• 소음진동
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• 제5권1호
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• pp.29-35
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• 1995

This paper presents the simultaneous optimal design of structure and LQG control systems for the improvement of riding comforts of active vehicle suspension systems. The performance index of riding comforts is extended to include frequency-weighted acceleration in the quadratic cost functional. Janeway human response curve with respect to acceleration is used to verify the usefulness of the presented method. The method is applied to a half model of an active vehicle suspension systems with elastic body moving on randomly profiled road. The values of stiffness of suspensions are used for the structural design variables. The conjugate gradient method is used for optimization. The simulated results of simultaneous optimization with frequency-weighted cost functional are compared with those without frequency- weighted cost functional.

• 한국생산제조학회지
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• 제25권5호
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• pp.313-320
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• 2016

The need for high-strength, multi-axis, and multi-functional machine tools has recently increased because of part complexity and workpiece strength. However, most of the machine tool manufacturers rely on experience for a detailed design because of the shortcomings in the existing design technology. This study uses a topology optimization method to more effectively design a large multi-functional machine tool considering static stiffness. The ram, saddle, and column parts are important structures in a machine tool. Hence, they are selected for the finite element method analysis. Based on this analysis, the optimized internal rib structure for those parts is designed for desirable rigidity and weight. This structure could possibly provide the required design technology for machine tool manufacturers.

• 대한간호학회지
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• 제42권3호
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• pp.311-321
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• 2012

Purpose: This study was designed to construct and test a structural equation modeling on specific domain health status and the Selection Optimization Compensation (SOC) strategy affecting successful aging in elderly people. Methods: The model construction was based on the SOC model by Baltes and Baltes. Interviews were done with 201 elderly people aged 65 or older. Interview contents included demographics, functional health status, emotional health status, social health status, SOC strategies, and successful aging. Data were analyzed using SPSS 15.0 and AMOS 7.0. Results: Model fit indices for the modified model were GFI=.93, CFI=.94, and RMSEA=.07. Three out of 7 paths were found to have a significant effect on successful aging in this final model. Functional health status had a direct and positive effect on successful aging. Emotional health status influenced successful aging through SOC strategies. Conclusion: This study suggests that interventions for improving functional health status and for strengthening SOC strategies are critical for successful aging. Continuous development of a variety of successful aging programs using SOC strategy is suggested.

• Nonlinear Functional Analysis and Applications
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• 제28권1호
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• pp.1-9
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• 2023

Our aim in this paper is to give some new proofs to fixed point theorems due to Abdou [1] for mappings satisfying Reich type contractions in modular metric spaces. We removed the restriction that ω satisfies the ∆₂-type condition imposed on the results of [1]. Furthermore, Lemma 2.6 of [1] which was crucial in the proofs of the results of [1] is not needed in the proofs of our results. Our method of proof is simpler and interesting.

• Nonlinear Functional Analysis and Applications
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• 제28권4호
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• pp.957-988
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• 2023

We define new classes of expansive-type mappings in the setting of modular 𝜔^G-metric spaces and prove the existence of common unique fixed point for these classes of expansive-type mappings on 𝜔^G-complete modular 𝜔^G-metric spaces. The results established in this paper extend, improve, generalize and compliment many existing results in literature. We produce some examples to validate our results.

• Nonlinear Functional Analysis and Applications
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• 제29권2호
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• pp.361-391
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• 2024

In this paper, a pair of ω-compatible self mappings in the setting of modular G-metric space is defined. We prove the existence and uniqueness of common fixed point of pairs of ω-compatible self mappings in a G-complete modular G-metric space. Furthermore, we give an example to justify our claims. The results established in this paper extend, improve, generalize and complement some existing results in literature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.870-875
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• 2004

Current trend of design technologies shows engineers to objectify or automate the given decision-making process. The numerical optimization is an example of such technologies. However, in numerical optimization, the uncertainties are uncontrollable to efficiently objectify or automate the process. To better manage these uncertainties, Taguchi method, reliability-based optimization and robust optimization are being used. To obtain the target performance with the maximum robustness is the main functional requirement of a mechanical system. In this research, the robust design strategy is developed based on the DACE and the global optimization approaches. The DACE modeling, known as the one of Kriging interpolation, is introduced to obtain the surrogate approximation model of the system. The robustness is determined by the DACE model to reduce the real function calculations. The simulated annealing algorithm of global optimization methods is adopted to determine the global robust design of a surrogated model. The mathematical problems and the MEMS design problem are investigated to show the validity of the proposed method.

• 대한수학회논문집
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• 제13권1호
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• pp.195-209
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• 1998

In this paper we present a new iteration method for solving optimization problems governed by partial differential equations. We generalize the existing methods such as simple gradient methods and pseudo-time methods to get an efficient iteration method. Numerical tests show that the convergence of the new iteration method is much faster than those of the pseudo-time methods especially when the parameter $\sigma$ in the cost functional is small.

• Nonlinear Functional Analysis and Applications
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• 제26권1호
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• pp.65-70
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• 2021

We characterize the solution set for a second-order cone linear fractional optimization problem (P). We present sequential Lagrange multiplier characterizations of the solution set for the problem (P) in terms of sequential Lagrange multipliers of a known solution of (P).

• Nonlinear Functional Analysis and Applications
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• 제26권3호
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• pp.611-628
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• 2021

In this paper, we propose a new branch-reduction-and-bound algorithm to solve the nonlinear knapsack problems by using general discrete monotonic optimization techniques. The specific properties of the problem are exploited to increase the efficiency of the algorithm. Computational experiments of the algorithm on problems with up to 30 variables and 5 different constraints are reported.