항혈소판제가 위 종양에 대한 내시경적 점막하 절제술 후 출혈 위험을 증가시키는가?

학위논문 (석사)-- 서울대학교 대학원 : 의학과 내과학 전공, 2013. 2. 김지원.Introduction: It is rarely known whether antiplatelets increase the risk of bleeding after endoscopic submucosal dissection (ESD). This study was designed to evaluate the effect of antiplatelets on post-ESD bleeding. Methods: This study involved 1591 gastric neoplasms (815 adenoma and 776 early gastric cancers) in 1503 patients who had ESD between April 2005 and April 2010. Primary outcome event was defined as overt hematemesis/hematochezia, a drop of hemoglobin >2 g/dL from baseline, or requirement of endoscopic hemostasis, angiographic embolization and/or transfusion. Results: Of 1591 subjects, 274 took antiplatelets, among whom 102 discontinued them for 7 days or more before ESD. Post-ESD bleeding occurred in 94 subjects including 20 from the continuation group, 6 from the withdrawal group, and 68 from the no-antiplatelet group. In univariate analysis, antiplatelets, early gastric cancer (EGC), comorbidity and specimen diameter were related to post-ESD bleeding. In multivariate analysis, EGC (odds ration [OR] 1.83995% confidence interval [CI], 1.168-2.896, P = .009), comorbidity (OR 2.24695% CI, 1.280-3.939, P = .005), and specimen diameter (OR 2.31595% CI, 1.282-4.180, P = .005) were independent risk factors of post-ESD bleeding, whereas antiplatelet usage was not (OR 1.59695% CI, 0.877-2.903, P = .126). In subgroup analysis, continuous antiplatelet usage was not found to be an independent risk factor of post-ESD bleeding in multivariate analysis (OR, 2.027P = .146). Among 102 subjects who discontinued antiplatelets, 1 developed an acute cerebral infarction (1.0%). Conclusions: In ESD for antiplatelet users, continuous administration was not found to have an independent significant association with bleeding. (Gastrointest Endosc 201275:719-27.)Abstract i Contents iii List of tables and figures iv Introduction 1 Materials and Methods 4 Results 11 Discussion 25 References 32 Abstract in Korean 37Maste

타이타니아를 기반으로 한 나노구조의 합성과 응용

학위논문 (박사)-- 서울대학교 대학원 : 화학부, 2015. 2. 이진규.Titania (TiO2) nanostructures have been widely researched over the past several decades because of their outstanding properties and applications in various fields, in addition to their abundance and low-cost. In particular, titania nanostructures have been used for energy generation in solar-cells and energy storage in batteries. In this thesis, three simple sol-gel synthetic methods for the preparations of titania of various sizes are reported. Spherical titania nanoparticles with sizes in the range of 60-300 nm could be obtained by changing the amount of reactants. Their size-dependent electrochemical properties are tested using Li-ion battery. Furthermore, simple preparation of hollow titania is also possible by using the soft-template method. Using this method, hollow (Sn,Ti) oxide and an iron oxide@titania yolk@shell structure could be obtained. Furthermore, their electrochemical properties are tested. Chapter 1 briefly describes the research background on titania nanostructures, including their synthesis methods, surface modifications, and their applications (photo-catalyst, solar-cells, and batteries). Chapter 2 describes the preparation of spherical titania nanoparticles by using ethylene glycol in acetone solvent to reduce the reactivity of the titania source. The size of obtained titania nanoparticles is approximately between 70 nm and 300 nmthis size variation is obtained by varying the amount of water and the titania source. Reaction conditions including the kind of solvents and chelating agents are investigated. Chapter 3 describes the preparation of spherical titania nanoparticles by using KCl in ethanol solvent to reduce the reactivity of titania source. The size of titania nanoparticles is controlled by the concentration of KCl and titania source, and the type of solvents. The prepared titania nanoparticles have similar or more powerful photo-catalytic property than that of very small and commercialized titania (P25). Chapter 4 describes the preparation of spherical titania nanoparticles using a mixed solvent of ethanol and acetonitrile. The size of titania nanoparticles is varied by varying the amount of reactant, especially the water. The size-dependent electrochemical properties of titania are examined by evaluating the Li-ion capacity of about 60 nm, 120 nm, and 280 nm. These properties are related with the surface area measured using both gas- and liquid- based methods. Chapter 5 describes the preparation of (Sn,Ti) oxide with a hollow structure by the soft-template method under various conditions such as different calcination temperatures and atomic ratio of Sn in the composite oxide. The electrochemical properties of (Sn,Ti) oxide for use as an anode for Li-ion battery are investigated by comparing them with those of hollow titania nanoparticles. Chapter 6 describes the preparation of an iron oxide@titania yolk@shell structure by the soft-template method. The ratio of the iron oxide core and titania shell could be controlled by changing the amount of the titania source. The electrochemical properties of a yolk@shell anode are compared with those of a just-mixed anode composed of iron oxide and hollow titania nanoparticles, by using Li-ion battery.Contents Abstract ...................................................................................i Contents.................................................................................iv List of Figures .......................................................................xi List of Scheme................................................................ xxviii List of Tables .....................................................................xxix Chapter 1. Research Background........................................1 1.1 Titania .....................................................................................2 1.2 Synthesis of titania nanostructures..........................................3 1.3 Surface modification of titania................................................4 1.4 Titania as a photo-catalyst.......................................................5 1.5 Titania in solar-cells ................................................................6 1.6 Titania as an energy storage material......................................8 1.7 References...............................................................................9 Chapter 2. Facile Preparation of Mono-dispersed Spherical Titania Nanoparticles by Using Ethylene Glycol with Precise Size Control....................................................11 2.1 Abstract .................................................................................11 2.2 Introduction...........................................................................12 2.3 Results and Discussion .........................................................13 2.4 Conclusions...........................................................................22 2.5 Experimental Section ............................................................22 2.6 References.............................................................................24 Chapter 3. Synthesis of Spherical Titania Nanoparticles with KCl Salt and Simple Size Control under Various Conditions ..........................................................................27 3.1 Abstract .................................................................................27 3.2 Introduction...........................................................................28 3.3 Results and Discussion .........................................................30 3.4 Conclusions...........................................................................38 3.5 Experimental Section ............................................................38 3.6 References.............................................................................40 Chapter 4. Preparation of Titania Nanoparticles with Various Sizes and Their Size-dependent Electrochemical Properties .........................................................................42 4.1 Abstract .................................................................................42 4.2 Introduction...........................................................................43 4.3 Results and Discussion .........................................................46 4.4 Conclusions...........................................................................64 4.5 Experimental Section ............................................................65 4.6 References.............................................................................68 Chapter 5. Hollow Nanoparticles of (Sn,Ti) Oxide Solid-solution as a High-rate Performance Anode for Lithium Ion Battery .........................................................................72 5.1 Abstract .................................................................................72 5.2 Introduction...........................................................................73 5.3 Results and Discussion .........................................................75 5.4 Conclusions...........................................................................87 5.5 Experimental Section ............................................................88 5.6 References.............................................................................91 Chapter 6. Synthesis of Iron Oxide@Titania Yolk@Shell Nanoparticles as a High-performance Anode for Lithium Ion Battery ...........................................................................94 6.1 Abstract .................................................................................94 6.2 Introduction...........................................................................95 6.3 Results and Discussion .........................................................97 6.4 Conclusions.........................................................................115 6.5 Experimental Section ..........................................................115 6.6 References...........................................................................119 Appendix/Chapter 1. Precise Size-control of Silica Nanoparticles via Alkoxy Exchange Equilibrium of Tetraethyl Orthosilicate in the Mixed Alcohol Solution.122 1.1 Abstract ...............................................................................122 1.2 Introduction .......................................................................123 1.3 Results and Discussion .......................................................125 1.4 Conclusions.........................................................................136 1.5 Experimental Section ..........................................................136 1.6 References...........................................................................141 Appendix/Chapter 2. Oligothiophene-modified Silver@Silica Core@Shell Nanoparticles for Inhibiting Open-circuit Voltage Drop and Aggregation in Polymer Solar Cells .........................................................................143 2.1 Abstract ...............................................................................143 2.2 Introduction .......................................................................144 2.3 Results and Discussion .......................................................147 2.4 Conclusions.........................................................................162 2.5 Experimental Section ..........................................................163 2.6 References...........................................................................169 Appendix/Chapter 3. Fullerene Derivative-modified Silver@Silica Core@Shell Nanoparticles as an Acceptor for Polymer Solar Cells.....................................................172 3.1 Introduction .......................................................................172 3.2 Results and Discussion .......................................................173 3.3 Conclusions.........................................................................178 3.4 Experimental Section ..........................................................179 3.5 References...........................................................................183 Appendix/Chapter 4. Colloidal Photonic Crystal Structure from Surface Modified TiO2 Nanoparticles under the Electric Field ....................................................184 4.1 Abstract .............................................................................184 4.2 Introduction .......................................................................185 4.3 Results and Discussion .......................................................186 4.4 Conclusions.........................................................................194 4.5 Experimental Section ..........................................................195 4.6 References...........................................................................197 Appendix/Chapter 5. Synthesis of Polystyrene@Titania Core@Shell Nanoparticles and Their Tunable Reflectance of Colloidal Photonic Crystal Structure..........................199 5.1 Introduction .......................................................................200 5.2 Results and Discussion .......................................................201 5.3 Conclusions.........................................................................208 5.4 Experimental Section ..........................................................209 5.5 References...........................................................................211 Appendix/Chapter 6. Synthesis of Au Rod@Titania Core@Shell Nanostructures and Their Photo-catalytic and Electron Dynamic Studies.........................................212 6.1 Abstract .............................................................................212 6.2 Introduction .......................................................................213 6.3 Results and Discussion .......................................................214 6.4 Conclusions.........................................................................221 6.5 Experimental Section ..........................................................222 6.6 References...........................................................................223 Appendix/Chapter 7. Silver@Titania Nanocomposite Additive as both Plasmonic and Scattering Material for Dye-sensitized Solar Cells.................................................225 7.1 Abstract .............................................................................225 7.2 Introduction .......................................................................226 7.3 Results and Discussion .......................................................227 7.4 Conclusions.........................................................................232 7.5 Experimental Section ..........................................................232 7.6 References...........................................................................235 Appendix/Chapter 8. Titania Coated Hierarchical Silica Nanostructure for the High Efficient Scattering Material...... ........................................................................237 8.1 Introduction .......................................................................237 8.2 Results and Discussion .......................................................238 8.3 Conclusions.........................................................................244 8.4 Experimental Section ..........................................................245 8.5 References...........................................................................247 Appendix/Chapter 9. Synthesis of Micron Sized Flower-like Hierarchical Iron Oxide from Primary Nanoparticles and Their Morphology Control........................................248 9.1 Introduction .......................................................................248 9.2 Results and Discussion .......................................................249 9.3 Conclusions.........................................................................262 9.4 Experimental Section ..........................................................262 9.5 References...........................................................................264 Korean Abstract ................................................................265Docto

헬리코박터 파일로리가 위암 발병에서 프로모터 메틸화를 통해 miR-133a 발현에 미치는 영향

학위논문 (박사)-- 서울대학교 대학원 : 의과대학 의학과, 2018. 2. 김상균.Background/Aims: To investigate whether Helicobacter pylori eradication can reverse epigenetic silencing of miRNAs which are associated with H. pylori-induced gastric carcinogenesis. Methods: We examined expression and promoter methylation of miR-34b/c, miR-133a, let-7a, and let-7i in gastric cancer cell line, before/after demethylation. Among them, epigenetically controlled miRNAs were identified. Their expression and promoter methylation was examined in human tissues of H. pylori-positive gastric cancer(T), H. pylori-positive gastritis(H), and H. pylori-negative controls(C). We also compared changes of miRNA expression and promoter methylation in H. pylori-positive patients who were endoscopically treated for early gastric cancer, between baseline and 1 year later according to eradication status. Results: In gastric cancer cell line, miR-34b/c, and miR-133a showed epigenetic silencing. In human tissues, miR-34b/c and miR-133a showed serial increase of promoter methylation in order of C, H, and T (all, p<0.01), and the miR-133a expression showed serial decrease (C vs. H, p=.02H vs. T, 0.01C vs Tp<0.01) while miR-34b and miR-34c expressions did not. H. pylori eradication induced decrease of methylation (p<0.01) and increase of miR-133a expression (p=0.03), compared with non-eradication group. Conclusions: This result suggests H. pylori eradication could reverse methylation-silencing of miR-133a which is involved in H. pylori-induced gastric carcinogenesis.Introduction 1 Materials and Methods 4 Results 11 Discussion 30 References 36 Abstract in Korean 44Docto

길이가 짧은 이젝터 성능에 대한 연구

학위논문 (박사)-- 서울대학교 대학원 : 기계항공공학부, 2011.8. 송성진.Docto

복부 대동맥류 진단을 위한 심층신경망 기반 질환 심각도 회귀

학위논문 (석사) -- 서울대학교 대학원 : 공과대학 기계공학부, 2021. 2. 윤병동.Disease in the medical field correspond to fault from an engineering point of view. In diagnosing machine failure, prognostics and health management (PHM) are essential. PHM chases the degradation of the health of the target system and produces information on health status. In this paper, the target system is selected as human. The target disease of human being the target system is selected as abdominal aortic aneurysm (AAA). Two of the main issues related to aneurysm are the lack of diagnostic indicators and lack of disease data. Aneurysm is not diagnosed using diagnostic indices, but is discovered using imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI). However, these techniques are expensive and time consuming. In addition, because it is difficult to diagnose this disease in advance, it is not easy to secure disease data. Against these issues, this study proposes a disease diagnosis and severity regression technique that combines deep learning. There are three research thrusts here: 1) generating normal and disease data through simulation model, 2) regression of disease severity, 3) reflecting individual diversity when generating data. In the first thrust, data is generated using a simulation model. One of the simulation models for diagnosing human disease is a transmission line model (TLM). A transmission line model modified from the model proposed in other previous papers [1] is used. In order to obtain blood pressure through the model, the input impedance needs to be calculated, which was calculated using a recursive algorithm. In the second thrust, disease incidence is monitored through severity regression. Deep neural network (DNN) is used as a tool to perform regression. In the third thrust, biometric parameter values are given as distributions. In consideration of the characteristics of each parameter, an appropriate distribution is assigned to each. The structure of this algorithm is formed of four tasks: simulation model modification, data generation, DNN design, and solving severity regression problem. It is confirmed that the blood pressure waveform data generated through literature research is valid and that the regression is well performed through the mean squared error (MSE) loss value.의학 분야에서의 질병은 공학적인 관점에서 보면 결함에 해당한다. 기계 고장을 진단할 때는 예측 및 상태 관리 (prognostics & health management; 이하 PHM)가 필수적이다. PHM은 대상 시스템의 상태 저하를 추적하고 상태에 대한 정보를 생성한다. 본 연구에서는 대상 시스템을 인간으로 선정하였다. 대상 시스템의 대상 질병은 복부 대동맥류로 선정하였다. 동맥류와 관련된 중요한 이슈 중 두 가지는 진단 지표의 부재와 질환 데이터의 부족이다. 동맥류는 진단 지표를 사용하여 진단되지 않고 컴퓨터 단층 촬영(computed tomography; 이하 CT) 또는 자기 공명 영상(magnetic resonance imaging; 이하 MRI)과 같은 영상 촬영 기법을 사용하여 진단된다. 또한 이 질환은 사전에 진단하기 어렵기 때문에 질환 데이터의 확보가 쉽지 않다. 이러한 이슈들에 대한 하나의 솔루션으로써 본 연구는 심층 학습을 결합한 질환 진단 및 심각도 회귀 기법을 제안한다. 세 가지 연구 요지는 다음과 같다. 1) 시뮬레이션 모델을 통해 정상 및 질환 데이터 생성, 2) 질환 심각도 회귀 분석, 3) 데이터 생성 시 개인의 다양성 반영. 데이터는 시뮬레이션 모델을 사용하여 생성된다. 인간의 질환을 진단하기 위한 시뮬레이션 모델 중 하나로 전송 선로 모델(transmission line model; 이하 TLM)이 있다. 본 연구에서는 관련 논문에서 제안된 모델을 수정한 전송 선로 모델을 사용한다. 모델을 통해 혈압 파형 데이터를 얻기 위해서는 재귀 알고리즘을 사용하여 입력 임피던스를 계산해야 한다. 질환 발생률은 질환 심각도 회귀를 통해 모니터링 된다. 이때 심층 신경망을 회귀 분석을 수행하는 도구로써 사용할 수 있다. 생체 관련 매개 변수 값을 분포로 제공하면 개인의 다양성을 반영할 수 있다. 본 연구에서는 각 변수의 특성을 고려하여 적절한 분포를 부여하였다. 본 연구의 구조는 시뮬레이션 모델 수정, 데이터 생성, 심층 신경망 설계 및 심각도 회귀 문제 해결이라는 네 가지 작업으로 구성된다. 문헌 조사를 통하여 본 연구에서 생성된 혈압 파형 데이터의 유효성을 검증하였고, 평균 제곱 오차 (mean squared error; 이하 MSE) 손실 값을 구해 회귀 분석을 잘 수행되었음을 확인하였다.Abstract i Nomenclatures viii Chapter 1. Introduction 1 1.1 Motivation 1 1.2 Research Thrust 4 1.3 Dissertation Layout 5 Chapter 2. Background 6 2.1 Abdominal Aortic Aneurysm (AAA) 6 2.1.1 Hypothesis for the Development of AAA and Rupture 7 2.1.2 Diagnosis and Treatment 7 2.2 Data Generation Model 9 2.2.1 Transmission Line Model (TLM) 9 2.2.2 Recursive Algorithm 10 2.2.3 Arterial Tree 10 2.3 Deep Neural Network (DNN) 13 2.3.1 Overview of DNN 13 2.3.2 General Structure of a DNN 13 2.4 Summary and Discussion 14 Chapter 3. Methodology 15 3.1 Alteration of Transmission Line Model 15 3.1.1 Materialization of AAA 15 3.1.2 Data Description 15 3.2 Materialization of Four Types of Aneurysms 17 3.3 Architecture of DNN 19 3.4 Summary and Discussion 19 Chapter 4. Data Generation Results 21 4.1 Blood Pressure Waveform Data 21 4.2 Validation of Blood Pressure Waveform Data 26 4.3 Summary and Discussion 27 Chapter 5. Regression Results 28 5.1 Loss and Regression Plots 28 5.2 Limitations 30 5.3 Summary and Discussion 30 Chapter 6. Conclusions 31 6.1 Summary and Contributions 31 6.2 Suggestions for Future Research 32 References 34 Abstract (Korean) 41 감사의 글 43Maste

An Analysis on Determinants of Debt Ratio :The difference depending on firm size, technical and industry characteristics

학위논문 (석사)-- 서울대학교 대학원 : 협동과정 기술경영·경제·정책전공, 2016. 2. 김연배.본 연구는 기업의 부채비율과 부채비율의 결정요인에 대한 관계를 기업의 규모 및 기술적 특징에 따른 자본조달시장과 산업적 특징에 따라 비교하여 분석하였다. 자본조달시장은 코스피 시장과 코스닥 시장으로 나누었고, 산업은 제조업과 지식 서비스 산업으로 분류하였다. 부채비율의 결정요인은 부채사용으로 기업가치를 극대화 시킬 수 있는 정태적 상충이론과 자본조달 순위이론을 바탕으로 기업 규모, 유형성, 총자산이익률로 선정하였다. 그 결과 코스피 시장과 제조업에서는 기업 규모와 부채비율 사이에는 역 U자 형태가 나타났지만, 코스닥 시장과 지식 서비스 산업에서는 기업 규모와 부채비율 사이에 역 U자 형태가 나타나지 않고 정(+)의 관계가 나타남을 확인하였다. 이는 코스닥 시장은 코스피 시장에 비해, 지식 서비스 산업은 제조업 산업에 비해 기업의 규모가 상대적으로 작은 편이고 기업의 자금조달 방식이 부채에 의존하기 때문이라고 판단되었다. 코스닥 시장 또는 지식 서비스 산업에 속하는 기업은 그 기업의 규모와 유형성이 커질수록 코스피 시장 또는 제조업에 속한 기업에 비해서 부채비율이 더 크게 증가하였고, 총자산이익률이 증가할수록 부채비율이 더 작은 비율로 감소하는 것을 확인하였다.This paper analyzes the relationship between the debt ratio of firms and the determinants of the debt ratio in respect to firm size, technical and industry characteristics. The market is categorized according to financing as either KOSPI or KOSDAQ. The industry sectors include manufacturing and knowledge service. Based on the static trade off theory that explains the optimal capital structure by balancing the advantage and disadvantage of debt and the pecking order theory that postulates debt as a need of external financing, this paper utilizes size, tangibility and return on assets as determinants of debt ratio. As a result, the findings on the KOSPI market and the manufacturing sector respectively show an inverted U shape between firm size and debt ratio. In the meantime, the findings on the KOSDAQ markets and knowledge service sector display a positive relationship. The results stem from market structure. Firm sizes in the KOSDAQ market and the knowledge service sector are relatively smaller and they rely on debt for financing than firms in the KOSPI market and the manufacturing sector. Debt ratio of firms in the KOSDAQ market or the knowledge service sector tends to increase as firm size grows and firms hold a higher degree of tangible assets. In comparison to firms in the KOSPI market or the manufacturing sector, debt ratio in the KOSDAQ market or the knowledge service sector decreases at a decreasing rate as return on assets (ROA) increases.1.서 론 1 2.문헌고찰 6 2.1자본구조이론 6 2.2부채비율 결정요인에 관한 선행연구 8 2.2.1기업 규모에 관한 선행연구 8 2.2.2유형성에 관한 선행연구 10 2.2.3이익률에 관한 선행연구 11 3.연구방법 12 3.1연구질문 12 3.2자 료 16 3.3추정방법 18 3.4변수의 정의 및 측정 19 3.4.1부채비율 19 3.4.2기업규모 19 3.4.3유형성 20 3.4.4이익률 20 3.4.5사업연령 20 4.연구결과 21 4.1기초 통계량과 상관관계 분석 21 4.2실증분석 결과 25 5.결 론 36 5.1결과 정리 및 시사점 36 5.2연구 한계점 및 발전 방향 39 참 고 문 헌 40 Abstract 44Maste

Adjuvant Low-dose Statin Use after Radical Prostatectomy: The PRO-STAT Randomized Clinical Trial.

PURPOSE: Statin use is reportedly associated with the risk of prostate cancer, outcomes after treatment, and prostate cancer-specific mortality. We sought to determine the efficacy of adjuvant atorvastatin in prostate cancer after radical prostatectomy. PATIENTS AND METHODS: In this randomized, double-blind trial, we assigned patients with pathologic high-risk prostate cancer to receive either low-dose atorvastatin (20 mg/day, n = 183) or placebo (n = 181) for 1 year after radical prostatectomy. The primary endpoint was the 1-year biochemical recurrence rate. The secondary endpoints included the 5-year biochemical recurrence-free survival and changes in lipid, testosterone, and sex hormone binding globulin levels. RESULTS: From October 2012 through January 2019, a total of 364 patients underwent randomization. Among 59 total primary end points, 30 (16.4%) and 29 (16.0%) occurred in the atorvastatin and placebo groups, respectively. Atorvastatin did not significantly reduce the primary endpoint of 1-year biochemical recurrence [HR, 0.96; 95% confidence interval (CI), 0.58-1.60]. During a median follow-up of 24 months, 131 patients experienced biochemical recurrence (68 in the atorvastatin group and 63 in the placebo group), representing Kaplan-Meier estimated event rates of 24.0% and 25.4% in the atorvastatin and placebo groups, respectively, at 24 months (HR, 1.00; 95% CI, 0.71-1.41). We observed no significant between-group differences in the testosterone and sex hormone binding globulin levels. CONCLUSIONS: Among patients with high-risk pathologic features after radical prostatectomy for prostate cancer, 1-year adjuvant use of atorvastatin was not associated with a lower risk of disease recurrence compared with that for placebo. (ClinicalTrials.gov number, NCT01759836).See related commentary by Murtola and Siltari, p. 4947

Bioevaluation Infra Project

바이오평가 기반구축 및 지원사업KGM421181