• Journal of the Korea Society of Computer and Information
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• v.20 no.2
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• pp.1-10
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• 2015

In this paper, we propose a new multiplication algorithm for primitive polynomial with all 1 of coefficient in case that m is odd and even on finite fields $GF(3^m)$, and design the multiplier with parallel input-output module structure using the presented multiplication algorithm. The proposed multiplier is designed $(m+1)^2$ same basic cells. Since the basic cells have no a latch circuit, the multiplicative circuit is very simple and is short the delay time $T_A+T_X$ per cell unit. The proposed multiplier is easy to extend the circuit with large m having regularity and modularity by cell array, and is suitable to the implementation of VLSI circuit.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.69-79
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• 2012

In this paper, we restrict the case as m odd, n=mk, and propose and explicitly exhibit the architecture of a new parallel multiplier over the field GF($2^m$) with a type k Gaussian period which is a subfield of the field GF($2^n$) implements multiplication using the parallel multiplier over the extension field GF($2^n$). The complexity of the time and area of our multiplier is the same as that of Reyhani-Masoleh and Hasan's multiplier which is the most efficient among the known multipliers in the case of type IV.

• Journal of Power Electronics
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• v.14 no.4
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• pp.671-677
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• 2014

In this paper, a new basic unit is proposed. Then, a cascaded multilevel inverter basded on the series connection of n number of these new basic units is proposed. In order to generate all of the voltage levels (even and odd) at the output, three different algorithms to determine the magnitude of the dc voltage source are proposed. Reductions in the number of power switches, driver circuits and dc voltage sources in addition to increases in the numbr of output voltage levels are some of the advantages of the proposed cascaded multilevel inverter. These results are obtained through a comparison of the proposed inverter and its algorithms with an H-bridge cascaded multilevel inverter from the point of view of the number of power electronic devices. Finally, the capability of the proposed topology with its proposed algorithms in generating all of the voltage levels is verified through experimental results on a laboratorary prototype of a 49-level inverter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.76-81
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• 2004

This paper presents the results of spectral analysis of leakage current waveforms on contaminated insulators under various fog and environment conditions(salt fog, clean fog, rain) The larger the leakage current during 200ms, the higer the power spectrum at 60Hz. For almost equal maximum current during 200ms, however, the spectrum at 60hz and the odd order harmonics increase emphatically when discharges occur continuously for several half-waves. If contaminated insulators suffers from high salt-density fog, the leakage current occurs with high crest value intermittently, results in the low spectrum. Analysis of leakage current data showed that this electrical activity was characterized by transient arcing behavior contaminants are deposited on the insulator surface during salt fog tests. This provides a path for the leakage current to flow along the surface of the insulator. It is important to have an indication of the pollution accumulation in order to evulate the test performance of a particular insulator. If the drop in surface resistivity is severe enough, then the leakage current may escalate into s service interrupting flashover that degrade power quality.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1096-1098
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• 2003

In this paper, the control algorithm and control methods for a combined system of shunt passive filter and series active filter in 3-phase 4-wire system are discussed. Moreover, the 3-phase 4-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. In such systems, the third harmonic and odd multiples of $3^{rd}$($9^{th}$, $15^{th}$, etc.) are termed as triple and zero sequence components that do not cancel each other in the system neutral. As a result, the triple harmonics add together creating a primary source of excessive neutral current. Regarding this concern, this paper presents a new control scheme for a series hybrid active system. This series active power filter acts not only as a harmonic compensator but also as a harmonic isolator. Hence the required rating of the series active filter is much smaller than that of a conventional shunt active filter. However, the performance of the combined system is greatly influenced by the filtering algorithm employed in the active power filter. This paper proposes a series active power filter scheme based on performance function. Some experiments was executed and experimental results from a prototype active power filter confirm the suitability of the proposed approach.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.290-297
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• 2004

The control laws for cart-pole system are studied to see the schemes on which the control laws are made. Also, the odd symmetry of the relation between the output of the control laws and the system state vector is observed. Utilizing the symmetry in quantizing the system state variables and implementing the control laws into look-up table is discussed. Then, a CMAC is trained for a nonlinear control law for a cart-pole system such that the symmetry is conserved and its learning performance is evaluated. It is found that utilizing the symmetry is to reduce the memory requirement as well as the training period while improving the learning quality in terms of preserving the symmetry.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1085-1092
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• 2015

In this paper, the expressions of the estimated information of a single-phase enhanced phase-locked loop (EPLL), when input signal contains harmonics and a DC offset while the fundamental component takes step changes, are derived. The theoretical analysis results indicate that in the estimated information, the n^th-order harmonics cause n+1^th-order periodic ripples, and the DC offset causes a periodic ripple at the fundamental frequency. Step changes of the amplitude, phase angle and frequency of the fundamental component cause a transient periodic ripple at twice the frequency. These periodic ripples deteriorate the performance of the EPLL. A hybrid filter based EPLL (HF-EPLL) is proposed to eliminate these periodic ripples. A delay signal cancellation filter is set at the input of the EPLL to cancel the DC offset and even-order harmonics. A sliding Goertzel transform-based filter is introduced into the amplitude estimation loop and frequency estimation loop to eliminate the periodic ripples caused by the residual input odd-order harmonics and step change of the input fundamental component. The parameter design rules of the two filters are discussed in detail. Experimental waveforms of both the conventional EPLL and the proposed HF-EPLL are given and compared with each other to verify the theoretical analysis and advantages of the proposed HF-EPLL.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.166-174
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• 2017

This study proposes a compensation method for the dead-time effects on a single-phase grid-connected inverter. Dead time should be considered in the pulse-width modulation gating signals to prevent the simultaneous conduction of switching devices, considering that a switching device has a finite switching time. Consequently, the output current of the grid-connected inverter contains odd-numbered harmonics because of the dead time and the nonlinear characteristics of the switching devices. The effects of dead time on output voltage and current are analyzed in this study. A new compensation algorithm based on second-order generalized integrator is also proposed to reduce the dead-time effect. Simulation and experimental results validate the effectiveness of the proposed compensation algorithm.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.983-984
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• 2007

The spindle motor used on the ODD has a characteristic that electromagnetic pulsation and noise change differently by magnetization pattern of rotor. Therefore, design of magnetizer yoke that make to have optimal magnetization pattern is very important. In this paper, we proposed an analysis method that applies magnetizer analysis result to the spindle motor. We measured back-EMF of the real spindle motor. And then, we verified validity of the proposed analysis method by comparing the measurement and analysis result. Also, we designed the magnetizer shape that has optimal magnetization pattern by using proposed method. As a result, we reduced cogging torque of the spindle motor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.764-774
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• 2002

Dynamic behaviors are analyzed for an automatic ball balancer (ABB) with triple races, which is a device to reduce the unbalanced mass of optical disk drives (ODD) such as CD-ROM or DVD drives. The nonlinear equations of motion are derived by using Lagrange's equations with the polar coordinate system. It is shown that the polar coordinate system provides the complete stability analysis while the rectangular coordinate system used in other previous studies has limitations on the stability analysis. For the stability analysis, the equilibrium positions and the linearized perturbation equations are obtained by the perturbation method. Based on the linearized equations, the stability of the system is analyzed around the equilibrium positions; furthermore, to confirm the stability, the time responses for the nonlinear equations of motion are computed by using a time integration method and experimental analyses are performed. Theoretical and experimental results show a superiority of the ABB with triple races.