• Journal of Power Electronics
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• v.9 no.3
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• pp.396-402
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• 2009

A DC/DC converter generally needs to work under high switching frequency when used as an adjustable power supply to reduce the size of magnetic elements such as inductors, transformers and capacitors, but with the rising of the switch frequency, the switch losses will increase and the efficiency will reduce. Recently, to solve these problems, research is actively being done on a soft switching method that can be applied under high frequency and on a PWM converter that can be applied under low frequency such as a multi-level topology. In this paper a novel DC-DC conversion method for reducing the ripple of output voltage is proposed. In the proposed converter, buck converters are connected in series to generate the output voltage. By using this method, the ripple of output voltage can be reduced compared to a conventional buck converter. Particularly when output voltage is low, the number of acting switching elements is less and the result of ripple reduction is more obvious. It is expected that the converter proposed in this paper could be very useful in the case of wide-range output voltage.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.1989-1992
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• 1997

A new soft switching single stage AC-DC full bridge boost converter with unit input power factor and isolated output is presented. Due to using of the non-dissipative snubber in the primary side, a single stage high-power factor isolated full bridge boost converter has a significant reduction of switching losses in main switching devices and output rectifiers of the primary and secondary side, respectively. The non-dissipative snubber adopted in this study is consisted of a snubber capacitor C. and a snubber inductor $L_r$, a fast recovery snubber diode $D_r$, a commutation diode $D_p$. This paper presents the complete operating principles, theoretical analysis and simulation results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12A
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• pp.1983-1989
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• 2001

A new two-step soft output Viterbi algorithm (SOVA) for turbo decoder is proposed and analyzed in 7his paper. Due to the algebraic structure of the proposed algorithm, slate and branch metrics can be obtained wish parallel processing using matrix arithmetic. As a result, the number of multiplications to calculate state metrics of each stage and total memory size can be decreased tremendously. Therefore, it can be expected that the proposed algebraic two-step SOVA is suitable for applications in which low computational complexity and memory size are essential.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.796-797
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• 2006

SMC(Soft Magnetic Composite) materials which we have newly developed were studied for their applying effects. It shows almost the same motor output power as the laminated Si-steels of 0.35mm in thickness, although core loss of SMC is about 1.5 times that of the laminations. As shown in the results, the SMC motor core is sufficient for real use as a motor core. Furthermore, a 3-D shaped motor core made of SMC can improve approximately 20% of the output compared with the same size motor made of laminations.

• Journal of Power Electronics
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• v.16 no.1
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• pp.93-101
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• 2016

A new four-primary-switch diode clamped soft switching three-level DC-DC converter (TLDC) with full zero-voltage switching (ZVS) load range and TL secondary voltage waveform is proposed. The operation principle and characteristics of the presented converter are discussed, and experimental results are consistent with theoretical predictions. The improvements of the proposed converter include a simple and compact primary structure, TL secondary rectified voltage waveform, wide load range ZVS for all primary switches, and full output-regulated range with soft switching operation. The proposed converter also has some disadvantages. The VA rating of the transformer is slightly larger than that of conventional TLDCs in variable input and constant output mode. The conduction loss of the primary coil is slightly higher because an air gap is inserted into the magnetic cores of the transformer. Finally, the secondary circuit is slightly complex.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.2
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• pp.69-82
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• 2000

Recently, as the prepress mainstream is changed to the digital workflow, various digital proofing systems such as high price dye sublimation printers and low price ink jet printers are widely used in printing industry. CRT monitors are also often used as a soft proofing device. However, it is very difficult to match the color image displayed on CRT monitors to the actual images printed on papers, because the color space of CRT monitors is RGB color system, and it is different with the CMY color system of the printing devices. Therefore, proper color compensations are needed to match the colors between hard-copy proofs on the printing device and soft copy proofs on CRT monitors. This paper shows the LUT and gamut mapping method considering the printing characteristics of output device is useful for the compensation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.7
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• pp.87-94
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• 2015

Recently, renewable energy sources are under the spotlight. due to the depletion of fossil fuels and environmental problem for the carbon dioxide. Among them, research on the Photovoltaic System using solar energy systems has been actively conducted. In this paper, we propose boosting the insulated DC/DC converter topologies Applied to soft-switching methods used in photovoltaic PCS. The proposed topology is of a type that combines a series of full-bridge converter and a boost converter, a full bridge converter and applying the insulation and soft switching system, the output voltage boost stage is carried out for the boost control. The proposed circuit validity was verified through the PSIM simulation and 5kW PV PCS Prototype and experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.103-107
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• 2016

In general, the voltage stability of induction generator is lower than synchronous generator. Induction generator has a number of advantages over the synchronous generator on the side of price and maintenance. So Induction generator has been applied to the small hydroelectric power of low output. Induction generator usually generates a high current during grid connection. The high current that occurs during grid connection can cause a voltage drop in the system. In order to increase the supply of the induction generator, it is necessary to propose a method of reducing high current. This paper proposes some method of the soft start to reduce voltage drop caused by the large starting current. soft-start method has high voltage drop effect than direct start method, control of firing angle can be increased the voltage drop effect.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.50-54
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• 2010

Soft recovery (SR) quasi-resonant converter (QRC) including a Folding snubber network (FSN) is introduced. It is obtained by combining normal quasi-resonant converter with folding snubber network of which the surrounding components are composed of passive devices only (diodes and capacitors). The reverse recovery loss of the main rectifier diode is eliminated by this method utilizing quasi resonance with Folding snubber network. By realizing soft switching condition, the proposed converter has PWM capability with high efficiency and is suitable for high output current and high power DC to DC converter application.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.1
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• pp.62-66
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• 2010

A new soft recovery pulse width modulation quasi resonant converter composed only passive devices snubber network is proposed. This passive devices snubber network is revised form of folding snubber network that suppressed the reverse recovery current of main rectify diode in PWM converter. It also makes the MOSFET switching devices operate in soft state. The efficient of the proposed converter is almost same level to that of the converter of active snubber type. The overall circuit is simple and easy to realized. Therefore, it is suitable to apply to middle range output power source.