Daegu Gyeongbuk Institute of Science and Technology
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Exploring potential of MXenes in smart sensing and energy harvesting
Get PDFIn present work, MXene based piezo-resistive stress sensor device is fabricated using a freeze-dry method. The device was tested to measure the mechanical stress, sensitivity, and triboelectric response by converting them into electrical signals as readout. With high electrical conductivity, mechanical flexibility, and piezo-resistive characteristics, MXene-based device offers novel sensing and triboelectric-related applications. This study showed an extensive characterization after fabricating the sensor using a simple and scalable process to ensure their performance in terms of sensitivity, stability, and repeatability. Using pure MXene layer as the core material, this paper pioneers an interesting investigation focusing on stress monitoring by piezoresistive stress sensor and triboelectric nanogenerator. © 2024 The AuthorsTRUEsciescopu
기능적 근적외선 분광법을 이용한 2차 판별분석 기반 운동 상상 상태 분류에 관한 연구
No full text뇌-컴퓨터 인터페이스; 근적외선 분광기; 신호처리; 선형 판별 분석; 부분공간방법Abstract i
List of contents ii
List of figures iii
Ⅰ. Introduction 1
Ⅱ. Background · 3
1. Modified Beer-Lambert Law (MBLL) 3
2. Temporal derivative distribution repair (TDDR) · 4
3. Mutual Subspace method (MSM) · 5
4. Linear discriminant analysis (LDA) · 6
Ⅲ. Method 8
1. Data acquisition 8
2. Data pre-processing 9
3. Conventional methods · 10
3.1 Statistical feature extraction for LDA 10
3.2 Mutual Subspace Method (MSM) · 11
4. Proposed Method · 11
5. Performance evaluation 13
Ⅳ. Result 14
Ⅴ. Conclusion 16
Ⅵ. Reference · 17MasterdCollectio
High-Throughput Quantitative Analysis of Amino Acids in Freeze-Dried Drops Using Time-of-Flight Secondary Ion Mass Spectrometry
No full textTime-of-flight secondary ion mass spectrometry (ToF-SIMS) has become a promising analytical tool for molecular profiling in biological applications. However, its ultrahigh vacuum environment and matrix effects hamper the absolute quantitation of solution samples. Herein, we present a rapid high-throughput platform for quantitative ToF-SIMS analysis of amino acids in matrix deposits formed from freeze-dried solution drops through ice sublimation on a parylene film microarray substrate. Droplets of the amino acid solutions, which were mixed with stable isotope-labeled phenylalanine (F*) of high concentration (10 mM), were loaded on wells of the microarray, then frozen and evaporated slowly below the freezing point, forming continuous solid-phase F* matrix deposits. The amino acids (≤500 μM), adequately well dispersed throughout the F* matrix deposits on each well, were quantitatively analyzed by ToF-SIMS in a rapid and high-throughput fashion. The lower limit of quantitation reached below 10 μM. © 2024 American Chemical Society.FALSEsciescopu
Electrical Manipulation and Detection of Antiferromagnetism by Utilizing the Spin Hall Effect
No full textAntiferromagnet;Spin Hall effect;Exchange bias;Spin-orbit torque;Spin Hall magnetoresistanceAntiferromagnetic materials, known for their zero net magnetic moment and the absence of a stray magnetic field, pose unique challenges for measurement and control compared to ferromagnetic counterparts. The Spin Hall effect-induced phenomena, including spin-orbit torque and spin Hall magnetoresistance, provide a promising avenue for manipulating and detecting antiferromagnetism. The thesis is divided into two parts, each dedicated to specific aspects of utilizing the Spin Hall effect for manipulating and detecting antiferromagnetic behavior. The first part delves into manipulating antiferromagnetic spin ordering through electrical means, with a focus on exchange bias manipulation in heavy metal-ferromagnet-antiferromagnet heterostructures. Spin-orbit torque's pivotal role in this manipulation is explored through a macrospin model, offering explanations for experimental results within these structures and reconciling previously reported data. The second part focuses on the electrical detection of antiferromagnetism, utilizing Fe2O3 as a model system with its intriguing physical properties, including weak ferromagnetism and magnetic phase transitions. Spin Hall magnetoresistance measurements on epitaxial Fe2O3 thin films are employed, along with X-ray diffraction and magnetic property measurements, to understand the antiferromagnetic behavior of Fe2O3. The study reveals that lattice strain, induced by a substrate's mismatch with Al2O3, plays a crucial role in determining the magnetic phase transition temperature of Fe2O3. It underscores the efficacy of spin Hall magnetoresistance measurements in detecting antiferromagnetism.|본 논문은 스핀 홀 효과를 이용한 반강자성체의 조작 및 측정을 연구하였다. 반강자성체는 스핀의 반평행한 배열로 인해 재료의 합 자화 0이고 누설 자계가 없어 강자성체에 비해 측정과 제어에 있어 한계를 가지고 있다. 스핀-궤도 토크 및 스핀 홀 자기 저항을 포함한 스핀 홀 효과 관련 현상들은 반강자성체를 제어하고 측정하기 할 수 있는 방법으로 대두되고 있다. 따라서 본 논문에서 스핀 홀 효과를 이용한 반강자성체의 제어와 측정으로 나누어 연구를 진행하였다.
첫 번째 연구에서는 중금속-강자성-반강자성체 이종 구조에서 스핀-궤도 토크에 의한 교환 바이어스 조작을 통해 전기적 반강자성체 스핀 조작을 연구하였다. 자화 시뮬레이션과 다양한 전자기적 환경에서의 교환 바이어스 조작 실험을 통해 교환 바이어스 조작 현상에서 스핀-궤도 토크의 역할을 조사하였다. 두 번째 연구에서는 Fe2O3를 반강자성체 모델 시스템으로 활용하여 반강자성의 전기적 측정을 연구하였다. Fe2O3는 약한 강자성 및 자기 상전이를 포함한 풍부한 물리 현상을 보여주는 물질로 알려져 있다. 이 연구에서는 Fe2O3 에피택셜 박막을 성장시키고 스핀 홀 자기저항을 측정하여 Fe2O3의 반강자성 특성을 측정하고 결정 구조와의 관계를 조사하였다. 본 논문은 두 연구를 통해 스핀 홀 효과가 반강자성체의 조작 및 측정에 중요한 현상임을 증명하였다.Abstract i
List of contents ii
List of tables and figures iii
I. Introduction · 1
II. Electrical manipulation of exchange bias in Pt/Co/IrMn heterostructure
2.1 Overview 2
2.2 Spin-orbit torque 3
2.3 Sample preparation 7
2.4 Assist magnetic field dependence 10
2.5 Electric current dependence 17
2.6 Contribution of thermal effect 22
2.7 Oscillation model 30
2.8 Macrospin simulation 31
2.9 Summary 42
III. Electrical detection of antiferromagnetism in -Fe2O3 thin film
3.1 Overview 43
3.2 Spin Hall magnetoresistance · 44
3.3 Antiferromagnetism in -Fe2O3 47
3.4 Growth of -Fe2O3 thin film · 52
3.5 Magnetic properties 59
3.6 Spin Hall magnetoresistance measurements 63
3.7 Summary 75
References 76DoctordCollectio
Open Innovation Signals: Exploring the Financial Data with Patents
Get PDFThe study aims to explore how to measure firms’ open innovation from financial statements. So, our research question is as follows: How can we determine firms’ open innovation signals directly or indirectly from financial statements? This study used data from the US financial statements and patent registration database from 2016 to 2018 to answer this research question. Three manifest signals of open innovation in financial data were found. First, subsidiary or related firm investment in financial data may have a negative relationship with open innovation because open innovation (i.e., the co-application of patents) could decrease subsidiary or related firm investment. But there are differences between the top and bottom twenty firms. Second, internal R&D investment (I R&D) in financial data may have a positive relationship with open innovation because I R&D could trigger inward open innovation. If I R&D combines with an open innovation strategy, it increases the size of subsidiary or related firm investment as a kind of inward open innovation. Third, free cash flow (FCF) in financial data may have a positive relationship with open innovation because high FCF could support outward open innovation. © 2024 SAGE Publications.TRUEssciscopu
DISTRIBUTED TACTILE SENSOR SYSTEM BASED ON RESONANCE FREQUENCY MULTIPLEXING AND METHOD FOR MEASURING USING THE SAME
No full textELECTRONIC APPARATUS FOR DETECTION OF OBJECT USING HIGH DEFINITION IMAGE AND METHOD THEREOF
No full text객체 검출 방법이 개시된다. 본 객체 검출 방법은 입력 영상을 입력받는 단계, 입력 영상을 제1 해상도로 축소한 축소 이미지, 입력 영상의 기설정된 부분 영역에 대한 부분 이미지를 생성하는 단계, 축소 이미지 및 부분 이미지 각각을 이용하여 객체를 검출하는 단계, 및 축소 이미지에서 검출된 객체 및 부분 이미지에서 검출된 객체를 병합하는 단계를 포함한다
Low Solvating Power of Acetonitrile Facilitates Ion Conduction: A Solvation-Conductivity Riddle
No full textAcetonitrile (AN) electrolyte solutions display uniquely high ionic conductivities, of which the rationale remains a long-standing puzzle. This research delves into the solution species and ion conduction behavior of 0.1 and 3.0 M LiTFSI AN and propylene carbonate (PC) solutions via Raman and dielectric relaxation spectroscopies. Notably, LiTFSI-AN contains a higher fraction of free solvent uncoordinated to Li ions than LiTFSI-PC, resulting in a lower viscosity of LiTFSI-AN and facilitating a higher level of ion conduction. The abundant free solvent in LiTFSI-AN is attributed to the lower Li-solvation power of AN, but despite this lower Li-solvation power, LiTFSI-AN exhibits a level of salt dissociation comparable to that of LiTFSI-PC, which is found to be enabled by TFSI anions loosely bound to Li ions. This work challenges the conventional notion that high solvating power is a prerequisite for high-conductivity solvents, suggesting an avenue to explore optimal solvents for high-power energy storage devices. © 2024 American Chemical Society.FALSEsciescopu
Recent Developments in Quantum Dot Light-Emitting Diodes for Skin-Attachable Electronics
No full textRecent advances in skin-attachable electronics have attracted substantial interest because of their potential in various fields such as robotics, healthcare, and wearable technology. Among various electroluminescent (EL) devices, quantum dot light-emitting diodes (QLEDs) are promising for next-generation displays due to their superior color purity, high brightness, excellent efficiency, high stability, and ultrathin form factors, making them promising for flexible electronic applications. This review outlines the recent progresses in QLEDs for skin-attachable electronics. First, materials selection and various structural designs that impart mechanical flexibility into QLEDs are discussed. We also discussed the design strategies of flexible displays based on the array of QLEDs. Then, we summarize skin-attachable displays based on the flexible QLEDs, including the integration with sensors capable of detecting various signals. The discussion includes the promising role of skin-attachable QLEDs in healthcare, particularly their potential as wearable light sources for monitoring biologic signals. Overall, this review article highlights the remarkable progress made in the skin-attachable QLEDs. © The Author(s), under exclusive licence to Korean Institute of Chemical Engineers, Seoul, Korea 2024.FALSEsciescopuskc