• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1997.10a
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• pp.88-92
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• 1997

Power conversion system must be increased swiching frequency in order to achieve a small size, a light weight and a low noise, However, the swiches 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. In this paper, the authors propose a DC-DC boost converter of high power by partial resonant switch method (PRSM). The switching devices in a proposed circuit are operated with soft swiching and the control technique of those is simplified for switch to drive in constant duty cycle. The partial resonant circuit makes use of a inductor suing step up and a condenser of loss-less snubber. Also the circuit has a merit which is taken to increase of efficiency, as if makes to a regeneration at input source of accumulated energy in snubber condenser without loss of snubber in conventional cirvuit. The result is the the switching loss is very low and the efficiency of system is high. The proposed converter is deemed the most suitable for high power applications where the power switching devices are used.

• 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.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.3
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• pp.115-121
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• 2015

A device which could cut off the consumption of standby power by electric or electronic devices at homes and offices while waiting for a command to carry out the main functions from the inside or the outside was developed at a low price. Efforts to save standby power have been made on a global scale as well as by advanced countries. The consumption of standby power in South Korea is also increasing gradually due to increasing trend in the number of electronic and electric devices per household, becoming a major factor for waste of electric energy. The previous standby power cutoff devices themselves have high electric energy consumption and complicated structures, making the purpose less meaningful. Therefore, a low-priced standby power cutoff device is suggested in this study, which compensates such problems and cuts off the consumption of standby power completely. The circuit of the suggested standby power cutoff device was designed and implemented by applying it to an earth leakage breaker and an (electrical) outlet. Experimental results show its superiority.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.527-529
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• 2002

본 논문에서는 저전압 기기의 전자회로를 보호하는 서지보호장치(surge protective devices, SPD)의 기술에 대하여 논의하고자 한다. 먼저 저압 전력계통에서 발생하는 전원장해(power disturbance) 종류 및 서지보호장치와의 상호관계를 고찰하였다. 또한 서지보호장치의 보호소자 및 특성, 구성기법을 고찰하고, 최근 IEC 및 IEEE 규격을 소개하고자 한다. 마지막으로 국내의 문제점 및 발전방안을 제안하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1996.11a
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• pp.116-121
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• 1996

An image of future power system which has introduced superconducting generator, cable, transformer, fault current limiter, SMES and so on is presented. Conceptual designs of each SC machines and devices are carried out. The SC cable and SFCL utilize the high Tc superconductor(HTS) cooled by liquid $N_2$Other devices use low temperature superconducting cooled by He. The SC power system models are proposed detailedly. In viewpoint of the operation and control SC power system, The concrete design direction and effective role of each SC apparatus are investigated. In this paper, it is pointed that superconducting fault limiters(SFCLs) should play an important part of the quenching current level coordination to prevent the other SC devices from quenching. Finially, SFCL are also expected to he very effective to introduce flexibility of power system configuration and operation due to their possibility to enhance transient stability and reduce short circuit current.

• Journal of Power Electronics
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• v.18 no.4
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• pp.985-996
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• 2018

The implementation and performance evaluation of an interleaved boundary conduction mode (BCM) boost power factor correction (PFC) converter is presented in this paper by employing three wide band-gap switching devices: a super junction silicon (Si) MOSFET, a silicon carbide (SiC) MOSFET and a gallium nitride (GaN) high electron mobility transistor (HEMT). The practical considerations for adopting wide band-gap switching devices to BCM boost PFC converters are also addressed. These considerations include the gate drive circuit design and the PCB layout technique for the reliable and efficient operation of a GaN HEMT. In this paper it will be shown that the GaN HEMT exhibits the superior switching characteristics and pronounces its merits at high-frequency operations. The efficiency improvement with the GaN HEMT and its application potentials for high power density/low profile BCM boost PFC converters are demonstrated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.10
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• pp.713-719
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• 2013

Power MOSFET operate voltage-driven devices, design to control the large power switching device for power supply, converter, motor control, etc. We have optimal designed planar and trench gate power MOSFET for high breakdown voltage and low on resistance. When we have designed $6,580{\mu}m{\times}5,680{\mu}m$ of chip size and 20 A current, on resistance of trench gate power MOSFET was low than planar gate power MOSFET. The on state voltage of trench gate power MOSFET was improved from 4.35 V to 3.7 V. At the same time, we have designed unified field limit ring for trench gate power MOFET. It is Junction Termination Edge type. As a result, we have obtained chip shrink effect and low on resistance because conventional field limit ring was convert to unify.

• The KIPS Transactions:PartC
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• v.12C no.2 s.98
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• pp.157-168
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• 2005

Group key agreement protocols are designed to provide a group of parties securely communicating over a public network with a session key. The mobile computing architecture is asymmetric in the sense of computational capabilities of participants. That is, the protocol participants consist of the stationary server(application servers) with sufficient computational Power and a cluster of mobile devices(clients) with limited computational resources. It is desirable to minimize the amount of computation performed by each group member in a group involving low-power mobile devices such as smart cards or personal digital assistants(PDAs). Furthermore we are required to update the group key with low computational costs when the members need to be excluded from the group or multiple new members need to be brought into an existing group. In this paper, we propose a dynamic group key protocol which offers computational efficiency to the clients with low-power mobile devices. We compare the total communicative and computational costs of our protocol with others and prove its suity against a passive adversary in the random oracle model.

• Journal of Power Electronics
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• v.11 no.4
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• pp.606-611
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• 2011

Power electronics is a key technology for electric, hybrid, plug-in hybrid, and fuel cell vehicles. Typical power electronics converters used in electric drive vehicles include dc/dc converters, inverters, and battery chargers. New semiconductor materials such as silicon carbide (SiC) and novel topologies such as the Z-source inverter (ZSI) have a great deal of potential to improve the overall performance of these vehicles. In this paper, a Z-source inverter for fuel cell vehicle application is examined under three different scenarios. 1. a ZSI with Si IGBT modules, 2. a ZSI with hybrid modules, Si IGBTs/SiC Schottky diodes, and 3. a ZSI with SiC MOSFETs/SiC Schottky diodes. Then, a comparison of the three scenarios is conducted. Conduction loss, switching loss, reverse recovery loss, and efficiency are considered for comparison. A conclusion is drawn that the SiC devices can improve the inverter and inverter-motor efficiency, and reduce the system size and cost due to the low loss properties of SiC devices. A comparison between a ZSI and traditional PWM inverters with SiC devices is also presented in this paper. Based on this comparison, the Z-source inverter produces the highest efficiency.

• Information Display
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• v.18 no.3
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• pp.3-12
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• 2017

In the recent years, significant advances have been made in the development of small form-factor, low power, and low cost 3D-sensing devices based on depth-imaging technologies with real-time performance. This has led to the advent of devices and machines that are able to sense and understand the world, navigate in the environment, and interact naturally with their human users. Human-computer interactions based on touch sensing and speech recognition have already become mainstream, and the rapid developments in 3D sensing is paving the path towards the next level of machine intelligence and interactions. This paper discusses the recent developments in real-time 3D sensing technologies and their emerging system application.