Daegu Gyeongbuk Institute of Science and Technology
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Engineering Implantable Bioelectronics for Electrophysiological Monitoring in Preclinical Animal Models
Get PDFImplantable bioelectronics capable of electrophysiological monitoring intimately interfacing with biological tissue have provided massive information for profound understanding of biological systems. However, their invasive nature induces a potential risk of acute tissue damage, limiting accurate and chronic monitoring of electrophysiological signals. To address this issue, advanced studies have developed effective strategies to engineer the soft, flexible device using preclinical animal models. In addition, the optional but innovative approaches to improve the device's function have been also explored. Herein, these strategies satisfying essential and supplemental requirements for engineering implantable bioelectronics are summarized. Three types of implantable devices, classified by their structural designs, are introduced to describe the approaches using suitable strategies for their specific purpose. In conclusion, the further advancement of engineering implantable bioelectronics addresses the remaining challenges. Such advancements have the potential to contribute to enhanced functionality, encouraging a more delicate understanding of the physiology of biological systems and further broadening the applicability of implantable bioelectronics in the field of biomedical technology. © 2024 The Author(s). Advanced Engineering Materials published by Wiley-VCH GmbH.TRUEsciescopu
Alleviating the cold-start problem in recommendation systems using early adopters
No full text본 논문은 얼리 어답터 집단을 파악하여 추천 시스템에서의 콜드 스타트 문제를 완화할 수 있는 방안을 제안한다. 리뷰/평점 데이터의 시간적 분포와 텍스트 리뷰의 언어적 분석을 통해 초기 소비 집단인 얼리 어답터 집단이 미래에 해당 항목을 소비할 집단을 대표할 수 있음을 보이고, 구분된 두 집단을 추천 시스템 모델에 적용할 수 있음을 제안한다. 실험 결과 얼리 어답터 집단이 나머지 사용자들을 대표할 만큼의 결과의 유사성을 보이며, 두 집단이 내포하고 있는 리뷰의 성향은 다르다는 것을 확인하였다
광학흐름을 이용한 연속사진 멀티 스케일 초해상도
No full textBurst super resolution, Super resolution, Optical flow, Implicit neural representations (INRs)Learning based-multi frame super-resolution (MFSR) achieves higher performance than single image super-resolution (SISR), because MFSR leverages abundant information from multiple frames. Recent MFSR approaches adapt the deformable convolution network (DCN) to align the frames. However, the existing MFSR suffers from misalignments between the reference and source frames due to the limitations of DCN, such as small receptive fields and the predefined number of kernels. From these problems, existing MFSR approaches struggle to represent high-frequency information. To this end, we propose Burst super resolution of multi-scale using optical flow (BurstM). The proposed method estimates the optical flow offset for accurate alignment and predicts the continuous Fourier coefficient of each frame for representing high-frequency textures. In addition, we have enhanced the network’s flexibility by supporting various super-resolution (SR) scale factors with the unimodel. We demonstrate that our method has the highest performance and flexibility than the existing MFSR methods. Keywords: Burst super resolution, Super resolution, Optical flow, Implicit neural representations (INRs)|딥러닝 기술의 도입으로 연속사진에서 많은 정보를 활용하여 고해상도 영상복원을 하는 연속사진 초해상도는 높은 성능을 보여준다. 최근 변형 가능한 합성곱 신경망의 높은 영상 정렬 능력을 활용한 연속사진 초해상도 기술들이 제안되고 있지만, 변형 가능한 합성곱 신경망은 영상간 상관관계에 상관없이 사전 정의된 정보의 양을 사용해야 하므로, 고주파수 영역의 부정확한 표현, 현실 영상 복원 시 가장자리에 있는 경계선 아티팩트 발생의 문제가 있다. 또한 기존의 방법들은 고정된 초해상도 비율로만 동작한다는 한계가 있다.
위와 같은 기존 한계점들을 극복하기 위해 광학흐름을 이용한 연속사진 멀티 스케일 초해상도( Burst super resolution of multi-scale using optical flow)를 제안한다. 경계선 아티팩트 방지를 위해 변형 가능한 합성곱 신경망 대신 광학흐름 만으로 이미지 와핑을 수행함으로써 영상간 상관관계가 높은 화소의 정보만을 활용했다. 또한 이미지 와핑 시 발생하는 블러링, 에일리어싱 등의 영향을 방지하기위해 푸리에 공간에서 고주파 특성을 파악하며 이미지 와핑 및 업스케일링을 수행했다. 또한 고정된 초해상도 비율로만 동작하는 한계를 극복하기 위해 암묵적 신경 표현 방법을 활용하여 푸리에 공간에서 와핑된 영상들의 정보를 연속신호로 해석하여 멀티 스케일 초해상도 기술을 구현했다. 실험결과에서 기존의 연속사진 초해상도 영상복원 방법과 비교할 때 정확하고 자연스러운 복원영상을 제공하며, peak-to-peak signal noise ratio (PSNR)과 structural similarity measure (SSIM)에서 객관적 성능 향상과 기존 대비 빠른 실행속도를 보인다.I. INTRODUCTION 1
1.1 Problem setting 1
1.2 Deep learning based super resolution 2
II. BACKGROUND 4
2.1 Multi frame super resolution (MFSR) 4
2.2 Optical flow 5
2.3 Implicit neural representation (INR) 6
III. PROPOSED METHOD 7
3.1 Problem formulation 7
3.2 Optical flow estimator 8
3.3 Learnable neural warping 8
3.4 Reconstruction module 9
3.5 Skip connection with upsampling 10
3.6 Loss function 10
IV. EXPERIMENTAL RESULTS 12
4.1 Network details 12
4.2 Implementation details 12
4.3 Validation results 16
4.3 Super resolution on BurstSR dataset 17
4.4 Super resolution on SyntheticBurst dataset 22
4.5 Fourier feature space 25
4.6 Alignment performance comparison 26
V. ABLATION STUDY 28
5.1 The comparison between with and without Fourier mapping 28
5.2 Relationship between flexibility and performance 28
5.3 Different optical flow estimator 29
VI. DISCUSSION 30
6.1 Boundary line artifacts 30
6.2 Computation complexity 31
6.3 Super resolution with floating scale factors 32
6.4 Corner case 32
6.5 Low light enhancement performance 34
VII. Conclusion 35
7.1 Conclusion 35
References 36
국문요약 40MasterdCollectio
METHOD AND APPARATUS FOR DETERMINING BIOMETRIC INFORMATION OF TARGET
No full text타겟의 생체 정보 결정 방법 및 장치가 개시된다. 타겟의 생체 정보 결정 방법은 두 개의 레이더를 통해 타겟의 서로 다른 두 지점을 향해 동시에 레이더 펄스를 방출하고, 각 지점에서 반사된 레이더 펄스로 구성된 각각의 프레임들을 미리 정해진 수신 시간에 따라 누적시켜 상기 서로 다른 두 지점에 대한 프레임 셋(Frame set)을 각각 생성하는 단계; 상기 서로 다른 두 지점에 대해 각각 생성된 프레임 셋의 관심 영역에 대응하는 샘플러들의 시계열 데이터에 주성분 분석(Principal Component Analysis)을 수행함으로써 상기 타겟의 생체 정보를 추출하기 위한 일차원의 시계열 데이터를 각각 획득하는 단계; 상기 각각 획득된 일차원의 시계열 데이터들을 이용하여 상기 서로 다른 두 지점에서의 생체 정보 트레인을 추출하는 단계; 및 상기 서로 다른 두 지점에서 각각 추출된 상기 생체 정보 트레인의 비트(beat) 간 간격을 이용하여 상기 서로 다른 두 지점에서 측정된 상기 타겟의 동일한 생체 정보에 대한 시간 지연을 결정하는 단계를 포함할 수 있다
A Systematic Structure-Function Characterization of a Human Mutation in Neurexin-3α Reveals an Extracellular Modulatory Sequence That Stabilizes Neuroligin-1 Binding to Enhance the Postsynaptic Properties of Excitatory Synapses
No full textα-Neurexins are essential and highly expressed presynaptic cell-adhesion molecules that are frequently linked to neuropsychiatric and neurodevelopmental disorders. Despite their importance, how the elaborate extracellular sequences of α-neurexins contribute to synapse function is poorly understood. We recently characterized the presynaptic gain-of-function phenotype caused by a missense mutation in an evolutionarily conserved extracellular sequence of neurexin-3α (A687T) that we identified in a patient diagnosed with profound intellectual disability and epilepsy. The striking A687T gain-of-function mutation on neurexin-3α prompted us to systematically test using mutants whether the presynaptic gain-of-function phenotype is a consequence of the addition of side-chain bulk (i.e., A687V) or polar/hydrophilic properties (i.e., A687S). We used multidisciplinary approaches in mixed-sex primary hippocampal cultures to assess the impact of the neurexin-3αA687 residue on synapse morphology, function and ligand binding. Unexpectedly, neither A687V nor A687S recapitulated the neurexin-3α A687T phenotype. Instead, distinct from A687T, molecular replacement with A687S significantly enhanced postsynaptic properties exclusively at excitatory synapses and selectively increased binding to neuroligin-1 and neuroligin-3 without changing binding to neuroligin-2 or LRRTM2. Importantly, we provide the first experimental evidence supporting the notion that the position A687 of neurexin-3α and the N-terminal sequences of neuroligins may contribute to the stability of α-neurexin-neuroligin-1 trans-synaptic interactions and that these interactions may specifically regulate the postsynaptic strength of excitatory synapses. Copyright © 2024 the authors.FALSEsciescopu
Spectroscopic Evidence of Ultrafast Topological Phase Transition by Light-Driven Strain
No full textEnabling reversible control over the topological invariants, transitioning them from nontrivial to trivial states, has fundamental implications for quantum information processing and spintronics. It offers a promising avenue for establishing an efficient on/off switch mechanism for robust and dissipationless spin-currents. While mechanical strain has traditionally been advantageous for such manipulation of topological invariants, it often comes with the drawback of in-plane fractures, rendering it unsuitable for high-speed, time-dependent operations. This study employs ultrafast optical and THz spectroscopy to explore topological phase transitions induced by light-driven strain in Bi2Se3. Bi2Se3 requires substantial strain for Z2 switching. Our observations provide experimental evidence of ultrafast switching behavior, demonstrating a transition from a topological insulator with spin-momentum-locked surfaces to hybridized states and normal insulating phases under ambient conditions. Notably, applying light-induced strong out-of-plane strain effectively suppresses surface-bulk coupling, facilitating the differentiation of surface and bulk conductance even at room temperature─significantly surpassing the Debye temperature. We expect various time-dependent sequences of transient hybridization and manipulation of topological invariant through photoexcitation intensity adjustments. The sudden surface and bulk transport alterations near the transition point enable coherent conductance modulation at hypersound frequencies. Our findings on the potential of light-triggered ultrafast switching of topological invariants hold promise for high-speed topological switching and its related applications. © 2024 American Chemical Society.FALSEsciescopu
Unlocking the Potential of Bi2S3-Derived Bi Nanoplates: Enhanced Catalytic Activity and Selectivity in Electrochemical and Photoelectrochemical CO2 Reduction to Formate
Get PDFVarious electrocatalysts are extensively examined for their ability to selectively produce desired products by electrochemical CO2 reduction reaction (CO2RR). However, an efficient CO2RR electrocatalyst doesn't ensure an effective co-catalyst on the semiconductor surface for photoelectrochemical CO2RR. Herein, Bi2S3 nanorods are synthesized and electrochemically reduced to Bi nanoplates that adhere to the substrates for application in the electrochemical and photoelectrochemical CO2RR. Compared with commercial-Bi, the Bi2S3-derived Bi (S-Bi) nanoplates on carbon paper exhibit superior electrocatalytic activity and selectivity for formate (HCOO−) in the electrochemical CO2RR, achieving a Faradaic efficiency exceeding 93%, with minimal H2 production over a wide potential range. This highly selective S-Bi catalyst is being employed on the Si photocathode to investigate the behavior of electrocatalysts during photoelectrochemical CO2RR. The strong adhesion of the S-Bi nanoplates to the Si nanowire substrate and their unique catalytic properties afford exceptional activity and selectivity for HCOO− under simulated solar irradiation. The selectivity observed in electrochemical CO2RR using the S-Bi catalyst correlates with that seen in the photoelectrochemical CO2RR system. Combined pulsed potential methods and theoretical analyses reveal stabilization of the OCHO* intermediate on the S-Bi catalyst under specific conditions, which is critical for developing efficient catalysts for CO2-to-HCOO− conversion. © 2024 The Authors. Advanced Science published by Wiley-VCH GmbH.TRUEsciescopu
Transcriptomic dynamics of ABA response in Brassica napus guard cells
Get PDFDrought has a significant, negative impact on crop production; and these effects are poised to increase with climate change. Plants acclimate to drought and water stress through diverse physiological responses, primarily mediated by the hormone abscisic acid (ABA). Because plants lose the majority of their water through stomatal pores on aerial surfaces of plants, stomatal closure is one of the rapid responses mediated by ABA to reduce transpirational water loss. The dynamic changes in the transcriptome of stomatal guard cells in response to ABA have been investigated in the model plant Arabidopsis thaliana. However, guard cell transcriptomes have not been analyzed in agronomically valuable crops such as a major oilseed crop, rapeseed. In this study, we investigated the dynamics of ABA-regulated transcriptomes in stomatal guard cells of Brassica napus and conducted comparison analysis with the transcriptomes of A. thaliana. We discovered changes in gene expression indicating alterations in a host of physiological processes, including stomatal movement, metabolic reprogramming, and light responses. Our results suggest the existence of both immediate and delayed responses to ABA in Brassica guard cells. Furthermore, the transcription factors and regulatory networks mediating these responses are compared to those identified in Arabidopsis. Our results imply the continuing evolution of ABA responses in Brassica since its divergence from a common ancestor, involving both protein-coding and non-coding nucleotide sequences. Together, our results will provide a basis for developing strategies for molecular manipulation of drought tolerance in crop plants. © The Author(s) 2024.TRUEscopu
Development of Flexure-Based Supernumerary Robotic Finger for Hand Function Augmentation
No full textThis study introduces a flexure-based supernumerary robotic finger (FBSF) inspired by the proportions of the human thumb, aiming to overcome existing limitations in robotic finger design. In pursuit of seamless cooperation with the user's hand, human finger proportions are replicated. Finite element analysis of all five fingers indicates that the thumb-mimicking configuration offers the largest workspace and bending angle. The FBSF, featuring a polycarbonate paired crossed flexural hinge structure and high impact polystyrene links, closely mirrors the human thumb. Weighing 59 g (main body) and 170 g (control box), the FBSF enables user-driven control and decoupled actuation based on user intent, utilizing the electromyographic signal of the extensor carpi ulnaris via isometric contractions. An experimental protocol, including task blocks (releasing, clenching), confirms the FBSF's responsiveness to user intentions. When utilizing FBSF, it has been verified using a motion capture camera system that it is possible to extend the existing hand workspace by approximately 29.72%. Performance tests demonstrate the FBSF's capability to grasp various objects and assist in tasks, with a maximum load-bearing capacity of 2.6 kg experimentally verified. This study demonstrates the potential of the developed FBSF to augment hand functionality in diverse applications. A flexure-based supernumerary robotic finger (FBSF), inspired by the human thumb, uses electromyographic signals from specific muscle contractions for input actuation, aligning with user intentions. It extends the workspace by approximately 29.72% compared to the original. Using FBSF, it is possible to grasp various objects, with a maximum payload of 2.6 kg.image (c) 2024 WILEY-VCH GmbHTRUEsciescopu
GPTs-based Safety Recommendation System to Respond to The Severe Accident Punishment Act
No full text본 논문은 중대재해처벌법에 따른 기업의 안전 보건 조치 강화 요구에 대응하기 위해 Custom GPT(Generative Pre-trained Transformer)를 기반으로 한 안전 권고 시스템의 개발 및 적용에 초점을 맞춘다. 특히, 소규모 사업장에서 안전 관리 체계 구축의 어려움을 해결하기 위한 저비용, 고효율의 AI 솔루션을 제안합니다. 이 시스템은 작업 현장의 실시간 이미지와 데이터를 기반으로 위험 요소를 식별하고, 적절한 안전 조치를 권고한다. 본 연구는 HCI(Human-Computer Interaction) 분야에서 인공지능의 활용 가능성을 탐구하며, 중대재해 예방 및 작업자 안전 보장에 기여하고자 한다