Daegu Gyeongbuk Institute of Science and Technology
DGIST Library Institutional RepositoryNot a member yet
12664 research outputs found
Sort by
On the Fundamental Tradeoff of Joint Communication and Quickest Change Detection
No full textIn this study, we investigate the tradeoff between communication rate and quickest change detection (QCD) in integrated sensing and communication. We establish a joint problem for QCD, utilizing constant subblock-composition codes and a modified CuSum detection rule, named subblock CuSum (SCS). This approach provides an inner bound for the tradeoff between communication rate and change point detection delay in low false alarm scenarios. Our findings show that SCS is asymptotically optimal for certain code classes. © 2024 IEEE
Silicon Photonics MEMS Platform-based Optomechanical Ultrasound Sensor Array for 3D Photoacoustic Deep Brain Region Imaging
No full textWe propose a silicon photonic optomechanical ultrasound sensor array for 3D photoacoustic imaging of a mouse brain’s deep region. The performance evaluation and 3D photoacoustic in-vitro imaging were conducted for the feasibility study. © 2024 The Author (s)
Differentiable Compliant Contact Primitives for Estimation and Model Predictive Control
No full textControl techniques like MPC can realize contact-rich manipulation which exploits dynamic information, maintaining friction limits and safety constraints. However, contact geometry and dynamics are required to be known. This information is often extracted from CAD, limiting scalability and the ability to handle tasks with varying geometry. To reduce the need for a priori models, we propose a framework for estimating contact models online based on torque and position measurements. To do this, compliant contact models are used, connected in parallel to model multi-point contact and constraints such as a hinge. They are parameterized to be differentiable with respect to all of their parameters (rest position, stiffness, contact location), allowing the coupled robot/environment dynamics to be linearized or efficiently used in gradient-based optimization. These models are then applied for: offline gradient-based parameter fitting, online estimation via an extended Kalman filter, and online gradient-based MPC. The proposed approach is validated on two robots, showing the efficacy of sensorless contact estimation and the effects of online estimation on MPC performance. Video results can be seen at https://youtu.be/CuCTcmn3H-o. © 2024 IEEE
The Irony of Sexuality and Violence (2) :The Making of the 1990s Political Subjectivity in Undongkwon Female College Student Novels
No full text부천서 성고문 폭로 사건 이후 권인숙이 운동권 여대생을 상징하는 인물이 되었을 때, 바야흐로 운동권 여대생 주체 구성의 상징체계에 지각 변동이 일어나기시작했다. 이를 징후적으로 보여 주는 것이 1980년대 말과 1990년대 초 사이에등장한 운동권 여대생 소설이다. 1991년 7월, 공교롭게도 거의 동시에 출간된김인숙의 『긴 밤 짧게 다가온 아침』과 공지영의 『그리고, 그들의 아름다운 시작』 에서는 운동권 경험을 지닌 두 여성 작가가 운동권 여대생의 서사를 통해 섹슈얼리티 문제와 함께 운동권 여대생의 정치적 주체 구성의 가능성을 탐색한다. 이글에서는 당대에 대중적인 파급력을 지녔던 김인숙과 공지영의 두 소설 텍스트에서 운동권 여대생의 섹슈얼리티 극복이라는 주제가 문학적으로 코드화되는 양상을 분석하고, 이를 바탕으로 1980년대에서 1990년대로 이행하는 주체의 헤게모니가 ‘숭고의 도덕’에서 ‘낭만적 윤리’로 변화한다는 점을 규명한다.
When Kwon In-sook became a symbolic figure representing undongkwon female college students in the late 1980s, a significant shift emerged in the symbolic system of the political subjectivity. This shift is symptomatically reflected in the novels about un-dongkwon female college students in the early 1990s. Kim Insuk’s Kinbam ch’alpke tagaon ach’im(The Long-Night and the Morning Coming Shortly) and Gong Jiyeong’s Kŭrigo kŭdŭrŭi arŭmdaun sijak(And Then, Their Beautiful Beginning), both by female writers with undongkwon backgrounds, explore the issues of undongkwon female college students’ sexuality and violence, and the construction of their political subjectivity. This paper analyzes how the theme of undongkwon female students overcoming their sexuality is codified in the two novels by Kim Insuk and Gong Jiyeong, which had considerable popular influence at the time. Based on this analysis, it elucidates how the hegemony of subjectivity transitions from the ‘sublime morality’ to the ‘romantic ethics’ from the 1980s to the 1990s.TRUEkc
Interfacial dipole moment engineering in self-recoverable mechanoluminescent platform
Get PDFHarnessing the potential of mechanoluminescence (ML) for practical applications necessitates innovations that maximize brightness while simplifying the platform. Our study introduces a pioneering interfacial modification technique that enhances the internal triboelectric field in a self-recoverable ML platform based on zinc sulfide@metal oxide phosphor and a polydimethylsiloxane matrix. By chemically functionalizing the surface of metal oxide shells with benzoic acid derivatives, we modulate surface charge density thereby intensifying the triboelectric field within the ML platform. Utilizing a range of derivatives with varying dipole moments establishes a direct relationship between dipole moment strength and triboelectric enhancement. Notably, introducing aminobenzoic acid (ABA) onto the surface of the aluminum oxide (AlOx) shell results in a significant increase in ML brightness. Our strategy to easily adjust the ML brightness has been applied to anti-counterfeiting applications. Our study not only reveals the correlation between surface triboelectric fields and ML performance but also provides the possibility for practical use of self-recoverable ML platforms in various application fields, including smart textiles, health monitoring systems, and wearable displays. © 2024 Elsevier LtdTRUEsciescopu
Felodipine attenuates neuroinflammatory responses and tau hyperphosphorylation through JNK/P38 signaling in tau-overexpressing AD mice
Get PDFWe previously demonstrated that felodipine, an L-type calcium channel blocker, inhibits LPS-mediated neuroinflammatory responses in BV2 microglial cells and wild-type mice. However, the effects of felodipine on tau pathology, a hallmark of Alzheimer's disease (AD), have not been explored yet. Therefore, in the present study, we determined whether felodipine affects neuroinflammation and tau hyperphosphorylation in 3-month-old P301S transgenic mice (PS19), an early phase AD mice model for tauopathy. Felodipine administration decreased tauopathy-mediated microglial activation and NLRP3 expression in PS19 mice but had no effect on tauopathy-associated astrogliosis. In addition, felodipine treatment significantly reduced tau hyperphosphorylation at S202/Thr205 and Thr212/Ser214 residues via inhibiting JNK/P38 signaling in PS19 mice. Collectively, our results suggest that felodipine significantly ameliorates tau hyper-phosphorylation and tauopathy-associated neuroinflammatory responses in AD mice model for tauopathy and could be a novel therapeutic agent for AD.TRUEsciescopu
주사 터널링 현미경을 통한 혼합 양자 물질 연구
No full textScanning Tunneling Microscopy, Superconductor, 2D electrideIn the first part of this dissertation, I investigate the competition between s-wave superconductivity and the superconductivity in FeSe films. When potassium (K) is deposited on bulk FeSe, the superconducting transition temperature (Tc) increases from 8K to 20K. This enhancement has been attributed to electron doping by K deposition. I grew FeSe films on an s-wave superconductor, lead (Pb), aiming to uncover new phenomena arising from the interplay between high-Tc superconductivity and conventional superconductivity. By depositing K on the FeSe films, I studied the changes in FeSe bands induced by electron doping.
In the next section, I report on the Fermi arc states of an electride material. Two-dimensional (2D) electrides can exhibit topologically non-trivial phases due to the intriguing interactions between their cationic atomic layers and anionic electron layers. However, experimental confirmation of topological surface states, which would support their non-trivial bulk topology, remains elusive. Here, I use scanning tunneling microscopy to probe the Weyl states in Gd2C. |본 논문에서는 주사 터널링 현미경 (Scanning Tunneling Microscopy, STM)을 통하여 흥미로운 물리적 특성을 가진 혼합 양자 물질(Hybrid Quantum Materials)에 대해서 연구하였다.
먼저, 전통 초전도체인 납에 고온 초전도체 FeSe 를 성장시켜 두 초전도체의 경쟁에 대한 연구를 진행했다. 납 위에 FeSe 섬을 성장시켰지만 FeSe 고유의 초전도성을 확인하지 못했다. FeSe 의 초전도성을 확인하기 위해 칼륨 (Potassium)을 in-situ 방식으로 증착시켜 초전도 강화를 시도하였다. 하지만 납 위에 성장시킨 FeSe 섬이 칼륨의 증착 효과를 제대로 받지 못해 FeSe 의 초전도 강화가 이뤄지지 않았다. 이를 해결하기 위해 납과 FeSe 섬 사이에 중간층인 PbSe 층을 성장시켜 FeSe 섬이 충분한 증착 효과를 받도록 하였다. PbSe 층의 존재로 인해 FeSe 섬에 칼륨을 증착하면 홀 밴드 위치가 이동함을 확인하였다. 하지만 여전히 FeSe 고유의 초전도성은 확인하지 못했다. FeSe 실험을 진행하면서 성공적인 FeSe 섬 성장을 성공했고, in-situ 증착 방식으로 특정 섬을 추적하며 비교실험을 성공하였다.
두 번째 실험에서는 최근 발견되여 많은 연구가 시작된 전자화합물 Gd2 C 에 대한 연구를 진행하였다. 저온 클리빙을 통해 Gd2 C 의 표면에서 순수 전자층을 최초로 관측에 성공하였고, 순수 전자층의 준입자 간섭 (quasi-particle interference, QPI)을 통해 측정 에너지에 따라 순수 전자층의 간섭 무늬가 바뀌는 것을 확인하였다. 또한 Gd2 C 를 80 K 까지 온도를 올려 순수 전자층을 제거해 Gd 표면을 직접 측정하였다. dI/dV map 을 통해 Gd 표면에서 Fermi arc 의 직접적인 증거를 관측하였다. 이를 통해 주장되어 오던 Gd2 C 의 Fermi arc 의 존재를 주사 터널링 현미경을 통해 확인하였다.List of Contents
Abstract i
List of Contents ii
List of Figures iv
Ⅰ. Introduction
1.1 FeSe-based superconductivity 1
1.1.1 Superconductivity 1
1.1.2 BCS theory 3
1.1.3 Fe-based superconductor 6
1.1.4 Superconductivity enhancement 7
1.2 Electride 10
1.2.1 Electride 10
1.2.2 History 11
1.2.3 Types of electrides 12
IⅠ. Scanning Tunneling Microscopy
2.1 Introduction 14
2.1.1 Operating STM 14
2.1.2 Information observed from STM 17
2.2 STM 19
2.2.1 Home-built STM 19
2.2.2 STM head 21
2.2.3 Preparation chamber 23
2.2.4 Tip making 24
2.2.5 Sample 26
2.2.6 Tip cleaning 28
IⅠI. FeSe island on Pb(111)
3.1 Introduction 29
3.2 Experimental results 33
3.2.1 Methods 33
3.2.2 Results 34
3.3 Conclusion 52
IV. [Gd2C]2+∙2e-
4.1 Introduction 54
4.1.1 2D electride 54
4.1.2 Weyl semimetal 57
4.1.3 Fermi arc 58
4.2 Experimental results 60
4.2.1 Methods 60
4.2.2 Results 62
4.3 Conclusion 75
Reference 77
Summary in Korean 81DoctordCollectio
Linkage of alternative exon assembly in Drosophila TrpA1 transcripts
Get PDFDrosophila TrpA1 (transient receptor potential ankyrin 1) transcripts are alternatively spliced at 2 distinct sites each with a choice of mutually exclusive exons. The first site determines exon1 encoding the amino terminus to produce either nucleophile-, electrophile- and noxious temperature-gated TRPA1(A) or electrophile- and innocuous warmth-gated TRPA1(B). The second site selects for exon10, resulting in TrpA1 variants with either exon10a or exon10b encoding a domain between the N-terminal ankyrin repeats and the transmembrane segments. Although unbiased assembly would generate TRPA1 with 4 different domain combinations, the functional impact of these alternative domains remains to be thoroughly examined. Here, we find that there is a relatively strong linkage in mRNA splicing between the 2 sites in the case of TrpA1(B), but not TrpA1(A), transcripts. Our semiquantitative assay, consisting of reverse transcription polymerase chain reaction and Sanger sequencing, revealed that exon10b is little coupled with TrpA1(B) transcripts, suggesting that only 3 isoforms, TRPA1(A)-exon10a [denoted as TRPA1(A)], TRPA1(A)-exon10b [TRPA1(A)10b], and TRPA1(B)-exon10a [TRPA1(B)], are present at detectable levels using our method. Interestingly, heterologously expressed TRPA1(A)10b showed elevated sensitivity to low concentrations of N-methyl maleimide, a cysteine-modifying electrophile, compared with other isoforms. Equivalent isoforms in malaria-transmitting Anopheles gambiae displayed a similar pattern of isoform-dependent N-methyl maleimide dose dependences, suggesting that the chemosensory regulation by selective domain assembly is conserved in insect TRPA1s. Thus, alternative RNA splicing of exon10 is coordinated in conjunction with the first exons, regulating chemical sensitivity of insect TRPA1s. © 2024 The Author(s)TRUEsciescopuskc
Biodegradation of Ethylene Vinyl Acetate Using Klebsiella aerogenes EM011 Isolated from Effective Microorganisms
No full textThe amount of global plastic waste on land or in marine environments is a critical environmental issue. Plastic biodegradation by microorganisms, insect larvae, and enzymes has become one of the most popular solutions due to the ability of this strategy to generate environmentally benign byproducts, addressing ecological plastic waste concerns. This study revealed the biodegradation of ethylene vinyl acetate (EVA) by the bacterial strain identified as Klebsiella aerogenes EM011, isolated from effective microorganisms. The study found that K. aerogenes EM011 can survive in a carbon-free medium for 30 days using EVA films as the sole energy source, decomposing 0.65 ± 0.04% of 1g of EVA film. The surface changes of the film were detected using scanning electron microscopy after treatment with K. aerogenes EM011. In addition, elemental modifications were detected in the imaged area of the plastic surfaces by energy-dispersive X-ray spectroscopy. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses were conducted to detect changes in the functional groups and chemical components, elucidating alterations on the surface of the EVA films. Through these physicochemical analyses, the formation of carbonyl groups (C=O), ester groups (C–O), and hydroxyl groups (–OH) confirmed the oxidation of EVA. Furthermore, the oxidation led to the decomposition of the EVA film, resulting in changes in its thermal stability and molecular weight distribution. These findings show that the K. aerogenes EM011 strain plays a role in accelerating the biodegradation of EVA. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.FALSEsciescopu
Complement receptor 4 mediates the clearance of extracellular tau fibrils by microglia
No full textTauopathies exhibit a characteristic accumulation of misfolded tau aggregates in the brain. Tau pathology shows disease-specific spatiotemporal propagation through intercellular transmission, which is closely correlated with the progression of clinical manifestations. Therefore, identifying molecular mechanisms that prevent tau propagation is critical for developing therapeutic strategies for tauopathies. The various innate immune receptors, such as complement receptor 3 (CR3) and complement receptor 4 (CR4), have been reported to play a critical role in the clearance of various extracellular toxic molecules by microglia. However, their role in tau clearance has not been studied yet. In the present study, we investigated the role of CR3 and CR4 in regulating extracellular tau clearance. We found that CR4 selectively binds to tau fibrils but not to tau monomers, whereas CR3 does not bind to either of them. Inhibiting CR4, but not CR3, significantly reduces the uptake of tau fibrils by BV2 cells and primary microglia. By contrast, inhibiting CR4 has no effect on the uptake of tau monomers by BV2 cells. Furthermore, inhibiting CR4 suppresses the clearance of extracellular tau fibrils, leading to more seed-competent tau fibrils remaining in the extracellular space relative to control samples. We also provide evidence that the expression of CR4 is upregulated in the brains of human Alzheimer's disease patients and the PS19 mouse model of tauopathy. Taken together, our data strongly support that CR4 is a previously undescribed receptor for the clearance of tau fibrils in microglia and may represent a novel therapeutic target for tauopathy. © 2024 Federation of European Biochemical Societies.FALSEsciescopu