Synaptic Plasticity Selectively Activated by Polarization-Dependent Energy-Efficient Ion Migration in an Ultrathin Ferroelectric Tunnel Junction

Yoon, Chansoo,Lee, Ji Hye,Lee, Sangik,Jeon, Ji Hoon,Jang, Jun Tae,Kim, Dae Hwan,Kim, Young Heon,Park, Bae Ho American Chemical Society 2017 Nano letters Vol.17 No.3

<P>Selectively activated inorganic synaptic devices, showing a high on/off ratio, ultrasmall dimensions, low power consumption, and short programming time, are required to emulate the functions of high-capacity and energy-efficient reconfigurable human neural systems combining information storage and processing (Li et al. Sci. Rep. 2014, 4, 4096). Here, we demonstrate that such a synaptic device is realized using a Ag/ PbZr0.52Ti0.48O3 (PZT)/La0.8Sr0.2MnO3 (LSMO) ferroelectric tunnel junction (FTJ) with ultrathin PZT (thickness of similar to 4 nm). Ag ion migration through the very thin FTJ enables a large on/off ratio (10(7)) and low energy consumption (potentiation energy consumption = similar to 22 aJ and depression energy consumption = similar to 2.5 pJ). In addition, the simple alignment of the downward polarization in PZT selectively activates the synaptic plasticity of the FTJ and the transition from short-term plasticity to long-term potentiation.</P>

저 경력 초등교사의 체육수업 운영에 관한 경험과 교육적 의미

윤찬수(Yoon ChanSoo) 학습자중심교과교육학회 2018 학습자중심교과교육연구 Vol.18 No.20

이 연구의 목적은 저 경력 초등교사의 체육수업 운영에 관한 경험과 교육적 의미를 총체적으로 분석하는데 있었다. 이러한 연구목적을 위하여 수도권 및 충청권 지역의 저 경력 초등교사 7명을 연구 참여자로 선정한 후 질적 연구를 수행하였다. 심층면담의 자료와 문서자료를 통해 수집한 자료는 Spradley(1980)의 영역분석과 분류 분석을 수행하였으며, 자료의 수집 및 분석과정에서 연구의 진실성과 윤리성을 확인 하였다. 이 연구에서 수집된 자료를 분석 및 해석한 결과는 다음과 같다. 첫째, 저 경력 초등교사의 경험은 ‘체육수업 운영 주체에 대한 이해’, ‘체육수업 운영을 위한 맥락 및 환경 지각’, ‘체육수업과 체육교육과정의 상호불가분성 인식’ 이었다. 둘째, 저 경력 초등교사의 체육수업 운영을 통한 교육적 의미는 현재의 체육수업에 대한 그들의 인식과 효과적인 체육교육을 실현하기 위한 저 경력 초등교사의 교육적 신념에 따라 분석되었다. 이에 ‘신체·정신·인성이 하나가 되는 통합적 체육수업’, ‘개인의 역량 강화를 통한 평생체육의 발판 마련’, ‘교사의 전문성 함양과 수업 환경 개선을 통한 체육교육의 질적 제고’로 분석되었다. The purpose of this study was placed on analyzing the overall experiential and educational means on operations of physical education classes of elementary school teachers with less teaching experiences. For the purpose of this study, 7 elementary school teachers with less teaching experience from the metropolitan area and the Chungchong Region were selected as participants and a qualitative research was conducted. The data collected through in-depth interviews and documentations were placed through the domain analysis and classification analysis of Spradley(1980) and in the data collection and analysis process, the veracity and ethicality of the research was confirmed. The results of analysis and interpretation of collected data are as follows. First, the experiences of elementary school teachers with less teaching experience were divided into ‘understanding the operator of physical education classes’. ‘perception of context and environment for operation of physical education classes’ and the ‘cognition of interconnectedness between physical education classes and physical education process.’ Secondly, the educational means through physical education classes operated by elementary teachers with less teaching experiences were analyzed in accordance with the educational beliefs of the elementary school teachers with less experience in actualizing effective physical education and their perception. In accordance, it was analyzed as ‘the integrated physical education classes where the body, mind and character becomes one,’ ‘the establishment of foothold for lifelong physical education through strengthening personal competence’ and ‘the qualitative enhancement of physical education through the betterment of the learning environment and cultivation in instructor’s specialty.‘

초등교사의 체육교과 지도역량 형성과정과 구성요인 탐색

윤찬수(Yoon ChanSoo) 학습자중심교과교육학회 2019 학습자중심교과교육연구 Vol.19 No.6

이 연구의 목적은 초등교사의 체육교과 지도역량의 형성과정과 구성요인을 총체적으로 분석하는데 있었다. 이러한 연구목적을 위하여 전국 각 지역에서 근무하는 초등교사 8명을 연구 참여자로 선정하였다. 연구방법으로는 질적 연구를 수행하였으 며, 심층면담의 자료와 수집된 문서자료를 바탕으로 Spradley(1980)의 영역분석과 분류분석을 수행하였다. 또한 자료의 수집 및 분석과정에서 연구의 진실성과 윤리성을 지속적으로 검토하였다. 이 연구 과정을 통해 도출된 결과는 다음과 같다. 첫째, 초등교육 현장에서 체육교육의 질적 평가에 중요한 영향을 미치는 초등교사의 체육교과 지도역량이 형성되는 과정은 ‘스포츠 활동 경험의 가치’, ‘교육활동 참여’, ‘멘토링 활동’, ‘자기개발을 통한 능력 함양’이었다. 둘째, 초등교사의 체육교과 지도역량을 형성하는 구성요인으로 ‘체육과 교육과정의 이해 및 재구성 능력’, ‘체육교과 지식과전략’, ‘체육교과 운동수행 능력’, ‘사회적 요구 수용 능력’으로 분석되었다. 이는 초등교사가 학교현장에서 효율적으로 체육교육을 운영하기 위해 필요한 지식, 기능, 태도와 같은 총체적 능력이었다. The purpose of this study is to comprehensively analyze formation process and constituting factors of elementary school teachers teaching competence in physical education. For this purpose, 8 elementary school teachers working in various regions across the country were selected as research participants. As a research method, qualitative research was conducted and, based on the data gathered from in-depth interviews and related literature, domain analysis and taxonomic analysis were performed which were presented by Spradley (1980). In addition, in the process of collecting and analyzing the data, authenticity and morality of the research were continuously examined. The results of this study are as follows; First, formation process of elementary school teachers teaching competence in physical education which has vital effect on the qualitative evaluation of physical education in the field of elementary education was ‘value of experience in sports activities’, participation in education activities , mentoring activities and developing abilities through self-development . Second, constituting factors of elementary school teachers teaching competence in physical education were analyzed to be understanding and reconstructing ability of physical education curriculum , knowledge and strategy in physical education’, ‘athletic performance ability in physical education and capacity to accept social demands , which are comprehensive abilities such as knowledge, function and attitude required for elementary school teachers to efficiently operate physical education in the field of school.

Flexible resistive random access memory devices by using NiO_<i>x</i>/GaN microdisk arrays fabricated on graphene films

Lee, Keundong,Park, Jong-woo,Tchoe, Youngbin,Yoon, Jiyoung,Chung, Kunook,Yoon, Hosang,Lee, Sangik,Yoon, Chansoo,Ho Park, Bae,Yi, Gyu-Chul IOP 2017 Nanotechnology Vol.28 No.20

<P>We report flexible resistive random access memory (ReRAM) arrays fabricated by using NiO<SUB> <I>x</I> </SUB>/GaN microdisk arrays on graphene films. The ReRAM device was created from discrete GaN microdisk arrays grown on graphene films produced by chemical vapor deposition, followed by deposition of NiO<SUB> <I>x</I> </SUB> thin layers and Au metal contacts. The microdisk ReRAM arrays were transferred to flexible plastic substrates by a simple lift-off technique. The electrical and memory characteristics of the ReRAM devices were investigated under bending conditions. Resistive switching characteristics, including cumulative probability, endurance, and retention, were measured. After 1000 bending repetitions, no significant change in the device characteristics was observed. The flexible ReRAM devices, constructed by using only inorganic materials, operated reliably at temperatures as high as 180 °C.</P>

Incidence and Temporal Feature of Community-acquired Pneumonia Along with Seasons in Korea

( Chansoo Youk ),( Seohyun Kim ),( Hyoung Kyu Yoon ),( Tai Joon An ) 대한결핵 및 호흡기학회 2023 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.136 No.0

High Efficiency Synthesis of F-18 Fluoromethyl Ethers: An Attractive Alternative for C-11 Methyl Groups in Positron Emission Tomography Radiopharmaceuticals

Park, Chansoo,Lee, Byoung Se,Chi, Dae Yoon American Chemical Society 2013 Organic letters Vol.15 No.17

<P>A rapid and efficient method for the synthesis of <I>O</I>-fluoromethyl aliphatic and aromatic ethers is presented. This method is so mild that it can be used for the preparation of positron emission tomography (PET) radiopharmaceuticals bearing <I>O</I>-[<SUP>18</SUP>F]fluoromethyl groups.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2013/orlef7.2013.15.issue-17/ol401792n/production/images/medium/ol-2013-01792n_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol401792n'>ACS Electronic Supporting Info</A></P>

중소기업 기술혁신 역량평가 및 글로벌 정책분석 Ⅶ

박찬수(Chansoo Park),임채윤(Chae Yoon Lim),이동우(Dong Woo Lee) 과학기술정책연구원 2016 조사연구 Vol.- No.-

Enhanced Performance of Field-Effect Transistors Based on Black Phosphorus Channels Reduced by Galvanic Corrosion of Al Overlayers

Lee, Sangik,Yoon, Chansoo,Lee, Ji Hye,Kim, Yeon Soo,Lee, Mi Jung,Kim, Wondong,Baik, Jaeyoon,Jia, Quanxi,Park, Bae Ho American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.22

<P>Two-dimensional (2D)-layered semiconducting materials with considerable band gaps are emerging as a new class of materials applicable to next-generation devices. Particularly, black phosphorus (BP) is considered to be very promising for next-generation 2D electrical and optical devices because of its high carrier mobility of 200-1000 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP> and large on/off ratio of 10<SUP>4</SUP> to 10<SUP>5</SUP> in field-effect transistors (FETs). However, its environmental instability in air requires fabrication processes in a glovebox filled with nitrogen or argon gas followed by encapsulation, passivation, and chemical functionalization of BP. Here, we report a new method for reduction of BP-channel devices fabricated without the use of a glovebox by galvanic corrosion of an Al overlayer. The reduction of BP induced by an anodic oxidation of Al overlayer is demonstrated through surface characterization of BP using atomic force microscopy, Raman spectroscopy, and X-ray photoemission spectroscopy along with electrical measurement of a BP-channel FET. After the deposition of an Al overlayer, the FET device shows a significantly enhanced performance, including restoration of ambipolar transport, high carrier mobility of 220 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP>, low subthreshold swing of 0.73 V/decade, and low interface trap density of 7.8 × 10<SUP>11</SUP> cm<SUP>-2</SUP> eV<SUP>-1</SUP>. These improvements are attributed to both the reduction of the BP channel and the formation of an Al<SUB>2</SUB>O<SUB>3</SUB> interfacial layer resulting in a high-<I>k</I> screening effect. Moreover, ambipolar behavior of our BP-channel FET device combined with charge-trap behavior can be utilized for implementing reconfigurable memory and neuromorphic computing applications. Our study offers a simple device fabrication process for BP-channel FETs with high performance using galvanic oxidation of Al overlayers.</P> [FIG OMISSION]</BR>

중소기업 기술혁신 역량 평가 및 글로벌 정책분석사업(Ⅷ)

임채윤(Chae Yoon Lim),손수정(Soojung Sohn),박찬수(Chansoo Park),이정우(Jungwoo Lee),김재원(Jaewon Kim) 과학기술정책연구원 2017 조사연구 Vol.- No.-

계통연계인버터의 안정도 및 고조파억제 성능 향상을 위한 DSOGI-FLL 기반 상태궤환 제어기법 연구

윤승진(Seung-Jin Yoon),김병기(Byungki Kim),김찬수(ChanSoo Kim),남양현(YangHyun Nam),김대진(DaeJin Kim) 한국산학기술학회 2023 한국산학기술학회논문지 Vol.24 No.5

본 논문은 Point of Common Coupling (PCC)의 전압에 고조파 왜곡이 포함되어 있을 때 LCL 필터를 사용하는 3상 계통연계 인버터의 계통 전압 주파수 추종 성능과 고조파 억제 성능을 향상시키기 위한 전류제어기법을 제시한다. 이를 위해 주파수 변동에 대응하고 보다 정확도 높은 주파수 추종성능 확보가 가능한 Dual Second Order Generalized integrator(DSOGI) 기반 Frequency Lock Loop(FLL) 기법을 적용하였으며 전류 품질 향상을 위해 계통의 고조파 왜곡 현상을 억제하는 DSOGI 기반 다중 공진제어기를 사용하는 상태궤환 제어기법이 제시된다. 일반적으로 주파수 변동에 따라 계통전압의 주파수 추종 성능이 저하될 경우 고조파 왜곡 현상을 보상하는 공진 제어기의 성능저하가 나타나게 되며 이는 인버터 전류 품질에 심각한 영향을 미치게 된다. 이러한 현상을 해결하기 위해 Phase Lock Loop 기법을 통해 계통전압 주파수를 추종하고 추종된 주파수를 공진제어기에 활용하는 기법이 제안되었으나 해당 기법은 안정적인 계통 하에서 효과적으로 고조파 왜곡 현상을 억제하는 반면 계통의 외란에 의한 주파수 변동 및 열화에 의한 시스템 파라미터의 변화와 같은 상황에 대응하지 못하는 한계를 가지고 있다. 이러한 문제를 해결하기 위해 본 논문은 계통 주파수 변동 하에서도 효과적으로 계통 주파수를 추종하는 DSOGI-FLL 기법을 사용하여 적분-공진 상태궤환제어 기법에서 요구하는 실제 계통 주파수를 빠르게 추종하고 이를 궤환신호로 사용하여 계통 주파수 변동이나 계통위상각 도약 조건과 같은 갑작스런 상황에도 대응 할 수 있도록 하였다. 또한, 체계적인 이득값 선정을 위해 DLQR을 사용하여 다수의 극점을 선택하여 이득값을 구하는 어려움을 해결하고 체계적인 방식으로 제어에 필요한 이득값을 구현할 수 있도록 하였다. This paper presents a frequency-adaptive integral-resonant full-state feedback control based on the DSOGI-FLL to improve the frequency tracking performance and harmonic suppression ability for inductive-capacitive-inductive (LCL) filtered grid-connected inverter (GCI) under grid disturbance, such as the grid frequency variation, system parameter uncertainty, and grid voltage harmonic distortion. Generally, the frequency tracking performance of the grid voltage deteriorates due to the grid disturbance. This degradation also affects the harmonic suppression performance of the resonance controller, which can seriously affect the quality of the inverter current. A technique was proposed to solve this problem: a PLL tracked the grid voltage frequency and utilized the frequency information in the resonance controller. On the other hand, the performance of the resonance controller significantly degraded in situations, such as system parameter variations or grid voltage harmonic distortion. This paper estimated the grid frequency through DSOGI-FLL to address this issue. The estimated grid frequency was used to modify the frequency information in the augmented resonant controller to produce high-quality grid currents even under both distorted grid voltages and grid currents even under both distorted grid voltages and grid frequency variation. The PSIM simulation was performed to verify the effectiveness and robustness of the proposed control scheme.