• Journal of Advanced Marine Engineering and Technology
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• v.27 no.3
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• pp.388-394
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• 2003

Hydraulic system is difficult to obtain a suitable performance due to the nonlinearity load pressure change and system parameter variation. The requirement of control a1gorithm has been complex in order to satisfy the performance. The adaptive control is a control method which is suggested to achieve the control object under the plant characteristics change. In spite of the case that plant characteristics and the degree of variation are difficult to grasp. the adaptive control could keep the characteristics of closed-loop system generally. In this study. a method of combined generalized minimum variance adaptive control (GMVAC) and output error feedback is proposed, in order to solve the problem of non-minimum phase of plant and the vibration and overshoot in initial response. The control performance according to the variation of characteristics of plant is evaluated by changing the supply pressure. The experimental results show the effectiveness of the proposed scheme.

• Journal of Mechanical Science and Technology
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• v.14 no.1
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• pp.57-64
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• 2000

Recent advances in the field of control theory have enabled us to design active vibration control systems for various structures. In many studies, the controller used to suppress vibration has been synthesized for the given mathematical model of structure. In these cases, the designer has not been able to utilize the degree of freedom to adjust the structural parameters of the control object. To overcome this problem, so called 'Structure/Control Simultaneous Optimization Method' is used. In this context of view, this paper is concerned with the active vibration control of bridge towers, platforms and ocean vehicles etc. Simultaneous design method is used to achieve optimal system performance. Here, a general framework for the simultaneous design problem of output feedback case is introduced based on LMI (Linear Matrix Inequality). The simulation results show that the proposed design method achieves desirable control performance.

• Journal of Electrical Engineering and Technology
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• v.2 no.4
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• pp.505-512
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• 2007

The object of this paper is to study a new control structure for sensorless induction machines dedicated to electrical drives using a three-level voltage source inverter VSI-NPC. The amplitude and the rotating speed of the flux vector can be controlled freely. The scheme investigated is an Enhanced direct torque control "EDTC" for electric vehicle propulsion. The considered application imposes some constraints which are achieved in EDTC control (fast torque response, optimal switching logic, torque control at zero speed, and large speed control. The results obtained for an induction motor indicate superior performance over the FOC type without need for any mechanical sensor.

• Journal of Korean Society for Geospatial Information Science
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• v.4 no.1 s.6
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• pp.103-114
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• 1996

A vehicle Control System that is a system combined by a Car Navigation System, a Geograhical Information System, and a Communication Network usually permit a central control room to detect vehicle's locations dynamically and manage these informations synthetically. Therefore, a vehicle control system can be used to control the rapid movement of patrol cars, freight transportation, and so on. In this paper, we designed and implemented a data manager for an application system, such as a vehicle control system, that usually manages road data, vehicle data, vehicle's location data, etc. The data manager that is implemented in this paper consists of system management module, road data management module, vehicle data management module, GPS(Global Positioning System) data management module, and additional data management module. Especially, we use the SHORE(Scalable Heterogeneous Object REpository) system as a storage system of the data manager.

• The Transactions of the Korea Information Processing Society
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• v.7 no.5S
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• pp.1726-1735
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• 2000

Internet purchase is increasing according to the activation of Electronic Commerce. Currently, the hardware is main purchase items in the Electronic commerce. The on-line purchase of digital product, that is electronic file type of product, has many merits such as, does not cost in logistics, is ease of searching the product, and is possible of 'Try and Buy' system. But, actually digital products have not been major proudct because of tits piracy problem. The piracy problem of digital products comes from the lack of safety in DP license control technology. Current EC has no method to identify the object that has the right ot use the digital product. The protecting of object change is impossible and the protection of hacking is not enough and EC has any problems in efficient license control because of the incompletion of EC structure. In this paper, e propose the design and implementation of on-line DP circulation system, which can activate on-line circulation of DP in EC and protect its piracy, by using the new license control technology, that is Dynamic License control technology.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.11
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• pp.63-77
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• 1994

This paper describes the real-time system which, through analyzing a sequence of images, can extract motional information on a moving object and can contol servo equipment to always locate the moving object at the center of an image frame. An image is a vast amount of two-dimensional signal, so it takes a lot of time to analyze the whole quantity of a given image. Especially, the time needed to load pixels from a memory to processor increase exponentially as the size of an image increases. To solve such a problem and track a moving object in real-time, this paper addresses how to selectively search the spatial and time domain. Based on the selective search of spatial and time domain, this paper suggests various types of techniques which are essential in implementing a real-time tracking system. That is, this paper describes how to detect an entrance of a moving object in the field of view of a camera and the direction of the entrance, how to determine the time interval of adjacent images, how to determine nonstationary areas formed by a moving object and calculated velocity and position information of a moving object based on the determined areas, how to control servo equipment to locate the moving object at the center of an image frame, and how to properly adjust time interval(${\Delta}$t) to track an object taking variable speed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.247-252
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• 2008

Recently, the virtual construction system in which project participants efficiently share and control the information throughout the life-cycle of construction project using 3D object models is being developed all over the world. In this paper, a design of interface between 3D object model of structures and structural analysis system that is essential for the analysis and design of civil structures in the virtual space is treated. The relation parametric modeling technique that is needed to make the 3D object models and the construction method of product breakdown structure(PBS) that considers the several parameters for the structural analysis are presented. PBS is built so that it is possible to extract needed attribute information from 3D object model and to apply it to the structural analysis. Design methodology for interface program is proposed that several numerical values determined by the cooperative work same as structural analysis are delivered to 3D object models without additional work. An interface program between 3D object models and structural analysis system developed based on the proposed method would be effectively used to develop virtual construction system.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.544-554
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• 2001

A shop floor can be considered as an important level to develop Computer Integrated Manufacturing system (CIMs). However, a shop floor is a dynamic environment where unexpected events continuously occur, and impose changes to the planned activities. To deal with this problem, a shop floor should adopt an appropriate control system that is responsible for the coordination and control of the manufacturing physical flow and information flow. In this paper, a hybrid control system is described with a shop floor activity methodology called Multi-Layered Task Initiation Diagram (MTD). The architecture of the control model contains three levels: i.e., he shop floor controller (SFC), the intelligent agent controller (IAC) and the equipment controller (EC). The methodology behind the development of the control system is an intelligent multi-agent paradigm that enables the shop floor control system to be an independent, an autonomous, and distributed system, and to achieve an adaptability to change of the manufacturing environment.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.906-915
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• 2004

In this paper, we address the development of magnetic levitation positioning system. This planar magnetic levitator employs four permanent magnet liner motors. Each motor generates vertical force for suspension against gravity, as well as horizontal force for driving levitation object called a platen. This stage can generate six degrees of freedom motion by the vertical and horizontal force. We derived the mechanical dynamics equation using Lagrangian method and used coenergy to express an electromagnetic force. We proposed a control algorithm for the position and posture control from its initial value to its desired value using sliding mode control. Some simulation results are provided to verify the effectiveness of the proposed control scheme.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.453-458
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• 2000

Design of an in-process feedback control system has been studied for precision grinding. A grinding system consists of a grinding tool, a turn table and a disk-shaped workpiece on the table is taken as an object. A grinding process model has been deduced which gives some reasoning about the process errors. In the control system the tool position is actively controlled by an electro-magnetic actuator in-process. The ground error is feedback to compose a closed-loop control system and an optimal PID controller is applied. Some control performances such as transient response and disturbance such as transient response and disturbance attenuation have been examined, which convinces the effectiveness of the control. Some methods for implementation of the control. Some methods for implementation of the control have been suggested from a standpoint of practical application.