• Journal of the Korean Mathematical Society
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• v.41 no.5
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• pp.821-864
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• 2004

Both parametric and parameter-free necessary and sufficient optimality conditions are established for a class of nondiffer-entiable nonconvex optimal control problems with generalized fractional objective functions, linear dynamics, and nonlinear inequality constraints on both the state and control variables. Based on these optimality results, ten Wolfe-type parametric and parameter-free duality models are formulated and weak, strong, and strict converse duality theorems are proved. These duality results contain, as special cases, similar results for minmax fractional optimal control problems involving square roots of positive semi definite quadratic forms, and for optimal control problems with fractional, discrete max, and conventional objective functions, which are particular cases of the main problem considered in this paper. The duality models presented here contain various extensions of a number of existing duality formulations for convex control problems, and subsume continuous-time generalizations of a great variety of similar dual problems investigated previously in the area of finite-dimensional nonlinear programming.

• Journal of the Ergonomics Society of Korea
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• v.32 no.6
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• pp.517-528
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• 2013

Objective: The objective of this study was to suggest a multi-modal controller type for Smart TV Control. Background: Recently, many issues regarding the Smart TV are arising due to the rising complexity of features in a Smart TV. One of the specific issues involves what type of controller must be utilized in order to perform regulated tasks. This study examines the ongoing trend of the controller. Method: The selected participants had experiences with the Smart TV and were 20 to 30 years of age. A pre-survey determined the first independent variable of five tasks(Live TV, Record, Share, Web, App Store). The second independent variable was the type of controllers(Conventional, Mouse, Voice-Based Remote Controllers). The dependent variables were preference, task completion time, and error rate. The experiment consist a series of three experiments. The first experiment utilized a uni-modal Controller for tasks; the second experiment utilized a dual-modal Controller, while the third experiment utilized a triple-modal Controller. Results: The first experiment revealed that the uni-modal Controller (Conventional, Voice Controller) showed the best results for the Live TV task. The second experiment revealed that the dual-modal Controller(Conventional-Voice, Conventional-Mouse combinations) showed the best results for the Share, Web, App Store tasks. The third experiment revealed that the triple-modal Controller among all the level had not effective compared with dual-modal Controller. Conclusion: In order to control simple tasks in a smart TV, our results showed that a uni-modal Controller was more effective than a dual-modal controller. However, the control of complex tasks was better suited to the dual-modal Controller. User preference for a controller differs according the Smart TV functions. For instance, there was a high user preference for the uni-Controller for simple functions while high user preference appeared for Dual-Controllers when the task was complex. Additionally, in accordance with task characteristics, there was a high user preference for the Voice Controller for channel and volume adjustment. Furthermore, there was a high user preference for the Conventional Controller for menu selection. In situations where the user had to input text, the Voice Controller had the highest preference among users while the Mouse Type, Voice Controller had the highest user preference for performing a search or selecting items on the menu. Application: The results of this study may be utilized in the design of a controller which can effectively carry out the various tasks of the Smart TV.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.506-511
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• 1998

In this paper we consider multiobjective linear programming problems with coefficients of the objective functions specified by possibility distributions. Possibly and necessarily efficient solution sets are defined as funny solution sets whose membership grades represent possibility and necessity degrees to which a feasible solution is efficient. Considering efficiency condition and its dual condition in ordinary multiobjective linear programming problem, we propose efficiency test methods based on an extreme ray generation method. Since the proposed methods can be put in the part of a bi-section method, we can develop calculation and methods of the degree of possible and necessary efficiency for feasible solutions.

• Journal of applied mathematics & informatics
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• v.18 no.1_2
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• pp.361-376
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• 2005

Optimality conditions are derived for a nonlinear fractional program in which a support function appears in the numerator and denominator of the objective function as well as in each constraint function. As an application of these optimality conditions, a dual to this program is formulated and various duality results are established under generalized convexity. Several known results are deduced as special cases.

• Physical Therapy Rehabilitation Science
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• v.10 no.4
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• pp.493-502
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• 2021

Objective: Older adults with mild cognitive impairment (MCI) are more likely to progress to dementia. Motor-cognitive training is applied as a dual-task to improve the cognitive and physical functions of older adults with MCI. The purpose of the study was to know the recent trends in motor training types and outcome measures used for motor-cognitive training in older adults with MCI. Design: Aliterature review Methods: This literature review was conducted in Pubmed, MEDLINE® and Google Scholar with the following key words: older adults, mild cognitive impairment, motor-cognitive training, cognition, and dual-task. The 7 studies were found with the search tool and all studies were randomized controlled trials. Results: In motor-cognitive training in older adults with MCI, 6 studies applied aerobic exercise. And 3 out of 6 studies also applied strengthening exercises. One study applied dual tasks without aerobic exercise. In the 6 studies, overall cognitive and executive function were used as outcome measures, and physical function was evaluated as gait performance. Memory and physical frailty were also used as measurement tools. As a result of all studies, when motor-cognitive training was applied, cognition and physical performance showed significant results. Conclusions: A recent five-year study applied mainly aerobic exercise and strength training to older adults with MCI and found it to improve cognitive and physical performance.

• Journal of Communications and Networks
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• v.18 no.5
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• pp.796-805
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• 2016

In many wireless sensor network (WSN) applications, the information transmitted by an individual entity or node is of limited use without the knowledge of its location. Research in node localization is mostly geared towards multi-hop range-free localization algorithms to achieve accuracy by minimizing localization errors between the node's actual and estimated position. The existing localization algorithms are focused on improving localization accuracy without considering efficiency in terms of energy costs and algorithm convergence time. In this work, we show that our proposed localization scheme, called DV-maxHop, can achieve good accuracy and efficiency. We formulate the multi-objective optimization functions to minimize localization errors as well as the number of transmission during localization phase. We evaluate the performance of our scheme using extensive simulation on several anisotropic and isotropic topologies. Our scheme can achieve dual objective of accuracy and efficiency for various scenarios. Furthermore, the recently proposed algorithms require random uniform distribution of anchors. We also utilized our proposed scheme to compare and study some practical anchor distribution schemes.

• Physical Therapy Rehabilitation Science
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• v.13 no.3
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• pp.332-342
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• 2024

Objective: With the proportion of the elderly population in Korea reaching 17.5% in 2022 and projected to increase to 20.6% by 2025, 30.1% by 2035, and 43% by 2050, the accelerated aging of the population is raising societal concerns about elderly care. Maintaining mobility is crucial for a healthy and independent old age. Design: Cross-sectional study Methods: This study investigates the effects of dual-task performance on gait variables and cognitive function in older adults. This cross-sectional study involved 60 older adults aged 65 and above, categorized into a dementia group (Korean version of Montreal Cognitive Assessment (MoCA-K) score ≤ 22) and a control group (MoCA-K score ≥ 23). Cognitive and gait functions were assessed using the GAITRite system (GAITRite system, CIR Systems Inc., USA), measuring gait variables (speed, stride length, etc.) before and after dual-task performance. The assessments were conducted under a single-blind condition, and data were analyzed using SPSS (ver. 25.0, SPSS Inc., USA). Results: The dementia group scored lower on cognitive assessments compared to the control group (p<0.05). In dual-task performance evaluations, the dementia group exhibited longer total task times and lower accuracy than the control group (p<0.001), while reaction times were longer but not statistically significant. GAITRite system analysis revealed that the dementia group had reduced gait speed and stride length compared to the control group (p<0.05). However, the difference in gait time was not statistically significant. The study results indicate that older adults with dementia show significant differences in cognitive function and gait performance, with notable impacts under dual-task conditions. Conclusions: These findings underscore the effect of cognitive decline on gait and provide valuable insights for predicting gait and cognitive function deterioration in dementia, which can aid in developing fall prevention strategies.

• Industrial Engineering and Management Systems
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• v.9 no.1
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• pp.10-19
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• 2010

This paper presents an extended computing procedure for the global optimization of the triple response system (TRS) where the response functions are nonconvex (nonconcave) quadratics and the input factors satisfy a radial region of interest. The TRS arising from response surface modeling can be approximated using a nonlinear mathematical program involving one primary (objective) function and two secondary (constraints) functions. An optimization algorithm named triple response surface algorithm (TRSALG) is proposed to determine the global optimum for the nondegenerate TRS. In TRSALG, the Lagrange multipliers of target (secondary) functions are computed by using the Hooke-Jeeves search method, and the Lagrange multiplier of the radial constraint is located by using the trust region (TR) method at the same time. To ensure global optimality that can be attained by TRSALG, included is the means for detecting the degenerate case. In the field of numerical optimization, as the family of TR approach always exhibits excellent mathematical properties during optimization steps, thus the proposed algorithm can guarantee the global optimal solution where the optimality conditions are satisfied for the nondegenerate TRS. The computing procedure is illustrated in terms of examples found in the quality literature where the comparison results with a gradient-based method are used to calibrate TRSALG.

• International Journal of Highway Engineering
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• v.17 no.5
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• pp.93-103
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• 2015

PURPOSES : The purpose of this study is to present a linear programing optimization model for the design of lane-based lane-uses and signal timings for an isolated intersection. METHODS: For the optimization model, a set of constraints for lane-uses and signal settings are identified to ensure feasibility and safety of traffic flow. Three types of objective functions are introduced for optimizing lane-uses and signal operation, including 1) flow ratio minimization of a dual-ring signal control system, 2) cycle length minimization, and 3) capacity maximization. RESULTS : The three types of model were evaluated in terms of minimizing delay time. From the experimental results, the flow ratio minimization model proved to be more effective in reducing delay time than cycle length minimization and capacity maximization models and provided reasonable cycle lengths located between those of other two models. CONCLUSIONS : It was concluded that the flow ratio minimization objective function is the proper one to implement for lane-uses and signal settings optimization to reduce delay time for signalized intersections.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.445-454
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• 2015

In this paper, we propose an optimal design method for a dual reflector antenna(DRA) using the Genetic algorithm. In order to reduce the computational burden during the optimal design, we exploit the iterative physical optics(IPO) to calculate the surface current distribution at each reflector antenna. To improve the accuracy, we consider the shadow effect by the structure and the coupling effect by the multi-reflection based on the iterative MFIE(Magnetic Field Integral Equation). To reduce the number of design variables and generate a smooth surface, we use the Bezier function with the control points, which become the design variables in this paper. We adopt the HPBW(Half Power Beam Width), the FNBW(First Null Beam Width), and the SLL(Side Lobe Level) as the objective or cost functions. To verify the results, we compare them with the those of the commercial tool.