• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.4
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• pp.313-320
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• 2015

This study deals with a bidirectional interleaved soft switching DC-DC converter for a wide range of input voltages. The proposed converter operates in complementary switching with the purpose of inductor size reduction and zero-voltage switching (ZVS) operation. The current ripple related to complementary switching is minimized by three-phase interleaved operation. The main characteristics of the proposed topology are its soft-switching method of operation and its simple structure. The soft-switching operation and the system efficiency of the proposed converter are verified by experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.502-509
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• 2013

It presents an efficient switching pattern, which expects a reduction of switching losses in a cascaded H-bridge PWM multilevel inverter. By the proposed switching scheme, the lower H-bridge module operates at low frequency of 60[Hz] because it assigns to transfer most load power. The upper H-bridge module operates at high frequency of PWM switching to improve THD of output voltage. The proposed switching pattern applies to cascaded H-bridge multilevel inverter with PD, APOD, bipolar, and unipolar switching methods. By computer-aided simulations, we verify the validity of the proposed switching scheme. Finally, we prove that the proposed PD and APOD switching patterns are better than those of the conventional one in efficiency.

• Korean Management Science Review
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• v.31 no.2
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• pp.87-103
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• 2014

This study looks for the service factors influencing to conversion among the domestic telecommunication companies and finds out the effect which the switching benefit affect the customer satisfaction and the switching intention. Eight service factors of the telecommunication company such as usability, call quality, terminal quality, auxiliary service, rates, after service, application and brand image are selected and verified using the structural equation model. Auxiliary service, rates and brand image give positive (+) effects to the customer's satisfaction, but the application gives negative (-) effects to the customer's satisfaction. Switching benefit affects significantly to the switching intention, but not to the customer satisfaction. The customer satisfaction gives a positive effect to the switching intention. The telecommunication service factors influence to customer satisfaction and switching intention, and switching benefit also influences to switching intention. It was analyzed that the significant influencing service factors were a little different among the telecommunication companies.

• Journal of Information Technology Applications and Management
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• v.17 no.3
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• pp.121-134
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• 2010

Past studies in e-commerce loyalty were mostly focused on the effects of customer satisfaction and trust on loyalty toward online vendors. Few studies investigated the impacts of switching barriers, whilst they are widely proven to affect customer loyalty in offline commerce. Even in a handful of studies that did deal with switching barriers, their treatment of the subject remained at best superficial. This may have to do with the fact that switching costs in e-commerce could be comparatively negligible, as switching to another online vendor often involves one simple mouse click. In this study, we investigated the impact of switching barriers on loyalty under the e-commerce context. Furthermore, the extent of switching barriers which could be affected by those positive factors (most constructs were adopted from IDT) was also examined. The statistical testing results revealed that combined model which includes both the positive factors and the switching barriers explains the loyalty formation process more strongly ($R^2$ = 0.543) than each separated models ($R^2$ = 0.468 for positive factor only model, and $R^2$ = 0.365 for switching barrier only model). While only the two switching barriers such as convenience and emotional were shown to be statistically significant, we found that trust strongly influences customer's emotional barrier, let alone direct impact on loyalty, which thereby influences loyalty. The results offer insights for better understanding switching barriers in e-commerce related applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5A
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• pp.452-456
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• 2010

SIR based beam switching in distributed controlled cellular systems is proposed to reduce intercell interference. Compared with Random beam switching that beam switching pattern is randomly selected and cannot avoid beam collision between neighboring cell, SIR based beam switching update its switching pattern based on SIR report from mobile. Neighboring cells independently update their switching patterns and the updated patterns converge to the patterns that minimize beam collision. We shows SIR base beam switching has 20% gain compared with random beam switching in two neighboring cell model.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1148-1150
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• 2003

Power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. However, the switches of converter are subjected to high switching power losses and switching stresses. As a result of those, the power system brings on a low efficiency. To improved these, a large number of soft switching topologies included a resonant circuit has been prosed. But these circuits increase number of switch in circuit and complicate sequence of switching operation. In this paper, the authors propose a high power factor and high efficiency DC-DC converter using single-pulse soft switching by partial resonant switching node. The switching devices in a prosed circuit are operated with soft switching by the partial resonant method, that is, Partial Resonant Switch Mode Power Converter. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. The result is that the switching loss is very low and the efficiency of system is high. Also the proposed converter is deemed the most suitable for high power applications where the power switching devices are used. Some simulative results on computer results are included to confirm the validity of the analytical results.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.149.2-149
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• 1998

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.141-144
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• 2000

Recently DC-DC converters significantly increase the total losses as rising switching frequency. Traditional soft switching technique for reducing switching losses even increase voltage/current stress of switch. In this paper Resonant circuit for soft switching is connected in parallel with power stage and only operates just before turn-on of the main operates just before turn-on of the main switch, Therefore This doesn't affect the total circuit operation. ZNT-PWM converter designed with 170-260V input 4--V 5A output and 100kHz switching frequency is tested respectively with 500W. 1kW, 1.5kW, and 2kW loads.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.3
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• pp.76-81
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• 2002

In high power motor drive system, the hard-switching topology produces severs switching losses and EMI noises. Also the inverter switching frequency is thus limited because of excessive loss and thermal handling problem. The primary purpose of the proposed works on the induction motor drive system is to develop an advanced soft-switching inverter topology that is most suitable for high power induction motor drive applications. To make the optimal selection EMI comparison of the switching losses presented. To verify the proposed design procedure, detailed simulation analysis with theoretical and experimental approaches have been done using laboratory prototype.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.261-265
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• 1997

Driving the electrodeless fluorescent lamp, the high ac voltage with high frequency is required. The linear power amplifier has been widely used as a driving circuit of electrodeless fluorescent lamp. However, the low efficiency of the power amplifier causes th driving circuit to be replaced by a PWM switching inverter. In order to use a PWM switching inverter as the driving circuit of an electrodeless fluorescent lamp, the high switching frequency is required. But due to the switching loss at switches of the inverter, the limitation of high switching frequency appears in the inverter. One solution to this limitation is to reduce the switching loss by using the zero voltage switching technique. In this paper, zero voltage switching resonant inverter for driving an electrodeless fluorescent lamp is discussed. The results of analysis about the inverter are presented and the equations for design are established. And the validity of the analyzed results are verified through the experiment.