Daegu Gyeongbuk Institute of Science and Technology
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Detection of Battery Defects with Image Augmentation in Battery Magnetic Field
No full text배터리를 분해하지 않고 내부 결함을 진단하는 기술은 이차전지 분야에서 지속적으로 요구되고 있다. 기존의 자기장 이미지를 통한 배터리 결함 진단은 전류가 흐르는 배터리의 자기장을 측정하여 자기장 이미지를 생성하고, 이를 분석하여 내부의 결함을 파악하는 방식이다. 그러나 이 방식은 사람이 직접 이미지를 보고 분석해야 하므로 다수의 배터리에 대해 결함을 진단하는 데 어려움이 있다. 본 논문에서는 데이터 증폭 기법을 적용한 머신러닝 모델을 통해 이 과정을 자동화하는 배터리 결함 감지 방법을 제안한다. 데이터 증폭은 기존 데이터를 바탕으로 새로운 데이터를 생성하는 프로세스이며, 이를 적용한 모델의 성능은 50% 향상되었다. 또한 기존의 SOTA 이상치 탐지 모델과 비교하였을 때 약 30% 높은 정확도를 보인다
A Comprehensive Exploration of Nanomaterials in Cosmetics
No full textNanomaterials attract great interest in developing advanced formulations with improved functionality in the cosmetics industry. This article focuses on using nanomaterials in cosmetics, particularly in developing smart delivery systems. A key advantage of using nanomaterials is their ability to encapsulate active ingredients such as vitamins, antioxidants, and moisturisers. This allows for a targeted and controlled release of these ingredients, optimising their effectiveness. Researchers actively explore novel nanomaterials with unique properties, such as enhanced bioavailability and increased stability, that potentially revolutionise cosmetic products. However, safety, regulatory requirements, and consumer acceptance must be carefully considered to ensure nanomaterials' responsible and successful integration into the cosmetics industry.FALSEscopu
Understanding of the Relationship between the Properties of Cu(In,Ga)Se2 Solar Cells and the Structure of Ag Network Electrodes
No full textThe relation between the structure of the silver network electrodes and the properties of Cu(In,Ga)Se2 (CIGS) solar cells is systemically investigated. The Ag network electrode is deposited onto an Al:ZnO (AZO) thin film, employing a self-forming cracked template. Precise control over the cracked template's structure is achieved through careful adjustment of temperature and humidity. The Ag network electrodes with different coverage areas and network densities are systemically applied to the CIGS solar cells. It is revealed that predominant fill factor (FF) is influenced by the figure of merit of transparent conducting electrodes, rather than sheet resistance, particularly when the coverage area falls within the range of 1.3–5%. Furthermore, a higher network density corresponds to an enhanced FF when the coverage areas of the Ag networks are similar. When utilizing a thinner AZO film, CIGS solar cells with a surface area of 1.0609 cm2 exhibit a notable performance improvement, with efficiency increasing from 10.48% to 11.63%. This enhancement is primarily attributed to the increase in FF from 45% to 65%. These findings underscore the considerable potential for reducing the thickness of the transparent conductive oxide (TCO) in CIGS modules with implications for practical applications in photovoltaic technology. © 2024 The Authors. Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University.TRUEsciescopu
데이터 센터 서버들에서 지연시간에 민감한 워크로드에 대한 동적 코어 할당
No full textData Centers, Network Packet Processing, Latency-Critical Application, Dynamic Core Management현대 데이터 센터는 지연에 민감한(Latency-Critical, LC) 애플리케이션의 서비스 수준 목표(Service Level Objectives, SLOs)를 달성하면서도 에너지 효율성과 성능을 개선해야 하는 복잡한 도전에 직면하고 있다. 기존 연구는 주로 LC 애플리케이션 스레드에만 초점을 맞추거나 네트워크 패킷 처리의 중요성을 고려하지 않는 한계가 있다. 이는 에너지 소비, SLO 위반 및 가상화에 따른 오버헤드 사이의 복잡한 상호작용을 충분히 고려하지 못한다는 문제점을 낳는다. 예를 들어, 기존 연구에서 네트워크 패킷 처리가 코어의 유휴 상태(C-states)에 미치는 영향을 간과하였고, 이는 응답 지연 및 에너지 효율성에 부정적인 영향을 미쳤다. 또한, 가상화 환경에서는 하이퍼바이저가 제공하는 병렬 패킷 처리 기술(예: multi queue virtio-net)로 인해 물리 CPU(pCPUs)간의 선점과 마이그레이션 빈도가 증가하여 심각한 성능 저하가 발생한다. 이에 본 연구에서는 두 가지 혁신적인 동적 코어 할당 전략인 CoreNap과 vSPACE를 제안한다. CoreNap은 네이티브 환경에서 LC 애플리케이션 스레드와 네트워크 패킷 처리에 할당된 코어 수를 동적으로 조절하여 유휴 코어를 최대화하고, 더 깊은 유휴 상태를 유지할 수 있도록 네트워크 패킷 처리 간격을 조정한다. 이를 위해, 경량화된 예측 모델을 이용하여 코어 설정에 따른 에너지 소비와 꼬리 지연 시간을 추정한 후, SLO를 위반하지 않는 범위에서 가장 에너지 효율적인 코어 설정을 선택한다. 실증적 평가를 통해 CoreNap이 기존 코어 할당 방법보다 에너지 절감 효과가 뛰어남을 입증하였다. vSPACE는 가상화 환경에서 병렬 네트워크 패킷 처리의 성능을 개선하기 위한 동적 코어 할당 전략이다. 이 전략은 온라인 통계 분석을 통해 pCPU 사용률과 SLO 위반의 상관관계를 분석하고, 스케줄링 경쟁을 완화하기 위해 가상 CPU(vCPUs)와 네트워크 큐(NQs)에 pCPUs를 별도로 할당하며, pCPU 사용률의 포화를 방지하는 휴리스틱 알고리즘을 적용하여 CPU 할당을 동적으로 조절한다. 성능, 에너지 효율성, 자원 효율성의 세 가지 모드에서 운영되는 vSPACE는 병렬 패킷 처리에 대한 기존 코어 할당 전략에 비해 처리량을 크게 향상하며, 에너지와 자원 효율성에서도 상당한 개선한다.|Modern data centers are facing a growing demand for energy efficiency while guaranteeing Service Level Objectives (SLO) for Latency-Critical (LC) applications. Prior core allocation studies often overlook the impact of network packet processing, resulting in energy/resource inefficiency and performance degradation. For instance, overlooking how packet processing influences core idle states (i.e., C-states), profoundly impacting response latency and energy consumption. In a virtualized environment, parallel packet processing exacerbates competition on processor cores, degrading performance. Addressing this oversight of network packet processing, this thesis presents two core allocation strategies: CoreNap for native environments and vSPACE for I/O virtualized environments. These strategies dynamically adjust the allocated cores for LC application and network packet processing, aiming to improve performance, energy efficiency, and resource efficiency while guaranteeing the target SLOs. CoreNap dynamically changes the number of cores allocated for LC application threads and network packet processing, which aims to extend the idle duration of cores for energy efficiency. Additionally, CoreNap adjusts the interval of network packet processing to enable cores involved in this packet processing to remain in deeper idle states for extended periods. Based on a lightweight predictive model, CoreNap estimates energy consumption and tail latency for various core management configurations, subsequently selecting the most energy-efficient configuration without violating SLOs. Our evaluation reveals that CoreNap surpasses existing core management approaches that focus solely on core allocation for LC application threads, achieving energy reduction across various load levels and applications without SLO violations. vSPACE is a dynamic core allocation strategy designed to enhance performance efficiency in virtualized environments supporting parallel packet processing. To moderate performance overheads induced by scheduling contentions, vSPACE allocates cores separately to virtual CPUs (vCPUs) and packet processing. Moreover, vSPACE dynamically adjusts the allocated cores for vCPUs and packet processing, employing a heuristic algorithm designed to prevent core utilization saturation. vSPACE identifies where the core utilization saturation occurs through an online statistical analysis, examining the correlation between SLO violations and core utilization. vSPACE operates in three distinct modes: performance, energy efficiency, and resource efficiency. Our evaluations indicate that vSPACE significantly enhances throughput (i.e., maximum Queries Per Second) compared to the existing approach for enhancing network I/O virtualization performance. Furthermore, vSPACE yields substantial improvements in both energy and resource efficiency compared to state-of-the-art dynamic core allocation. Keywords: Data Centers, Network Packet Processing, Latency-Critical Application, Dynamic Core ManagementI. Introduction 1
1.1. Contributions 3
1.2. Organization 4
II. Background 6
2.1. Power Management with C-States 6
2.2. Network Packet Processing Techniques Supported by NICs 6
2.3. Parallel Network Packet Processing in Virtualization Environment 7
III. Related Work 9
3.1. Dynamic Core Management for Energy Efficiency 9
3.2. Idle Power Management in Processors 9
3.3. Dynamic Core Management for Improving Resource Utilization 9
3.4. Hardware-Assisted Approaches 10
3.5. Userspace Network 10
3.6. Scheduling Techniques 11
3.7. I/O Handling Techniques 11
3.8. Dynamic Resource Management 12
IV. CoreNap: Energy Efficient Core Management for Latency-Critical Applications 14
4.1. Core Management for Energy Efficiency 14
4.2. Impact of Core Management on Latency-Critical Applications 15
4.2.1. Core Allocation for Application Threads and Network Packet Processing 16
4.2.2. Network Packet Processing Interval Management with Core Allocation 17
4.3. Energy Efficient Core Management for Latency-Critical Applications 21
4.3.1. Challenges 21
4.3.2. CoreNap Architecture 22
4.3.3. Exploration Process 23
4.3.4. Online Training 26
4.3.5. Implementation 26
4.4. Evaluation 27
4.4.1. Experimental Methodology 27
4.4.2. Energy Efficiency and Performance 28
4.4.3. Scalability Evaluation 32
4.4.4. Energy Efficiency and Performance with Dynamic Load 32
4.4.5. Evaluation of Prediction Performance 33
4.4.6. Online Training Efficacy under Spike Load 35
4.4.7. Overhead Analysis of CoreNap 36
4.5. Discussion About Core Placement 37
4.6. Summary 38
V. vSPACE: Supporting Parallel Network Packet Processing in Virtualized Environments through Dynamic Core Management 39
5.1. Parallel Network Packet Processing in Virtualized Environments 39
5.2. Impact of Parallel Packet Processing with I/O Virtualization 40
5.2.1. Impact of Parallel Packet Processing on LC Workload 41
5.2.2. Impact of Core Allocation and Parallel Packet Processing on LC Workload 43
5.3. Architecture 45
5.3.1. Overview 45
5.3.2. Dynamic Core Allocation 46
5.3.3. Exploration of Thresholds 48
5.3.4. Implementation 49
5.4. Evaluation 50
5.4.1. Experimental Methodology 50
5.4.2. Comparison with Static Loads 52
5.4.3. Comparison with Dynamic Loads 56
5.5. Summary 57
VI. Conclusion 60
References 62
요약문 71DoctordCollectio
Focal stimulation of retinal ganglion cells using subretinal 3D microelectrodes with peripheral electrodes of opposite current
No full textSubretinal prostheses have been developed to stimulate survived retinal ganglion cells (RGCs), indirectly following the physiological visual pathways. However, current spreading from the prosthesis electrode causes the activation of unintended RGCs, thereby limiting the spatial resolution of artificial vision. This study proposes a strategy for focal stimulation of RGCs using a subretinal electrode array, in which six hexagonally arranged peripheral electrodes surround a stimulating electrode. RGCs in an in-vitro condition were subretinally stimulated using a fabricated electrode array coated with iridium oxide, following the three different stimulation configurations (with no peripheral, six electrodes of opposite current, and six ground). In-vitro experiments showed that the stimulation with six electrodes of opposite current was most effective in controlling RGC responses with a high spatial resolution. The results suggest that the effective utilization of return electrodes, such as by applying an opposite current to them, could help reduce current spreading beyond the local area targeted for stimulation and elicit RGC responses only in the vicinity of the stimulating electrode. © 2023, Korean Society of Medical and Biological Engineering.FALSEsciescopuskc
Recent Advances in Smart Tactile Sensory Systems with Brain-Inspired Neural Networks
No full textTactile sensory systems play a vital role in various emerging fields including robotics, prosthetics, and human-machine interfaces. However, traditional tactile sensors are typically designed to detect a single stimulus through a lock-and-key mechanism, which poses substantial challenges in the realization of multimodal tactile sensors. To address this issue, the convergence of tactile sensory systems with artificial neural network and machine learning (ML) platforms has been utilized to enhance the capabilities of multimodal sensors and enable signal decoupling/interpretation of mixed tactile stimuli. Herein, recent progress in multimodal sensors that can simultaneously identify various stimuli such as strain, pressure, and temperature is reviewed, providing in-depth understanding of materials, structures, and methodologies. In addition, accurate interpretation of signals from mixed tactile stimuli under complex conditions remains challenging. This review presents a comprehensive exploration of ML algorithms that mimic human neural networks, discussing their significance in advancing smart sensory systems and improving signal interpretation in complex and dynamic environments. Herein, a smart tactile sensory system is investigated that consists of strain, pressure, temperature, multisensor, and machine learning analysis, having advantages of the big data processing by using neural network. Analysis types such as classification, regression, and spike neural network can be used appropriately for each purpose to implement a future tactile sensor platform.image © 2024 The Authors. Advanced Intelligent Systems published by Wiley-VCH GmbHTRUEsciescopu
A self-assembled three-dimensional hierarchical nanoflower: an efficient enzyme-mimetic material for cancer cell detection that improves ROS generation for therapy
No full textThree-dimensional (3D) nanomaterials with high functional properties are emerging as the most promising artificial enzymes for overcoming the significant disadvantages of natural enzymes. Anticancer therapy using 3D-enzyme mimetic materials has emerged as an essential development for catalyzing cancer cell destruction. We report for the first time a novel 3D-based enzyme mimetic material, CaMoO4/MoS2/CuS nanoflower (CMC NF), that exhibits a large specific surface area, uniform flower-like structure, excellent biocompatibility, and high porosity, making it a suitable candidate for cancer detection and therapy. Additionally, CMC NFs were conjugated with folic acid (FA) to selectively target cancer cells, resulting in FA–CMC NFs explicitly binding to overexpressed folate receptor alpha (FRα) in MDA-MB-231 cells. Based on the peroxidase activity, the FA–CMC NFs are an effective nanoprobe for the selective detection of MDA-MB-231 cells over a wide detection range (50 to 5.5 × 104 cells per mL) with a low limit of detection (LOD) value of 10 cells per mL. In addition to their cancer detection capability, the FA–CMC NFs also effectively generated ˙OH radicals in a concentration-dependent manner to treat cancer cells. Under light conditions, the FA–CMC NFs with H2O2 solution showed efficient degradation of methylene blue (MB) dye, and the solution color appeared to fade within 15 min, indicating that they generated ˙OH radicals, which can efficiently kill cancer cells. Thus, the superior functionality of FA–CMC NFs offers cost-effective, facile, and reliable cancer cell detection, providing a new treatment option for cancer treatment and diagnosis. © The Royal Society of Chemistry 2024TRUEsciescopu
Accelerate the Shift to Green Energy with PVDF Based Piezoelectric Nanogenerator
No full textThe two greatest difficulties humanity faces are environmental catastrophe and air degradation, and renewable energy from the ocean, solar, and wind offers a possible answer. This research describes a piezoelectric energy harvester (PENG) for harvesting low-frequency water wave energy. The poled PENG device based on a ferroelectric polymer polyvinylidene fluoride (PVDF) delivers a voltage of 32 V and a current of 130 nA. The PENG achieves a power of 1.38 µW at 500 MΩ. The low-frequency vibrations generated from the laboratory equipment were effectively converted into usable electrical energy. Furthermore, the output performance of four PVDF-based PENG units connected in parallel was placed inside a 3D printed housing after being exposed to water waves delivered a voltage of 1.1 V and current of 170 nA. This work presents an efficient approach for gathering low-frequency wave energy and realizing the blue-energy dream. This study offers a cost-effective approach for gathering low-frequency water wave energy and realizing the blue-energy vision. © 2023, The Author(s), under exclusive licence to Korean Society for Precision Engineering.FALSEsciescopuskc
Effect of proton irradiation on superconducting fluctuations of SmBCO-coated conductor tapes
No full textSuperconductivity fluctuations are behaviors in which a finite probability of a Cooper pair above T c due to thermal fluctuations produces excess conductivity. The dimensionality analysis of this behavior can accurately evaluate essential superconducting parameters such as the higher critical field and coherence length. To investigate the fluctuation effect of SmBa2Cu3O7-δ (SmBCO) superconducting tapes and two types of proton-irradiated SmBCO tapes, we measured the temperature dependence of the detailed in-plane electrical resistivity at various magnetic fields and extracted the temperature dependence of the excess conductivity from these results. The excess conductivity was analyzed by the Aslamazov–Larkin (AL) theory and the Ullah and Dorsey (UD) scaling method. The fluctuations occurred in three dimensions in all samples regardless of the proton irradiation, and the evaluated higher critical field showed a significant increase due to the proton irradiation. Proton irradiation improves the operating potential at higher magnetic fields in high-T c superconductors. These results show that SmBCO superconducting coated conductor tape is a versatile core industrial material. © 2024, The Korean Physical Society.FALSEsciescopuskc