Daegu Gyeongbuk Institute of Science and Technology
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차량 엣지 컴퓨팅에서 효율적인 자원 관리를 위한 심층 강화 학습 기반 정책
No full textLoad balancing, vehicle-to-everything, vehicle edge computing, autonomous driving, deep reinforcement learningRecently, the rapid development of autonomous vehicles has significantly increased the demand for data processing, making edge computing, which offloads computational tasks from the vehicle to nearby servers, essential. However, excessive offloading can overload network traffic, emphasizing the need for efficient resource management policies. In this paper, we propose a dynamic resource allocation model using a deep queueing network within a three- tier structure of local, edge, and cloud servers to optimize data processing for high-priority vehicles such as emergency vehicles. This approach can keep vehicle queues stable and reduce offload costs. Although the usage cost of cloud servers is generally higher than that of edge servers, this paper considers several scenarios, including a realistic scenario where the usage cost of edge servers is higher due to the installation cost. The proposed policy aims to efficiently allocate resources in an autonomous vehicle network by differentiating the resource allocation according to vehicle priority and offloading cost. Our analysis shows that the cost structure and vehicle priority have a significant impact on the resource allocation in an autonomous vehicle network. Keywords: Load balancing, vehicle-to-everything, vehicle edge computing, autonomous driv- ing, deep reinforcement learning|최근 자율주행차의 급속한 발전으로 데이터 처리 수요가 크게 증가하였으며, 차량에서 인근 서버로 연산 작업을 오프로딩하는 엣지 컴퓨팅 기술이 부각되고 있다. 그러나 과도한 오프로딩은 네트워크 트래픽을 과부하시키기 때문에 효율적인 자원 관리 정책이 필요하다. 본 논문에서는 로컬, 엣지, 클라우드 서버로 구성된 3계층 구조 내에서 심층 Q-네트워크를 활용한 동적 자원 할당 모델을 제안하여, 응급 차량과 같은 고우선순위 차량의 데이터 처리를 최적화한다. 이를 통해 차량의 대기열을 안정적으로 유지하고 오프로딩 비용을 절감할 수 있다. 일반적으로 클라우드 서버의 사용 비용이 엣지 서버보다 더 높지만, 본 논문에서는 설치 비용으로 인해 엣지 서버의 사용 비용이 더 높은 현실적인 시나리오를 포함한 여러 시나리오를 고려하였다. 제안된 정책은 차량의 우선순위와 오프로딩 비용에 따라 자원을 효율적으로 배분하는 것을 목표로 한다. 분석 결과, 자율주행 네트워크에서 비용 구조와 차량 우선순위가 자원 할당에 중요한 영향을 미친다는 점을 확인하였다.1. Introduction 1
2. Background 4
2.1 V2X Technology 4
2.2 Mobile Edge Computing 5
2.3 Vehicular Edge Computing 7
2.4 Deep Reinforcement Learning 8
2.5 Related Works 10
3. Research Method 12
3.1 Scenario Description 12
3.1.1 Overview of the Local-Edge-Cloud 3-Tier System 12
3.1.2 Vehicle Prioritization 14
3.1.3 Costs of Offloading 14
3.1.4 Data Processing Flow 15
3.2 Simulation Setup 16
3.2.1 Queue Management 18
3.2.1.1 Queue Length Update 18
3.2.1.2 Processed Data Calculation 19
3.2.2 Dynamic Determination of Data Processing Location in Vehicle Networks through DRL 20
3.2.2.1 Balancing Exploration and Exploitation: ϵ-Greedy Policy 20
3.2.2.2 Q-Value Update: Bellman Equation 22
3.3 Algorithm Description 23
4. Performance Analysis 27
4.1 Processing Queue of Each Vehicle 27
4.2 Data Processing Ratios 29
4.3 Cost Comparison of Scenarios 35
5. Conclusion 37MasterdCollectio
고체에서의 시간분해 초고속 동력학: 광전효과 및 관련 현상들
No full textTime-resolved dynamics, ultrafast, photoemission, topology, exciton, FloquetAn investigation of the nonequilibrium dynamics uncovers the underlying physical properties that are veiled in the static ground state. Time-resolved pump-probe spectroscopy is one of the most powerful tools for investigating the nonequilibrium phenomena in atoms, molecules, and solid states. In particular, pump-probe spectroscopy deals with laser interaction, and the optical excitation inevitably induces a photo-induced hole in the system. In this thesis, we present our theoretical calculation for the time-resolved dynamics driven by laser and photo-induced hole in solids. One of the related and fascinating topics is attosecond photoemission delay. We study the properties of photoemission delay in 2D materials related to anisotropic screening and Berry curvature by numerically evaluating the attosecond streaking. The result shows that these intrinsic features of 2D systems strongly affect the emission delay. Furthermore, we calculate the time- and angle-resolved photoemission spectroscopy to investigate exciton and Floquet dynamics during the light-matter interaction in 2D materials. From the calculation, it is found that the exciton and Floquet states form a novel quantum state through the electron-hole interaction.|본 논문은 광전효과 및 관련 현상들을 통해 고체에서의 시간분해 초고속 동력학에 대해 다룬다. 시간분해 초고속 동력학은 원자, 분자, 고체 상태의 근본적 물리현상을 분석하는 강력한 기법이다. 비평형 동력학에 대한 연구는 바닥 상태에서는 잘 보이지 않는 물리적 특성들에 대한 실마리를 제공한다. 이에 주로 사용되는 펌프-프로브 (pump-probe) 분광법은 레이저 상호작용을 다루며 이에 의한 고체 내 전자의 들뜸은 필연적으로 홀(hole)을 만들어낸다. 이와 관련된 흥미로운 주제 중 하나는 아초토 광전효과 지연 현상이다. 우리는 2 차원 물질에서의 광전효과 지연 현상에 대해서 연구하였으며 특히, 비등방적 가림(anisotropic screening)현상과 베리 곡률(Berry curvature)에 의해 발생하는 광전효과 지연에 대해서 수치적으로 계산하였다. 그 결과, 2차원 물질 본연의 특성이 지연 현상에 큰 영향을 주는 것을 밝혀냈다. 추가로, 우리는 시간분해 각도분해 전자분광(time- and angle- resolved photoemission spectroscopy)을 활용하여 엑시톤(exciton) 및 플로케(Floquet) 동역학에 대하서 살펴보았다. 이 계산으로부터 엑시톤과 플로케 상태가 전자-홀 상호작용을 통해 새로운 양자상태를 형성한다는 것을 알아냈다.Ⅰ. Introduction 1
Ⅱ. Theoretical framework 4
2.1 Halimtonian for many-particle system 4
2.2 Light-matter interaction 7
2.3 Peierls Substitution 9
2.4 Photoemission process 11
2.5 Floquet theory 13
2.6 Topology and Berry curvature 14
2.7 Exciton in 2D materials 16
2.8 Attosecond photoemission delay 22
2.9 Numerical approach to the time-dependent Schrodinger equation 28
2.10 Entanglement and information 34
2.11 Photoelectron emission delay in spherically symmetric systems 37
Ⅲ. Anisotropic photoelectron emission delay in two-dimensional atomic arrangement 45
3.1 Modeling the anisotropic hole potential of graphene 45
3.2 Photoemission delay induced by the anisotropy 47
Ⅳ. Berry curvature in the photoelectron emission delay 55
4.1 The Berry curvature of the Haldane model 59
4.2 Pump-probe interaction and time-dependent perturbation theory 59
4.3 Coherent superposition induced photoemission delay 66
4.4 Long duration XUV limit 67
4.5 Short duration XUV limit 70
4.6 Berry curvature dependent photoemission delay 74
Ⅴ. Exciton-Floquet composites. . 86
5.1 Theoretical calculation of exciton creation in 2D materials 88
5.2 ARPES of exciton and unbounded electron-hole pair 92
5.3 Time-resolved ARPES of exciton state 97
5.4 Quantum entanglement and information 103
ⅤI. Summary and Outlook. 108
ⅤII. References 110DoctordCollectio
Rational Design for the Highly Performing Inverted PbS Quantum Dot Solar Cell
No full textPbS quantum dotList of Contents
Abstract i
List of contents ii
List of tables iii
List of figures vi
Ⅰ. Introduction
1.1 Advancing Inverted PbS Quantum Dot Solar Cells Beyond Standard Designs 1
1.2 Instability of the PbS Quantum Dot inverted structure 1
Ⅱ. Experimental
2.1 materials 3
2.2 Synthesis of OA-capped PbS Colloidal Quantum Dot 3
2.3 Ligand Exchange Step for CQD ink 3
2.4 Device fabrication 4
2.5 Device characterization of PbS CQD SC 4
2.5.1 Note 1 5
Ⅲ. Results and discussion
3.1 Common ETL materials 6
3.2 Rational structure of Inverted PbS quantum dot 6
3.3 Photovoltaic performance of Devices Using N2200 as the ETL 10
3.4 Solar cell structure and performance 13
3.5 Stability of N2200 as ETL 15
Ⅳ. Conclusion 17
Ⅴ. Reference 18
Ⅵ. 요약문 20MasterdCollectio
Polyvinylpyrrolidone-mediated shape-tailored CuS core with biocompatible Fe3O4 for core@shell robotic nanozymes in targeted dual-mode oncotherapy
No full textRobotic nanozymes offer precise, efficient, and localized cancer treatment with minimal adverse effects. The study reports the polyvinylpyrrolidone (PVP)-mediated synthesis of various copper sulfide (CuS) core morphologies, which were combined with a biocompatible Fe3O4 shell (CuS@Fe3O4) via 3-aminopropyltriethoxysilane (APTES) to form two types of robotic systems (nano- and microrobots) for dual-mode cancer therapy. For this approach, PVP with varying molecular weights (10 k, 40 k, and 360 k) was utilized to modulate the CuS core morphologies during synthesis, producing hollow spherical (CuS10k), rod-like (CuS40k), and elongated (CuS360k) structures. Owing to their suitable sizes, the developed folic acid (FA)-conjugated CuS10k@Fe3O4 and CuS40k@Fe3O4, with magnetic targeting capabilities, were employed as nanorobots (250 ± 100 nm) and microrobots (1 µm), respectively. FA-conjugation enhanced the specificity toward folate receptors, improving the uptake efficacy in MDA-MB-231 cells. Under near-infrared irradiation, the nanorobot and microrobot achieved photothermal conversion efficiencies of 38.8 % and 32.5 %, respectively, significantly reducing cell viability by 23.6 % and 47.5 %. The use of PVP as a morphology-modulating agent to create multifunctional properties (e.g., enzyme-like activity, photothermal therapy, and magnetic control) within a single robotic nanozyme system represents a significant advancement in nanomedicine. This study introduces a novel cancer therapy platform to address current treatment challenges, minimize adverse effects, and optimize therapeutic outcomes. © 2025 Elsevier B.V.FALSEsciescopu
Soft-Actuated Cuff Electrodes with Minimal Contact for Bidirectional Peripheral Interfaces
No full textNeural interfaces with embedded electrical functions, such as cuff electrodes, are essential for monitoring and stimulating peripheral nerves. Still, several challenges remain with cuff electrodes because sutured devices can damage the nerve by high pressure and the secured contact of electrodes with the nerve is hard to accomplish, which however is essential in maintaining electrical performance. Here, a sutureless soft-actuated cuff electrodes (SACE) that can envelop the nerve conveniently by creating a bent shape controlled upon fluid injection, is introduced. Moreover, fluid injection protrudes part of the device where electrodes are formed, thereby achieving minimized, soft but secure contact between the electrodes and the nerve. In vivo results demonstrate the successful recording and stimulation of peripheral nerves over time up to 6 weeks. While securing contact with the nerve, the implanted electrodes can preserve the nerve intact with no reduction in blood flow, thereby indicating only minimal compressive force applied to the nerve. The SACE is expected to be a promising tool for recording and stimulation of peripheral nerves toward bidirectional neuroprostheses. © 2024 The Author(s). Advanced Materials published by Wiley-VCH GmbH.TRUEsciescopu
UNet-based multi-organ segmentation in photon counting CT using virtual monoenergetic images
No full textBackground: Multi-organ segmentation aids in disease diagnosis, treatment, and radiotherapy. The recently emerged photon counting detector-based CT (PCCT) provides spectral information of the organs and the background tissue and may improve segmentation performance. Purpose: We propose UNet-based multi-organ segmentation in PCCT using virtual monoenergetic images (VMI) to exploit spectral information effectively. Methods: The proposed method consists of the following steps: Noise reduction in bin-wise images, image-based material decomposition, generating VMIs, and deep learning-based segmentation. VMIs are synthesized for various x-ray energies using basis images. The UNet-based networks (3D UNet, Swin UNETR) were used for segmentation, and dice similarity coefficients (DSC) and 3D visualization of the segmented result were evaluation indicators. We validated the proposed method for the liver, pancreas, and spleen segmentation using abdominal phantoms from 55 subjects for dual- and quad-energy bins. We compared it to the conventional PCCT-based segmentation, which uses only the (noise-reduced) bin-wise images. The experiments were conducted on two cases by adjusting the dose levels. Results: The proposed method improved the training stability for most cases. With the proposed method, the average DSC for the three organs slightly increased from 0.933 to 0.95, and the standard deviation decreased from 0.066 to 0.047, for example, in the low dose case (using VMIs v.s. bin-wise images from dual-energy bins; 3D UNet). Conclusions: The proposed method using VMIs improves training stability for multi-organ segmentation in PCCT, particularly when the number of energy bins is small. © 2024 American Association of Physicists in Medicine.FALSEsciescopu
Immortalization of epidural fat-derived mesenchymal stem cells: In vitro characterization and adipocyte differentiation potential
Full text linkBACKGROUND Mesenchymal stem cells (MSCs) are promising candidates for regenerative therapy due to their self-renewal capability, multilineage differentiation potential, and immunomodulatory effects. The molecular characteristics of MSCs are influenced by their location. Recently, epidural fat (EF) and EF-derived MSCs (EF-MSCs) have garnered attention due to their potential benefits to the spinal microenvironment and their high expression of neural SC markers. However, their clinical applications are limited due to cell senescence and limited accessibility of EF. Although many studies have attempted to establish an immortalized, stable SC line, the characteristics of immortalized EF-MSCs remain to be clarified. AIM To establish and analyze stable immortalized EF-MSCs. METHODS The phenotypes of EF-MSCs were analyzed using optical microscopy. Cell immortalization was performed using lentiviral vectors. The biomolecular characteristics of the cells were analyzed by immunoblotting, quantitative PCR, and proteomics. RESULTS The immortalized EF-MSCs demonstrated a significantly extended lifespan compared to the control group, with well-preserved adipogenic potential and SC surface marker expression. Introduction of human telomerase reverse transcriptase genes markedly increased the lifespan of EF-MSCs. Proteomics analysis revealed substantial increase in the expression of DNA replication pathway components in immortalized EF-MSCs. CONCLUSION Immortalized EF-MSCs exhibited significantly enhanced proliferative capacity, retained adipogenic potential, and upregulated the expression of DNA replication pathway components. ©The Author(s) 2025.TRUEsci
Frictional heat-assisted performance enhancement in dynamic Schottky contact of Al/Ag2Se-based tribovoltaic nanogenerator
Full text linkThe tribovoltaic nanogenerator (TVNG) has evolved in recent years as a novel type of nanogenerator designed to address the limitations of the standard triboelectric nanogenerator in terms of output signal and charge generation. Besides the outstanding characteristics, the tribovoltaic effect can also well be coupled with another effect to further boost the output performance. In this work, we proposed firstly a frictional heat-assisted performance enhancement in dynamic Schottky contact from the rubbing between n-type silver selenide (Ag2Se) and aluminum. The chemical composition and physical characteristics of the Ag2Se ceramic were analyzed using X-ray diffraction, scanning electron microscopy, and Synchrotron X-ray tomography techniques. UV–Vis spectroscopy and UPS were also utilized in order to validate the semiconducting property of the n-type Ag2Se ceramic. Moreover, the presence of the Schottky junction was demonstrated through the analysis of the current-bias voltage characteristic curve of the Ag2Se/aluminum (Al) contact under varying stress and temperature conditions. The built-in electric field plays a crucial part in the tribovoltaic effect by efficiently transferring the excited carriers to an external load through sliding contact between Ag2Se and Al. Demonstrating the synergy between tribovoltaic and thermoelectric effects becomes achievable through the excellent thermoelectric property of Ag2Se. Herein, the proposed TVNG generated a peak output voltage and current of around 0.7 V and 24.8 nA, respectively, achieving a maximum output power of 12.6 nW at a load resistance of 10 kΩ. The influence of frictional heat on the output performance of the proposed TVNG was well demonstrated by the thermal-induced voltage and enhanced electrical output from continuous sliding. The concepts given in this study establish the basis for the progress of effective energy collection employing semiconducting materials and the advancement of flexible harvesting and sensing device development in the future. © 2024 The Author(s)TRUEsciescopu
Open Innovation Over the Regional and National Boundaries in the Semiconductor Industry: The Effects of Digital Transformation and Decoupling of the Global Value Chain
No full textDecoupling of the global value chains in the semiconductor industry under digital transformation has not been adequately investigated, although it is a popular topic with the emerging technological rivalry globally. This study empirically examines the following research question to contribute to the limited research. How do firms’ collaborations across regional and national boundaries moderate the effects of open innovation on performance in the semiconductor industry after digital transformation under the decoupling of the global value chain? This study analyses patents which had been registered at the United States Patent and Trademark Office (USPTO) and the Korean Intellectual Property Office (KIPO) in the semiconductor industry during 2004 and 2020 at the representative terms of before and after digital transformation. Findings are as follows: First, digital transformation motivates semiconductor enterprises’ collaboration effects over regional and national boundaries. Second, the decoupling of the semiconductor industry in the global value chain negatively moderates the effects of open innovation on firms’ performance across regional and national boundaries. Therefore, by reconstructing the global value chain of the semiconductor industry, the negative moderating effects of the semiconductor industry’s decoupling could be diminished. In addition, by constructing a national semiconductor cluster in South Korea, the benefits of digital transformation in the semiconductor industry could be increased. © 2024 SAGE Publications.FALSEssciscopu
비파괴적 가교 매트릭스를 기반으로 신뢰할 수 있는 발광 특성을 구현한 양자점의 직접 광리소그래피
No full textQuantum Dot, Direct Photolithography, Thiol-Ene Chemistry, Crosslinking Matrix , Quantum Dot light-Emitting Diodes1. Introduction 1
2. Experimental Section 5
3. Characterization 9
4. Result and Discussion 10
4.1 Quantum Dot Patterning via Dual-Crosslinking Chemistry 11
4.2 Crosslinking Mechanism of Quantum Dots 14
4.3 High-Resolution Patterns of Quantum Dots 19
4.4 Optical Properties of Crosslinked Quantum Dots 23
4.5 Application of Quantum Dot Patterning : QLED 27
5. Conclusion 30
Reference 31MasterdCollectio