• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1689-1696
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• 2000

This paper proposes a new adaptive control scheme for flexible-link robots. A model-based nonlinear control scheme is designed based on a V-shape Lyapunov function, and then the nonlinear control i s extended to a model-based adaptive control to cope with parametric uncertainties in the dynamic model. The proposed control guarantees the global exponential or global asymptotic stability of the overall control system with all internal signals bounded. The effectiveness of the proposed control is shown by computer simulation.

• Korean Management Science Review
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• v.16 no.2
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• pp.33-49
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• 1999

The management of enterprise knowledge has been increasingly important because knowledge emerges as the new basis of competition in postcapitalist society. One of the key issues in knowledge management is to put knowledge into a repository where it can be easily stored, reused, and recreated. This paper proposes a model repository and the corresponding knowledge management framework. The emphases of model repository is on abstraction knowledge in the form of schematic models. Two major benefits are model independence and model integration. A metaschema is constructed according to six conceptual components: separate unit, external link, internal link, separate unite descriptor, link descriptor, and composite descriptor, which can be applied for a variety of models. A prototype system with a case illustrates the practical usefulness of model repository for knowledge management.

• Journal of Communications and Networks
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• v.4 no.2
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• pp.136-147
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• 2002

In this paper, the maximal capacity of the data network link has attempted to be exploited by using the dynamic allocation strategy. We propose a new methodology based on the economic models for competing traffic classes (classes of sessions) in packet networks. As the demand for network services accelerates, users' satisfaction to the service level might decrease due to the congestion at the network nodes. To prevent this, efficient allocation of a networks resources, such as available bandwidth and switch capacity, is needed. By using the so-called user profile as well as the utility (e.g., data rate) functions, it is possible to allocate data rates and other utilities using the arbitrary number of QoS classes, say $0.01,...,$10.

• International Journal of Control, Automation, and Systems
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• v.6 no.2
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• pp.223-233
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• 2008

A new output feedback controller design approach for flexible-joint (FJ) robots via the observer dynamic surface design technique is presented. The proposed approach only requires the feedback of position states. We first design an observer to estimate the link and actuator velocity information. Then, the link position tracking controller using the observer dynamic surface design procedure is developed. Therefore, the proposed controller can be simpler than the observer backstepping controller. From the Lyapunov stability analysis, it is shown that all signals in a closed-loop system are uniformly ultimately bounded. Finally, the simulation results of a three-link FJ robot are presented to validate the good position tracking performance of the proposed control system.

• Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.1-12
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• 2014

In this paper, we propose a new method of reconstructing the hand models for individuals, which include the link structure models, the homologous skin surface models and the homologous tetrahedral mesh models in a reference posture. As for the link structure model, the local coordinate system related to each link consists of the joint rotation center and the axes of joint rotation, which can be estimated based on the trajectories of optimal markers on the relative skin surface region of the subject obtained from the motion capture system. The skin surface model is defined as a three-dimensional triangular mesh, obtained by deforming a template mesh so as to fit the landmark vertices to the relative marker positions obtained motion capture system. In this process, anatomical dimensions for the subject, manually measured by a caliper, are also used as the deformation constraints.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.290-298
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• 2010

This paper proposes an adaptive carrier-based pulse width modulation (PWM) method for a four-switch three-phase (4S3P) inverter under dc-link voltage ripple conditions. The proposed method guarantees balanced output currents despite of the existence of the voltage oscillations across two dc-link capacitors. And also, this new approach achieves a linear over-modulation with calculation time reduction. Simulation and experimental results are given to validate the feasibility of the proposed method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.100-105
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• 2003

This paper proposes a new auxiliary resonant DC link(ARDCL)snubber circuit and deals with its power loss on the basis of actually-measured conduction loss characteristic of switching device module. Voltage-fed soft switching three-phase inverter using proposed ARDCL snubber circuit is presented along with its performance evaluations. And, the power loss analysis of three-phase hard and soft switching inverter are carried out from the point of simulation and experimental results.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.695-697
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• 1993

In this paper, a novel concept for a static three-phase to three-phase power converter for an AC drive with an unity power factor and reduced harmonics on the utility line is presented. The power circuit consists of two back-to-back connected six-pulse bridges having only a $5{\mu}F$ ceramic capacitor in the DC link. By controlling the active power balance between two bridges, the DC link voltage can be maintained within 20V deviation from the nominal value with the small ceramic capacitor regardless of the load variation even in the unbalanced source condition.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.396-398
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• 2003

Recently as users' requests for geographic information systems are being more various, several new functions are being added to existing geographic information systems. One of them is linkage of spatial geographic data and video / image data to offer more realistic information of geographic objects to users. Geographic information systems implementing this function are called video geographic information system. In this paper, we design and implement a video geographic information system for providing map data, video data and link information of them to web applications. We 1) design system architecture of a video geographic information system, 2) analyze some processes to construct link information of map data and video data, 3) design database schema to store map data, video data, and link information, and 4) design some XML/GML schema used to query and retrieve these data for web applications.

• Electronics and Telecommunications Trends
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• v.37 no.3
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• pp.41-51
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• 2022

This article presents an overview of the key technologies in the communications payload of broadband LEO satellite communications systems. In recent years, new developments have been realized for LEO satellite communications. SpaceX's Starlink, a technology leader in this field, offers premium services with satellites carrying in-house developed communications payloads. OneWeb, Amazon, Telesat, and Boeing are also developing LEO satellite communications payloads. The communications payload consists of user link antennas, inter-satellite link communications equipment, feeder link antennas, and a digital processor. Highly sophisticated technologies of compact active phased array antennas for generating multiple hopping beams and light laser communication equipment for ultra-high-speed inter-satellite communication will be applied to next- generation payloads.