• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.830-832
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• 2014

In this study, friction stick-slip vibration're interpretation of the phenomenon, we used a statistical model of friction. In a previous study using a definite friction factor, but to a dynamic simulation using a constantly changing during the integration time by a Monte Carlo simulation method, not the average coefficient of friction and the dynamic friction coefficient and a constant value in this study.

• Structural Engineering and Mechanics
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• v.5 no.1
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• pp.69-83
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• 1997

A new efficient hybrid/mixed thin~moderately thick plate bending element with 6-node (HM6-14) is formulated based on the Reissner-Mindlin plate bending theory. The convergence of this element is proved by error estimate theories and verified by patch test respectively. Numerical studies on such an element as HM6-14 demonstrate that it has remarkable convergence, invariability to geometric distorted mesh situations, to axial rotations, and to node positions, and no "locking" phenomenon in thin plate limit. The present element is suitable to many kinds of shape and thin~moderately thick plate bending problems. Further, in comparison with original hybrid/mixed plate bending element HP4, the present element yields an improvement of solutions. Therefore, it is an efficient element and suitable for the development of adaptive multi-field finite element method (FEM).

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.4
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• pp.310-315
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• 2005

This paper proposes a fast optimization method by combining queen-bee evolution and derivative evaluation in genetic algorithms. These two operations make it possible for genetic algorithms to focus on highly fitted individuals and rapidly evolved individuals, respectively. Even though the two operations can also increase the probability that genetic algorithms fall into premature convergence phenomenon, that can be controlled by strong mutation rates. That is, the two operations and the strong mutation strengthen exploitation and exploration of the genetic algorithms, respectively. As a result, the genetic algorithm employing queen-bee evolution and derivative evaluation finds optimum solutions more quickly than those employing one of them. This was proved by experiments with one pattern matching problem and two function optimization problems.

• Proceeding of KASS Symposium
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• 2006.05a
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• pp.214-223
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• 2006

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and happen large deformation phenomenon. Therefore, in this study, to find the structural shape after large deformation caused by initial stress, we need the shape analysis considering geometric nonlinear term. And we investigate the evaluation of shape analysis technique's convergence and efficiency according to the control method

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.89-95
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• 2017

In this paper, we suggest the method for a mobile robot to move safely from an initial position to a goal position in the wide environment like a building. There is a problem using odometry encoder sensor to estimate the position of a mobile robot in the wide environment like a building. Because of the phenomenon of wheel's slipping, a encoder sensor has the accumulated error of a sensor measurement as time. Therefore the error must be compensated with using other sensor. A vision sensor is used to compensate the position of a mobile robot as using the regularly attached light's panel on a building's ceiling. The method to create global path planning for a mobile robot model a building's map as a graph data type. Consequently, we can apply floyd's shortest path algorithm to find the path planning. The effectiveness of the method is verified through simulations and experiments.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.2
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• pp.133-139
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• 2001

The nonlinear response statistics of an spring-pendulum system with internal resonance under narrow band random excitation is investigated analytically- The center frequency of the filtered excitation is selected to be close to natural frequency of directly excited spring mode. The Fokker-Planck equations is used to generate a general first-order differential equation in the dynamic moment of response coordinates. By means of the Gaussian closure method the dynamic moment equations for the random responses of the system are reduced to a system of autonomous ordinary differential equations. The nonlinear phenomena, such as jump and multiple solutions, under narrow band random excitation were found by Gaussian closure method.

• Journal of Internet Computing and Services
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• v.22 no.2
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• pp.19-27
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• 2021

Fireworks Algorithm (FWA) is a new heuristic swarm intelligent algorithm inspired by the natural phenomenon of the fireworks explosion. Though it is an effective algorithm for solving optimization problems, FWA has a slow convergence rate and less information sharing between individuals. In this paper, we improve the FWA. Firstly, explosion operator and explosion amplitude are analyzed in detail. The coefficient of explosion amplitude and explosion operator change dynamically with iteration to balance the exploitation and exploration. The convergence performance of FWA is improved. Secondly, differential evolution and commensal learning (CDE) significantly increase the information sharing between individuals, and the diversity of fireworks is enhanced. Comprehensive experiment and comparison with CDE, FWA, and VACUFWA for the 13 benchmark functions show that the improved algorithm was highly competitive.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1261-1273
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• 2022

Homeownership is much more than a financial calculation. It is a socio-psychological phenomenon. During the last decade studies of homeownership have demonstrated a positive link between homeownership and positive social outcomes including welfare perceptions and attitudes. This study compared welfare perceptions between homeowners and renters in Korean Welfare Panel Survey using data collected in 2019. The study analyzed six continuous outcomes of welfare perceptions. Six variables indicating welfare perceptions included: (1) welfare and work disincentives; (2) welfare recipients are lazy; (3) welfare selectivism; (4) national minimum; (5) free university education and; (6) free child care and kindergarten. This study acknowledged bias arising from selection on observables. To control these biases, this study employed analytical approaches including the treatment effect model. Results of this study confirmed that attainment of homeownership is not possible for everyone. Findings from this study have provided some evidence that homeowners and renters have different perceptions on welfare listed above. Finally, issues relating to homeownership and welfare perceptions were discussed. Implications for social work practice and research were further discussed.

• Convergence Security Journal
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• v.14 no.6_1
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• pp.99-112
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• 2014

National Defense & IT Convergence is ensuring actual force integration by developing new IT Convergence Technology for the purpose of realizing the concept of Network Centric Warfare. The Ministry of Defense has appointed National Defense & IT Convergence Center of Defense Agency for Technology and Quality as a specialized agency for the National Defense & IT Convergence development, a mission in the creative economy era and has been active in military demand inquiry and prior technology plan with the industrial-academic research institute for discovery of National Defense IT Convergence projects based on the Convergence Center. Further, it is promoting focused on the timely introduction of private IT new technology by operating the project planning team comprised of defense domain specialists and by applying the advanced planning method etc. Accordingly, for the development of National Defense & IT convergence, developmental strategy is urgently required to be utilized effectively after considering theoretically on the national IT Convergence policy enforcement and phenomenon of National Defense & IT Convergence technology and analyzing them comprehensively. This thesis promotes in phases the IT Convergence projects which are identified for the development, improves the efficiency of newly created National Defense & IT Convergence center and suggests training program of IT Convergence personnel related to the defense reforms. With such, it will achieve smart defense in advance and will also contribute largely for the realization of the immediate paradigm shift and of the creative economy.

• Journal of Digital Convergence
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• v.13 no.7
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• pp.323-331
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• 2015

21st Century is getting into Super aging society worldwide basis. Among those population, silver(aged) generation users' physical condition, such as sight, hearing and body, is getting older, especially sight ability which processes 80% of input data, it requires us studying new smartphone GUI designs convergence for the elderly. In light of this social phenomenon, this study suggests smartphone GUI designs convergence guideline for the silver generation through the research of text, icon which are basic elements of smartphone GUI with proper visual attributes. I had inferred UX designs, expert group and evaluation categories from existing papers, related books and designed some displays for the survey. I also offered this guideline with the deep survey of 101 people over 65 years old.