임상연구를 위한 신경수초물영상

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 전기·정보공학부, 2019. 2. 이종호.신경수초는 몸 안의 전기적 신호를 전달하는데 있어 중요한 역할을 한다. 신경퇴행성질환은 신경수초 손상과 연관성이 있으며 이는 전기적 신호 전달의 손실을 유발한다. 병원에서 사용하는 자기 공명 영상법인 T1, T2 강조영상들은 신경수초의 양을 정량화 할 수 없고 신경퇴행성질환 환자의 신경수초의 손상된 정도를 확인 할 수 없다. 본 연구에서는 신경수초의 손상된 정도를 예측하기 위해 새롭게 개발 된 신경수초물영상을 신경퇴행성질환에 적용하였다. 이를 위해 신경다발의 물교환 및 머리로 유입되는 혈류로 인한 신경수초물영상법에 미치는 영향에 대하여 탐구하였다. 또한, 신경수초물영상법을 이용한 임상적 연구를 위하여 분석 파이프라인을 개발하였다. 첫째로 신경다발의 생물, 물리적학적 특성을 시뮬레이션화한 Monte-Carlo 시뮬레이션 모델을 개발하였다. 시뮬레이션에서 계산된 신경수초물의 거주 시간을 이용하여 신경수초물영상법이 신경수초물을 측정하고 있는 것을 검증하였다. 둘째로 본 연구에서는 머리로 유입되는 혈류로 인한 artifact을 제거하기 위해 혈류 시뮬레이션 모델을 개발하였다. 혈류 시뮬레이션 모델을 통하여 유입되는 혈류로 인한 artifact을 최소화 하는 혈류포화펄스의 최적 시간을 제안하였다. 최종적으로, 신경수초물 영상의 임상연구 적용을 위하여 분석 파이프 라인을 개발 및 요약하였다. 이를 이용하여 신경퇴행성질환인 다발성경화증, 시신경척수염, 외상성 뇌손상 환자의 정상으로 보이는 영역에서 신경수초물변화를 관찰하였다. 본 연구의 결과는 추후 수초관련 뇌 질환의 진단, 치료의 효용성 및 예후 평가뿐 아니라 학습에 의한 뇌 가소성 연구 및 재활 치료 효과 평가에 이용될 수 있을 것이라 사료된다.Myelin plays an important role in transmitting electrical signals in the body. Neurodegenerative diseases are associated with myelin damage and induce a loss of the electrical signals. The conventional T1 and T2 weighted imaging, used in clinics, cannot quantify the amount of myelin and confirm the degree of myelin damage in patients with neurodegenerative diseases. This thesis applied newly developed myelin water imaging, named ViSTa, to the neurodegenerative diseases to estimate changes in myelin. To utilize ViSTa myelin water imaging in clinical studies, I explored the effects of water exchange and inflow in ViSTa myelin water imaging. Then, I developed new data analysis pipelines to apply ViSTa myelin water imaging for the clinical studies. First, the Monte-Carlo simulation model that has the biological and physical properties of white matter fiber was developed for myelin water residence time. The simulation model validated the origin of ViSTa as myelin water. Second, the thesis developed a flow simulation model to compensate artifacts from inflow blood in ViSTa myelin water imaging. The flow simulation model suggested the optimal timing of flow saturation pulse(s) to suppress the inflow of blood. Finally, I summarized new data analysis pipelines for clinical applications. Using the analysis pipelines, ViSTa myelin water imaging revealed reduced apparent myelin water fraction in normal-appearing white matter for three prominent brain diseases and injury (neurodegenerative diseases): multiple sclerosis, neuromyelitis optica spectrum disorders, and traumatic brain injury. The developments in this thesis can be utilized not only in the diagnosis, treatment, and prognosis of various diseases but also in neuroplasticity and rehabilitation studies to explore the answer for the questions related to myelin issues.Chapter 1. Introduction 1 1.1 Myelin 1 1.2 Myelin Water 1 1.3 ViSTa Myelin Water Imaging 4 1.4 Purpose of Study 7 Chapter 2. Water Exchange Model 8 2.1 Introduction 8 2.2 Methods 8 2.3 Results 14 2.4 Discussion 16 Chapter 3. Blood Flow Simulation Model 17 3.1 Introduction 17 3.2 Methods 18 3.3 Results 25 3.4 Discussion 30 Chapter 4. Clinical Applications 32 4.1 Multiple Sclerosis 32 4.1.1 Introduction 32 4.1.2 Methods 33 4.1.3 Results 42 4.1.4 Discussion 52 4.2 Neuromyelitis Optica Spectrum Disorder 56 4.2.1 Introduction 56 4.2.2 Methods 57 4.2.3 Results 60 4.2.4 Discussion 65 4.3 Traumatic Brain Injury 68 4.3.1 Introduction 68 4.3.2 Methods 69 4.3.3 Results 75 4.3.4 Discussion 80 Chapter 5. Conclusion 84 Reference 85 Abstract 100Docto

조선소 소조립 주판 배치 시뮬레이션 기반 공간 계획 시스템 개발

학위논문 (석사) -- 서울대학교 대학원 : 공과대학 조선해양공학과, 2021. 2. 우종훈.In the shipbuilding subassembly process, space is one of the main resource constraints limiting production capacity. To efficiently manage the space resource, how subassembly parts will occupy the workshop floor need to be analyzed before production. In this study, a methodology of controlling the subassembly space resource is proposed. In this methodology, first the impact of space on the production capacity for a given time period is analyzed. This analysis is performed through a framework of discrete event simulation modelling the subassembly process using subassembly part scheduling algorithm and spatial arrangement planning algorithm. The production schedules feasibility in terms of space resource utilization is examined through the simulation model. Second, a detailed subassembly part arrangement layout is generated using a genetic algorithm based spatial arrangement algorithm. The algorithm is used to efficiently utilize the work area and accurately predict the amount of area required for a subassembly production lot. After the methodology is presented, a case study of the simulation model is analyzed, and the performance of the genetic algorithm based spatial arrangement algorithm is evaluated.조선소의 소조립 공정에서 공간 자원은 생산 능력을 결정하는 주요 자원이다. 공간 자원을 효율적으로 관리하기 위해서는 생산 계획 검토 단계에서 소조립품 배치 위치 및 공간 활용에 대한 분석이 필요하다. 본 연구에서는 이산사건 시뮬레이션 모델링 및 공간 배치 알고리즘에 기반한 소조립 공간 자원 활용 계획을 분석하는 방법론을 제안한다. 시뮬레이션 모델과 모델 내 탑재되어 있는 소조립 계획 및 공간 배치 모듈을 활용하여 생산 계획 기간동안의 생산성 및 계획준수율에 공간 자원이 미치는 영향을 분석할 수 있다. 이를 통해 생산 계획의 타당성을 검증하고 개선 방안 도출에 도움이 될 수 있다. 다음으로 유전알고리즘에 기반한 소조립 주판 배치 레이아웃 생성 알고리즘 및 방법론을 제안한다. 소조립 주판 배치 레이아웃 생성 알고리즘을 통해 소조립 작업장 공간 활용률을 높일 수 있으며 작업에 필요한 공간을 정확하게 예측할 수 있다. 마지막으로 소조립 생산 사례를 시뮬레이션 모델로 분석하고 소조립 주판 배치 레이아웃 생성 알고리즘의 성능을 평가하였다.1. Introduction 1 1.1 Study background 1 1.2 Past research 4 1.3 Research scope and methodology 6 2. Defining the subassembly process 8 2.1 Defining the part object 8 2.2 Defining the workshop 11 2.3 Defining the scheduling methodology 13 3. Developing the simulation model 15 3.1 Representing the product object 15 3.2 Subassembly part scheduling algorithm 18 3.3 Spatial arrangement planning algorithm 22 3.3.1 Factors in evaluating algorithm result 29 3.4 Simulation case study and analysis 30 3.5 System based on simulation model 35 4. Detailed spatial arrangement 38 4.1 Motivation and relation to simulation model 38 4.2 Algorithm structure and details 41 4.3 Detailed arrangement layout system 47 4.4 Algorithm evaluation and analysis 48 5. Conclusion 51Maste

랜덤 포리스트를 이용한 비제어 급성 출혈성 쇼크의 흰쥐에서의 생존 예측

Hemorrhagic shock is a primary cause of deaths resulting from injury in the world. Although many studies have tried to diagnose accurately hemorrhagic shock in the early stage, such attempts were not successful due to compensatory mechanisms of humans. The objective of this study was to construct a survival prediction model of rats in acute hemorrhagic shock using a random forest (RF) model. Heart rate (HR), mean arterial pressure (MAP), respiration rate (RR), lactate concentration (LC), and peripheral perfusion (PP) measured in rats were used as input variables for the RF model and its performance was compared with that of a logistic regression (LR) model. Before constructing the models, we performed 5-fold cross validation for RF variable selection, and forward stepwise variable selection for the LR model to examine which variables were important for the models. For the LR model, sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (ROC-AUC) were 0.83, 0.95, 0.88, and 0.96, respectively. For the RF models, sensitivity, specificity, accuracy, and AUC were 0.97, 0.95, 0.96, and 0.99, respectively. In conclusion, the RF model was superior to the LR model for survival prediction in the rat model.ope

젖산 농도와 관류 비를 이용한 흰쥐에서의 출혈성 쇼크의 사망 예측 지표 개발

Purpose: We proposed a new index for predicting death resulting from hemorrhagic shock, which was calculated by dividing measured lactate concentration by perfusion. Methods: Using 24 Sprague-Dawley (S-D) rats, we induced uncontrolled hemorrhage and then measured blood lactate concentration and perfusion in addition to vital signs such as heart rate, blood pressure, respiration rate and temperature. Perfusion and lactate concentration were measured by laser Doppler flowmetry and a lactate concentration meter, respectively. We collected the data for 15 min, which consisted of 3 intervals after homeostasis, and thus obtained a new index. Results: The proposed index revealed an earlier death prediction than lactate concentration alone with the same timing as perfusion. The new index showed generally better sensitivity, specificity and accuracy than lactate concentration and perfusion. Using a receiver operating characteristic curve method, the mortality prediction with the proposed index resulted in a sensitivity of 98.0%, specificity of 90.0%, and accuracy of 93.7%. The mortality prediction with the proposed index resulted in a sensitivity of 98.0%, specificity of 90.0% and accuracy of 93.7%. Conclusion: This index could provide physicians, in emergency situations, with early and accurate mortality predictions for cases of human hemorrhagic shock.ope

Development of an Optical Probe for Measuring Blood Flow in Dental Pulp

To diagnose dental pulp vitality, electric pulp tester has been widely used, which is a method to test condition of nerve. However, especially in the case of patients with trauma, nerve desensitization could temporarily occur even though nerve might be recovered by blood flow within the pulp later, which implies that blood flow in dental pulp is also an important factor for diagnosing vitality. This paper described the development of a probe that relatively measured blood flow in dental pulp using photoplethysmography (PPG). The probe emits four different wavelength light sources including three visible and an infrared light. We tested which light source detect sensitively the blood flow in dental pulp. As a result, green light had the largest peak to peak voltage and the power spectrum among different wavelengths.ope

Cardio-pulmonary effects of RF fields emitted from WCDMA mobile phones

With rapid increasing usage of smart phones, social concerns have arisen about the possible effects of electromagnetic fields emitted from wideband code division multiple access(WCDMA) mobile phones on human health. The number of people with self-reported electromagnetic hypersensitivity(EHS) who complain of various subjective symptoms such as headache, insomnia etc. has also recently increased. However, it is unclear whether EHS results from physiological or other origins. In this double-blinded study, we investigated physiological changes such as heart rate, respiration rate, and heart rate variability with real and sham exposures for 15 EHS and 17 non-EHS persons using a module inside a dummy phone. Experiment was conducted using a WCDMA module with average power of 24 dBm at 1950 MHz with the specific absorption rate of 1.57 W/kg using a headphone for 32 min. As a conclusion, WCDMA RF exposure did not have any effects on the physiological variables in either group.ope

저산소재산소화 과정에서의 사람 림프구에서 유도되는 세포독성

학위논문(석사) --서울대학교 대학원 :보건학과(보건학전공),2007.Maste

한국산 검정알벌과의 분류 :벌목 :납작먹좀벌상과

Thesis (doctoral)--서울대학교 대학원 :농생물학과 곤충학전공,1999.Docto

다양한 기계 학습법을 이용한 급성 출혈성 쇼크의 흰쥐에서의 사망 예측 모델

Dept. of Medical Science/석사Casualty triage at initial contact on scene by first responders is crucial to save hemorrhagic patents'' lives in civilian trauma or on the battlefield. However, there are few studies to demonstrate important physiological variables related to mortality and the most suitable machine learning techniques for casualty triage among various techniques. This study was conducted to suggest a mortality predicting model for casualty triage on scene using various machine learning techniques through a rat model in acute hemorrhage. Furthermore, this study determined important physiological variables for mortality prediction to effectively minimize impression time for first responders.Thirty-six anesthetized rats were randomized into three groups according to volume of controlled blood loss. Uncontrolled hemorrhage was induced simultaneously by combination of controlled blood loss and tail amputation in all rats. This study measured heart rate (HR), systolic and diastolic blood pressures (SBP and DBP), mean arterial pressure (MAP), pulse pressure (PPR), respiration rate (RR), temperature (TEMP), lactate concentration (LC), peripheral perfusion (PP), shock index (SI, SI=HR/SBP), and the new hemorrhage-induced severity index (NI, NI=LC/PP) as candidates for input variable of each machine learning techniques. All variables were analyzed for changes between pre- and post-hemorrhage to investigate the effects of hemorrhage on mortality.The training data set was used to construct models based on popular machine learning techniques including logistic regression (LR), artificial neural networks (ANN), random forest (RF), and support vector machines (SVM). To select important variables for mortality prediction in a rat model, variables selection was performed with algorithm of consistency subset evaluation using 10-fold cross validation. The testing data set was used to assess the performance of the optimized models consisting of the selected variables for predicting mortality using sensitivity, specificity, accuracy and area under curve (AUC) of the receiver operating characteristic (ROC).For the LR model, sensitivity, specificity, accuracy, and AUC were 0.678, 1.000, 0.833, and 0.833, respectively. For the ANN model, sensitivity, specificity, accuracy, and AUC were 0.833, 1.000, 0.917, and 0.917, respectively. For the RF model, sensitivity, specificity, accuracy, and AUC were 0.833, 1.000, 0.917, and 0.903, respectively. For the SVM model, sensitivity, specificity, accuracy, and AUC were 1.000, 0.833, 0.917, and 0.972, respectively. The SVM model showed better AUC than that of the LR, ANN, and RF models for mortality prediction. The important variables selected by SVM were LC and NI.In conclusion, the SVM model with selected variables, LC and NI, was superior to the LR, ANN, and RF models in predicting mortality resulting from acute hemorrhagic shock in a rat model. These machine learning techniques may be very helpful to first responders to accurately make causality triage decisions and rapidly perform proper treatments for hemorrhagic patients in civilian trauma or on the battlefield in the future.ope

생쥐 체세포에서의 Nek2 단백질의 세포주기단계 특이성과 세포 내 분포에 관한 연구

Thesis (master`s)--서울대학교 대학원 :생명과학부,2001.Maste