• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.15 no.5
• /
• pp.72-78
• /
• 2006

The paper proposes reference model error feedback control scheme for motion control system with hard non-linear components as like saturation and dead-zone in plant input part. Additionally, the plant has the system uncertainty effected by plant model parameter deviation and disturbance. The control algorithm uses the reference model to apply additional feedback loop with the error between reference model output and actual output effected by disturbance and non-linear components. And the stability evaluation based on Popov stability and controller design method are formulated to be performed. The effectiveness of the proposed scheme is examined by simulations. The results are proven by reasonable performances following reference model responses with good disturbance rejection performance without over-tuning of controller.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.10a
• /
• pp.305-306
• /
• 2006

• Journal of Korea Society of Industrial Information Systems
• /
• v.27 no.2
• /
• pp.61-69
• /
• 2022

A multi-agent system is a system that aims at achieving the best-coordinated decision based on each agent's local decision. In this paper, we consider a multi agent-multi task assignment problem. Each agent is assigned to only one task and there is a completion probability for performing. The objective is to determine an assignment that maximizes the sum of the completion probabilities for all tasks. The problem, expressed as a non-linear objective function and combinatorial optimization, is NP-hard. It is necessary to design an effective and efficient solution methodology. This paper presents an approximation algorithm using submodularity, which means a marginal gain diminishing, and demonstrates the scalability and robustness of the algorithm in theoretical and experimental ways.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2001.10a
• /
• pp.203-206
• /
• 2001

Finding the optimal solution in the river water quality management system is very hard with the non-linearity of the water quality model. Many suggested methods for that using the linear programming, non-linear programming and dynamic programming, are failed to give an optimal solution of sufficient accuracy and satisfaction. We studied a method to find a solution optimizing the river water quality management in the aspect of the efficiency and the cost of the waste water treatment facilities satisfying the water Quality goals. In the suggested method, we use the QUAL2E water quality model and the genetic algorithm. A brief result of the project to optimize the water quality management in the Youngsan river is presented.

• Journal of Sensor Science and Technology
• /
• v.13 no.4
• /
• pp.309-315
• /
• 2004

In the pressure sensor, about below 20 kPa, the center boss diaphragm structure is generally used, but it is hard to obtain the high sensitivity because the center boss structure is limited at the thickness and size of diaphragm with chip size. Therefore, this paper suggests that the Center boss structure has surface etched diaphragm using a stress concentration to improve the sensitivity. We carried out the simulation and fabrication applied new diaphragm design. In the result, the sensitivity is improved to 60% without the change of non-linearity (0.14%FS). So, the Center boss of surface etched diaphragm can be applied for the high sensitivity in the low-pressure sensor.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.12
• /
• pp.1153-1160
• /
• 2008

In this paper, the algorithm of Abaqus UMAT is introduced to analyze the shape memory alloy. The SMA has two main effects which show non-linearity. Due to this, it is hard to analyze SMA using analysis tools and to describe all of two effects. Therefore, in this study, the program using Abaqus UMAT based on Modified Brinson model is used to analyze SMA. The martensite fraction, the most important factor which defines SMA motion, is also calculated by Fortran program in UMAT. In addition, the tensile test of SMA specimen is conducted. The availability of algorithm is proved by comparing analysis to experimental result.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.5 s.170
• /
• pp.144-151
• /
• 2005

To predict the shrinkage of molded parts using numerical simulations, the mathematical model should be simplified to overcome the difficulties of formulation due to non-linearity of problems. So it is hard to predict the shrinkage exactly because of the simplification. In the present work, the neural network is used to predict the shrinkage which can implement nonlinear models very well. Comparison between the results of neural network and that of the commercial analysis software, ABAQUS, shows that the result of the neural network is in better agreement with that of the experiments.

• Journal of Korea Society of Industrial Information Systems
• /
• v.27 no.4
• /
• pp.37-45
• /
• 2022

In this paper, a multi agent-multi task assignment problem, which is a representative problem of combinatorial optimization, is presented. The objective of the problem is to determine the coordinated agent-task assignment that maximizes the sum of the achievement rates of each task. The achievement rate is represented as a concave down increasing function according to the number of agents assigned to the task. The problem is expressed as an NP-hard problem with a non-linear objective function. In this paper, to solve the assignment problem, we propose a hybrid cross-entropy algorithm as an effective and efficient solution methodology. In fact, the general cross-entropy algorithm might have drawbacks (e.g., slow update of parameters and premature convergence) according to problem situations. Compared to the general cross-entropy algorithm, the proposed method is designed to be less likely to have the two drawbacks. We show that the performances of the proposed methods are better than those of the general cross-entropy algorithm through numerical experiments.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3A
• /
• pp.323-330
• /
• 2008

The ship collision analysis of steel pile group as protection system of bridge in navigable waterways was performed to analyze the structural characteristics of protective structure during ship collision. The analysis encompassed finite element modeling of ship and pile, modeling of material non-linearity, hard impact analysis, displacement-based analysis and soft impact analysis for collision scenarios. Through the analysis of hard impact with a rigid wall, impact load for each collision type of ship bow was estimated. In the displacement-based analysis the estimate of energy which protection system can absorb within its maximum horizontal clearance so as to secure bridge pier from vessel contact during collision was performed. Soft impact analysis for various collision scenarios was conducted and the collision behaviors of vessel and pile-supported protection system were reviewed for the design of protection system. The understanding of the energy dissipation mechanism of pile supported structure and colliding vessel would give us the optimized design of protective structure.

• Korean Institute of Interior Design Journal
• /
• v.15 no.6 s.59
• /
• pp.77-88
• /
• 2006

According to critics and architects, non-linear structure is not only an organic form of space, but also a form of space detached from modem style. Accordingly, non-linear structure can be accepted as an alternative to what has remained unsolved by deconstructionist. However, they are criticized for not clarifying the interdependent relationship between non-linearity of space and cognitive structure of human being. They ended up remaining the hypothesis just an intuitive and abstract one. This research began on the basis that their hypothesis is hard to be objectified, and it needs further inquiry. The purpose of this thesis is to explore how the redundant factors constitute non-linear structures of digital media centered space design. Geometric compositions of space structure were analyzed to define what types of redundant factors are contrived in the process of visual information. This study about the visual form, researching the Information Theory, and then offer a quantitative analysis that makes those more objective. Space structure and geometric composition were analyzed to define what types of redundancy are contrived in the process of visual information. In particular, I put higher theoretical emphasis on what characteristics are ensued in the process of structuring spaces than any other subjects. Followings are the conclusion of analysis. First, as a result of examining, we can assume that NOX' space structure is not a chaotic form, but has an operating the form of its own. Second, in case of curvilinear, the structure was found redundancy on mid deviation ratio and discontinuous circular fabric. Although most of their structures appeared complex with a higher coherent constant, they were found to be stable factors because of the low deviation ratio between systems. The amount of surplus information was stable structure as well.