• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.885-890
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• 2009

A fault location algorithm using estimated local source impedance after a fault is proposed in this paper. The method uses after fault data only at the local end. It uses the negative sequence current distribution factor for more accurate estimation. The proposed algorithm can keep up with the variation of the local source impedance. Therefore, the proposed algorithm especially is valid for a transmission line interconnected to a wind farm that the equivalent source impedance changes continuously. The performance of the proposed algorithm was verified under various fault conditions using the Simpowersystem of MATLAB Simulink. The proposed algorithm is largely insensitive to the variation in fault distance and fault resistance. The test results show a very high accurate performance.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.1
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• pp.122-129
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• 1998

For generation and analysis of the multi-sensory image, we propose a new three dimensional (3D) modeling method considering an iternal heat source. We represent the heat conduction process within th object as an equivalent thermal circuit. Therefore, without a complex computation, our modeling approach can obtain thermal features of the object. By using the faceted model, the proposed method can express the accurate visual signatures of the object. Comparing the estimates datum with the obtained surface temperatures, we have demonstrated that the proposed method can provide a precise thermal features. The thermal images by out model is applicable to simulate a tracking loop of an IR missile.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.32-35
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• 1996

This paper analyzes characteristics of PMLSM using 3 dimensional equivalent magnetic circuit network method (3-D EMC). PMLSM of which the effective electric-airgap is not only very large, but also the width is finite width lateral edges has much leakage flux. Therefore, 2-D analysis method cannot consider it so carefully that 3-D analysis method must required. 3-D EMC which will be used for analysis of PMLSM performs modeling of it including solt and teeth structure, uses the magnetic motive force of stator winding and permanent magnet as source. and calculates magnetic flux density and force considering nonlinear characteristics of materials. we verified analysis validity by comparing simulation results with expermental results.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1844-1854
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• 2018

Isolated power systems (IPS) are often characterized by a weak grid due to small power grids. The grid side voltage is no longer equivalent to an ideal voltage source of an infinitely big power grid. The conversion control of new energy sources, parameter perturbations as well as the load itself can easily cause the system voltage to oscillate or to become unstable. To solve this problem, increasing the energy-storage power sources is usually used to improve the reliability of a system. In order to provide support for the voltage, the energy-storage power source inverter needs an method to control the voltage source. Therefore, this paper has proposed the active damping control of a voltage source inverter (VSI) based on virtual compensation. By simplifying the VSI double closed-loop control, two feedback compensation channels have been constructed to reduce the VSI output impedance without changing the characteristics of the voltage gain of a system. This improvement allows systems to operate stably in a larger range. A frequency-domain analysis, and simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.1 no.1
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• pp.23-35
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• 1983

In its global meaning language translation refers to the process whereby a program which is executable in one computer can be executed in another computer directly to obtain the same result. There are four different ways of approaching translation. The first way is translation by a Translator or a Compier, the second way is Interpretation, the third way is Simulation, the last way is Emulation. This paper introduces the M-C Translator which was designed as the first way of translation. The MUSS 80 language (the subsystem of the UNIVAC Solid State 80 S-4 assembly language system) was chosen as the source language which includes forty-three instructions, using the CYBER COMPASS as the object language. The M-C translator is a two pass translator and is a two pas translator and es written in Fortran Extended language. For this M-C Translation, seven COMPASS subroutines and a set of thirty-five macros were prepared. Each executable source instruction corresponds to a macro, so it will be a macro instruction within the object profram. Subroutines are used to retain and handle the source data representation the same way in the object program as in the source system, and are used to convert the decimal source data into the equivalent binary result into the equivalent USS-80digits before and after arithmetic operations. The source instructions can be classified into three categories. First, therd are some instructions which are meaningless in the object system and are therefore unnecessary to translate, and the remaining instructions should be translated. Second, There are some instructions are required to indicate dual address portions. Third, there are Three instructions which have overflow conditions, which are lacking in the remaining instructions. The construction and functions of the M-C Translator, are explained including some of the subroutines, and macros. The problems, difficulties and the method of solving them, and easier features on this translation are analysed. The study of how to save memory and time will be continued.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.53-57
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• 1989

Until now, method of equivalent circuit is generally used in analyzing the characteristic of the synchronous alternator. But this method can't apply when loads are connected to alternator. In this paper, we analyzed the load characteristic of the synchronous alternator with permanant magnet using 2-dimensional finite element method having voltage source. The loads of a alternator are battary and diodes which are used to rectify. also, we used half periodic boundary condition in the F.E.M calculation

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.151-152
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• 2013

Multilevel Voltage Source Converter HVDC presents a new method for the energy transmission, The multilevel requires the converter bridge includes more than 100 converter modules, for the EMT simulation file, the simulation time increases to several hours; it can depress the research process. In the paper, author describes a method to simulate the multilevel arm based on time-varying equivalent. The result shows the extremely calculation time reduced with almost the same accuracy.

• The Journal of the Acoustical Society of Korea
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• v.9 no.2
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• pp.42-52
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• 1990

A method of measuring impulse response of acoustic system, two kinds of cross-correlation methods (the direct correlation method and the M-sequence modulation correlation method) were applied. According to the direct correlation method, by using stationary random noise source and by calculating the cross-correlation function between the sourece and the output signal, equivalent impulse response can be obtained not being influenced by the back ground noises. By applying this method, the measurement of echo-time patterns in rooms and oblique incident sound absorption characteristics of sound absorbing materials was carried out. In the case of the M-sequence modulation correlation method which was contrived by Aoshima, an intermittent random nosie modulated by M-sequence signal is used as the source signal, and the cross-correlation function between the M-sequence signal and the squared output signal is calculated. According to this method, equivalent energy impulse response (squared impulse response) of te propagation system can be obtained without being influenced by the back ground noises and the air fluctuation caused by wind. As the applcaition of this measuring method to the architectural acoustics, the meaurements of echo-time patterns, reverberation decays and sound pressure lev디 distributions in rooms and sound insulation efficiencies in buildings were carried out. From these experimental studies, it has been found that this M-sequence modulation correlation method is markedly useful especially for the field masurement of sound insulation under high back ground noise condition.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1421-1430
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• 2022

The computation of the solid angle and the detector efficiency is considering to be one of the most important factors during the measuring process for the radioactivity, especially the cylindrical γ-ray NaI(Tl) detectors nowadays have applications in several fields such as industry, hazardous for health, the gamma-ray radiation detectors grow to be the main essential instruments in radiation protection sector. In the present work, a generic numerical simulation method (NSM) for calculating the efficiency of the γ-ray spectrometry setup is established. The formulas are suitable for any type of source-to-detector shape and can be valuable to determine the full-energy peak and the total efficiencies and P/T ratio of cylindrical γ-ray NaI(Tl) detector setup concerning the truncated conical radioactive source. This methodology is based on estimate the path length of γ-ray radiation inside the detector active medium, inside the source itself, and the self-attenuation correction factors, which typically use to correct the sample attenuation of the original geometry source. The calculations can be completed in general by using extra reasonable and complicate analytical and numerical techniques than the standard models; especially the effective solid angle, and the detector efficiency have to be calculated in case of the truncated conical radioactive source studied condition. Moreover, the (NSM) can be used for the straight calculations of the γ-ray detector efficiency after the computation of improvement that need in the case of γ-γ coincidence summing (CS). The (NSM) confirmation of the development created by the efficiency transfer method has been achieved by comparing the results of the measuring truncated conical radioactive source with certified nuclide activities with the γ-ray NaI(Tl) detector, and a good agreement was obtained after corrections of (CS). The methodology can be unlimited to find the theoretical efficiencies and modifications equivalent to any geometry by essential sufficiently the physical selective considered situation.

• Journal of the Korean Mathematical Society
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• v.50 no.6
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• pp.1291-1310
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• 2013

This paper develops least-squares pseudo-spectral collocation methods for elliptic boundary value problems having interface conditions given by discontinuous coefficients and singular source term. From the discontinuities of coefficients and singular source term, we derive the interface conditions and then we impose such interface conditions to solution spaces. We define two types of discrete least-squares functionals summing discontinuous spectral norms of the residual equations over two sub-domains. In this paper, we show that the homogeneous least-squares functionals are equivalent to appropriate product norms and the proposed methods have the spectral convergence. Finally, we present some numerical results to provide evidences for analysis and spectral convergence of the proposed methods.