• Journal of Institute of Control, Robotics and Systems
• /
• v.1 no.2
• /
• pp.88-93
• /
• 1995

This paper presents a study using neural networks in the design of the tracking controller of robotic systems. Our strategy is to put to use the available knowledge about the robot manipulator, such as estimation models, in the contoller design via the computed torque method, and then to add the neural network to control the remaining uncertainty. The neural network used here learns to provide the inverse dynamics of the plant uncertainty, and acts as an inverse controller. In the simulation study, we verify that the proposed neural network controller is robust not only to structured uncertainties, but also to unstructured uncertainties such as friction models.

• Journal of the Korean Society for Railway
• /
• v.9 no.1 s.32
• /
• pp.63-68
• /
• 2006

This paper proposes a fast Fourier transform(FFT)-based spectral analysis method(SAM) for the dynamic responses of the linear discrete dynamic models with non-proportional damping. The SAM was developed by using discrete Fourier transform(DFT)-theory. To verify the proposed SAM, a three-DOF system with non-proportional viscous damping is considered as an illustrative example. The present SAM is evaluated by comparing the dynamic responses obtained by SAM with those obtained by Runge-Kutta method.

• Proceedings of the KOSOMBE Conference
• /
• v.1997 no.05
• /
• pp.145-149
• /
• 1997

This paper describes a methodology for the development of models of discrete event system. The methodology is based on transformation of continuous state space into discrete one to homomorphically represent dynamics of continuous processes in discrete events. This paper proposes a formal structure which can coupled discrete event system models within a framework. The structure employs the discrete event specification formalism for the discrete event system models. The proposed formal structure has been applied to develop a discrete event specification model for the complex spectral density analysis of strip for urin analyzer system. For this, spectral density data of strip is partitioned into a set of Phases based on events identified through urine spectrophotometry. For each phase, a continuous system of the continuous model for the urine spectral density analysis has been simulated by programmed C++. To validate this model, first develop the discrets event specification model, then simulate the model in the DEVSIM++ environment. It has the similar simulation results for the data obtained from the continuous system simulation. The comparison shows that the discrete event specification model represents dynamics of the urine spectral density at each phase.

• Journal of Environmental Impact Assessment
• /
• v.20 no.3
• /
• pp.337-348
• /
• 2011

Urban environmental problem became one of major issues during its urbanization processes. Environmental impacts are assessed during recent urban planning and development. Though the environmental impact assessment considers meteorological impact as a minor component, changes in wind environment during development can largely affect the distribution pattern of air temperature, humidity, and pollutants. Impact assessment of local wind is, therefore, a major element for impact assessment prior to any other meteorological impact assessment. Computational Fluid Dynamics (CFD) models are utilized in various fields such as in wind field assessment during a construction of a new building and in post analysis of a fire event over a mountain. CFD models require specially formatted input data and produce specific output files, which can be analyzed using special programs. CFD's huge requirement in computing power is another hurdle in practical use. In this study, a CFD model and related software processors were automated and integrated as a microscale wind environmental impact assessment system. A supercomputer system was used to reduce the running hours of the model. Input data processor ingests development plans in CAD or GIS formatted files and produces input data files for the CFD model. Output data processor produces various analytical graphs upon user requests. The system was used in assessing the impacts of a new building near an observatory on wind fields and showed the changes by the construction visually and quantitatively. The microscale wind assessment system will evolve, of course, incorporating new improvement of the models and processors. Nevertheless the framework suggested here can be utilized as a basic system for the assessment.

• Journal of applied mathematics & informatics
• /
• v.26 no.1_2
• /
• pp.355-364
• /
• 2008

Under pathological stress stimuli, dynamics of a biological system can be changed by alteration of several components such as functional proteins, ultimately leading to disease state. These dynamics in disease state can be modeled using differential equations in which kinetic or system parameters can be obtained from experimental data. One of the most effective ways to restore a particular disease state of biology system (i.e., cell, organ and organism) into the normal state makes optimization of the altered components usually represented by system parameters in the differential equations. There has been no such approach as far as we know. Here we show this approach with a cardiac hypertrophy model in which we obtain the existence of the optimal parameters and construct an optimal system which can be used to find the optimal parameters.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.1
• /
• pp.46-53
• /
• 2002

The brake system of a high speed train has a crucial role for the safety of the train. To develop a safe brake system of the high speed train, it is necessary to understand the braking principle and phenomena of the total brake system and its subsystems. In this paper, we have suggested a mathematical model which includes car dynamics, interactions between cars, adhesive forces, brake blending algorithm, and the dynamics of each brake devices. Also, we have proposed a ready-time compensation algorithm of eddy-current brake system and a brake control logic on electric-pneumatic blending. A simulation study has shown the proposed models and algorithms are effective on the braking of the train.

• Korean System Dynamics Review
• /
• v.17 no.3
• /
• pp.51-90
• /
• 2016

Learning is naturally embedded in organizational ongoing-processes and routines. Recent many research models of organizational failure ignore how failing masks breakdowns and recoveries of organization-embedded learning as a naturally occurring process. Organizational learning is the platform in tandem with base-modules of organization in this point. Organizations learn and unlearn while they acquire, discard, and forget organizational experiences or knowledges. These processes in public sector organizations are different from learning behaviors in private sector. This study expects to explore architectural components of learning organization in public sector, focusing on distinct characteristics of public organizations, and to implement learning model based on system thinking(system dynamic) approach.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.12
• /
• pp.1103-1110
• /
• 2013

Based on the string, Euler beam, and Timoshenko beam theories, the transfer functions of axially translating web system to predict the lateral tracking are introduced in this paper. In addition, total transfer function of a multi-span web handling system is developed by the combination of the transfer functions of each single span. Experiments and computations are carried out and the results obtained for the Timoshenko beam model are compared with those of other models. The comparison indicates that the predictions from the Timoshenko and Euler beam models are quite different from that of the classical string model in both the gain and phase response. The results are expected to help in the development of high fidelity models of web tracking systems within a general computational framework.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.838-843
• /
• 2001

Internal damping plays an important role in some rotor dynamic systems with the use of various materials for shafts, for example, composite material. However, although the effects of internal damping have been investigated for a couple of decades, there are several different internal damping models in use, none of which are accepted as the most reliable model. The purpose of this paper is to compare the results of dynamic analysis of rotor systems with several different internal damping models. The exact dynamic element method is used to formulate and analyze the problem. The simulation results provided in this paper may be useful for the dynamic analysis of high rotor systems subject to significant internal damping.

• Journal of Korean Institute of Industrial Engineers
• /
• v.12 no.1
• /
• pp.55-61
• /
• 1986

Mathematical forecasting models and a practical computer based forecasting system are developed for planning production in a manufacturing and distribution network. The forecasting system works at the highest level of a hierarchical computer-based decision support system consisting of the forecasting system, an aggregate planning system and a shop floor scheduling system. The dynamics of business operations for an actual company have been considered to make this study a unique comprehensive analysis of a real world forecasting problem.