• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.7
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• pp.712-718
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• 2008

This paper deals with a development of flight control law switching system which can be used for flight test of the research control law by switching control law during flight. Through this research program, fader logic and integrator stabilization design has been introduced to minimize the transient response of aircraft caused by flight control law switching and to prevent the divergence of the integrator included in the control law in standby mode. MIL-STD-1553B communication was applied to transfer the data between the two control laws. This paper introduce the control law switching system architecture and major design concept and include the system verification and validation result performed on the flying quality simulator of the advanced trainer.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.567-570
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• 2005

Most researches on monostable LCD and bistable LCD have separately been carried out. We introduce a novel liquid crystal display mode which can be operated as both memory mode and dynamic mode. The novel LCD mode has not only a long term memory time of memory mode but also a fast response time of dynamic mode. We describe switching characteristics of dual mode. Electro-optical characteristics of memory mode and dynamic mode are unique and show the possibility of device application.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.401-402
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• 2016

This paper presents interleaved bi-directional LDC(Low DC-DC converter) with soft-switching for 48V system of Mild-HEV(Hybrid Electric Vehicles). The proposed LDC is composed of interleaved bi-directional converter and small resonant inductor and capacitors. Comparing the conventional converter, the proposed LDC improves the problem of switching loss by employing soft-switching. In this paper, mode analysis is described in detail for operating the soft-switching. The proposed LDC is verified by PSIM simulation.

• Journal of Power Electronics
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• v.9 no.6
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• pp.929-939
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• 2009

This paper presents a new soft-switching boost converter based on the LC resonance and passive clamping technique without additional active switches. The circuit achieves high efficiency and low voltage stress by adopting a soft switching method using LC resonance. This paper gives a mathematical analysis of each mode and a detailed design procedure of the proposed boost converter. First of all, the operational principles are verified through simulation results. Then, according to the design procedure, we designed and built a 1.5[kW] prototype soft switching boost converter. Through the experimental results, we demonstrated the validity and usefulness of the proposed boost converter.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.343-352
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• 1998

Higher frequency of energy transfer or at least energy conversion has to be used in order to reduce the size of inductors and capacitors required in the power supplies. Conventional PWM switching-mode power supplies have a limitation of operating frequency due to switching losses in the switching transistors and rectifier diodes. Means of reducing switching losses have been developed for high-frequency resonant amplifiers or more exactly dc/ac inverters. Because of smooth current and voltage waveforms resonant convertesrs havelower device switching losses and stresses lower electromagnetic interference(EMI) and lower noise than PWM converters. Therefore in this paper design equations of Classs E resonant low dv/dt rectifier with a series resonant capacitor drived using Fourier series techniques. The theory is compared with simulation results obtained for the rectifier operating at 10[MHz] ac input and 5[V] coutput.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.1-2
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• 2014

In this paper the partial switching PFC converter which is based on predictive control is proposed. In terms of satisfying the harmonic standard, the predictive control shows a similar performance to the conventional average current mode control PFC in the normal input condition. Moreover, the current harmonic characteristic is insensitive to the distorted input voltage. With predictive control method, novel on-line partial switching strategy is suggested in this paper. Depending on the operating condition, the partial switching PFC converter can boost its output voltage. Also when its efficiency needs to be improved, according to load condition, the partial switching can be achieved. The proposed strategy is proved by the results of FFT and the loss analysis using PSIM 9.0.

• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.60-63
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• 1998

The widely used power supply (Switched Mode Power Supply : SMPS) as a source in order to stabilize direct current for electronics or communication systems has merits, when it is compared to the existing source for stability, such as high efficiency, small size, light weight by means of switching process of the semiconductor device which controls the flow of power. However, due to existence of inductors and capacitors used for charging energy, the source part in electronic or communication systems hasn't reached the speed, that is supposed to get, for achieving smaller size and lighter weight. In order to get smallness in size, it is necessary to increase switching frequency. And that makes devices for measuring energy smaller. Nevertheless, the rise switching frequency brings increases in switching loss, inductor loss, and power loss. Also, the occurrence of surge and noise caused by high frequency switching is getting higher. The resonant converter has been considered as one of methods that give solutions for the problems of SMPS and that method have been paid attention as a source technology in electronics and communication.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.197-205
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• 1996

Four types of three-waveguide optical switches are analyzed by measns of the coupled mode theory. Assuming that three proximate waveguides of an optical switch are identical and equally spaced, we examine the switching behavior for both cases where an incident beam is launched into 1) the outer waveguide, 2) the center waveguide. For each beam-launching case, switching voltage is applied so that three waveguides refractive indices be detuned 1) symmetric, 2) anti-symmetric. It is concluded that only three types of optical switches out of four an perform the switching operation. We derive the switching conditions for ach of three possible types and draw the corresponding switching diagrams.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.1
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• pp.47-59
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• 1993

Recently, Broadband ISDN(B-ISDN) has received increased attention as a communication architecture which can support multimedia applications. Also, Asynchronous Transfer Mode(ATM) is considered as a promising technique to transfer and switch various kinds of media, such as telephone speech, data and motion video. Comparisons among a variety of ATM switching systems which have already been proposed will provide quite useful information for the new ATM switching system design. To facilitate the comparison, we introduce the design requirements and classification criteria for the ATM switch, and propose a performance analysis model for the Banyan network which is the basic switching fabric of most multi-stage ATM switching systems. The model is based on the standard discrete-time Markov chain analysis and can be conveniently used for extensive Banyan network analysis. The computational results are also presented.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.477-483
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• 2010

This paper is studied on a novel buck-boost isolated converter for high efficiency and high power factor. The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit, and are driven with discontinuous conduction mode (DCM) according to pulse width modulation (PWM). The quasi-resonant circuit makes use of a step up-down inductor and a loss-less snubber capacitor. The proposed converter with DCM also simplifies the requirement of control circuit and reduces a number of control components. The input ac current waveform in the proposed converter becomes a quasi sinusoidal waveform in proportion to the magnitude of input ac voltage under constant switching frequency. As a result, it is obtained by the proposed converter that the switching power losses are low, the efficiency of the converter is high, and the input power factor is nearly unity. The validity of analytical results is confirmed by some simulation results on computer and experimental results.