• International Journal of Control, Automation, and Systems
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• v.6 no.1
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• pp.15-23
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• 2008

This paper considers the problem of delay-dependent guaranteed cost controller design for uncertain neutral systems with distributed delays. The system under consideration is subject to norm-bounded time-varying parametric uncertainty appearing in all the matrices of the state-space model. By constructing appropriate Lyapunov functionals and using matrix inequality techniques, a state feedback controller is designed such that the resulting closed-loop system is not only robustly stable but also guarantees an adequate level of performance for all admissible uncertainties. Furthermore, a convex optimization problem is introduced to minimize a specified cost bound. By matrix transformation techniques, the corresponding optimal guaranteed controller can be obtained by solving a linear matrix inequality. Finally, a simulation example is presented to demonstrate the effectiveness of the proposed approach.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.9
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• pp.59-70
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• 2020

Three-dimensional (3D) design data is used for various purposes throughout the life cycle of a plant construction project. Plant 3D CAD systems support 3D modeling based on specs-catalogs, which contain data that are used for different purposes such as design, procurement, production, and handover. Therefore, it is important to share the spec-catalog data in the 3D design model with other application systems. Sharing this data thus requires a system that extracts spec-catalog data from plant 3D CAD systems and converts them into neutral model data. In this paper, we analyze equipment spec-catalog data of plant 3D CAD systems and, based on these analyses, define the data structure for neutral spec-catalog data. We subsequently propose a procedure that translates native spec-catalog data to neutral model data and develop a prototype system that performs this operation. The proposed method is then experimentally validated for the test spec-catalog data.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.4
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• pp.483-487
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• 2007

This paper is concerned with the observer design problem for linear neutral systems with time-varying delays. The problem addressed is that of designing a full-order observer that guarantees the exponential stability of the error system. An effective algebraic matrix equation approach is developed to solve this problem. In particular, both observer analysis and design problems are investigated. Sufficient conditions for a linear neutral system to be stable are first established. Furthermore, an illustrative example is used to demonstrate the validity of the proposed design procedure.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.359-365
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• 2002

Three-phase four-wire electrical distribution systems have been widely employed in manufacturing plants, commercial and residential buildings. Due to the nonlinear loads, the neutral conductor carries excessive harmonic currents resulting in wiring failure of the neutral conductor, overloading of the distribution transformer and a voltage drop between the neutral and the ground. This paper proposes a reduced rating active power filter to suppress neutral current harmonics in three-phase four-wire electrical distribution systems. The proposed system is simple in control and the VA rating of the inverter could be significantly reduced since only the fundamental current due to unbalanced loading flows through the inverter switch. The experimental results on a prototype validate the proposed control approach.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.111-116
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• 2002

With the proliferation of nonlinear loads such as personal computers in an educational office building, high neutral harmonic currents have been observed. High neutral currents in three-phase four-wire distribution power systems can cause overloaded neutral conductors, overloaded transformers, voltage distortion, common mode noise, and malfuntion of protective equipment. On-site measurements of harmonic currents and voltages were made and the corresponding equivalent circuits was developed. The circuit model under study was simulated numerically and graphically through the use of the software MATLAB.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.715-719
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• 2002

Recently, Dangers due to harmonics emanated from all sorts of machinery have been on the increase with the development in industry. One of them is that Zero Sequence harmonic currents flow from the neutral wires in 3 phases - 4 wire systems. The flowing of harmonic currents in neutral wires brings about the superheating and falloff in output of transformer, the overheating of them, a rise in ground potential and the wrong movement of machinery, so has a bad influence on this system. To develop the machinery to decrease neutral wires Zero sequence harmonic currents and apply it help solve these problems and bring about the effects of a improvement in power factor and energy savings.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2005-2010
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• 2011

On AC railway systems, the neutral sections are installed in front of substations and sectioning posts in order to avoid crash between power that have differing phases. In case railway vehicles pass through these neutral sections, it is necessary for them to switch to coasting driving by notch-off. This may reduce speed of the vehicles, resulting lowered train operation efficiency. The usage of automatic power switching systems makes it possible to pass neutral sections at notch-on, enhancing operation efficiency so that it is appropriate for high-speed railway applications. This paper analyzed inrush current of main transformer that installed on the train while passing through the neutral section using the simulator.

• Korean Journal of Computational Design and Engineering
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• v.13 no.3
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• pp.175-186
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• 2008

For the success to PLM in manufacturing industries, the creation, management and coordination of all product-related information are essential, and the exchange of product information and data has become an important part of the product development. In this paper, we define the neutral schema, and it refers to PLM Services. Based on this neutral schema, we develop the PLM Integrator to exchange product information and data between diverse heterogeneous systems including PDM systems. We apply the PLM Integrator developed in this paper to commercial PDM systems such as SmarTeam, Teamcenter Engineering and MEMPHIS which is a data exchange middleware system for VR applications. By implementations, exchanges of product information and data can be done without loss of information. Also, the PLM Integrator can upload and download product information, data and related files. The result of this paper can not only reduce unnecessary efforts for data exchanging between different information systems including PDM/PLM systems but also provide a collaborative environment for PLM.

• 전기의세계
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• v.18 no.6
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• pp.23-32
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• 1969

The thesis has derived the formulas and computational algorithms useful for predicting and constraining the potential rises on the neutral line in 3-phase, 4-wire distribution line systems in the case of contact faults and single-line grounding faults. In addition it has suggested economically optimal designing conditions herewith of the distribution line systems in conduction with the potential restraining cost functions.

• Journal of applied mathematics & informatics
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• v.8 no.1
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• pp.297-303
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• 2001

In this paper, the problem of the stability analysis for a class of linear neutral systems with time-varying delay is investigated. Using the Lyapunov method, a delay-dependent sufficient condition for asymptotic stability of the systems in terms of linear matrix inequalities (LMIs) is presented. The LMIs can be easily solved by various convex optimization algorithms.