• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.343-349
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• 2005

This paper proposes a novel zero-voltage-switching (ZVS) Push-pull DC-DC Converter for high input voltage and high power applications. This topology utilizes two switches in series to replace one switch in conventional push-pull converter, and two clamping diodes are introduced. The voltage stress of the switches is the input voltage, and the switches can realize ZVS with the use of the leakage inductance of the transformer. Furthermore, secondary full-wave rectifier with a clamping capacitor is used to eliminate the voltage oscillation and spike of the rectifier diodes due to the reverse recovery. Therefore, the electromagnetic interference is reduced effectively. The operation principle of the proposed converter is analyzed theoretically. The output characteristic, ZVS condition and design principle of the clamping capacitor are discussed. Experimental results obtained from a 270V input 2kW prototype with $95.8\%$ high efficiency confirms the design.

• Journal of Power Electronics
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• v.6 no.4
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• pp.298-306
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• 2006

A high efficiency and low cost sustain driver for a plasma display panel (PDP) utilizing a current pumping method is proposed. The main concept of the proposed circuit is using the current source to charge and discharge the panel. As a result, all power switches can achieve zero voltage switching (ZVS) and every auxiliary switch can also achieve zero current switching (ZCS). Since the inductor current can compensate for the discharge current, the current stress of all the power switches can be reduced considerably. Furthermore, it has features such as a simpler structure, less mass, lower cost, and lower electromagnetic interference than in previous circuits.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.216-220
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• 2013

The rated voltage has been rising in order to minimize the losses in power transmission. The high voltage electric machines should be minimized due to the constraints of space. Therefore, the temperature of high voltage electric apparatuses easily exceeds the temperature limits. In this paper, it is investigated that how to minimize the internal temperature rising of a high voltage switchgear by adjusting the arrangement of bus bars. High voltage switchgears consist of a circuit breaker, a CT, a PT, a earthing switches, bus bars, and so on. It is very difficult to estimate the electromagnetic properties of a high voltage switchgear due to these various environments and structures. In this paper, analyses are focused on the electromagnetic characteristics of bus bars according to the arrangement method and the enclosures to simplify the electromagnetic characteristics of a switchgear. It is found that the characteristics of electric field intensity and electromagnetic losses in bus bars are influenced by the arrangement method of bus bars. However, it is confirmed that the electromagnetic characteristics of enclosures are not affected by the arrangement of bus bars. In this paper, the arrangement methods of bus bars to minimize the electric field intensity and electromagnetic losses are suggested. It is expected that the research results are helpful to design and develop an electrically reliable high voltage switchgear.

• Journal of electromagnetic engineering and science
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• v.8 no.3
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• pp.96-99
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• 2008

This paper describes a $0.13-{\mu}m$ CMOS RF switch for $3{\sim}5$ GHz UWB band(mode 1). It can improve isolation characteristics between ports by using deep n-well RF devices while their source and body terminals are separated. From the measurement results, the proposed T/R switch is comparative to the on-wafer probing measurement results of the series-shunt T/R switches. When the proposed T/R switch operates as Tx mode, measured insertion loss from Tx to output port is less than 1.5 dB and isolation between Tx and Rx is more than 27 dB for $3{\sim}5$ GHz. Return loss for the Tx port is more than -10 dB and input P1dB is +10 dBm.

• Journal of Industrial Technology
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• v.34
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• pp.71-78
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• 2014

Recently, using the electronic devices was increased with semiconductor developments. So, the EMI(Electromagnetic interference) problem become to important issue for coexistence with each electronic devices. The EMI is caused by switching operation from the power switches as the FET and the transistor in power conversion devices. In this paper, the hybrid EMI filter that composed with active components and passive components was described. The EMI filter is applied to the 160 watts LED driver experimentally verify the performance. The hybrid EMI filter is compared with non-filter, only passive filter and only active filter. The proposed EMI filter attenuated CM noise more than traditional passive filter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.952-958
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• 2000

다양한 구조위 트랜스미션 라인과 힌지들을 갖는 고주파용 마이크로머신드 용량성 스위치들이 새롭게 디자인되었고 전기도금 기술, 저온 공정기술, 그리고 건식 식각기술들을 이용하여 제작되었다. 특히, 집적화된 용량성 스위치들이 높은 스위칭 on/off ratio와 on 캐패시턴스를 갖도록 하기 위하여 고유전율을 갖는 SrTiO3라는 상유전체를 절연체로 사용하였다. 제작된 스위치들은 8V의 구동전압, 0.08dB의 삽입손실, 42dB의 높은 isolation, 600의 on/off ratio, 그리고 50pF의 on 캐패시턴스의 특성들을 갖는다.

• Journal of the Korean Magnetics Society
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• v.26 no.5
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• pp.154-158
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• 2016

A CRDM (Control Rod Drive Mechanism) is an electromagnetic device which drives a control rod assembly linearly to regulate the reactivity of a nuclear core. An RPIS (Rod Position Indication System) is used as a position indicator for a control rod assembly of a CRDM of SMART, and an RPIS consists of permanent magnets and reed switches. SMART is designed for the maximum coolant temperature of $350^{\circ}C$, and the permanent magnets are installed inside of the reactor. The reed switches and electrical circuit are installed outside of the reactor on the other hand. Test coil for a reed switch is test equipment for quality verification of a reed switch, and a test coil consists of a coil and core. In this study, magnetic property of test coil and permanent magnet on a reed switch is compared by using finite element electromagnetic simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.8
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• pp.754-760
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• 2011

Reconfigurable beam steering using microstrippatch antenna with U-slot is proposed for wearable fabric applications. The proposed antenna is manufactured on a fabric substrate, and designed to steer the beam directions at the operation frequency of 6.0 GHz. The U-shaped slot and the indirect feeding-techniques are utilized in designing the proposed antenna. By the configuration of two artificial switches($S_0$, $S_1$, $S_2$) in between the indirect feed and the antenna patch, the antenna has three beam directions. The maximum beam directions are steerable in the yz-plane(${\theta}=0^{\circ}$, $30^{\circ}$, $331^{\circ}$), and the overall HPBW is $115^{\circ}$. The measured peak gains are 6.11~6.69 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.11
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• pp.924-927
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• 2017

This paper presents a 6~18 GHz 8-bit true time delay (TTD) circuit. The unit delay circuit is based on m-derived filter with relatively constant group delay. The designed 8-bit TTD is implemented with two single-pole double-throw (SPDT) switches and seven double- pole double-throw (DPDT) switches. The reflection characteristics are improved by using inductors. The designed 8-bit TTD was fabricated using $0.18{\mu}m$ CMOS. The measured delay control range was 250 ps with 1 ps of delay resolution. The measured RMS group delay error was less than 11 ps at 6~18 GHz. The measured input/output return losses are better than 10 dB. The chip consumes zero power at 1.8 V supply. The chip size is $2.36{\times}1.04mm^2$.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.5
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• pp.431-439
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• 2014

The two-phase interleaved bidirectional DC-DC converter (TIBDC) is a very attractive solution to problems related to battery energy storage systems. However, the hard-switching TIBDC increases the switching loss and electromagnetic interference noise when the switching frequency increases. Hence, a soft-switching technique is required to overcome these disadvantages. In this study, a novel TIBDC with zero-voltage transition (TIBDC-ZVT) is proposed. Soft switching in the boost and buck main switches is achieved through a resonant cell that consists of a single resonant inductor and four auxiliary switches. Given its single resonant inductor, the proposed TIBDC-ZVT has a reduced size and can easily be implemented. The validity of the proposed TIBDC-ZVT is verified through experimental results.