cables is proposed to achieve active surface adjustment or surface profile reconfiguration of cable net structures. Piezoelectric actuators and voice coil actuators are selected for constructing active cable structures and their simplified mechanical models are proposed. A bilevel optimization model of active surface adjustment is proposed based on the nonlinear static model established by the direct stiffness method. A pattern search algorithm combined with the trust region method is developed to solve this optimization problem. Numerical examples of a parabolic cable net reflector are analyzed and different distribution types of active cables are compared.

• Journal of Ship and Ocean Technology
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• v.8 no.3
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• pp.50-60
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• 2004

In this paper, a continuum-based design sensitivity analysis (DSA) method is developed for the weakly coupled thermo-elasticity problems. The temperature and displacement fields are described in a common domain. Boundary value problems such as an equilibrium equation and a heat conduction equation in steady state are considered. The direct differentiation method of continuum-based DSA is employed to enhance the efficiency and accuracy of sensitivity computation. We derive design sensitivity expressions with respect to thermal conductivity in heat conduction problem and Young's modulus in equilibrium equation. The sensitivities are evaluated using the finite element method. The obtained analytical sensitivities are compared with the finite differencing to yield very accurate results. Extensive developments of this method are useful and applicable for the optimal design problems incorporating welding and thermal deformation problems.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.26 no.4
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• pp.333-342
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• 2022

In this paper, we perform a direct comparison study of real experimental data for domain rearrangement and the Cahn-Hilliard (CH) equation on the dynamics of morphological evolution. To validate a mathematical model for physical phenomena, we take initial conditions from experimental images by using an image segmentation technique. The image segmentation algorithm is based on the Mumford-Shah functional and the Allen-Cahn (AC) equation. The segmented phase-field profile is similar to the solution of the CH equation, that is, it has hyperbolic tangent profile across interfacial transition region. We use unconditionally stable schemes to solve the governing equations. As a test problem, we take domain rearrangement of lipid bilayers. Numerical results demonstrate that comparison of the evolutions with experimental data is a good benchmark test for validating a mathematical model.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.4
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• pp.209-215
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• 2022

This paper proposes a novel approach for training an unsupervised depth estimation algorithm. The objective of unsupervised depth estimation is to estimate pixel-wise distances from camera without external supervision. While most previous works focus on model architectures, loss functions, and masking methods for considering dynamic objects, this paper focuses on the training framework to effectively use depth cue. The main loss function of unsupervised depth estimation algorithms is known as the photometric error. In this paper, we claim that direct depth cue is more effective than the photometric error. To obtain the direct depth cue, we adopt the technique of knowledge distillation which is a teacher-student learning framework. We train a teacher network based on a previous unsupervised method, and its depth predictions are utilized as pseudo labels. The pseudo labels are employed to train a student network. In experiments, our proposed algorithm shows a comparable performance with the state-of-the-art algorithm, and we demonstrate that our teacher-student framework is effective in the problem of unsupervised depth estimation.

• Journal of the Korea Society of Computer and Information
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• v.25 no.10
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• pp.193-201
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• 2020

This study is to evaluate the effectiveness of problem-solving ability by applying a team-based learning model to the classes of humanities and social science students, and to conduct a structural model analysis on the relationship between sub-factors. Team-based learning was conducted six times in six teams with 30 students in the second and third grades of the humanities and social sciences. The problem solving ability score of the target students was significantly higher after team-based learning and was statistically significant. There was no problem in normality with the latent variables, which are the sub-factors of problem solving ability, and the factor load value was statistically significant at the .001 level in the confirmatory factor analysis of the observed variables for the latent variables, which was a valid model. A good level of fitness was also shown in the verification of the fitness of the research model. As a result, it was analyzed that latent variables of cause analysis, problem clarification, planning execution, performance evaluation, and alternative development had an indirect or direct influence on each other.

• Korean Journal of Social Welfare
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• v.56 no.4
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• pp.269-290
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• 2004

The purpose of this study was to examine the impact of psychosocial protective and risk factors on problem drinking among American adolescents. In addition, this study investigated the compensatory and buffering effects of psychosocial protective factors. The sample consisted 4,362 10th graders taken from the Monitoring the Future Study 2002. This study performed the hierarchical regression analysis for data analyses. The main findings provided that friend influence, sensation-seeking, and tolerance of deviance had significant positive relationships with problem drinking as risk factors. This study also revealed that negative perception on drinking, parental bonding, school bonding, and prosocial activity had significant direct impacts in decreasing problem drinking, which explains the compensatory effect of protective factors. Additionally, this study showed that negative perception on drinking had a significant buffering effect moderating friend influence on adolescents' opportunities exposed to problem drinking. The results of this study suggest some practical implications for preventive intervention programs that target adolescent problem drinking.

• Journal of Distribution Science
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• v.22 no.2
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• pp.71-82
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• 2024

Purpose: Despite significant research on decision-making, researchers struggle to comprehend the decision-making process. This paper aims to not only examine the relationship between problem-solving skills, cognitive competency, and decision-making but also develop measurement instruments for cognitive competency and problem-solving skills to better model decision-making. Research Design, Methodology and Approach: A cross-sectional study was conducted by surveying 292 university students in HCM City, Vietnam, via email sent randomly by Google Forms. This study identifies the conceptual framework and tests the hypotheses using a deductive approach. The SPSS program was used to evaluate the scales' reliability, and the SmartPLS program was used to assess the measurement and structural models. Results: The results show that the research model better modelled the relationship between problem-solving skills, cognitive competency, and decision-making. Although thinking ability has no direct impact on decision-making, both creativity and problem-solving skills have a positive impact on decision-making. The mediating role of problem-solving skills is also determined by the positive relationship between cognitive competency and decision-making. Conclusions: This study highlights decision-making efficiency through the cognitive process from low to high levels and provides for policymakers and managers to explain the decision-making process in a variety of sectors, such as distribution chains, marketing, and human resource distribution.

• Management & Information Systems Review
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• v.33 no.3
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• pp.21-33
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• 2014

This study investigated the effect of protection of property right on foreign direct investment. With the US. multinational corporations over the periods from 2000 to 2008, this study used the FEM and system GMM, and found that the change of protection of property right level positively affects attracting foreign direct investment while protection of property right level itself does not. In the analyses on high income and low income countries(by income level), only the change of protection of property right level positively affects attracting foreign direct investment in low income countries. In considering the problem of heteroscedasticity on the error term, this study used FGLS and PCSE estimation methods. It is reported that the change of protection of property right level positively affects attracting foreign direct investment while protection of property right level itself does not. And only the change of protection of property right level positively affects attracting foreign direct investment in low income countries. This result means the change of protection of property right level is a key determinant to attract foreign direct investment.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.903-912
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• 2009

There are still many difficulties in developing techniques for modifying or transforming the flickering of motion capture data or in modifying motion capture data in such a way that suits the animation timing sheet. There is a problem in the existing method of modifying motion capture data. It requires almost same time as in the key frame animation work by a very skilled animator or even more time in modifying. It is believed that this kind of problem can be a basis for a more effective problem-solving method through creating the key animation data node and direct blend layer and replacement layer nodes. This study presents a new method which enables to modify animation data in a nonlinear way without modifying the existing animation data by creating an animation layer node for a direct connection to the animation node. 'Maya' API will be utilized in order to realize this method and the research range will be limited to 'Maya' 3D software which is generally used in motion picture and animation films. According to the results of this study, the new method is much more intuitive than the nonlinear one and does not require the preceding working of making animation clips. In addition, it has enabled to modify flickering and to extract key frames, and due to the compatibility with other programs, it has been possible to modify motion capture data by creating a direct layer node. Finally, in this study, the existing method of modifying animation will be examined, compared and analyzed.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.3-10
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• 2014

Direct conversion receiver(DCR) gets noticed for integration and cost reduction of wireless communication systems instead of the heterodyne receiver which uses complex filter. But DCR has several factors in performance degradation. One of them is I/Q imbalance phenomenon, that is amplitude and phase mismatch between real and imaginary part of receiver. Accordingly, researches are being carried to improve the I/Q imbalance problem. However, the tendency of the broaden bandwidth of communication systems, low pass filter(LPF) mismatch problem affects severely in I/Q mismatch phenomenon at the DCR. To study this problem, we generated 10MHz broadband signal and shifted it ${\pm}8MHz$ from the center frequency. The signal is affected by LPF mismatch and it appears as frequency selective distortion. Thus, LPF mismatch model is added to I/Q imbalance model which conventionally dealt with amplitude and phase mismatches. In addition, we proposed the compensation method for each factors of mismatch. As the simulation results, the proposed I/Q mismatch compensator resolves the frequency selective distortion which occurred by the existing LPF mismatch.