[이슈분석] 청년층 해외취업·해외인턴 사업의 글로벌 역량 강화를 위한 과제

Ⅰ. 논의 배경과 목적 Ⅱ. 해외취업지원사업 추진현황 및 문제점 1. 해외취업지원사업 추진경과 2. 해외취업지원사업 현황 3. 청년 해외진출사업의 문제점 Ⅲ. 향후 과

높은 성능과 확장성을 위한 메모리 관리 시스템 최적화

학위논문(박사)--서울대학교 대학원 :공과대학 컴퓨터공학부,2019. 8. 염헌영.One common characteristic of modern workloads which appeared with recent computing paradigms including cloud, big data and machine learning is memory intensiveness. Such workloads usually have huge working sets that cannot be fully accommodated in DRAM in many case. Those also tend to show only low locality so that the small CPU cache cannot hide DRAM or lower level memory access overhead. Meanwhile, computing hardware has also evolved to keep pace with this change. (1) Computing systems are increasing the size of their main memory so that those could accommodate more of the huge working sets. As a result, data center servers utilizing few hundreds of gigabytes of DRAM have been common and even terabytes of DRAM equipped systems exist. (2) Massive parallelism is becomming common and essential. CPU vendors have started to increase the number of CPU cores instead of the CPU frequency due to the heat dissipation and power consumption problem since the early 2000s. Prevalent datacenter systems provide few hundreds of CPU cores; Few thousands of CPU cores are not rare. Such many-core systems are normally constructed in non-uniform memory access (NUMA) architecture. Therefore, efficient, effective and NUMA-awared use of this parallelism is especially important for the memory intensive workloads. Compared to these rapid changes of workload characteristics and hardware, memory management system software has not sufficiently optimized. Consequently, the memory management system software has been a bottleneck. In other words, the memory intensive modern workloads cannot fully utilize the evolved modern hardware unless the underlying memory management system is completely optimized. This paper provides an overview of a few limitations in existing memory management systems and introduces two optimization approaches for high performance and scalability of the memory management systems. The first approach improves the performance of the memory systems by guaranteeing huge page utilization under memory fragmentation situation. For the guarantee, we introduce a contiguous memory allocator that guarantees success and low latency of its allocations. The second approach intends to optimize the NUMA-aware system scalability. For that, we optimize virtual memory address space management system by substituting virtual memory area (VMA) managing red-black tree protection from global reader-writer locking to an RCU extension. Because no RCU extension including state-of-the-arts are NUMA oblivious, we also designed new RCU extension that provides NUMA-aware scalable update-side synchronization.Abstract 1 Chapter 1 Introduction 6 1.1 Motivation 6 1.2 Approaches 7 1.2.1 An Optimization for High Performance 7 1.2.2 An Optimization for High Scalability 9 1.3 Dissertation Structure 10 Chapter 2 Guaranteed Transparent Huge Pages Allocations 12 2.1 Introduction 12 2.2 Background 16 2.2.1 Devices using DMA 16 2.2.2 Huge Pages 17 2.2.3 Buddy Allocator 20 2.2.4 Memory Reservation 21 2.2.5 Contiguous Memory Allocator 21 2.3 Guaranteed CMA 22 2.3.1 Secondary Class Clients of GCMA 23 2.3.2 Limitations and Optimizations 26 2.4 Implementation 27 2.4.1 Contiguous Memory Allocation 29 2.4.2 DMEM: Discardable Memory 30 2.5 Guaranteed THP 30 2.6 Evaluation 32 2.6.1 Evaluation on a Mobile System 32 2.6.2 Evaluation on a Server System 38 2.7 Related Work 45 2.8 Conclusion 47 Chapter 3 A Scalable Virtual Address Space Protected by an HTM-based NUMA-aware RCU Extension 48 3.1 Introduction 48 3.2 Background and Related Work 50 3.2.1 Read-Copy Update 50 3.2.2 Hardware Transactional Memory 53 3.2.3 Related Work 54 3.3. An RCU Extension for NUMA Systems 57 3.3.1 Root Cause of HTM Performance Degradation on NUMA systems 57 3.3.2 Design of RCX 62 3.3.3 Implementation 70 3.4 Evaluation 71 3.4.1 Evaluation Setup 71 3.4.2 Micro-benchmarks 72 3.4.3 Macro-benchmark 76 3.5 Conclusion. 80 Chapter 4 Conculsion 81Docto

Social Engagement Moderates the Relationship between Age-related White Matter Hyperintensity Volume and Episodic Memory in Older Adults

학위논문 (석사) -- 서울대학교 대학원 : 사회과학대학 심리학과, 2021. 2. 최진영.노년기에는 신체적 기능뿐만 아니라 인지기능이 감퇴하는 양상을 보인다. 특히 노년기에 빠른 속도로 감퇴하는 일화기억 기능은 개인의 일상생활 수행능력을 예측하는 것을 알려져 있어 성공적 노년기를 영위하는 데에 매우 중요한 요인이다. 노화에 따른 백질병변의 축적은 이러한 일화기억 기능을 비롯해 노년기 인지기능 감퇴를 야기하는 위험요인으로 밝혀져 왔다. 한편, 사회참여는 노년기 인지기능에 대한 보호요인으로 지목되어 활발하게 연구되어 왔으나, 뇌 병리의 수준과 인지기능 간의 관계에서 사회참여의 조절효과를 탐색한 연구는 많지 않다. 이에 본 연구에서는 163명의 정상 노인을 대상으로 신경심리검사 및 자기공명영상 촬영을 실시하여 일화기억 기능과 백질병변 부피를 측정하였고, 사회참여의 양적 측면에 해당하는 사회연결망 크기, 접촉 빈도, 그리고 사회활동 수준을 조사하였다. 노화에 따른 백질병변 부피와 일화기억 기능 사이의 관계를 사회참여가 조절하는지 확인하기 위해 조절된 매개모형을 사용하여 검증하였다. 연구 결과, 연령에 따른 일화기억 기능의 감퇴에서 백질병변 부피의 매개효과가 유의한 것으로 나타났다. 조절효과 분석 결과, 백질병변 부피와 일화기억 기능의 관계는 중요한 관계에 있는 사람과의 접촉 빈도와 사회활동 수준에 의해 조절되었다. 접촉 빈도가 높거나 사회활동 수준이 높은 노인일수록 백질병변 부피가 일화기억 기능에 미치는 영향을 덜 받는 것으로 나타났다. 이러한 결과는 사회참여가 뇌 병리의 존재에도 불구하고 인지기능을 유지할 수 있도록 돕는 인지 예비능으로서 작용할 수 있음을 시사한다.Episodic memory, which shows accelerated decline pattern in old age, predicts instrumental activities of daily living(IADL) well so it is an important factor for independence of daily life and successful aging. White matter hyperintensity volume, which increases according to aging, has been reported as a risk factor for episodic memory decline. Meanwhile, social engagement has been reported as a protective factor for cognitive function in old age and has been actively studied. However, few studies have explored the moderation effect of social engagement in the relationship between the level of brain pathology and cognitive function. In this study, neuropsychological test and magnetic resonance imaging were performed on 163 normal elderly people to measure episodic memory and white matter hyperintensity volume. As measure of quantitative aspect of social engagement, social network size, contact frequency, and social activity level were investigated. The present work performed moderated-mediation analysis to examine the moderating role of social engagement in the relationship between age-related white matter hyperintensity volume and episodic memory. As a result, the relationship between white matter hyperintensity volume and episodic memory was moderated by contact frequency and social activity level. Elderly people with high contact frequency or high level of social activity were found to be less affected by the white matter hyperintensity volume on episodic memory. These results suggests that social engagement may contribute to cognitive reserve that explains the gap between brain states and the level of cognitive function.서 론 1 1. 노화와 기억 기능 감퇴 2 2. 백질병변의 축적과 인지노화 3 3. 인지노화의 개인차와 인지 예비능 5 4. 노년기 사회참여와 인지기능 7 5. 연구 목적 10 연구 방법 12 1. 연구 참가자 12 2. 측정 도구 13 3. 분석 방법 18 연구 결과 20 논 의 41 참고문헌 48 Abstract 56Maste

Development of electrocardiography system for implantation

학위논문(석사) --서울대학교 대학원 :협동과정 바이오엔지니어링전공,2010.2.Maste

The Adhesion Properties of CF/PEKK Composites with PEI and PEEK Adhesive Film in Oven Welding Process

Recently, there has been an increasing movement in the aerospace industry to increase the use of thermoplastic composites. Moreover, interest in fusion bonding and adhesive bonding is increasing because it can reduce cracking, unlike mechanical bonding. In addition, interest in the oven welding process increases in bonding such thermoplastic composite materials by applying fusion bonding and adhesive bonding. However, there is a lack of research on the adhesion performance when using a thermoplastic polymer as an adhesive for bonding using a thermoplastic composite material as a substrate material. In addition, research about the effect of the interphase on an adhesion properties is insufficient, even though adhesive bonding generate interphase through chemical bonding between a substrate and adhesive. And it is unknown whether applying the vacuum bag only(VBO) method to the oven welding process is appropriate. Therefore, lap shear strength test and fracture surfaces observation through digital optical microscope(Digital OM) and scanning electron microscope(SEM) were performed after bonding by varying the pressing force of carbonfiber/polyetherketoneketone(CF/PEKK) fusion bonding and adhesive bonding using polyetheretherketone(PEEK) and polyetherimide(PEI) as adhesive materials in order to evaluate whether the application of the VBO method is appropriate. In addition, lap shear strength tests were performed at room temperature, 100 and 160 and analysis using Fourier transform infrared spectroscopy(FT-IR) and differential scanning calorimetry(DSC) and fracture surface observation using digital OM and SEM were conducted to understand the adhesion properties of the bonding of PEEK and PEI adhesives having ether and ketone groups. Moreover, the conclusion is as follows. Applying vacuum pressure by the VBO method was inappropriate when bonding CF/PEKK through oven welding process, as the pressing force was too high. In addition, the PEEK and PEI adhesive bonded CF/PEKK showed higher adhesive strength than the fusion bonded CF/PEKK because the increase of molecular formation of ether, ketone and imide constituting the interphase during the adhesive bonding enhance the adhesive strength. Furthermore, at high temperatures, the tendency of the change in strength differed depending on the type of bonding, which was judged to be due to the formation of adhesive layer, respectively different glass transition temperature, and the increased ductility with temperature increase. Therefore, this experiment shows the effect of adhesive application having similar chemical structure with thermoplastic of substrate material on the adhesive strength enhancement. In addition, it was suggested that it is essential to consider the glass transition temperature of the adhesive when using the structure to which adhesive bonding is applied in a high temperature environment.1. 서론 1 1.1. 연구의 배경 1 1.2. 연구의 필요성과 목적 3 2. 재료 및 실험 방법 5 2.1. 실험 재료 5 2.1.1. 탄소섬유 5 2.1.2. Polyetherketoneketone(폴리에테르케톤케톤, PEKK) 7 2.1.3. Polyetheretherketone(폴리에테르에테르케톤, PEEK) 9 2.1.4. Polyetherimide(폴리에테르이미드, PEI) 11 2.2 제작 공정 13 2.2.1. 진공 백 성형 공정(Vacuum bag only process, VBO process) 13 2.2.2. 오븐 접합 공정(Oven welding process) 16 2.2.3. 핫 프레스 공정(Hot press process) 20 2.3 특성 분석 시험 23 2.3.1. Lap 전단 강도 시험(Lap shear strength test, LSS test) 23 2.3.2. 푸리에 변환 적외선 분광법(Fourier transform infrared spectroscopy, FT-IR) 30 2.3.3. 시차 주사 열량법(Differential scanning calorimetry, DSC) 32 2.4 파단면 관찰 34 2.4.1. 디지털 광학 현미경(Digital optical microscope) 34 2.4.2. 주사 전자 현미경(Scanning electron microscope, SEM) 36 3. 실험 결과 및 고찰 38 3.1. Lap 전단 강도 시험(LSS test) 결과 38 3.1.1. 실온 Lap 전단 강도 시험 결과 38 3.1.2. 고온 환경 Lap 전단 강도 시험 결과 40 3.2. 푸리에 변환 적외선 분광법(FT-IR) 결과 41 3.3. 시차 주사 열량법(DSC) 시험 결과 45 3.4. 파단면 관찰 결과 47 3.4.1. 디지털 광학 현미경(Digital optical microscope) 파단면 관찰 결과 47 3.4.2. 주사 전자 현미경(SEM) 파단면 관찰 결과 63 3.5. 고찰 71 4. 결론 75 참고문헌 78 국문초록 83 감사의 글 86Maste

한국 대중가요의 정치 : 1970~1990년대 지배와 저항의 동원

학위논문(석사)--서울대학교 대학원 :언론정보학과,2005.Maste