• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.502-504
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• 2009

We demonstrate a pixel-isolated bistable twist-splay namatic (PI-BTSN) liquid crystal (LC) cell which has two stable states of splay and ${\pi}$-twist. Each state is stabilized by a multi-dimensional anchoring effect of pixel-isolating polymer walls without any chiral additives. Polymer walls are formed around the pixel region by anisotropic phase separation between LCs and reactive mesogens. Switching between the two states is archived by using vertical and horizontal electric fields. The memory mode of the fabricated LC cell has shown infinity memory time.

• Journal of information and communication convergence engineering
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• 제5권1호
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• pp.23-28
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• 2007

In this paper, we propose ATM switch structure including AAL type 2 switch which can efficiently transmit low-bit rate data, even if the network has many endpoints. We simulate the architecture of ATM switch fabric that is modeled in computer program and analyze the performance according to offered loads. ATM switch proposed in this paper can support cell switching for all types of AAL cells which consist of AAL type 1, AAL type 2, AAL type 3/4, and AAL type 5 cells. We propose two switch fabric methods; One supports the AAL type 2 cell processing per input port, the other global AAL type 2 cell processing for every input port. The simulation results show that the latter is superior to the former. But the former has a strong point for easy implementation and extensibility. The proposed ATM switch fabric architecture is applicable to mobile communication, narrow band services over ATM network.

• Journal of Power Electronics
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• 제3권4호
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• pp.215-223
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• 2003

In this paper, a new zero-current-transition (ZCT) circuit cell is proposed. The main switch is turned-off under the zero current and zero voltage condition, and there is no additional current stress and voltage stress in the main switch and the main diode, respectively. The auxiliary switch is turned-off under the zero voltage condition, and the main diode is turned-on under the zero voltage condition. The resonant current required to obtain the ZCT condition is relatively small and regenerated to the input voltage source. The operational principles of a boost converter integrated with the proposed ZCT circuit cell are analyzed and verified by the simulation and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.217-219
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• 2005

This paper presents an improved ZCT (Zero-Current-Transition) PWM DC/DC Boost Converter without additional current stress and conduction loss on the main switch during the resonance period of the auxiliary cell. The auxiliary cell consists of a resonance inductor, a resonant capacitor, an auxiliary switch and the Zero-Current-Switching ranges of the main and the auxiliary switch of the proposed converters are entirely achieved by operating the auxiliary cell. Then Improved ZCT soft switching converter will be discussed. Therefore, the proposed converter has a high efficiency. To show the superiority of this converter is verified through the experiment with a 640W, 50kHz prototype converter.

• 한국전기전자재료학회논문지
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• 제17권10호
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• pp.1100-1106
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• 2004

In this paper, we intend to make fringe-field switching (FFS) mode cell by the ion beam (IB) alignment method on the a-C：H thin film, to analyze electro-optical characteristics in this cell. We studied on the suitable inorganic thin film for fringe-field switching (FFS) cell and the aligning capabilities of nematic liquid crystal (NLC) using the alignment material of a-C：H thin film as working gas at 30 W rf bias condition. A high pretilt angle of about 5 $^{\circ}C$ by ion beam (IB) exposure on the a-C：H thin film surface was measured. Consequently, the high pretilt angle and the good thermal stability of LC alignment by the IB alignment method on the a-C：H thin film surface as working gas at 30 W rf bias condition can be achieved. An excellent voltage-transmittance (V -T) and response time curve of the IE-aligned FFS-LCD was observed with oblique IB exposure on the a-C：H thin films. Also, AC V-T hysteresis characteristics of the IB-aligned FFS-LCD with IE exposure on the a-C：H thin films is almost the same as that of the rubbing-aligned FFS cell on a polyimide (PI) surface.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.326-326
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• 2014

It has been known since the mid 1960s that Ag can be photodissolved in chalcogenide glasses to form materials with interesting technological properties. In the 40 years since, this effect has been used in diverse applications such as the fabrication of relief images in optical elements, micro photolithographic schemes, and for direct imaging by photoinduced Ag surface deposition. ReRAM, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of a conductive filament in a solid electrolyte. Especially, Ag-doped chalcogenide glasses and thin films have become attractive materials for fundamental research of their structure, properties, and preparation. Ag-doped chalcogenide glasses have been used in the formation of solid electrolyte which is the active medium in ReRAM devices. In this paper, we investigated the nature of thin films formed by the photo-dissolution of Ag into Ge-Se glasses for use in ReRAM devices. These devices rely on ion transport in the film so produced to create electrically programmable resistance states [1-3]. We have demonstrated functionalities of Ag doped chalcogenide glasses based on their capabilities as solid electrolytes. Formation of such amorphous systems by the introduction of Ag+ ions photo-induced diffusion in thin chalcogenide films is considered. The influence of Ag+ ions is regarded in terms of diffusion kinetics and Ag saturation is related to the composition of the hosting material. Saturated Ag+ ions have been used in the formation of conductive filaments at the solid electrolyte which is the active medium in ReRAM devices. Following fabrication, the cell displays a metal-insulator-metal structure. We measured the I-V characteristics of a cell, similar results were obtained with different via sizes, due to the filamentary nature of resistance switching in ReRAM cell. As the voltage is swept from 0 V to a positive top electrode voltage, the device switches from a high resistive to a low resistive, or set. The low conducting, or reset, state can be restored by means of a negative voltage sweep where the switch-off of the device usually occurs.

• 전력전자학회논문지
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• 제16권5호
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• pp.440-447
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• 2011

본 논문에서는 계통연계를 위한 연료전지 발전시스템에서 부하 급증시 연료전지의 느린 응답특성 보상용 슈퍼커패시터 에너지 저장시스템에 대해 다루고자 한다. 이러한 경우 슈퍼커패시터의 충 방전을 위해서 양방향 DC/DC 컨버터가 사용되는데 기존의 컨버터는 넓은 영역에서 소프트 스위칭을 가능하게 하고 스위칭 시 순시 과전압을 감쇠시키기 위하여 클램핑 회로를 부가하는 등의 방법을 사용한다. 본 논문에서 제안하는 방식은 부가회로 없이 스위칭 패턴을 충전 및 방전 특성에 적합하게 함으로써 하드웨어 구성을 최소화 하였으며, 아울러 전 동작영역에서 영전압 또는 영전류 스위칭이 가능하도록 하여 효율이 극대화 되도록 하였다. 1 kW급 충 방전 시스템을 구현하여시뮬레이션과 실험을 통하여 제안한 방식의 타당성을 검증하였다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2014년도 임시총회 및 하계학술연구발표회
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• pp.120-121
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• 2014

We investigate the field-dependence of energy barrier for various cell diameters and two type of geometry through the NEB method. We find that the energy barrier can depend strongly on the cell size when the switching is governed by the domain wall motion. Moreover we also examine the cell size dependence of energy barrier for two type of cell geometry. In the presentation, we will discuss the effect of domain wall formation and more various cell size on the energy barrier in detail.

• BMB Reports
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• 제51권11호
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• pp.545-546
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• 2018

With emerging evidence on the importance of non-cell autonomous toxicity in neurodegenerative diseases, therapeutic strategies targeting modulation of key immune cells. including microglia and Treg cells, have been designed for treatment of ALS and other neurodegenerative diseases. Strategy switching the patient's environment from a pro-inflammatory toxic to an anti-inflammatory, and neuroprotective condition, could be potential therapy for neurodegenerative diseases. Mesenchymal stem cells (MSCs) regulate innate and adaptive immune cells, through release of soluble factors such as $TGF-{\beta}$ and elevation of regulatory T cells (Tregs) and T helper-2 cells (Th2 cells), would play important roles, in the neuroprotective effect on motor neuronal cell death mechanisms in ALS. Single cycle of repeated intrathecal injections of BM-MSCs demonstrated a clinical benefit lasting at least 6 months, with safety, in ALS patients. Cytokine profiles of CSF provided evidence that BM-MSCs, have a role in switching from pro-inflammatory to anti-inflammatory conditions. Inverse correlation of $TGF-{\beta}1$ and MCP-1 levels, could be a potential biomarker to responsiveness. Thus, additional cycles of BM-MSC treatment are required, to confirm long-term efficacy and safety.

• 전력전자학회논문지
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• 제23권4호
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• pp.273-280
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• 2018

This paper proposes a zero-voltage-transition pulse-width modulation (PWM) DC-DC converter that uses a new active-snubber-cell. The converter main switch can be turned on and off with ZVS, while the snubber switch is turned on with ZCS and turned off with ZVS. Other semiconductor devices are operated under the soft-switching condition. Normal PWM control can be used, the proposed active-snubber-cell does not impose any additional voltage and current stresses. The active-snubber-cell is suitable for high-power applications due to its easy integration into interleaved converters. This paper discusses the operation of the converter, presents some design guidelines, and provides the results of an experiment with a 100 kHz and 1 kW prototype. A peak efficiency of 97.8% is recorded.