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24-GHz 4TX-4RX Phased Array Transceiver With Automatic Beam Steering Mode for FMCW Radar Applications
No full textThis article presents a 24-GHz highly integrated phased array radar transceiver with four transmitters (TXs) and four receivers (RXs). To realize a wide field of view (FoV) and more efficiently reject the clutters, an automatic beam steering mode is realized. A beam scanning generator (BSG) and a frequency sweep generator (FSG) are proposed to steer the beam for each frequency-modulated continuous wave (FMCW)waveform sequence. The shape of the FMCW waveform, the number of beams, and the steering angles of beams can bere c on figured by initially setting the FSG and BSG. The TXs achieve an output power of 10.6 dBm and beam steering covering angles up to +/- 50(degrees)through a three-stage power amplifier (PA),a 6-bit phase shifter, and a 4-bit attenuator. The RXs achieve a noise figure (NF) of 13.5 dB and an overall gain of 105 dB. In the RXs, a two-stage low-noise amplifier (LNA) employs a low-k transformer for flat band gain. A range-compensation filter with a total 40-dB slope is realized using a trans-impedance amplifier(TIA) with DC offset cancellation (DCOC) and first-stage biquad bandpass filter (BPF). The proposed transceiver was fabricated using 65-nm CMOS with an area of 3x2.8 mm2FALSEsciescopu
EduLive: Re-Creating Cues for Instructor-Learners Interaction in Educational Live Streams with Learners' Transcript-Based Annotations
Get PDFEducational live streaming has become a complement to in-person teaching. While synchronous instructor-learner communication is useful, the technology-mediated nature of live streaming can obscure many interaction cues (e.g., learners’ facial expressions and body language), which dampens the instructors’ ability to respond to remote learners’ needs. We explore the opportunity of leveraging real-time transcripts generated from instructors’ audio as a basis for re-creating interaction cues. Transcripts can be leveraged to reveal the content of live streams in a form that learners can trace back and annotate, and such annotations can be further aggregated and presented to instructors as signals to assist them in tracking learners’ engagement. By designing and evaluating our proof-of-concept prototype system, EduLive, we show that instructors benefited from the summative information extracted from learners’ annotations, and the context provided by the transcript enhanced their ability to answer learners’ questions. Our system contributes to the design space of social annotations in CSCW by employing social annotations in educational live streaming scenarios. © 2024 Copyright held by the owner/author(s).TRUEscopu
An Integrated Process-Network Load Balancing in Edge-Assisted Autonomous Vehicles Using Multimodal Applications With Shared Workloads
Get PDFRecently, as computing-intensive services such as object recognition for autonomous vehicles have increased, power consumption and computational loads of vehicles have been prominent. To tackle this issue, there have been growing interests in edge computing technology, which offloads workloads of services to nearby vehicle edge computing (VEC) servers. However, the existing offloading technologies in the VEC server made independent offloading decisions for each service, and they did not consider shared workloads of multimodal vision applications. In this paper, we first aim to capture the intricate workload relationships among multimodal applications in modeling an integrated process-network load balancing for a VEC-assisted autonomous vehicle system. To this end, we formulate an energy minimization problem of a vehicle constrained by outage probability of service requests where the decision variables are (i) dynamic offloading policy between vehicle and VEC server and (ii) onboard CPU clock frequency of a vehicle every time slot. To solve this problem, we leverage Lyapunov optimization to transform the long-term average problem into a slot-by-slot problem. Then, by minimizing the slot-by-slot objective function every time slot, we develop a latency-sensitive energy minimization (LEMON) algorithm. Finally, we evaluate the performance of the proposed algorithm in realistic vehicular network environment, and show that the proposed LEMON algorithm which captures the shared workloads reduces 57% of average queue backlog and 37% of average power consumption compared to the existing algorithm which does not consider shared workload characteristics. © IEEE.TRUEsciescopu
Crystal structure of AlPCl8
Get PDFThe crystal structure of aluminium phosphorus chloride (systematic name: phosphorus tetrachloride tetrachloridoaluminate), (PCl4)[AlCl4] or AlPCl8, was determined and refined using single-crystal X-ray diffraction data. The compound crystallizes in the orthorhombic space group Pbcm. The asymmetric unit comprises one Al atom, one P atom, and five Cl atoms. The structure is characterized by isolated AlCl4 and PCl4 tetrahedra, isostructural with FePCl8 and GaPCl8 © 2024 International Union of Crystallography. All rights reserved.TRUEscopu
Design and application of Forearm mount for Controlling Under-actuated robotic hand
No full text로봇 손의 활용 범위가 넓어지기 위해서 매니퓰 레이터 등과의 체결되는 성능이 중요하다. 그리고 인간 모사형 로봇 설계는 로봇 공학의 중요한 연 구 요소 중 하나이다(1). 하지만, 로봇 손에 대한 최신 연구에서는 이러한 요소들을 고려했으나 많 은 기능을 탑재하기 위해 부피가 큰 형태의 로봇 손 마운트를 설계된 바 있다 (2). 본 연구에서는 상용 매니퓰레이터와 통합이 용 이하며 실제 사람 팔의 전완부를 모사한 마운트를 개발했다. 또한, 개발된 마운트를 UR5 매니퓰레이 터에 장착 후 로봇 손 제어 실험을 수행하였으며, 그 결과에 대해 소개한다
Designing Functional Polymers with Tunable Tribopolarity for Advanced Triboelectric Nanogenerator
No full texttriboelectric nanogenerator, functional polymer, biodegradability, self-healingⅠ. INTRODUCTION
1.1 Energy harvesting 1
1.2 Triboelectric nanogenerator 3
1.3 Theoretical background 6
1.3.1 Triboelectrification 6
1.3.2 Triboelectric series 12
1.3.3 Working mechanism of triboelectric nanogenerator 14
1.4 Strategies for improving triboelectric performance 17
1.4.1 Dipolar polarization 17
1.4.2 Ionic polarization 18
1.4.3 Interfacial polarization 18
1.5 Importance of developing advanced triboelectric nanogenerator 21
1.5.1 Biodegradable triboelectric nanogenerator 21
1.5.2 Self-healable triboelectric nanogenerator 22
1.6 Objectives 23
Ⅱ. PCL-BASED POLYURETHANE MODIFIED WITH PDMS AND FLUORINE UNIT
2.1 Abstract 24
2.2 Introduction 24
2.3 Experimental details 27
2.4 Results and Discussion 32
2.5 Conclusion 79
Ⅲ. IMIDAZOLIUM BASED IONIC POLYURETHANE
3.1 Abstract 80
3.2 Introduction 80
3.3 Experimental details 82
3.4 Results and Discussion 86
3.5 Conclusion 139
Ⅳ. POLY(IONIC LIQUIDS)
4.1 Abstract 142
4.2 Introduction 142
4.3 Experimental details 144
4.4 Results and Discussion 150
4.5 Conclusion 179
Ⅴ. CONCLUSION
5.1 Summary 180
5.2 Suggestions for future improvement 185
References 187
요약문 201
Appendix A: List of Publications 203
Appendix B: List of Conference 205DoctordCollectio
DynamicLabels: Supporting Informed Construction of Machine Learning Label Sets with Crowd Feedback
No full textLabel set construction - deciding on a group of distinct labels - is an essential stage in building a supervised machine learning (ML) application, as a badly designed label set negatively affects subsequent stages, such as training dataset construction, model training, and model deployment. Despite its significance, it is challenging for ML practitioners to come up with a well-defined label set, especially when no external references are available. Through our formative study (n=8), we observed that even with the help of external references or domain experts, ML practitioners still need to go through multiple iterations to gradually improve the label set. In this process, there exist challenges in collecting helpful feedback and utilizing it to make optimal refinement decisions. To support informed refinement, we present DynamicLabels, a system that aims to support a more informed label set-building process with crowd feedback. Crowd workers provide annotations and label suggestions to the ML practitioner's label set, and the ML practitioner can review the feedback through multi-aspect analysis and refine the label set with crowd-made labels. Through a within-subjects study (n=16) using two datasets, we found that DynamicLabels enables better understanding and exploration of the collected feedback and supports a more structured and flexible refinement process. The crowd feedback helped ML practitioners explore diverse perspectives, spot current weaknesses, and shop from crowd-generated labels. Metrics and label suggestions in DynamicLabels helped in obtaining a high-level overview of the feedback, gaining assurance, and spotting surfacing conflicts and edge cases that could have been overlooked. © 2024 Owner/Author
Facile supramolecular processing of recyclable adaptive polymer composites for highly reproducible sensory materials
No full textDynamic polymer networks (DPNs), when cross-linked, can display chemical and physical adaptiveness due to their dynamic connections and associated phase transitions. However, the reliable preparation of these conductive composites and achieving consistent performance through recycling remain challenging, primarily due to a lack of systematic approaches. Herein, we describe synergistic association of supramolecular gel and high density dynamic crosslinking using vinylogous urethane (VU) bond that enable highly reliable sensitivity and reproducibility after recycling to high performance adaptive dynamic polymer networks containing conductive fillers. We introduce a straightforward method to create DPNs-single-walled carbon nanotube (SWCNT) composites. This involves facile grinding a random copolymer in a supramolecular eutectic liquid, resulting in a supramolecular gel. Subsequently, dynamic cross-linking is applied. The resulting dynamic polymer-SWCNT (DPC) composites, incorporating a supramolecular gel, demonstrate adjustable electrical conductivity and high sensitivities to various mechanical motions and irradiations, including specific light and heat. Significantly, the DPC exhibits excellent recyclability, along with enhanced reproducibility and sensitivity as a strain sensor compared to other recyclable sensors. Furthermore, we establish a strong correlation between the sensitivity and stiffness of the DPC composite with dynamic cross-linking density. These findings highlight the promising potential of adaptive gel-based processing of DPNs for highly sensitive, recyclable sensory materials with excellent reproducibility. © 2024 Elsevier B.V.FALSEsciescopu
Compact Solid Electrolyte Interface Realization Employing Surface-Modified Fillers for Long-Lasting, High-Performance All-Solid-State Li-Metal Batteries
No full textThe implementation of polymer-based Li-metal batteries is hindered by their low coulombic efficiency and poor cycling stability attributed to continuous electrolyte decomposition. Enhancement of the solid electrolyte interface (SEI) stability is key to mitigating electrolyte decomposition. This study proposes surface-functionalized silica mesoball fillers to fabricate a composite polymer electrolyte (MSBM-CPE). As a result of surface modification, the polyethylene oxide matrix benefits from the uniform distribution of the filler, which provides a large surface area and Lewis acid sites. Molecular dynamics simulations reveal that the dissociation energy of lithium bis(trifluoromethanesulfonyl)imide in the filler is fourfold higher (−1.95eV) than that of the filler-free electrolyte. Consequently, the MSMB-CPE diffusivity is 30 times higher than its filler-free counterpart. The MSMB-CPE of ionic conductivity of 1.16 × 10−2Scm−1 @60 °C and a venerable Li-ion transference number of 0.81. The excellent compatibility of MSMB-CPE with the Li anode is demonstrated by its stable symmetric cell performance under high current density (200µA cm−2 @60 °C) for over 5000h. Approximately 85.60% retention capacity of the [Li/MSMB-CPE/LiFePO4] full cell after 700 cycles. Furthermore, compositional analysis reveals that the SEI layer in MSMB-CPE is smooth with fewer by-products at the electrolyte/Li interface. © 2024 Wiley-VCH GmbH.FALSEsciescopu
Adaptive Data I/O Management Scheme to Maximize Real-Time Guarantee Duration of Flash Memory
No full text본 논문에서는 낸드 플래시 내의 작업들의 P/E cycle에 따른 실행 시간 변화가 실시간성 보장을 위해 반드시 고려되어야 함을 보인다. 제시하는 문제를 해결하기 위해 P/E cycle에 따라 달라지는 데이터 I/O 실행 시간을 고려하여 실시간성 보장 여부를 판단하는 새로운 스케줄 가능성 분석과, 이 분석을 바탕으로 실시간성 보장 기간을 최대화하는 데이터 관리 기법을 제안한다. 제안하는 관리 기법은 일반적인 데이터 관리 기법과 대표적인 플래시 수명 연장 기법인 wear-leveling에 비해 실시간성 보장 기간을 향상시킨다. 임의 생성된 태스크 셋을 대상으로 제안된 기법을 실험하였을 때 일반적인 관리 기법에 비해 최대 81%, wear-leveling 기법에 비해 최대 63%까지 실시간성 보장 기간을 연장함을 확인하였다. 본 기법은 실시간 I/O를 필요로 하는 시스템의 신뢰성과 성능을 높이는 데 기여할 것으로 기대된다.
This paper demonstrates that variation of NAND flash operation latency must be considered to ensure real-time guarantees. To address this issue, a new schedulability analysis is proposed, which considers varying I/O execution time resulting from P/E cycle increase. An I/O management mechanism designed to maximize the duration of real-time guarantees is then suggested. The proposed technique can improve the duration of real-time guarantees compared to conventional flash firmware and wear-leveling technique, commonly used to extend the lifespan of flash storage. In evaluation, our proposed technique extended the real-time guarantee duration by up to 81% compared to conventional management methods, and up to 63% compared to wear-leveling techniques. Our solution is expected to enhance the reliability and performance of systems requiring real-time data I/O.FALSEkc