정상노인, 경도인지장애, 알츠하이머병에서 뇌 아밀로이드 축적, 혈관성 위험과는 독립적인 해마 위축에 대한 호모시스테인의 영향 연구

학위논문 (석사)-- 서울대학교 대학원 : 의학과 정신과학 전공, 2013. 2. 이동영.Objectives: To clarify whether homocysteine has any independent effect, not mediated by cerebral beta amyloid protein (Aβ) deposition and vascular burden, on whole brain or hippocampal atrophy in elderly individuals with normal cognition, mild cognitive impairment (MCI) and Alzheimers disease (AD). Methods: Fourteen cognitively normal, 19 MCI, and 24 AD individuals were included. All subjects received three-dimensional volumetric MRI, Pittsburgh Compound B - positron emission tomography and comprehensive clinical evaluation including vascular burden assessment for diabetes, hypertension, dyslipidemia, coronary artery disease, stroke and transient ischemic attack. Blood homocysteine, vitamin B12, and folate levels were also measured. Results: Multiple linear regression analyses showed that plasma total homocysteine level was significantly associated with hippocampal atrophy even after controlling the degree of global cerebral Aβ deposition and vascular burden as well as other potential confounders including age, gender, education and apolipoprotein E ε4 genotype. In contrast, plasma total homocysteine level did not show any significant association with whole brain volume. Conclusions: Our finding of the independent negative association between plasma homocysteine and hippocampal volume suggests that homocysteine has a direct adverse effect, not mediated by cerebral Aβ deposition and vascular burden, on the hippocampus.Abstract i Contents iii List of tables and figures v Introduction 1 Methods Subjects 3 Clinical and neuropsychological assessment 4 MRI image acquisition and analysis 5 11C-PiB PET image acquisition and analysis 7 Blood sample collection and analysis 9 Statistical analysis 9 Results Subject characteristics 11 Simple correlations between brain volume and related variables 13 Simple correlations between homocysteine and related variables Results 14 Partial correlations between homocysteine and brain volume 15 Multiple regression analysis between homocysteine and brain volume for overall subjects 16 Multiple regression analysis between homocysteine and brain volume only for 11C-PiB negative subjects 18 Discussion 20 References 24 Abstract in Korean 32Maste

A Research on the Ecological Time Expression

OAIID:oai:osos.snu.ac.kr:snu2010-01/104/0000025799/19SEQ:19PERF_CD:SNU2010-01EVAL_ITEM_CD:104USER_ID:0000025799ADJUST_YN:NEMP_ID:A075458DEPT_CD:611CITE_RATE:0FILENAME:생태적_시간_표현에_관한_연구 (1).pdfDEPT_NM:디자인학부EMAIL:[email protected]:

Research on the Ecological Time Expression

본 연구는 생태정보와 인류학정보를 기반으로 색다른 시간 전달을 유도하는 것을 목적으로 꽃의 개화시기에 따른 시계를 제안하고자 한다. 시간은 하나의관념이며 시간의 측정은 인간의 본성이다. 기존의 시계는 필수적이고, 인간의 생체주기와 일상생활 방식에도 도움 되기 때문에 적절한 것이라고 할 수 있다. 이는 시간 속에서 자신의 위치를 정하고, 현재를 정확하게 응시할 수 있게 하며 과거를 정돈하고 미래를 계획할 수 있도록 도움을 주기 때문이다. 연구의 범위는 과거에서부터 현대까지 시계를 통시적으로 조사하였다. 또한 디지털시계와 아날로그 시계에서 시간을 명시하는 방식을 고려해 보았을 때, 시계를 숫자와 시침으로만 구성하는 것도 논리적으로 이상은 없으며 조금은 감성적이기에 디지털 시계라는 대상과는 다르다. 그래서 생태시계를 기반으로 한 시간 표현법도 필요하다고 할 수 있다. 아날로그 시계는 기술에 힘을 얻어 디지털화 되었고, 같은 방식으로 식물과 꽃의(생태학)변화 정보도 시간표현의 방법 중에 하나가 될 수 있다. 일반적으로 학습하고 이해하는 개념의 시계보다 생태정보에 디지털기술을 적용하여 감성적으로 표현하는 시간 전달 방법을 제안 한다. 해결방안으로는 천체와 자연, 그리고 인간의 활동에 관한 연력을 조사 하였다. 그 중에서도 꽃의 개화시기와 인류학적 농경활동의 변화 과정을 그래픽 정보 요소와 함께 고려하여 연구를 진행하였다. 인류학 활동과 생태적 변화과정 단계는 무수히 많았다. 다양한 정보가 시각적 흐름상 혼란을 줄 수 있지만, 인터랙션의 장점을 살려 핸드폰 속의 스킨으로 생태정보(꽃개화 시기)를 시간대 별로 구성 했을때, 생태적 시간을 자연스럽게 이해 할 수 있을 것이다. 디지털꽃시계는 웹상의 위젯 기능처럼 언제나 어디서나 볼 수 있다. 햇빛의 역할과 일조량 등은 친환경 관점에서도 도움 될 것이며, 인간이 느끼는 생체리듬 적응에도 효과적일 것이다. 향후 연구과제로는 시계를 순차적으로 구성하는 것뿐만 아니라 색다른 관점에서도 시간을 볼 수 있고, 새로운 의미를 부여하는 방안을 적절히 이용한 창의적 발상이 깃든 디자인이 제시 되어야 할 것이다.This research induces an effective time conveyance based on ecological information and anthropological information. The range of research is about the clock from the past to the modern times in the order of time diachronically. In addition, when considering the time in a digital clock and an analog clock, the construction of a clock with only numbers and an hour hand is not abnormal logically but an ecological expression method of time that is more emotional and sophisticated and suits the modern senses and has a standard is also needed. There are various types of clocks. The analog clock was digitalized with the power of technology, and the (ecological) change information of plants and flowers is one of the methods for time expression. A time conveyance method that expresses emotion by applying digital technology to ecological information than an analog clock of the concept that is generally learned and understood is suggested. The history of the activities of heavenly bodies, nature and humans was examined as a solution. Among those, the blossom time of flowers and the progress of change in the anthropological agricultural activities were considered with graphic information elements and the research was conducted.The stages of anthropological activities and ecological changes are countless. A digital flower clock can be seen universally like the widget function on the Web. The role and the amount of sunshine will be helpful for the eco-friendly viewpoint and will be effective in the adaptation of the human biorhythm. the research subject of a design with a creative idea that successively constructs a clock and allows the examination of time from an exotic viewpoint that uses a method to grant a proper new meaning is presented in this study.OAIID:oai:osos.snu.ac.kr:snu2010-01/102/0000025799/1SEQ:1PERF_CD:SNU2010-01EVAL_ITEM_CD:102USER_ID:0000025799ADJUST_YN:NEMP_ID:A075458DEPT_CD:611CITE_RATE:0FILENAME:생태적_시간_표현에_관한_연구.pdfDEPT_NM:디자인학부EMAIL:[email protected]_YN:NCONFIRM:

An Analysis of Turbo codes with Asymmetric Modulation

Maste

Performance and study of J. S. Bach Partita No.2 in c minor, BWV 826, C. Debussy Pour le Piano, L. 95, F. Liszt Sonata in b minor, S. 178

학위논문 (석사)-- 서울대학교 대학원 : 음악과, 2011.2. 문익주.Maste

터널 발파패턴 설계 자동화 프로그램의 개발에 관한 연구

학위논문(석사)--서울대학교 대학원 :자원공학과,1998.Maste

고대 이스라엘 전통의 재해석에 관한 연구 : 『역대기』의 기록을 중심으로

학위논문(석사) --서울대학교 대학원 :종교학과,2008. 8.Maste

The Effect of heat treatment and deformation temperatures on the shape memory effect of Fe--Si-Cr-Ni shape memory alloys

Maste

초다분광 영상의 endmember 추출을 위한 iterative error analysis 알고리즘에서의 오차 측정방법 비교

학위논문 (석사)-- 서울대학교 대학원 : 에너지시스템공학부, 2015. 2. 박형동.This study represents the effect of methods for estimating error in iterative error analysis (IEA) algorithm. Three different methods are presented for estimating error in each iteration: the L2-norm, which is used in the original IEA, the L1-norm and the spectral angle. For comparing the effect of applying those error metrics and evaluating the performance of each algorithm, two hyperspectral datasets, simulated and real hyperspectral images, were used. The results of endmember extraction with those algorithms were compared to spectral library by spectral distance and the 2-D plane projection of datasets. The results with the simulated image indicated that the spectral angle based IEA algorithm performed better than other two IEAs, the original and the L1-norm based algorithm. The spectral angle based IEA selected correct locations of endmember pixels while other two algorithms worked poorly. In addition, the spectral angle IEA produced stable results with various signal-to-noise ratio (SNR). In particular, the algorithm with the spectral angle showed a robustness when the data was highly affected by changes in pixel brightness. The 2-D projection illustrated illumination insensitivity of the spectral angle based IEA algorithm. The experiment with the real hyperspectral data displayed similar results to those of the simulated image. Even though big difference was not detected, the spectral angle based IEA produced slightly better results of endmember spectra. The 2-D projection plane of extracted endmembers also showed that the spectral angle based algorithm produced reliable results when the image contains topographically complex regions. The result of this study suggest that the IEA algorithms with different error metrics produce different results and the algorithm based on the spectral angle error is a reliable approach to extract endmembers from the image of topographically complex region.Chapter 1 Introduction 1 Chapter 2 Theoretical Backgrounds 5 2.1 Linear Mixing Model 5 2.2 Linear Spectral Unmixing 7 2.3 Spectral Error Metrics 8 2.4 Comparison of Spectral Error Metrics 10 Chapter 3 The Modified IEA algorithms 13 3.1 Original IEA algorithm 13 3.2 IEA algorithm based on the Spectral Angle Error 15 3.3 IEA algorithm based on the L1-norm Error 15 Chapter 4 Description of Datasets 17 4.1 Simulated Hyperspectral Image 17 4.2 Real Hyperpsectral Image 20 Chapter 5 Results and Discussion 23 5.1 Evaluation with Simulated Hyperspectral Image 23 5.1.1 Results of Extracted Endmembers 23 5.1.2 Comparison of Endmembers on 2-D Plane 31 5.2 Evaluation with Real hyperpsectral image 34 5.2.1 Results of Extracted Endmembers 34 5.2.2 Comparison of Endmembers on 2-D Plane 42 Chapter 6 Conclusions 46 References 48 Abstract 52Maste

Comparison Study on Multi Logit and Stepwise Classification

학위논문 (석사)-- 서울대학교 대학원 : 통계학과, 2012. 2. 김우철.Multi class classification is an important topic in real world problems. The most popular strategy in doing multi class classification is classifying all at once based on posterior probability or distance metric. Discriminant analysis, k-nearest neighbors, neural network and multi logit regression are belong to this strategy. Friedman(1996) suggested the a new intuitive approach for the multi class problems: solve each of the two-class problems and combine all the results of pairwise decisions to form a multiclass classifier. Trevor Hastie and Robert Tibshirani(1998) developed this strategy and applied it to many other areas in their studies. Linear discriminants, K nearest neighbors and support vector machine were used as classifiers. In this paper, we construct pairwise classifiers for multi class problems by using binary logit regressions and compare the results with those of classical multinomial logit model. We use the forest cover type data from US Forest Service inventory information and predict forest cover types from cartographic variables.Maste