• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.152-172
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• 1992

The ship sailing among waves are suffered the various wave loads that comes from its motion throughout its life. Because there are dynamic, the analysis of ship structure must be considered as the dynamic problem precisely. In the rationally-based design, the dynamic structural analysis is carried out using dynamic wave loads provided from the results of the ship mouton calculation as the rigid body. This method is based on the linear theory assumed low wave height and small amplitude of motion. But at the rough sea condition, high wave height, relatively ship's depth, is induced the large ship motion, so the ship section configulation below water line is rapidly changed at each time. This results in non-linear problem. Considering above situation in this paper, the strength analysis method is introduced for the hull glider among waves considering non-linear hydrodynamic forces. This paper considers that the overall or primary level of the ship structural dynamic loading and dynamic response provided from the non-linear wave forces, and bottom and bow flare impact forces estimated by momentum slamming theory, in which the ship is idealized as a hollow thin-walled box beam using thin-walled beam theory and the finite element method. This method is applied to 40,000 Ton Double-Skin Tanker and attention is paid to the influence of the response of ship speed, wave length and wave height compared with linear strip theory.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.418-429
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• 2018

This paper studies the decentralized position/force control problem for constrained reconfigurable manipulator without torque sensing. A novel joint torque estimation scheme that exploits the existing structural elasticity of the manipulator joint with harmonic drive model is applied for each joint module. Based on the estimated joint torque and dynamic output feedback technique, a decentralized position/force control strategy is presented. In order to solve the problem of controller parameter perturbation, the non-fragile robust technique is introduced into the dynamic output feedback controller. Subsequently, the stability of the closed-loop system is proved using the Lyapunov theory and linear matrix inequality (LMI) technique. Finally, two 2-DOF constrained reconfigurable manipulators with different configurations are applied to verify the effectiveness of the proposed control scheme in numerical simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1353-1362
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• 2003

This paper considers a simultaneous optimization problem of structure and control systems. The problem is generally formulated as a non-convex optimization problem for the design parameters of mechanical structure and controller. Therefore, it is not easy to obtain the global solutions for practical problems. In this paper, we parameterize all design parameters of the mechanical structure such that the parameters work in the control system as decentralized static output feedback gains. Using this parameterization, we have formulated a simultaneous optimization problem in which the design specification is defined by the Η$_2$and Η$\_$$\infty$/ norms of the closed loop transfer function. So as to lead to a convex problem we approximate the nonlinear terms of design parameters to the linear terms. Then, we propose a convex optimization method that is based on linear matrix inequality (LMI). Using this method, we can surely obtain suboptimal solution for the design specification. A numerical example is given to illustrate the effectiveness of the proposed method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.608-612
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• 2012

To reduce these costs and time by finite element analysis program has been much research (3~4). At virtual CAE program as like Abaques, Ansys, Ls-dyna and Nastran, the input data of material is got bellow coupon test. In case of carbon composite, it is also put in lamina/laminate properties. There have big problem. If you want to simulate FW(filament winding or wind blade) how do you input material data. Each area of FW is different stacking conditions. It's too hard that each area is tested for inputting lamina or laminate properties. The composite structure increasing load is applied occurred as the matrix dependence of the crack-induced nonlinearity and nonlinear mobility appears since the initial damage. And uni-direction for this research applies the theory to have been confined to. On this study, we are going to get basically fiber properties and matrix than carbon composite properties for simulating according stacking method by GENOA-MCQ. It is help to simulate easily composite material. Also Calculate the matrix nonlinear for simulating non-linear.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.385-390
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• 2003

Recently, use of Continuous Welded rail(CWR) is increased for structural, economical reason but new problem is caused accordingly and phenomenon that give threat in traveling by ship stability of train is led. According as rail is prolonged, excessive relative displacement and longitudinal force can happen to rail by temperature change and external force. Specially, buckling or fracture of rail can happen in railroad bridges because relative displacement by bridge and properties of matter difference between rail grows and additional axial force happens to rail by behavior of bridge. According to several study, longitudinal force of rail in bridge is influenced with ballast resistance, elongation length, boundary condition, stiffness of framework. Non-linear behavior of ballast acts by the most important factor in interaction between rail and bridge. Therefore, must consider stiffness of bridge construction with non-linear characteristic of ballast and stiffness of base for accuracy with longitudinal force calculation and analyze. In this study, perform material non-linear analysis for longitudinal force of CWR and three dimensional buckling analysis to decide buckling force.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.53-58
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• 2007

A particle method, recognized as one of gridless methods, has been developed to investigate non-linear free-surface motions interacting with structures. This method is more feasible and effective than conventional grid methods for solving flow fieldswith complicated boundary shapes. The method consists of particle interaction models representing pressure gradient, diffusion, incompressibility, and the free-surface boundary conditions without grids. In the present study, broken dam problems with various viscosity values are simulated to validate the developed method.

• Coupled systems mechanics
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• v.10 no.1
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• pp.1-19
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• 2021

Composite nature of the masonry structures in general causes complex and non-linear behaviour, especially in intense vibration conditions. The presence of different types and forms of structural elements and different materials is a major problem for the analysis of these type of structures. For this reason, the analysis of the behaviour of masonry structures requires a combination of experimental tests and non-linear mathematical modelling. The famous UNESCO Heritage Old Bridge in Mostar was selected as an example for the analysis of the global behaviour of reinforced stone arch masonry bridges. As part of the experimental research, a model of the Old Bridge was constructed in a scale of 1:9 and tested on a shaking table platform for different levels of seismic excitation. Non-linear mathematical modelling was performed using a combined finite-discrete element method (FDEM), including the effect of connection elements. The paper presents the horizontal displacement of the top of the arch and the failure mechanism of the Old Bridge model for the experimental and the numerical phase, as well as the comparison of the results. This research provided a clearer insight into the global behaviour of stone arch masonry structures reinforced with steel clamps and steel dowels, which is significant for the structures classified as world cultural heritage.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.169-180
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• 2015

Recently, scheduling problems with position-dependent processing times have received considerable attention in the literature, where the processing times of jobs are dependent on the processing sequences. However, they did not consider cases in which each processed job has different learning or aging ratios. This means that the actual processing time for a job can be determined not only by the processing sequence, but also by the learning/aging ratio, which can reflect the degree of processing difficulties in subsequent jobs. Motivated by these remarks, in this paper, we consider a two-agent single-machine scheduling problem with linear job-dependent position-based learning effects, where two agents compete to use a common single machine and each job has a different learning ratio. Specifically, we take into account two different objective functions for two agents: one agent minimizes the total weighted completion time, and the other restricts the makespan to less than an upper bound. After formally defining the problem by developing a mixed integer non-linear programming formulation, we devise a branch-and-bound (B&B) algorithm to give optimal solutions by developing four dominance properties based on a pairwise interchange comparison and four properties regarding the feasibility of a considered sequence. We suggest a lower bound to speed up the search procedure in the B&B algorithm by fathoming any non-prominent nodes. As this problem is at least NP-hard, we suggest efficient genetic algorithms using different methods to generate the initial population and two crossover operations. Computational results show that the proposed algorithms are efficient to obtain near-optimal solutions.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.19-26
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• 2016

In the consumer products industry, it has been highly desirable to develop objective test methods to replace subjective evaluation methods. In developing an objective test method, subjective evaluation data should be on a linear scale. According to Thurstone's theory of comparative judgment, a%-preference from a paired-comparison test can be converted to a linear-scale value. The required number (N) of paired-comparison tests increases dramatically as the number of products increases. This problem should be solved by classifying the total products into several subgroups consisting of 3-4 products in each group. By doing so, it can not only significantly reduce the number of required paired-comparison tests, but it can also obtain more reliable, reproducible data.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1738-1739
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• 2011

In this paper, the range difference based the moving target tracking problem using multiple UAVs is solved within the new framework of linear robust state estimation. To do this, the relative kinematics is modeled as an uncertain linear system containing stochastic parametric uncertainties in its measurement matrix. Applying the non-conservative robust Kalman filter for the uncertain system, a quasi-optimal linear target tracking filter is designed. For its recursive linear filter structure, the proposed method can ensure the fast convergence and reliable target tracking performance. Moreover, it is suitable for real-time applications using multiple UAVs.