안정한 리튬 금속 전지를 위한 리튬 금속 표면 제어

학위논문 (박사) -- 서울대학교 대학원 : 융합과학기술대학원 융합과학부(나노융합전공), 2020. 8. 김연상.Batteries constitute a core technology in modern society. Batteries are found in many devices, including smartphone, smart watch, laptop, and electric vehicle, all commonly used in daily life. As the demand for batteries has increased, various studies on batteries have been conducted. One of the major topics in this field is the expansion of battery capacity, which corresponds to a key consumer concern. In order to increase capacity, it is necessary to use an electrode material of high capacity. However, the graphite-based negative electrode material continues to impose various constraints in commercialized battery production. Lithium (Li) metal is emerging as a promising next-generation material for negative electrodes with its superior capacity, low electrochemical potential, and low density. Attempts have been made to use Li metal, but obstacles remain, such as stability and safety issues. Li metal is a hostless material, so instead of maintaining the solid electrolyte interphase (SEI) layer, it will continually expand volumetrically and break. Retention of a stable SEI layer is thus a key element in implementation of Li metal as a negative electrode. Li ion flux is concentrated on the broken gap and dendrite growth, causing an internal short circuit or increasing surface resistance due to an accumulation of electrolyte decomposition, ultimately decreased cycle stability. This paper deals with three studies of SEI layer stabilization. The first part presents a method of uniformly distributing the current density by applying a 3D structure to the Li metal surface. The second part introduces a method of polymer protective coating on the Li metal surface applied by thermal curing. The third part consists of a method of imparting a lithium fluoride layer to the Li surface through thermal curing. These methods have shown to improve the stability of the Li metal surface and thus the safety of the Li metal battery.배터리는 현대사회의 핵심 기술이다. 우리가 일상생활에서 흔히 사용하는 스마트폰, 스마트워치, 노트북에서부터 전기 자동차에 이르기까지 대부분의 소자에 배터리를 사용하고 있다. 소비자는 한번 충전했을 때 더 오랜 시간 사용하기를 원하는데 배터리 기술에서 용량은 가장 중요한 부분을 차지한다. 배터리는 음극과 양극, 전해질과 분리막으로 나눌 수 있는데, 용량을 높이기 위해서는 음극과 양극에서 높은 용량을 갖는 전극 물질을 사용해야 한다. 리튬 금속은 음극 물질 중에서도 이론 용량이 가장 높고 전기화학 전위가 낮아 차세대 고용량 전지의 물질로 각광을 받고 있다. 하지만 리튬 금속의 표면 안정성 문제는 상업화의 걸림돌이 되어 여전히 흑연 기반의 음극 물질에 머무르고 있다. 이 논문에서는 리튬 금속 표면을 제어하기 위한 세 가지 연구를 다룬다. 첫 번째 연구는 리튬 금속 표면에 스테인리스강 성분의 3차원 구조를 적용하는 것이다. 3차원 구조는 리튬 금속 표면에서 부피 팽창하는 힘을 완화시켜주고 전류 밀도를 분산시켜 주기 때문에 리튬이 수지상으로 성장하는 것을 막아준다. 그리고 전자 이동 경로를 제공하여 높은 쿨롱 효율을 유지할 수 있도록 도와준다. 이를 리튬 금속 전지를 제작하여 적용했을 때 향상된 수명 특성을 보여주었다. 두 번째 연구는 열 경화를 통해 리튬 금속 표면에 고분자 층을 형성하는 것이다. 사용한 고분자는 ethylene oxide unit을 갖고 있기 때문에 리튬 금속 표면에서 리튬 이온을 전달해 주는 역할과 동시에 리튬 금속의 부피 팽창을 억제해 준다. 전기화학 특성 실험을 통해 제작된 고분자 보호막 층이 리튬 금속 표면을 안정화 시켜준다는 것을 확인하였다. 얇고 가벼운 고분자 층을 사용하기 때문에 전지 시스템에서 에너지 밀도 손실을 최소화로 줄여준다. 세 번째 연구는 열 경화를 통해 리튬 표면에 lithium fluoride (LiF) 층을 부여하는 것이다. LiF 는 solid electrolyte interphase (SEI) 층의 주요 구성 성분으로 전기화학적으로 가장 안정하기 때문에 리튬 금속에 LiF 층이 형성되면 SEI 층을 보다 안정하게 유지시킬 수 있다. LiF를 리튬 금속 표면에 적용하는 방법이 복잡한 이전 연구와는 다르게 리튬 금속 표면에 보호막 층을 코팅하여 열을 가하기만 하면 형성되는 매우 간단한 방식으로 제작되었다. 이 보호막 층은 리튬 금속 전지에서 우수한 특성을 보여준다. 이 논문에서 제시된 연구들은 공정이 간단하면서도 더 얇고 더 가볍게 제작되어 보호막의 근본적인 단점이라고 할 수 있는 에너지 밀도 손실을 최소화하는 방향으로 실험이 진행되었다. 이 기술들은 리튬 금속 음극을 상용화할 수 있는 가능성을 제시해 준다.Chapter 1 Introduction 13 1.1 Overview 13 1.2 References 16 Chapter 2 Fundamental and literature review 17 2.1 Background on Li metal anode 17 2.2 Issues with Li metal anode 17 2.3 References 20 Chapter 3 Three-dimensional mesh structure interlayer 22 3.1 Introduction 22 3.2 Experimental section 28 3.2.1 Fabrication of stainless steel mesh interlayer 28 3.2.2 Characterization of stainless steel mesh interlayer 31 3.2.3 Surface analysis and electrochemical measurement 32 3.2.4 Effect of stainless steel mesh interlayer for Li metal battery 48 3.3 Conclusion 50 3.4 Experimental details 51 3.5 References 53 Chapter 4 Thermal crosslinked polymer protective layer 56 4.1 Introduction 56 4.2 Experimental section 59 4.2.1 Fabrication of PEGDMA protective layer 59 4.2.2 Characterization of PEGDMA protective layer 59 4.2.3 Surface analysis and electrochemical measurement 66 4.2.4 Effect of PEGDMA protective layer for Li metal battery 81 4.3 Conclusion 90 4.4 Experimental details 91 4.5 References 93 Chapter 5 In situ LiF protective layer 96 5.1 Introduction 96 5.2 Experimental section 99 5.2.1 Fabrication of in situ LiF protective layer 99 5.2.2 Characterization of in situ LiF protective layer 99 5.2.3 Surface analysis and electrochemical measurement 105 5.2.4 Effect of in situ LiF protective layer for Li metal battery 119 5.3 Conclusion 124 5.4 Experimental details 125 5.5 References 125 Chapter 6 Conclusion 129 List of publications 131 요약 (국문초록) 133Docto

U형 강재단부요소를 지닌 합성벽체에 대한 반복가력실험 및 강도예측모델

학위논문(박사) -- 서울대학교대학원 : 공과대학 건축학과, 2022. 8. 박홍근.Generally, RC walls are used as the primary lateral load-resisting system in buildings. On the other hand, in high-rise buildings and large industrial buildings (e.g., factories and power plants), high structural performance is required to satisfy the high safety and serviceability demands (e.g., story drift ratio, floor vibration). For such high structural performance, a steel-concrete composite wall with boundary element of steel U-section (SUB-C wall) was developed. In the proposed method, large steel area is concentrated at the wall ends to maximize flexural strength and stiffness, and to minimize steel connection and weld length. The structural integrity and constructability can be improved by using an open section of U-shaped steel element; by concrete pouring, boundary steel element and reinforced concrete are integrated with conventional headed studs. Further, the U-shaped element can provide lateral confinement to the boundary zone, and increase the shear strength of walls. Thus, labor works related to vertical reinforcement and hoop reinforcement can be reduced. Cyclic lateral loading tests were performed on the proposed walls to investigate the flexural and shear performances. As the steel U-sections provided high confinement to the boundary concrete, crushing of the boundary concrete was restrained, which developed strain hardening of the steel U-section in tension. Thus, the flexural strength of the SUB-C wall was 37% greater than that of the counterpart RC wall. Further, the steel U-sections restrained shear cracking and shear sliding. Thus, the deformation capacity and energy dissipation were increased by 38%-53% and 99%-173%, respectively. The SUB-C walls exhibited ultimate drift ratios over 3%, and failed due to web crushing in the plastic hinge zone (i.e., post-yield shear failure). On the other hand, the shear strength of the SUB-C walls was 13%–54% greater than that of the counterpart RC walls. This is because the steel U-sections not only resisted shear transferred from the diagonal struts, but also restrained diagonal tension cracking in the web and crack penetration into the boundary zone. For this reason, the shear strength of the SUB-C walls was determined by web crushing, without diagonal tension failure and crushing of the boundary concrete. The increase in flexural and shear strengths was more pronounced when steel U-sections with greater area were used. Nonlinear finite element analysis was performed for the walls that failed in elastic web crushing (before flexural yielding). The analysis results reveal that the compressive strength of the diagonal struts is significantly degraded due to large horizontal tensile deformation in the mid-height of the walls, which ultimately leads to web crushing. Such mechanism is named “horizontal elongation mechanism”, and an empirical equation to predict the maximum horizontal elongation was developed based on the parametric analysis. The horizontal elongation is greatly affected by shear reinforcement ratio and aspect ratio of walls. However, the boundary steel area has little effect on the maximum horizontal elongation. For the shear strength model, two shear failure mechanisms were defined: elastic and inelastic web crushing failures. Those mechanisms were implemented by the traditional truss analogy, and the model improvement was achieved by considering distinctive features of SUB-C walls: For the elastic web crushing strength (shear strength), the horizontal elongation mechanism was implemented, but the contribution of boundary elements was neglected for conservatism and simplicity in design. On the other hand, for the inelastic web crushing strength (i.e., post-yield shear strength), the vertical elongation and frame action of boundary elements in the plastic hinge zone were considered. In particular, since the vertical elongation is defined as a function of deformation demand, the post-yield shear strength can be calculated at every deformation levels of walls. The accuracy of the proposed model was validated from the comparison with the test results. For an advanced design of the shear strength (elastic web crushing strength), an equivalent elastic analysis method using commercial analysis programs was developed. The deformation-based design method for SUB-C walls was developed using the proposed shear strength model. The deformation capacity was defined at the intersection of the shear demand and inelastic web crushing strength. In general, the predicted deformation capacities, in terms of overall lateral drift ratio and normalized plastic hinge deformation, agree with the test results. Based on the test results and existing design methods, allowable material strengths and detailing requirements for SUB-C walls were provided. Note that the proposed design strengths are valid only when the design requirements are satisfied. The detailing methods outside the scope of the requirements should be applied after in-depth verification through further experimental and analytical studies.고층건물과 대규모 산업건물(공장, 발전소 등)에서는 높은 안전성과 사용성(예, 층류비, 바닥진동)을 만족시키기 위해 상당한 구조성능이 요구된다. 이러한 높은 구조성능을 만족시키기 위해 강철 U-단면의 경계요소가 있는 강철-콘크리트 복합 벽체(SUB-C 벽체)가 개발되었다. 제안된 방법에서는 휨강도 및 강성을 최대화하고 강재 접합부와 용접 길이를 최소화하기 위해 강재면적을 벽체 양 단부에 집중배치하였다. U자형 강재요소의 열린 단면으로 인하여, 콘크리트 타설시 단부 강재요소와 철근콘크리트가 일반 전단연결재를 사용하여 간단히 일체화되므로 구조적 건전성 및 시공성을 크게 향상시킬 수 있다. 또한 U자형 요소는 벽체 단부영역에 횡구속을 제공하고 벽의 전단강도를 증가시키므로 수직보강 및 횡보강 철근공사를 최소화할 수 있다. 휨전단 성능을 조사하기 위해 제안된 벽체에 대한 반복 횡가력 실험을 수행했다. U형 형강이 단부콘크리트에 높은 구속력을 제공함에 따라 단부콘크리트의 압괴가 억제되어 인장측 U형 형강의 변형 경화가 발생했다. 따라서 SUB-C 벽의 휨강도는 RC 벽의 휨강도보다 37% 더 큰 것으로 나타났다. 또한, U-형강은 복부영역에서 전단균열 및 전단미끄러짐을 억제했다. 따라서 변형 능력과 에너지 소산은 각각 38–53 % 및 99–173 % 증가했다. SUB-C 벽은 3% 이상의 극한 변형능력을 보였고 결과적으로 소성힌지 영역에서 복부압괴로 인해 강도가 저하되었다(휨항복 후 전단 파괴). SUB-C 벽의 전단강도는 RC 벽의 전단강도보다 13–54 % 더 큰 것으로 나타났다. 이는 U형강이 대각스트럿에서 전달되는 전단력에 저항할 뿐만 아니라 대각 인장균열을 억제하고 경계부를 보호하기 때문이다. 이러한 이유로, SUB-C 벽체의 전단강도는 사인장 전단파괴 등 다른 파괴유형 없이 모두 복부압괴에 의해 결정되었다. 탄성복부압괴(휨항복 이전)로 파괴된 벽체실험체에 대해 비선형 유한 요소 해석을 수행하였다. 해석결과, 벽체 중앙높이에서 나타난 큰 수평인장영역으로 인해, 대각스트럿의 압축강도가 현저히 저하되어 복부압괴에 이르는 것으로 나타났다. 이러한 파괴메커니즘을 "수평 연신" 이라 명명하였고, 매개변수 분석을 기반으로 수평 연신율을 예측하는 경험식을 개발하였다. 수평 연신율은 벽체의 전단보강비와 종횡비에 의해 크게 영향을 받는다. 그러나 경계 보강비 (단부 U형 형강의 단면적)는 수평 연신율에 거의 영향을 미치지 않았다. 전단강도모델 개발을 위해 “탄성 및 비탄성 복부 압괴” 두 가지 전단파괴 메커니즘이 정의되었다. 이러한 메커니즘은 전통적인 트러스모델 방식으로 구현하였으며, SUB-C 벽체의 특성을 고려하여 모델을 개선하였다. 탄성 및 비탄성 복부압괴강도(휨항복 이후 전단강도)는 각각 수평연신 및 수직연신 메커니즘을 고려하였으며, 비탄성 복부압괴강도의 경우 소성힌지영역에서 경계요소의 골조 작용을 추가적으로 고려하였다. 특히, 수직연신은 벽체변형의 함수로 정의되므로 벽체의 휨항복 이후 모든 변형수준에서 전단강도 평가가 가능하였다. 제안된 모델의 정확도는 실험결과와의 비교를 통해 검증되었다. 보다 정밀한 탄성 복부압괴강도 예측을 위하여 상용 해석프로그램을 이용한 등가탄성해석법을 개발하였다. SUB-C 벽체의 변형기반 설계방법은 제안된 전단강도 모델을 사용하여 개발되었다. 설계변형능력은 요구전단력과 비탄성 복부압괴강도가 교차하는 점에서 정의되었다. 일반적으로, 예측된 벽체 최상부 및 소성힌지부 변형능력은 실험결과와 일치하였다. 실험결과 및 기존 설계방법을 기반으로 SUB-C 벽에 대한 허용 재료강도와 상세설계 요구사항을 정리하였다. 제안된 설계강도는 설계요구사항이 충족되는 경우에만 유효하며, 요구사항 범위를 벗어난 상세설계방법은 추가 실험 및 분석 연구를 통해 심층 검증 후 적용되어야 한다.Abstract i Contents iv List of Tables x List of Figures xii List of Symbols xxi Chapter 1. Introduction 1 1.1 General 1 1.2 Scope and Objectives 6 1.3 Outline of dissertation 10 Chapter 2. Literature Review 12 2.1 Code-Based Shear Strength 13 2.1.1 ACI 318 (ACI Committee 318, 2019) 13 2.1.2 Eurocode 2 & 8 (British Standards Institution, 2004) 15 2.1.3 fib MC 2010 17 2.1.4 JGJ 138 (China Building & Construction Standards, 2016) 19 2.1.5 ANSI/AISC 341 (2016) 22 2.1.6 AISC N 690 (2018) 23 2.2 Existing Models for Web Crushing Capacity 24 2.2.1 Oesterle et al. (1984) 24 2.2.2 Paulay and Priestley (1992) 26 2.2.3 Hines and Seible (2004) 27 2.2.4 Eom and Park (2013) 30 2.3 Literature Reviews on Existing Composite Walls 32 2.3.1 RC walls with composite boundary elements 32 2.3.2 Concrete-encased steel plate walls 39 2.3.3 Concrete-filled steel plate walls 45 2.4 Discussion and Research Hypothesis 53 Chapter 3. Cyclic Lateral Test of Flexural Specimens 55 3.1 Overview 55 3.2 Design Strengths 56 3.2.1 Nominal flexural strength 56 3.2.2 Nominal shear strength 56 3.2.3 Design of failure mode 56 3.3 Test Plan 58 3.3.1 Test parameters and specimens 58 3.3.2 Material strengths 70 3.3.3 Lateral confinement to wall boundary 71 3.3.4 Test setup for loading and measurement 72 3.4 Test Results 75 3.4.1 Lateral load-displacement relationship 75 3.4.2 Failure mode 82 3.4.3 Flexural rotation in plastic hinge zone 88 3.4.4 Shear deformation 95 3.4.5 Displacement contributions 99 3.4.6 Flexural and shear stiffness 104 3.4.7 Deformation capacity 108 3.4.8 Energy dissipation 110 3.4.9 Vertical strain distribution 112 3.4.10 Horizontal strain distribution 114 3.4.11 Shear strain of steel plates 117 3.5 Effect of Design Parameters 121 3.5.1 Arrangement of vertical steel section 122 3.5.2 Type of boundary reinforcement 123 3.5.3 Sectional area of steel U-sections 124 3.5.4 Type of web reinforcement 125 3.6 Evaluation of Flexural Capacity 128 3.6.1 Flexural strength 128 3.6.2 Flexural stiffness 132 3.6.3 Displacement ductility and plastic rotation 136 3.7 Summary 138 Chapter 4. Cyclic Lateral Test of Shear Specimens 140 4.1 Overview 140 4.2 Test Plan 141 4.2.1 Design of shear failure mode 141 4.2.2 Test parameters and specimens 142 4.2.3 Material strengths 154 4.2.4 Test setup for loading and measurement 155 4.3 Test Results 156 4.3.1 Lateral load-displacement relationship and failure mode 156 4.3.2 Cracking and maximum crack width 167 4.3.3 Displacement contributions 169 4.3.4 Horizontal strain distribution 172 4.3.5 Vertical strain distribution 178 4.3.6 Strains of steel plates 180 4.3.7 Shear strength contributions 187 4.4 Effect of Design Parameters 196 4.4.1 Type of boundary reinforcement 196 4.4.2 Sectional area of steel U-sections 198 4.4.3 Type of web reinforcement 200 4.4.4 Spacing of web reinforcement 201 4.4.5 Effect of wall aspect ratio 202 4.5 Strength Predictions of Existing Design Methods 203 4.5.1 Diagonal tension strength 203 4.5.2 Web crushing strength 204 4.5.3 Comparison with composite design methods 208 4.6 Summary 212 Chapter 5. Nonlinear Finite Element Analysis 214 5.1 Overview 214 5.2 Finite Element Modeling 216 5.3 Comparison with Test Results 219 5.3.1 Strength and load-displacement behavior 219 5.3.2 Damage pattern of concrete 221 5.4 Shear Strength Contribution 234 5.5 Horizontal Elongation Model 241 5.6 Summary 247 Chapter 6. Development of Shear Strength Model 248 6.1 Overview 248 6.2 Background 249 6.2.1 Web crushing capacity 249 6.2.2 Observed web crushing behavior 252 6.3 Modified Truss Analogy 257 6.4 Elastic Web Crushing Strength 259 6.4.1 Model assumptions 259 6.4.2 Shear degradation of concrete 260 6.4.3 Strain compatibility 263 6.4.4 Strength equation and verification 267 6.5 Inelastic Web Crushing Strength 270 6.5.1 Model assumptions 270 6.5.2 Strength degradation of concrete 273 6.5.3 Truss-beam model (Modified truss analogy) 274 6.5.4 Displacement compatibility 278 6.5.5 Strength contribution of concrete 283 6.5.6 Simplified expression for concrete contribution 286 6.5.7 Strength contribution of steel U-section 289 6.5.8 Strength equation 293 6.6 Comparison with Test Results 294 6.7 Effect of Axial Force 301 6.8 Summary 305 Chapter 7. Design Strengths and Recommendations 306 7.1 Equivalent Elastic Analysis 307 7.1.1 Background 307 7.1.2 Strip model 309 7.1.3 Diagonal strip 311 7.1.4 Horizontal tie 317 7.1.5 Boundary elements 319 7.1.6 Boundary conditions 321 7.1.7 Analysis procedure 322 7.1.8 Application to test specimens 326 7.2 Design Strengths and Deformation Capacity 335 7.2.1 Deformation-based design approach 335 7.2.2 Flexural strength 338 7.2.3 Shear strength 341 7.2.4 Deformation capacity 345 7.2.5 Comparison to test results 353 7.3 Materials and Detailing Recommendations 356 7.3.1 Material strengths 356 7.3.2 Boundary element 359 7.3.3 Web reinforcement 366 7.4 Summary 370 Chapter 8. Conclusions 371 References 378 Appendix I: Calculations of Displacement Contributions 387 Appendix II: Summary of Existing SC Composite Wall Specimens 389 초 록 401박

Comparison of glidescope video laryngoscopy and conventional laryngoscopy for endotracheal intubation in the ED : an observational study

Dept. of Medicine/석사Objectives In a previous manikin study, we suggested that the GlideScope® Video Laryngoscope (GVL) could be an option for airway management by emergency physicians and might be useful in patients with difficult airways compared to the classic Macintosh laryngoscope (ML). The purpose of this study was to compare GVL with ML in emergency endotracheal intubation.Materials and methodsA prospective multicenter observational study was performed. Emergency physicians performed tracheal intubations using ML or GVL at their discretion. The time required to intubate, the success rate, number of intubation attempts, Cormack and Lehane (C&L) grade, and percentage of glottis opening (POGO) scores were recorded and compared between the two groups.ResultsGVL was used in 27 (37.5%) of 72 endotracheal intubations at three emergency centers. The overall success rate in the GVL group on the first attempt was not higher than that in the ML group (66.7% vs 60.0%, P=0.572). Although the success rate for difficult airway patients on the first attempt seemed to be higher in the GVL group than in the ML group, there was not a statistically significant difference between the two groups (70% vs 46.7%, p=0.250). The overall time required to successfully intubate was shorter in the ML group than in the GVL group (18.3 sec vs. 36.8 sec, p<0.05). In the difficult airway subgroup, the time required to successfully intubate was shorter in the ML group (15.9 sec vs. 36.3 sec, p<0.05). The POGO score and the C&L grade were not statistically different between the two groups although the GVL group appeared to allow a better glottic view in the difficult airway subgroup (POGO: 39.3 ± 36.9 vs. 55.5 ± 32.7, p = 0.394; GEG I & II: 55.3% vs. 70%, p=0.405).ConclusionThe emergency airway management using GVL did not show difference in success rate compared with ML. However, the required time for intubation was longer in GVL than ML. This study suggests that GVL is not as suitable for emergency airway management as ML, even in patients with difficult airways.ope

Closed-loop separation control system design using model-based observer

본 연구는 유동 박리 상에서의 synthetic jet의 효과를 파악하고 synthetic jet을 이용한 유동 박리 폐루프 제어 시스템을 설계한다. 유동 박리 폐루프 제어 시스템의 설계는 본 연구에서 제안하는 유동 모델을 이용한다. synthetic jet의 물리적 현상을 기반으로 하는 유동 모델이 유도되며, 풍동 실험 데이터를 바탕으로 유동 모델의 변수들을 추정한다. 본 연구에서는 박리의 효과적인 추정을 위한 모델 기반 관측기를 사용한다. 모델 기반 관측기를 이용한 결과로부터, 효과적인 유동 제어 시스템 설계의 가능성을 파악한다.The objective of this research is to assess the effect of synthetic jets on flow separation and provide a feedback control strategy for flow separation using synthetic jets. A feedback control loop is crucial for the efficient operation of synthetic jets. Constructing the flow model with synthetic jet actuators is important to accomplish such feedback control. The mathematical model whose structures are based on physical knowledge of synthetic jets is derived to estimate the model coefficients from experimental data. In order to estimate the separation, this research employs an observer. The results performed with an observer, it showed the possibility of reliable flow control system design using model-based observer.This work was supported by Defense Acquisition Program Administration and Agency for Defense Development(UC100031JD).OAIID:oai:osos.snu.ac.kr:snu2011-01/104/0000004648/28SEQ:28PERF_CD:SNU2011-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:모l델_기반_관측기를_이용한_폐루프_박리_제어_시스템_설계.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]:

Chlamydia pneumoniae accompanied by inflammation is associated with the progression of atherosclerosis in CAPD patients: a prospective study for 3 years

BACKGROUND: The causes of accelerated atherosclerosis in end-stage renal disease (ESRD) patients are unknown, although recent studies have suggested that Chlamydia pneumoniae (Cp) infection and inflammation might be contributing factors. We aimed to evaluate the association of carotid atherosclerosis progression with Cp infection and inflammation in patients undergoing peritoneal dialysis (PD). METHODS: This is a prospective observational study. A total of 52 non-diabetic prevalent PD patients were included. The intima-media thickness of a common carotid artery (CCA-IMT) was measured at baseline and after 36 months by B-mode ultrasonography. Serum antibodies to Cp and inflammatory markers were obtained at the time of initial measurement of the CCA-IMT. RESULTS: CCA-IMT progressors (deltaCCA-IMT > or = 0.015 mm/year) had a higher prevalence of seropositivity for Cp IgA antibody, a higher level of Cp IgA antibodies indices, log IL-(interleukin-)6, and intercellular adhesion molecule-1 (ICAM-1) compared to the non-progressors (deltaCCA-IMT < 0.015 mm/year). On multivariate analysis, Cp IgA index and log IL-6 were independent risk a factors for CCA-IMT progression. Also, Cp IgA index had independent positive correlation with the magnitude of annual deltaCCA-IMT. Cp IgA antibody seropositive patients showed significantly higher mean annual deltaCCA-IMT than seronegative patients. Moreover, patients with both positive Cp IgA antibodies and elevated IL-6 above the median level showed higher deltaCCA-IMT than those with either factor alone. CONCLUSIONS: Our data showed that Cp and inflammation were significant risk factors of CCA-IMT change in PD patients. This study strengthens evidence that Cp is involved in the pathogenesis of atherosclerosis and also suggests that the effect of Cp infection under high inflammatory status might be a risk factor for progression of atherosclerosis.ope

태내 다중 약물 노출이 보상 처리와 충동성에 미치는 영향 규명

학위논문 (석사) -- 서울대학교 대학원 : 사회과학대학 심리학과, 2020. 8. 안우영.The prenatal substance exposure has persisting effects on neurocognitive dysfunction from fetuses to children and adolescents. Among various neurocognitive functions, many studies focused on reward processing and impulsivity as they are key functions related to many psychiatric disorders. However, there were some limitations: previous studies had a relatively small sample size and the effects of prenatal polysubstance exposure were rarely investigated, even though many individuals with substance use disorders are polysubstance users. Also, the moderation effects of demographic and postnatal environmental factors were not considered in many previous studies. Here, the current study aimed 1) to replicate or further investigate the effects of prenatal exposure to each of the two most commonly used drugs (nicotine and alcohol) in a large sample, 2) to examine the effects of prenatal polysubstance exposure on reward processing and impulsivity, and 3) to investigate the influence of demographic and postnatal factors on the outcomes of prenatal drug exposure. For the goal, we used the behavioral and neuroimaging measures of reward processing and impulsivity from the Adolescent Brain Cognitive Development study in the US (N=10,161). We found that prenatal nicotine exposure was associated with hyperactivation in the inhibitory region, inferior frontal gyrus (IFG) during response inhibition. Also, we found a significant interaction effect of nicotine and alcohol on hyperactivation in ACC and IFG during response inhibition, which might indicate additive or synergistic effects of nicotine and alcohol. Lastly, we found an alteration in reward processing in the ethnically minor group and alteration in inhibitory function in children given birth from old mothers. Overall, the results suggest that there is a need to pay close attention to the complex effects of prenatal polysubstance exposure and its interaction with demographic and postnatal factors.태내 약물 노출은 태아에서 아동, 청소년에 이르기까지 인지신경적 기능에 지 속적인 영향을 끼친다. 기존 연구들은 많은 인지신경 기능들 중 다양한 정신 질환과 주요한 관련성을 보이는 보상 처리와 충동성에 주목해왔다. 그러나 기존 연구에는 다음과 같은 한계가 있었다. 먼저 상대적으로 적은 수의 표본을 사용했고, 일상에서 는 많은 약물 중독자들이 하나 이상의 약물을 사용하고 있는 데에도 불구하고 다중 약물 사용이 태내 노출에 미치는 영향에 대한 연구는 드물었다. 또한, 인구통계학 적 요인이나 생후 환경적 요인이 태내 약물 노출의 영향에 어떻게 관여하는지에 대한 연구가 부족했다. 따라서 본 연구에서는 1) 대규모 표본을 사용해 가장 흔히 사용되는 니코틴과 알코올에 대한 노출 효과를 반복 검증 및 확장하고자 하며, 2) 태내 다중 약물의 보상 처리와 충동성에 대한 상호작용 효과를 검증하고, 3) 인구 통계학적 요인이나 생후 환경적 요인이 태내 약물 노출의 영향에 어떻게 관여하 는지 살펴보고자 한다. 이러한 목표를 위해 미국의 Adolescent Brain Cognitive Development 연구에서 제공하는 보상 처리와 충동성에 대한 행동 및 뇌 영상 지 표를 사용하였다 (N = 10,161). 분석 결과, 태내 니코틴 노출은 반응 억제 동안 또 다른 억제 영역인 하전두회의 과잉 활성과 관련있었고 더불어 반응을 억제하 는 동안의 전대상회와 하전두회의 과잉 활성에 대해 니코틴과 알코올이 유의미한 상호작용 효과를 보였다. 이는 태내에서 니코틴과 알코올에 동시 노출되는 것이 가산 효과나 시너지 효과를 내고 있을 가능성을 시사한다. 마지막으로 소수 인종 집단과 나이 많은 어머니로 부터 태어난 자녀의 경우 보상 처리와 반응 억제 중에 서 유의미하게 다른 패턴이 나타났다. 종합해보면, 이러한 연구 결과는 태내 다중 약물 노출의 복잡한 효과와 환경적 요인과의 상호작용에 앞으로 더욱 주목해야할 필요성을 제기한다.Abstract i 1 Introduction 1 1.1 Substance use disorder........................ 1 1.1.1 Nicotine............................ 3 1.1.2 Alcohol ............................ 5 1.1.3 Nicotine and alcohol ..................... 6 1.2 The maternal substance use..................... 8 1.2.1 Nicotine............................ 9 1.2.2 Alcohol ............................ 11 1.2.3 Nicotine and alcohol ..................... 13 1.2.4 Effects of demographic and postnatal environment . . . . 14 1.3 Objectives and hypotheses...................... 15 2 Methods 17 2.1 Participants.............................. 17 2.2 Measurement ............................. 19 2.2.1 Demographic information .................. 19 2.2.2 Prenatal exposure to substance............... 19 2.2.3 Reward processing ...................... 20 2.2.4 Impulsivity .......................... 21 2.2.5 Neuroimaging......................... 22 2.2.6 Postnatal environment.................... 23 2.3 Analysis................................ 24 2.3.1 Effects of prenatal mono substance . . . . . . . . . . . . . 24 2.3.2 Effects of prenatal polysubstance . . . . . . . . . . . . . . 26 2.3.3 Propensity score matching................. 27 2.3.4 Effects of demographic and postnatal environment . . . . 27 3 Results 28 3.1 Demographic information ...................... 28 3.2 Effects of prenatal mono substance ................. 28 3.3 Effects of prenatal polysubstance .................. 31 3.4 Effects of demographic and postnatal environment . . . . . . . . 32 4 Discussion 38 4.1 Main findings............................. 38 4.2 Interpretation on findings ...................... 39 4.2.1 Effects of prenatal mono substance . . . . . . . . . . . . . 39 4.2.2 Effects of prenatal polysubstance . . . . . . . . . . . . . . 40 4.2.3 Effects of demographic and postnatal environment . . . . 41 4.3 Limitations .............................. 42 4.4 Implications and further directions ................. 43 References 44 Appendix A Supplementary 58 국문초록 89 감사의 글 91Maste