• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.814-815
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• 2015

본 논문에서는 단상 LSM(Line-Start Permanent Magnet Motor)의 토크리플 저감을 위하여 고정자 슬롯의 보조권선의 턴 수의 배치를 최적화 하였다. 보조권선의 최적화 과정은 고정자 슬롯 보조권선의 턴수 배치를 통하여 고정자 자속이 가장 정현파에 가까워지는 권선배치를 선정하였으며, DOE(Design of Experiment)를 통해 수행하였다. FEM(Finite Element Method)을 통하여 기존 모델과 최적화 모델의 특성을 비교 검토하였다.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.535-538
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• 1994

In this paper, an isolated ZVS-PWM boost converter is proposed for single stage line conversion. For power factor correction, we used the half bridge topology at the primary side of isolation transformer permitting switching devices to operate under ZVS by using circuit parastics and operating at a fixed duty ratio near 50%. Thus the relatively continuous input current distortion and small size input filter are also achievable. The ZVS-PWM boost operation of the proposed converter can be achieved by using the boost inductor $L_f$, main switch $Q_3$, and simple auxiliary circuit at the secondary side of isolation transformer. The secondary side circuit differ from a conventional PWM boost converter by introduction a simple auxiliary circuit. The auxiliary circuit is actived only during a short switching transition time to create the ZVS condition for the main switch as that of the ZVT-PWM boost converter. With a single stage, it is possible to achieve a sinusoidal line current at unity power factor as well as the isolated 48V DC output. Comparing to the two stage schemes, overall effiency of the proposed converter is highly improved due to the effective ZVS of all devices as well as single stage power conversion. Thus, it can be operated at high switching frequency allowing use of small size input filter. Minimum voltage and current stress make it high power application possible.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.3
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• pp.499-505
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• 2020

Capacitor-run single-phase induction motor is cheaper than motors that use permanent magnets and is widely used in home appliances and industries based on relatively high durability and productivity. It can also be operated by line. However speed cannot be controlled because the line frequency is free. In this paper we dealt pole change method one of the method controlling speed of capacitor-run single-phase induction motor. The conventional pole change method is difficult to improve the power and efficiency of the motor because the composition of the pole change device is complex and do not have enough area of the windings because of windings not used according to the driving conditions. In this paper, we proposed the pole change method that is used main windings and auxiliary windings at 4 poles operation and used auxiliary windings as compensation windings at 2 poles operation. The proposed method was verified through finite element analysis.

• 전기의세계
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• v.31 no.1
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• pp.50-58
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• 1982

As a method for improving the power factor and the waveform of ac line current drawn by ac to dc converters, converters of pulse-width control type with forced commutation circuits have been developed in recent years. However, these converters have rather complex commutation circuits which contain auxiliary thyristors in addition to the main thyristors, and their performance is not satisfactory. This paper proposes a new pulse-width controlled ac to dc converter, and analyses its commutation mechanism and its input and output characteristics. The proposed converter circuit consists of a usual thyristor bridge circuit with series diodes to which reactors and diodes are added. This circuit dose not contain auxiliary thyristors, and in this sense it is simpler than the previous converter circuits of pulse-width control type. Since the main thyristors of the converter can be forcedly turned off several times in a half cycle of source voltage, a pulse-width modulation control is possible in order to improve the current waveform as well as the power factor on ac line side. As to dc output side it is shown that the adjustable range of output voltage is wide and the voltage regulation is good due to a rapid reversal of voltage across the commutating capacitors by LC resonance during commutation period. It is also shown that the regenerative operation of the converter is possible.

• Journal of Power Electronics
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• v.3 no.4
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• pp.239-248
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• 2003

This paper presents a novel prototype of three-phase voltage source type zero voltage soft-switching inverter with the auxiliary resonant snubbers suitable for high-power applications with IGBT power module packages in order to reduce their switching power losses as well as electromagnetic conductive and radiative noises. A proposed single inductor-assisted resonant AC link snubber circuit topology as one of some auxiliary resonant commutation snubbers developed previously to achieve the zero voltage soft-switching (ZVS) for the three-phase voltage source type sinewave PWM inverter operating under the instantaneous space voltage vector modulation is originally demonstrated as compared with the other types of resonant AC link snubber circuit topologies. In addition to this, its operation principle and unique features are described in this paper. Furthermore, the practical basic operating performances of the new conceptual instantaneous space voltage vector modulation resonant AC link snubber-assisted three-phase voltage source type soft-switching PWM inverter using IGBT power module packages are evaluated and discussed on the basis of switching voltage and current waveforms, output line to line voltage quality, power loss analysis, actual power conversion efficiency and electromagnetic conductive and radiative noises from an experimental point of view, comparing with those of conventional three-phase voltage source hard-switching PWM inverter using IGBT power modules.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2335-2343
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• 2018

This paper proposes an optimal damping control algorithm of the DTI (Direct Two-level Inverter) to miniaturize and reduce the weight of auxiliary power supply for railway vehicles. The conventional auxiliary power supply for railway vehicles uses a DC-DC converter to maintain the inverter input power from the line voltage smoothly. The proposed topology does not use a DC-DC converter for reducing of manufacturing and maintenance costs. It also proposes a DTI topology removed damping resistors that generate ground signal noise in a certain period. At this time, a resonance phenomenon of DC-link voltage occurs due to variation of the inductive load, and a method of controlling the resonance phenomenon of DC-link voltage is required. In order to suppress the resonance phenomenon of the DC-link voltage, at a point before resonance occurs, this paper introduces an algorithm to suppress the resonance phenomenon of DC-link voltage by compensating the resonance component of the q axis voltage of the synchronous reference frame. The proposed algorithm verifies the effect through simulation and experiment.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1230-1232
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• 2000

To reduce harmonics in the AC line and achieve a unit power factor, A 4 paralled single phase PWM AC/DC converter has been proposed. In this paper, the coupling components are derived analytically from PWM converter input transformer model and control scheme to solve this problem is proposed. Unit power factor was obtained and the AC-side current harmonics were reduced. Simulation results show the usefulness of the proposed method and applicability to PWM converter in auxiliary block of high speed train.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.85-89
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• 2001

In this paper, a new line-commutated SCR inverter for renewable power generation system is proposed. The proposed inverter system includes a 6-pulse SCR inverter and an auxiliary circuit. By the proper operation of the auxiliary circuit, the pulse number of the inverter system is increased and the output harmonic currents are reduced. Analysis, control and simulation for 24 pulse operation of the proposed scheme is presented and the experimental results will be provided in the final paper.

• Journal of the Korean School Mathematics Society
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• v.20 no.2
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• pp.119-139
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• 2017

The construction in the ancient Greek era had more meanings than a construction in the present education. Based on this fact, this study examines the meaning of the current textbook. In contrast, we have extracted the meaning of the constructions in Euclid Elements. In addition, we have been thinking about what benefits can come up if the meaning of the construction in Euclid Elements was reflected in current education, and suggested a way to exploit that advantage. As results, it was confirmed that the construction in the current textbook was merely a means for introducing and understanding the congruent conditions of the triangle. On the other hand, the construction had four meanings in Euclid Elements; Abstract activities that have been validated by the postulates, a mean of demonstrating the existence of figures and obtaining validity for the introduction of auxiliary lines, refraining from intervening in the argument except for the introduction of auxiliary lines, a mean of dealing with numbers and algebra. Finally we discussed the advantages of using the constructions as a means of ensuring the validity of the introduction of the auxiliary line to the argument. And we proposed a viewpoint of construction by intervention of virtual tools for auxiliary lines which can not be constructed with Euclid tool.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.310-313
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• 1996

In this paper, a neural control algorithm is proposed on the automation of adjustment process. The adjustment processes in camcoder production line are modelled, and the processes are adjusted automatically by means of off-line supervisory trained multi-layer neural network. We have made many experiments on the several adjustment processes by using the control algorithm. There are many unexpected troubles to achieve the desirable adjust time in the practical application. To overcome those, some auxiliary algorithms are demanded. As a result, our proposed algorithm has some advantages - simple architecture, easy extraction of the training data without expertises, adaptability to the varying systems, and wide application for the other resemble processes.