• Journal of Power Electronics
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• 제19권2호
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• pp.413-430
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• 2019

This paper presents an optimum hybrid SVPWM technique for three-level voltage source inverters (VSIs). The proposed hybrid SVPWM technique aims to minimize total harmonic distortion (THD). A new parameter is introduced to incorporate the heterogeneous nature of switching sequences of SVPWM technique. The proposed hybrid SVPWM technique is implemented on a low-cost PIC microcontroller (PIC18F452) and verified experimentally with a 2 KVA three-phase three-level insulated gate bipolar transistor-based VSI. Optimum switching sequence results in the three-level inverter configuration are demonstrated. The proposed hybrid SVPWM technique improves the THD performance by 17.3% compared with the best available three-level SVPWM technique.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.237.2-237.2
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• 2013

ReRAM cell, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of conductive filament in a solid electrolyte [1,2]. Especially, Chalcogenide-based ReRAM have become a promising candidate due to the simple structure, high density and low power operation than other types of ReRAM but the uniformity of switching parameter is undesirable. It is because diffusion of ions from anode to cathode in solid electrolyte layer is random [3]. That is to say, the formation of conductive filament is not go through the same paths in each switching cycle which is one of the major obstacles for performance improvement of ReRAM devices. Therefore, to control of nonuniform conductive filament formation is a key point to achieve a high performance ReRAM. In this paper, we demonstrated the enhanced repeatable bipolar resistive switching memory characteristics by spreading the Ag nanocrystals (Ag NCs) on amorphous GeSe layer compared to the conventional Ag/GeSe/Pt structure without Ag NCs. The Ag NCs and Ag top electrode act as a metal supply source of our devices. Excellent resistive switching memory characteristics were obtained and improvement of voltage distribution was achieved from the Al/Ag NCs/GeSe/Pt structure. At the same time, a stable DC endurance (>100 cycles) and an excellent data retention (>104 sec) properties was found from the Al/Ag NCs/GeSe/ Pt structured ReRAMs.

• 디지털콘텐츠학회 논문지
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• 제18권6호
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• pp.1193-1198
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• 2017

본 논문에서 개발된 IGBT 구조는 DC 송배전을 위한 고전력 스위치 반도체로서 사용되며, 빠른 스위칭 속도 및 개선된 항복전압 특성을 확보하여, 향후 신재생 장거리 DC 송전을 위한 중요한 전자 소자로서 이용될 것이 기대되고 있다. 새로운 타입의 차세대 전력 반도체로서, 스위칭 속도를 향상시키면서 동시에 항복 전압의 특성을 개선시켜, 전력 손실 특성을 줄이도록 설계되었고, 높은 전류 밀도의 장점을 동시에 획득 가능하다. 이러한 개선된 특성은 Planar IGBT의 N-drift 영역에 $SiO_2$를 추가로 도입함으로서 얻어지며, Sentaurus TCAD 시뮬레이션 툴을 사용하여, 비교 분석하였다.

• 조명전기설비학회논문지
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• 제28권9호
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• pp.52-59
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• 2014

The aims of this paper are to characterize the transient overvoltages(TOVs) and to evaluate the risk occurring at 22.9kV consumer's substation. The measurements of lightning- and switching-caused TOVs were made during Mar. 2013 and Feb. 2014. As a consequence, 47 events of TOVs were recorded and 4 of them were higher than the input voltage envelope(IVE) of the information technology industry council(ITI) curve. The measured TOVs are characterized by longer front times and longer durations compared to the $1.2/50{\mu}s$ standard impulse voltage waveform, and some of them represent bipolar waves with lower oscillation frequencies. It suggests that the test of non-standard impulse voltage waveforms is needed for effective risk assessments of power apparatus. Lightning- and switching-caused TOVs exceeding IVE of ITI curve are induced at the secondary of 22.9kV potential transformer(PT). We may, therefore, conclude that the surge protection devices should be applied at the secondary of PT and the surge absorbers should be installed at the primary of VCB or PT. The results presented in this paper could be useful to design the reasonable insulation coordination for 22.9kV consumer's substation.

• 한국전기전자재료학회논문지
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• 제27권2호
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• pp.81-84
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• 2014

The bipolar resistive switching characteristics of resistive random access memory (ReRAM) based on $HfO_2$ thin films have been demonstrated by using Ag/$HfO_2$/Pt structured ReRAM device. MIcrowave irradiation (MWI) treatment at low temperature was employed in device fabrication with $HfO_2$ thin films as a transition layer. Compared to the as-deposited Ag/$HfO_2$/Pt device, highly improved uniformity characteristics of resistance values and operating voltages were obtained from the MWI treatment Ag/$HfO_2$/Pt ReRAM device. In addition, a stable DC endurance (> 100 cycles) and a high data retention (> $10^4$ sec) were achieved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1238-1240
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• 2003

A new soft switching technique that improves performance of the high power factor boost rectifier by reducing switching losses is introduced. The losses are reduced by air active snubber which consists of an inductor, a capacitor a rectifier, and an auxiliary switch. Since the boost switch turns off with zero current, this technique is well suited for implementations with insulated gate bipolar transistors. The reverse recovery related losses of the rectifier are also reduced by the snubber inductor which is connected in series with the boost switch and the boost rectifier. In addition, the auxiliary switch operates with zero voltage switching. A complete design procedure and extensive performance evaluation of the proposed active snubber using a 1.2[kW] high power factor boost rectifier operating from a 90 [$V_{rms}$] input are also presented.

• 전기전자학회논문지
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• 제12권2호
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• pp.110-117
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• 2008

본 연구는 전력용 스위칭 소자로 널리 활용되고 있는 IGBT(Insulated Gate Bipolar Transistor)소자로서 NPT(Non Punch Through) IGBT 구조에 기반 한 새로운 구조의 IGBT를 제안하였다. 제안된 구조는 기존 IGBT 구조의 P-베이스 영역 우측 부분에 N+를 도입함으로 N-드리프트 영역의 정공분포를 N+영역으로 밀집시켜 턴-오프 시 정공의 흐름을 개선, 기존 구조보다 더 빠른 턴-오프 시간과 더 낮은 순방향 전압강하를 갖는 구조이다. 또한 P+를 게이트 우측 하단에 형성함으로써 순방향 전압 강하 특성을 개선시키기 위해 도입한 캐리어 축적 층인 N+에 의해 발생하는 낮은 래치-업 특성과 낮은 항복 전압 특성을 개선시킨 구조이다. 시뮬레이션 결과 제한된 구조의 턴-오프와 순방향 전압강하는 기존 구조대비 각각 0.3us, 0.5V 향상된 특성을 보였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.286-287
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• 2012

Reset-first resistive switching mechanism based on reduction reaction in HfO2-x with oxygen drift-diffusion was studied. we first report that the indirect evidence of local filamentary conductive path formation in bulk HfO2 film with local TiOx region at Ti top electrode formed during forming process and presence of anion-migration at interface between electrode and HfO2 during resistive switching through high resolution transmission electron microscopy (HRTEM), electron disperse x-ray (EDX), and electron energy loss spectroscopy (EELS) mapping. Based on forming process mechanism, we expected that redox reaction from Ti/HfO2 to TiOx/HfO2-x was responsible for an increase of initial current with increasing the post-annealing process. First-reset resistive switching in above $350^{\circ}C$ annealed Ti/HfO2 film was exhibited and the redox phenomenon from Ti/HfO2 to TiOx/HfO2-x was observed with high angle annular dark field (HAADF) - scanning transmission electron microscopy (STEM), EDX and x-ray photoelectron spectroscopy. Therefore, we demonstrated that the migration of oxygen ions at interface region under external electrical bias contributed to bipolar resistive switching behavior.

• 정보처리학회논문지C
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• 제10C권3호
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• pp.317-324
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• 2003

PN 부호와 광 스위치를 사용하여 시간영역에서 확산하는 CDMA 방식에 의한 광 가입자 액세스 망을 제안한다. 무선통신에 널리 사용되는 PN 계열 부호를 사용하여 양극성(bipolar) 데이터를 수신측에서 상관할 수 있는 구조를 제안한다. 광 스위치의 ON/OFF를 통하여 PN 부호를 소프트웨어적으로 구성할 수 있어 광 가입자에 배분할 수 있는 부호계열의 수가 증가 증가하고, 부호 배분에 있어서 유연성을 갖고 있다. 그리고 이론적으로 제안한 광 가입자 액세스 망의 성능을 해석하고 종래의 광섬유 형 정합필터를 이용한 광 CDMA 방식을 적용한 광 가입자 액세스 망에 비하여 성능이 향상됨을 수치 계산을 통하여 명확히 한다.

• 한국전기전자재료학회논문지
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• 제28권8호
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• pp.486-489
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• 2015

Power semiconductor device has a very long history among semiconductor, since the invention of low-pressure bipolar transistor 1947, and so far from small capacity to withstand voltage-current, high-speed and high-frequency characteristics have been developed with high function. In this study, the PWM IC Switch to the main parts used in IGBT (insulated gate bipolar transistor) for the low power loss and high drive capability of the simulator to Synopsys' T-CAD used by the 1,700 V NPT Planar IGBT, 1,700 V FS was a study of the Planar IGBT, the results confirmed that IGBT 1,700 V FS Planar is making about 11 percent less than the first designed NPT Planar IGBT.