• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.27-37
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• 2011

dth-order power analysis can safely be defended by dth-order masking method. However, as the degree of applied masking method increases, it can significantly decrease effectiveness of cryptosystem. The existing statistical analysis on high-order power analysis contains only analysis on second power analysis. However, this means absent of safety standards when crypto engineers apply 3rd or more order masking. this absent of standards can lead to insignificant usage of masking method which can significantly decrease effectiveness of cryptosystem. In this dissertation, we have generalize statistical values on high-order power analysis to establish these standards. In other words, we have generalized the value of a correlation coefficient when calculation of high-order power analysis methods are performed. That is to say, it can greatly be used to indicate a degrees that can be applied on further usage of masking method.

• 전기의세계
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• v.24 no.5
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• pp.67-71
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• 1975

A dynamic stability analysis of a large interconnected power system takes much time even though the modern large computer is used because of the high order of the system dynamic equations. By the necessity of the low order power system models, a simplified power system model of the generator with the high speed solid state exciter is developed in this paper. The usefulness of the reduced model is confirmed by comparing its eigenvalues and the transient responses with those of the original model in the single machine to infinite bus power system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1123-1129
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• 2012

This paper presents the fast steady state analysis using time-stepping finite element method for a high power three-phase transformer. The high power transformer spends huge computational cost of the time-stepping finite element method. It is because that the high power transformer requires a lot of time to reach steady state by its large inductance component. In order to reduce computational cost, in this paper, the adaptive time-step control algorithm combined with the embedded 2nd 4th singly diagonally implicit Runge-Kutta method and the analysis strategy using variation of the winding resistance are studied, and their numerical results are compared with those from the typical time-stepping finite element method.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.114-120
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• 2014

In this paper, a method for multi-physics analysis of the temperature-dependent properties of an oil-immersed transformer is discussed. To couple thermal fields with electromagnetic and fluid fields, an algorithm employing a user defined function (UDF) is proposed. Using electromagnetic analysis, electric power loss dependent on temperature rise is calculated; these are used as input data for multi-physics analysis in order to predict the temperature rise. A heat transfer coefficient is applied only at the outermost boundary between transformer and the atmosphere in order to reduce the analysis region. To verify the validity of the proposed method, the predicted temperature rises in high-voltage (HV) and low-voltage (LV) windings and radiators were compared with the experimental values.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.259-261
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• 1996

In this paper, active input filter for power factor correction(PFC) circuit employing ripple arrent and voltage cancellation is proposed to reduce filter's size and cost, and to make filter design easy. Switching ripple current and voltage can be sensed through the secondary windings of filter inductor. Single stage passive filter can achieve high order filter characteristics by using active ripple current and voltage cancellation technique. Conventional high order passive filter and its problems are suggested. Analysis of active filter and design procedure are detailed. Simulation result is presented to verify high order filter characteristics of proposed scheme.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.5
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• pp.22-28
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• 1977

This is a design and analysis of the D.C. highly stabilized power source. This appratus has 10**-7 order of the voltage regulation and 40V, 1.5A, continuosly variable D.C. output. Authors inspected the effect of the OP Amp, FET and the load circuit to the stationary and transient characteristics of the apparatus. Authors found that it is a useful method for high performance of the stabilized power source to utilize IC OP Amp and FET as the elements of it.

• Journal of Power Electronics
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• v.10 no.4
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• pp.335-341
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• 2010

In this paper, an interleaved soft switching boost converter for a Photovoltaic Power Conditioning System (PV-PCS) with high efficiency is proposed. In order to raise the efficiency of the proposed converter, a 2-phase interleaved boost converter integrated with soft switching cells is used. All of the switching devices in the proposed converter achieve zero current switching (ZCS) or zero voltage switching (ZVS). Thus, the proposed circuit has a high efficiency characteristic due to low switching losses. To analyze the power losses of the proposed converter, two experimental sets have been built. One consists of normal devices (MOSFETs, Fast Recovery (FR) diodes) and the other consists of advanced power devices (CoolMOSs, SiC-Schottky Barrier Diodes (SBDs)). To verify the validity of the proposed topology, theoretical analysis and experimental results are presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.10
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• pp.935-940
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• 2016

Directed energy weapon enables to radiate the concentrated energy so as to result in distraction and overload of the target electronics. Analysis on effectiveness of weapon system can be important consideration in order to determine performance and design weapon system. In this paper, air defense weapon system, which is one of directed energy weapon system is studied. In order to analyze the effectiveness, the reflector antenna with high power circularly polarized horn antenna is designed, and power density in axial effective area is simulated and calculated using Friis formula. Through the study, the validity of antenna system is verified, and the effectiveness of directed energy weapon system on the target is evaluated.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.553-555
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• 1996

This paper concerns with a method to improve the current and power waveforms of the variable speed $3{\Phi}$ AC motor system driven by the single-pulse PWM, and the current waveforms and $3{\Phi}$ power waveforms are analyzed by FFT under various running conditions. By the performance analysis through the experiments, the following results have been obtained. AC source of pseudo sine waveform can be obtained from the modulated alternating square voltage by means of the well designed LC filter. It is confirmed that current waveforms and $3{\Phi}$ power waveforms can be improved by utilizing the high order low pass LC filter than that of lower order. Especially, current waveforms and $3{\Phi}$ power waveforms tan be much improved at low frequency domain. $3{\Phi}$ power waveforms have a smatter ripple and bigger power by utilizing the high order low pass LC filter than that of lower order. Also, the running condition of $3{\Phi}$ AC motor is good at low frequency domain.

• Journal of Power Electronics
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• v.17 no.2
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• pp.453-463
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• 2017

This paper discusses the measurement of frequency response functions for various dc-dc converters. The frequency domain identification procedure is applied to the measured frequency responses. The identified transfer functions are primarily used in developing behavioral models for dc-dc converters. Distributed power systems are based upon such converters in cascade, parallel and several other configurations. The system level analysis of a complete system becomes complex when the identified transfer functions are of high order. Therefore, a certain technique needs to be applied for order reduction of the identified transfer functions. During the process of order reduction, it has to be ensured that the system retains the dynamics of the full order system. The technique used here is based on the Hankel singular values of a system. A systematic procedure is given to retain the maximum energy states for the reduced order model. A dynamic analysis is performed for behavioral models based on full and reduced order frequency responses. The close agreement of results validates the effectiveness of the model order reduction. Stability is the key design objective for any system designer. Therefore, the measured frequency responses at the interface of the source and load are also used to predict stability of the system.