• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.2
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• pp.223-230
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• 1998

This paper describes a phase-shift pulse-width modulation and pulse-frequency modulation series resonant high-frequency inverter using IGBT(Insulated-Gated Bipolar Transistor) for the power control of high-frequency induction heating using neuro-fuzzy, which is practically applied for 20KHz~500KHz induction-heating and melting power supply in industrial fields. The adaptive frequency tracking based phase-shifting PWM(Pulse-Width Modulation) regulation scheme is presented in order to minimize switching losses. The trially-produced breadboards using IGBT are successfully demonstrated and discussed.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.477-484
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• 2013

This paper proposes a novel switching method of active clamp snubber for efficiency improvement of PV module integrated converter(MIC) system. Recently, MIC solar system is researched about the efficiency and safety. PV MIC system is used active clamp method of snubber circuit for the price and reliability of the system. But active clamp snubber circuit has the disadvantage that system efficiency is decreased for switch operating time because of heat loss of resonant between snubber capacitor and leakage inductance. To solve this problem, this paper proposes a novel switching method of the active clamp. The proposed method is a technique to reduce power consumption by reducing the resonance of the snubber switch operation time and through simulations and experiments proved the validity.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.191-192
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• 2014

Multiple output converters (MOCs) are widely used for applications which require various levels of the output voltages due to their benefits in cost, volume, and efficiency. However, most of the MOCs developed so far can regulate only one output tightly and require as many secondary windings in the transformer as the number of the outputs. In this paper, a novel Time Division Multiple Control (TDMC) method to regulate all the outputs in high precision is proposed and applied for the multiple output battery charger based on the phase shift full bridge topology to charge a multiple number of batteries at one time. The proposed converter can charge three different kinds of batteries or same kind of batteries in different state of charges (SOCs) by using constant current/constant voltage (CC/CV) charge mode independently. At the same time it can provide an even degree of tight regulation for each output to satisfy the strict ripple requirement of the battery. The validity and feasibility of the proposed method are verified through the experiments.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.419-422
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• 2000

현재의 인터넷은 IPv4를 기반으로 하며, CIDR(Classless InterDomain Routing)을 이용하여 IP의 고갈을 막으려고 노력하고 있다. 그러나, 이는 근본적인 대책이 아니다. 그 때문에 IP는 점차 고갈되어 미래에는 IPv6로 옮겨갈 것이다. 이렇게 IPv6로 발전함에 따라 IP 주소는 매우 늘어날 수 있으나, 출발지 주소와 목적지 주소의 헤더가 커짐에 따라 헤더의 IP 주소를 모두 읽어보는 데에 많은 비용(cost)이 들게 된다. 따라서, 각각의 ISP(Internet Service Provider)들은 MPLS(Multiprotocol Label Switching)를 사용하여 이 문제를 해결하려 노력할 수 있다. 또한, MPLS는 기존의 IP 주소를 이용한 라우팅은 경로를 찾기 위해 필요이상으로 많은 정보를 요구한다고 보고, 레이블 개념을 도입하여 스위칭해주는 역할을 하기 때문에 라우팅을 위해 IPv6로 인하여 더욱 길어진 IP 주소를 요구하지 않고 단지 레이블을 붙임으로 속도를 향상시킬 수 있다. 이러한 환경에서의 이동 IP는 COA를 얻게되면 레이블을 붙여서 목적지까지 전달되게 되고, 이렇게 전달되는 이동 IP에서 COA와 레이블을 합쳐서 하나로 보내는 방식으로 이동 IP의 효율을 높일 수 있다.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.2
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• pp.43-49
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• 1998

This paper describes a phase-shift pulse-width modulation and pulse-frequency modulation seriesresonant high-frequency inverter using IGBT for the power control of high-frequency inductionheating using fuzzy, which is practically applied for 2 0- 5~0 0~~ ~in 1d uction-heating and meltingpov~er supply in industrial fields. The adaptive frequency tracking based phase-shifting PWMregillation scheme is presented in order to minimize switching losses. The trially-producedbreadboards using IGBT are succesfully demostrated and discussed.discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.391-394
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• 2014

In this paper, we introduce a method of determining the absolute position of the rotor for the vector control of Hall sensor type multi-pole BLDC motor using the DSP(TMS320F28335), and implement an algorithm to complement the problems of the conventional method. The switching method of the inverter for providing desired sinusoidal current to each phase of a motor, we adopt Space-Vector pulse width modulation method. In order to increase the speed range, Field-Weakness control method are used. In order to verify the proposed algorithm, we compare the value of Iqe, Ide and phase currents with the values before compensated.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.68-70
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• 2019

본 논문은 8.1kW/L($132W/in^3$)의 전력밀도를 갖는 전기자동차(xEV)용 저전압 배터리 충전기(Low voltage DC-DC converter, LDC)를 위한 절연형 DC-DC컨버터의 설계 방법을 제안한다. 전체 부피 중 가장 큰 비중을 차지하는 자성체의 부피를 줄이기 위해 GaN소자를 채택하여 700kHz의 스위칭 주파수를 적용하였으며, GaN 스위치를 고주파에서 원활히 동작시키기 위한 게이트 드라이버를 직접 제작하였다. 또한 자속 상쇄 개념이 적용된 매트릭스 평면 변압기를 설계하여 적용함으로써 변압기의 부피를 크게 줄일 수 있었고, 8.1kW/L의 전력밀도를 달성하였다. 본 논문에서는 후보 토폴로지들의 비교를 통해 고 전력 밀도에 가장 적합한 토폴로지를 선정하였으며, 자속 상쇄 기법이 적용된 매트릭스 평면 변압기의 설계방법을 제안하였다.

• Journal of IKEEE
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• v.23 no.1
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• pp.68-73
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• 2019

This paper presents a novel fast shut-down scheme for Buck converter by using a coupled inductor. Generally, a controller for Buck converter stops generating PWM patterns in various fault cases: Overcurrent, Short circuit, or Overvoltage, but the inductor and capacitor keep supplying their stored energy to loads although the switching operations in Buck converter stopped. The stored energy in the inductor and capacitor could cause electrical stresses on breakers and safety problems. The main idea of the proposed fast shutdown scheme is to demagnetize the inductor core by using a coupled inductor, and its performance and operations are verified by using PSIM Simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.7
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• pp.39-47
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• 2012

The combination of the broadband property and the wide area coverage of satellite communications enables high speed transmission. Every user in the region under the satellite beam coverage can tranceiver and one can simultaneously communicate with multiple users. For these reasons, it is one of commendable telecommunication networks for information transfer. Since the satellite communications use open channels, it is likely to cause jamming with unwanted interference signals. In the thesis, APSK (Amplitude Phase Shift Keying) is employed, which is recommended for DVB-S2 due to high-speed transmission and excellent bandwidth efficiency. For obtaining reliable communication under the jamming environments, the communication satellite transponder rests on the polyphase filter bank structure, which enables switching among the subchannels and gain control on each subchannel, resulting in effectively eliminating jamming. Furthermore, the nulling scheme, one of the various anti-jamming approaches, is investigated, in which unwanted jamming signals are eliminated in the frequency domain after passing through the analysis part of the polyphase filter bank. The performance of the nulling scheme is evaluated for tone jamming and partial band jamming in terms of BER and EVM. The simulation results indicate that the nulling scheme improve the BER and EVM performance over the case without any anti-jamming approach.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.9 s.351
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• pp.23-30
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• 2006

This paper presents a design of a high-efficiency CMOS DC-DC boost converter using a current-sensing feedback method. High-precision current-sensing circuity is incorporated in order to sense the current flowing in the inductor, which determines the switching scheme of the pulse-width modulation. The external components or large chip area for the frequency compensation can be avoided while maintaining the stable operations of the converter. Various input/output voltage levels can be available through the external resistor strings. The designed DC-DC converter is fabricated in a 0.18-um CMOS technology with a thick-gate oxide option. The converter shows the maximum efficiency over 90% for the output voltage of 3.3V and load current larger than 200mA. The load regulation is 1.15% for the load current change of 100mA.