Discretization approach

학위논문(박사)--서울대학교 대학원 :공과대학 화학생물공학부(에너지환경 화학융합기술전공),2019. 8. 이원보.In recent years, many researchers in chemical engineering have made great efforts to develop mathematical models on the theoretical side that are consistent with experimental results. Despite these efforts, however, establishing models for a system with complex phenomena such as multiphase flow or stirred reactors is still considered to be a challenge. In the meantime, an increase in computational efficiency and stability in various numerical methods has allowed us to correctly solve and analyze the system based on the fundamental equations. This leads to the need for a mathematical model to accurately predict the behavior of systems in which there is interdependence among the internal elements. A methodology for building a model based on equations that represent fundamental phenomena can lower technical barriers in system analysis. In this thesis, we propose three mathematical models validated from laboratory or pilot-scale experiments. First, an apparatus for vaporizing liquid natural gas is surrounded with a frost layer formed on the surface during operation, and performance of the apparatus is gradually deteriorated due to the adiabatic effect. Because the system uses ambient air as a heat sink, it is necessary to consider the phase transition and mass transfer of water vapor, and natural gas in the air in order to understand the fluctuation of system characteristics. The model predicts the experimental data of a pilot-scale vaporizer within a mean absolute error of 5.5 %. In addition, we suggest the robust design methodology and optimal design which is able to maintain the efficiency under the weather conditions for a year. Two or more data analysis techniques including discrete waveform transformation and k-means clustering are used to extract features that can represent time series data. Under the settings, the performance in the optimized desgin is improved by 22.92 percentage points compared to that in the conventional system. In the second system, the continuous tubular crystallization reactor has advantages in terms of production capacity and scale-up compared with the conventional batch reactor. However, the tubular system requires a well-designed control system to maintain its stability and durability, and thus; there is a great deal of demand for the mathematical model of this system. We were able to estimate crystal size distribution by considering the population balance model simultaneously with several heat exchanger models. The model constructed based on the first principle reaction scheme successfully predicted the results from the full-factorial experiment. The experiments were conducted with LAM (L-asparagine monohydrate) solution. In the prediction, the average crystal length and standard deviation were within 20% of the results of an experiment where the crystals were not iteratively dissolved in the liquid but maintained a low-level supersaturation. Furthermore, to confirm the controllability of the crystal size distribution in the system, we replaced the LAM solution with HEWL (Hen-egg white lysozyme) solution. Finally, we propose a multi-compartment model to predict the behavior of a high-pressure autoclave reactor for polymer production. In order to simulate a complex polymer synthesis mechanism, the rotation effect of impellers in the reactor on polymerization and the influence caused by polymerization heat were sequentially evaluated. As a result, This model turned out to be able to predict the physical properties of the polymers produced in an industrial-scale reactor within 7% accuracy. In this thesis, all three systems are distributed parameter systems which can be expressed as partial differential equations for time and space. To construct a high order model, the system was interpreted based on discretization approach under minimal assumptions. This methodology can be applied not only to the systems suggested in this thesis but also to those consisting of interpdependent variables. I hope that this thesis provides guidance for further researches of chemical engineering in nearby future.최근에 몇 년에 걸쳐서 많은 연구자들이 이론을 기반으로 실험 결과와 일치하는 수학 모델을 개발하고자 많은 노력을 기울여 왔다. 하지만 이런 노력에도 불구하고 다상 흐름 혹은 교반 반응기와 같은 복잡한 현상을 내포한 시스템을 위한 모델을 수립하는 것은 여전히 화학 공학 분야에서 쉽지 않은 일로 여겨진다. 이 와중에 다양한 수치적 방법에서의 계산 효율의 증가와 안정성의 향상은 기본방정식에 기초한 시스템을 정확하게 해결하고 분석할 수 있게 해주었다. 이로 인하여 내부 요소들 간의 상호 의존성이 존재하는 시스템의 거동을 정확하게 예측하기 위한 수학적 모델의 필요성이 부각되었다. 기본 현상들을 표현할 수 있는 방정식들을 기반으로 모델을 구축하기 위한 방법론은 시스템 해석에 있어서 기술적 장벽을 낮출 수 있다. 이 학위 논문에서 우리는 실험실 또는 파일럿 규모의 실험으로부터 입증된 세 가지 수학적 모델을 제안한다. 첫 번째로, 공기를 사용하여 액상의 천연가스를 기화시키는 장치는 운전 도중에 기화기 표면에 서리 층이 형성되고 그로 인한 단열 효과로 장비의 성능이 서서히 저하된다. 시스템은 주변 공기를 열 흡수원으로 사용하기 때문에 시스템 특성의 변동을 파악하기 위해서는 공기 중 수증기 및 천연 가스의 상전이 및 전달 현상을 동시에 고려하여야 한다. 제시된 수학적 모델에 의해 예측한 결과는 파일럿 규모 기화기로부터 얻은 실험 데이터와 5.5% 평균 절대 오차를 보였다. 이에 더하여, 앞에서 제시한 기화기 모델을 이용하여 1년 동안의 기상 조건에서 운전 효율을 유지하면서 지속 운전이 가능한 기화기의 설계 방법과 결과를 제안하였다. 이산 파형 변환과 k-평균 군집화를 포함하는 두 가지 이상의 데이터 분석 기법을 사용하여 시계열 데이터를 대표할 수 있는 특징을 추출한다. 추출된 특징 아래에서 최적화된 디자인은 기존 제시된 안에 비해 22.92% 만큼 향상된 성능을 보여주었다. 두 번째 시스템은 신 제약 기술 공정인 연속 관형 결정화 반응기는 기존에 널리 쓰이던 회분식 반응기에 비하여 생산 속도 및 스케일 업 측면에서 장점이 많다. 하지만 제어기술이 기반이 되어야한다는 점에 있어서 그 도입이 늦어졌고 이에 따라 자연스럽게 개발된 모델 또한 전무하다. 우리는 이 장치에서 결정 크기 분포를 추산하기 위한 인구 균형 모델을 열 교환 모델과 동시에 고려하여 결정 크기 분포를 추산할 수 있었다. 제 1원리 결정 반응식을 기반으로 구축된 모델은 완전 요인 배치법을 기반으로 실험된 데이터를 성공적으로 예측하였다. 결정이 액상에 용해되지 않으면서 낮은 수준의 과포화 상태를 유지한 실험에 대해서는 평균 결정 길이와 표준편차가 실험 결과와 20% 이내의 오차를 보였다. 앞에서 모델의 검증에 사용된 데이터가 LAM (L-아스파라긴 일 수화물)용액으로부터 얻어진 것이었다면 이후에는 HEWL (달걀 흰자 리소자임)를 사용하여 제품의 결정 크기 분포의 조절 가능성을 보였다. 마지막으로 폴리머 생산을 위한 고압 오토클레이브 반응기의 거동을 예측하기 위한 다중 구획 모델을 제안하였다. 복잡한 고분자 합성 메커니즘을 모사하기 위하여 반응기 내 임펠러의 회전이 중합에 미치는 효과와 중합 열로 인한 영향력을 순차적으로 평가하였다. 제안된 모델은 3D 구조를 가진 산업화된 반응기에서 생산된 두 가지 고분자의 물성을 7%이내 정확도로 예측할 수 있다. 본 학위논문에서는 다루는 시스템은 모두 분포 정수계 시스템으로 시간과 공간에 대하여 편미분방정식으로 표현할 수 있다. 고차 모델을 구축하기 위해 이산화 접근법을 기반으로 최소한의 가정 하에 시스템을 해석하였다. 이는 논문에 제시한 시스템 뿐만 아니라 시공간에서 예측 어려운 분포를 가지는 변수를 가진 모든 시스템에 대하여 적용이 가능하다. 이 논문이 앞으로 화학 공학 분야의 시스템을 해석하는 데 있어서 더 발전된 연구를 위한 지침서가 되기를 희망한다.Abstract i Contents iv List of Figures viii List of Tables xii Chapter 1 1 Introduction 1 1.1 Research motivation 1 1.2 Research objective 3 1.3 Outline of the thesis 4 1.4 Associated publications 9 Chapter 2 10 Distributed parameter system 10 2.1 Introduction 10 2.2 Modeling methods 11 2.3 Conclusion 16 Chapter 3 17 Modeling and design of pilot-scale ambient air vaporizer 17 3.1 Introduction 17 3.2 Modeling and analysis of frost growth in pilot-scale ambient air vaporizer 24 3.2.1 Ambient air vaporizer 24 3.2.2 Experimental measurement 27 3.2.3 Numerical model of the vaporizer 31 3.2.4 Result and discussion 43 3.3 Robust design of ambient air vaporizer based on time-series clustering 58 3.3.1 Background 58 3.3.2 Trend of time-series weather conditions 61 3.3.3 Optimization of AAV structures under time-series weather conditions 63 3.3.4 Results and discussion 76 3.4 Conclusion 93 3.4.1 Modeling and analysis of AAV system 93 3.4.2 Robust design of AAV system 95 Chapter 4 97 Tunable protein crystal size distribution via continuous crystallization 97 4.1 Introduction 97 4.2 Mathematical modeling and experimental verification of fully automated continuous slug-flow crystallizer 101 4.2.1 Experimental methods and equipment setup 101 4.2.2 Mathematical model of crystallizer 109 4.2.3 Results and discussion 118 4.3 Continuous crystallization of a protein: hen egg white lysozyme (HEWL) 132 4.3.1 Introduction 132 4.3.2 Experimental method 135 4.3.3 Results and discussion 145 4.4 Conclusion 164 4.4.1 Mathematical model of continuous crystallizer 164 4.4.2 Tunable continuous protein crystallization process 165 Chapter 5 167 Multi-compartment model of high-pressure autoclave reactor for polymer production: combined CFD mixing model and kinetics of polymerization 167 5.1 Introduction 167 5.2 Method 170 5.2.1 EVA autoclave reactor 170 5.2.2 Multi-compartment model of the autoclave reactor 173 5.2.3 CFD simulation of mixing effects in the autoclave reactor 175 5.2.4 Region-based dividing algorithm 178 5.2.5 Polymerization kinetic model 182 5.3 Results and discussion 191 5.4 Conclusion 203 5.5 Appendix 205 Chapter 6 210 Concluding Remarks 210 6.1 Summary of contributions 210 6.2 Future work 211 Appendix 214 Acknowledgment and collaboration declaration 214 Supplementary materials 217 Reference 227 Abstract in Korean (국문초록) 249Docto

초고 열전 성능 지수 ZT를 가지는 새로운 틴 셀레나이드 기반 소재 개발

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 화학생물공학부, 2020. 8. 정인.With the rapid increase in population and the depletion of fossil fuels, the demand for new energy sources is increasing worldwide. More than 60% of the energy produced is wasted in the form of heat. Thermoelectric technology can convert thermal energy into electrical energy, and since it can use waste heat as electrical energy, it has attracted much attention as a next-generation eco-friendly energy source. For the commercialization and practical use of the technology, the most problematic at present is the low performance of the thermoelectric material. Thermoelectric materials such as bismuth telluride and lead telluride, which have been studied the most in the past, have high thermoelectric performance through various strategies, but have limitations because they have elements such as toxic lead or very expensive tellurium. This dissertation will discuss the study of thermoelectric performance improvement of SnSe, an eco-friendly material among various thermoelectric materials. First, PbSe and Na were introduced into polycrystalline SnSe. Through the alloying of PbSe, it was confirmed that the phase transition temperature from the crystal structure of Pnma to the crystal structure of Cmcm decreased. Also, by introducing Na, the optimum carrier concentration could be improved to a level of 1019. Improved electrical conductivity and power factor were confirmed by optimized carrier concentration and lowered phase transition temperature. In addition, it was observed through aberration-corrected transmission electron microscopy that the introduction of PbSe formed nanostructures in SnSe materials, unlike the information in the existing phase diagram, which was thought to form solid solutions. Through this, it was found that the introduction of PbSe causes scattering by nanostructures, thereby lowering the thermal conductivity. The p-type SnSe-based material with a thermoelectric performance index ZT of about 1.2 was successfully developed in the composition of Na0.01(Sn0.95Pb0.05)0.99Se due to the improved power factor and reduced thermal conductivity. Second, a study was conducted to improve the thermoelectric performance of SnSe by defect engineering. Sample groups were constructed by introducing vacancy and indium into SnSe. It was confirmed that the electrical conductivity and the thermal conductivity decreased simultaneously as the vacancy content increased. However, through the introduction of indium, the electronic band structure was changed to improve the Seebeck coefficient, thereby minimizing the reduction in power factor. The thermoelectric figure of merit ZT ~2.0 was confirmed in the composition of Na0.01(Sn0.97In0.01)0.99Se through the lowered thermal conductivity and the improved power factor. Despite the same composition, when the annealing process was performed, the thermal conductivity was lowered. In order to investigate the cause of this, changes in the microstructure according to annealing time were observed through a Cs-corrected transmission electron microscope. It was confirmed that vacancies are distributed in clusters in a SnSe matrix that has not undergone annealing, and as the annealing progresses, vacancy clusters gather to form a heterostructure in a certain direction in SnSe matrix. Through the Cs-corrected transmission electron microscope observation and phase analysis, it was confirmed that the heterogeneous phase of In2Se3 was formed in the bulk SnSe, and through this, the cause of the lowered thermal conductivity was identified. In addition, the mechanism of formation of heterostructures in SnSe was suggested, and the possibility of formation of nanostructures in the SnSe bulk material through the introduction of other elements and vacancies was suggested. Third, the purpose of this study was to find out the cause of the difference in thermoelectric performance between single crystal SnSe and polycrystalline SnSe that have not been identified. The formation of tin oxide having a thermal conductivity of about 140 times higher than that of SnSe was confirmed in SnSe through Cs-corrected transmission electron microscopy, which is the cause of high thermal conductivity of polycrystalline SnSe. To solve this, a ball mill and a reduction process were performed. The content of oxide in the material was reduced, and at the same time, the thermal conductivity was also lower than that of a single crystal. Through this, materials with thermoelectric figure of merit ZT 2.5 were developed. In addition, in order to more fundamentally prevent the formation of oxides, a purification and reduction process of tin used in synthesis was performed. Samples synthesized using this showed a very low oxide content, and had a lower lattice thermal conductivity than single crystal SnSe. By improving the electrical conductivity and power factor through doping of Na, the power factor was significantly improved. As a result, the cause of thermal conductivity of SnSe higher than that of single crystal was found experimentally and theoretically, and ZT 3.0 having the highest thermoelectric performance among the thermoelectric materials reported so far was developed. In this thesis, various elements and vacancy were introduced into polycrystalline SnSe. The understanding of the material as a whole was improved by confirming the change in its thermoelectric performance and the microstructure of the material. In addition, the performance difference between single crystal and polycrystalline SnSe was overcome through the element purification, ball mill, and reduction processes. Since this strategy can be applied to all thermoelectric materials, it can contribute to improving the performance not only of tin selenide, but also of the overall thermoelectric material field.인구의 급격한 증가와 화석연료가 점점 고갈됨에 따라 전 세계적으로 새로운 에너지원에 대한 수요가 급증하고 있다. 이렇게 생산되는 에너지 중 60% 이상이 폐열의 형태로 낭비되고 있다. 열전 기술은 열에너지를 전기에너지로 변환시킬 수 있는 기술로, 버려지는 폐열을 전기에너지로 사용할 수 있기 때문에 차세대 친환경 에너지원으로 많은 각광을 받고 있다. 해당 기술의 상용화, 실용화를 위해서 현재 가장 문제가 되는 것은 열전 소재의 낮은 성능이다. 기존에 가장 많이 연구된 비스무스 텔루라이드, 리드 텔루라이드와 같은 열전 소재는 다양한 전략을 통해 높은 열전성능을 보이고 있으나 독성이 있는 리드 또는 매우 값비싼 텔루륨과 같은 원소를 지니고 있어 한계를 지니고 있다. 본 학위논문은 다양한 열전 소재 중, 친환경인 소재인 틴 셀레나이드의 열전 성능 향상 연구에 대해 논의 하고자 한다. 첫번째로 다결정 틴 셀레나이드에 리드셀레나이드 및 소듐을 도입하였다. 리드셀레나이드의 합금화를 통해 780 K 부근에서 일어나는 Pnma의 결정구조에서 Cmcm의 결정구조로의 상전이 온도가 감소하는 것을 확인하였다. 또한 소듐을 도입하여 최적의 캐리어 농도를 10의 19승 수준으로 향상시킬 수 있었다. 최적화된 캐리어 농도와 낮아진 상 전이 온도에 의해 향상된 전기전도도 및 파워팩터를 확인하였다. 또한 리드 셀레나이드의 도입은 고용체를 형성한다고 여겨지던 기존의 상태도의 정보와 다르게 나노구조를 틴 셀레나이드 소재 내에 형성함을 수차보정 투과전자현미경을 통해 관찰하였다. 이를 통해 리드 셀레나이드의 도입은 점산란 및 나노구조에 의한 산란을 유발하며 이에 의해 열전도도가 낮아짐을 규명하였다. 파워팩터의 향상 및 감소된 열전도도에 의해 Na0.01(Sn0.95Pb0.05)0.99Se의 조성에서 약 1.2의 열전성능지수 ZT를 보이는 p형 틴셀레나이드계 소재를 성공적으로 개발하였다. 두번째로, 결함을 이용하여 틴 셀레나이드의 열전성능을 향상시키는 연구를 진행하였다. 틴 셀레나이드에 공극 및 인듐을 도입하였으며, 함량의 조절을 통해 각 인자가 도입됨에 따라 전기전도도 및 열전도도가 동시에 감소함을 확인하였다. 하지만 인듐의 도입을 통해 전자 밴드구조가 변화되어 제백계수가 향상되었고 이를 통해 파워팩터의 감소를 최소화 하였다. 낮아진 열 전도도 및 향상된 파워팩터를 통해 Na0.01(Sn0.97In0.01)0.99Se의 조성에서 약 2.0의 열전 성능지수를 확인하였다. 동일한 조성임에도 불구하고 어닐링 공정을 진행한 경우 열전도도가 보다 낮아지는 현상을 발견하여 수차보정 투과전자현미경을 통해 어닐링 시간에 따른 미세구조의 변화를 확인하였다. 어닐링을 진행하지 않은 소재에서 공극들이 클러스터를 이루며 분포되어 있으며, 어닐링이 진행됨에 따라 공극 클러스터들이 모여 일정한 방향으로 헤테로스트럭쳐를 형성함을 확인하였다. 시간별 투과전자현미경 이미지 및 상 분석을 통해 인듐 셀레나이드의 이종상이 벌크 틴 셀레나이드 내에 형성되었음을 확인하였으며 이를 통해 낮아진 열전도도의 원인을 규명하였다. 더불어 틴 셀레나이드 내에 공극의 형성 및 헤테로스트럭쳐의 규명 매커니즘을 제시하여 다른 원소의 도입을 통한 틴 셀레나이드 벌크 소재 내의 나노구조체의 형성 가능성을 제시하였다. 마지막으로, 지금까지 규명되지 않았던 단결정 틴 셀레나이드와 다결정 틴 셀레나이드의 열전 성능 차이에 대한 원인을 밝히고자 하였다. 틴 셀레나이드보다 약 140배의 열전도도를 가지는 틴 산화물의 형성을 다결정의 틴 셀레나이드의 높은 열전도도의 원인임을 수차보정 투과전자현미경을 통해 확인하였다. 이를 해결하고자 볼밀 및 환원공정을 진행하였으며 공정 후의 소재에서 산화물의 함량이 줄어듦과 동시에 단결정 수준의 낮은 열전도도를 확인하였다. 이를 통해 열전성능지수 ZT 2.5를 가지는 소재를 개발하였다. 또한 합성 시 사용되는 틴 내부의 틴 산화물을 제거하기 위해 정제 및 환원공정을 진행하여 낮은 산화물의 함량을 가지는 틴 셀레나이드를 개발하였으며 단결정 틴 셀레나이드보다 낮은 격자 열전도도를 확인하였다. 또한 소듐의 도핑을 통해 전기전도도 및 파워팩터를 향상시켜 파워팩터를 단결정 수준으로 향상시켰다. 결과적으로, 단결정에 비해 높은 틴셀레나이드의 열전도도의 원인을 실험적, 이론계산적으로 밝혀내었으며, 지금까지 보고된 열전 소재 중 가장 높은 열전성능인 ZT 3.0 가지는 소재를 개발하였다. 다결정 틴 셀레나이드의 다양한 원소 및 공극의 도입을 통해 열전 성능의 변화 및 소재의 미세구조 변화 등을 확인하여 소재 전반에 대한 이해도를 높였으며, 원소의 정제, 볼밀 및 환원 공정을 통해 단결정과 다결정 틴셀레나이드의 성능차이의 원인을 규명하였다. 이와 같은 전략은 모든 열전 소재에 적용될 수 있으므로 비단 틴 셀레나이드 뿐 아니라 전반적인 열전 소재 분야의 성능 향상에 기여할 수 있다.Chapter 1. Introduction. 1 1.1 Background. 1 1.2 Strategy for enhancing thermoelectric performance. 7 1.2.1. Enhancing the power factor. 7 1.2.1.1. Resonant level 7 1.2.1.2. Band convergence 10 1.2.2. Reducing the thermal conductivity 12 1.2.2.1 Nanostructuring. 12 1.2.2.2 Defect engineering 16 1.3 SnSe. 19 1.4 References. 24 Chapter 2. Improved thermoelectric performance of polycrystalline SnSe by controlling phase transition temperature 28 2.1 Introduction. 28 2.2 Experimental section. 32 2.3 Results and discussion. 35 2.4 Conclusion. 77 2.5 References. 78 Chapter 3. Defect engineering for high-performance SnSe thermoelectrics 83 3.1 Introduction. 83 3.2 Experimental section. 85 3.3 Results and discussion. 89 3.4 Conclusion. 130 3.5 References. 131 Chapter 4. Revealing intrinsic charge and thermal transport properties of SnSe - Removal of surface SnOx by a chemical reduction process. . 134 4.1 Introduction. 134 4.2 Experimental section. 137 4.3 Results and discussion. 139 4.4 Conclusion. 171 4.5 References. 181 Chapter 5. Revealing and removing the origin of surface SnOx: Uncovering intrinsic charge and thermal transport properties of SnSe . 187 5.1 Introduction. 187 5.2 Experimental section. 190 5.3 Results and discussion. 202 5.4 Conclusion. 237 5.5 References. 238 Bibliography. 242 Korean Abstract 244Docto

Effects of Oral Adsorbent AST-120 (Kremezin®) on the Progression of Chronic Kidney Disease

Purpose: AST-120 is known to delay progression of chronic kidney disease (CKD) when combined with other proven therapy. AST-120 is an oral adsorbent for uremic toxin, such as indoxyl sulfate from the gastrointestinal tract. There have been a lot of studies to show its effect in other countries, but there are few studies done in Korea yet. Methods: 195 patients were included in the study (mean age, 64±14 years; diabetes mellitus (DM), 104 patients; male, 130 patients). The patients with CKD who started AST-120 and maintained the medication for at least 6 months were enrolled. The patients’ laboratory results for 6 months before and after administrating AST-120 was surveyed. Then the rate of patients’ renal functional deterioration was compared before and after AST-120. In addition, adverse effects during the medication were surveyed. Results: There were no statistically significant differences in laboratory data between before and after AST-120 administration. But, after administrating AST-120, the renal deterioration slope has blunted significantly from -0.0123±0.0318 to -0.0013±0.0184 dL/mg/month (p<0.01) in 1/sCr and from -1.1423± 2.3906 to 0.0639±1.3825 ml/min/1.73m2/month (p<0.01) in estimated glomerular filtration rate (eGFR). There were no differences between DM and non-DM patients in the effect of AST-120, as well as ages over 70 and below 70. There were no serious adverse effects during medication. Conclusion: This study showed that AST-120 had additive effect on retarding the CKD progression when combined with established therapy regardless of DM and ages without serious adverse effects.ope

A Case of Distal Renal Tubular Acidosis and Sjögren’s Syndrome in a Patient with Autoimmune Thyroiditis

A 52-year old woman, who had hypothyroidism associated with autoimmune thyroiditis for 5 years, was hospitalized for tingling sensation and muscle weakness of both lower extremities. Her initial laboratory findings showed severe hypokalemia, metabolic acidosis, and high titer of thyroid autoimmune antibodies. She was diagnosed of distal renal tubular acidosis by bicarbonate loading testope

Serum Adiponectin as a Predictor for Cardiovascular Outcomes in Non-Diabetic End-Stage Renal Disease Patients

Purpose: Adiponectin (ADPN) has been known to protect against cardiovascular disease (CVD) in metabolic syndrome with normal renal function for its anti-inflammatory and anti-atherogenic property. However, it is still unclear whether ADPN is associated with cardiovascular outcomes in end-stage renal disease (ESRD) patients. Methods: This study included 80 non-diabetic ESRD patients [mean age, 52.8±13.7 years; dialysis duration, 67.1±52.0 months; hemodialysis (HD), 35 pts; peritoneal dialysis (PD), 45 pts] who survived for more than 3 months after the start of dialysis, and serum ADPN levels were measured at the beginning of the study. We conducted a longitudinal follow-up to evaluate the association of serum ADPN level with cardiovascular outcomes for 29.3±6.7 months. Results: ADPN was inversely correlated with fasting serum insulin (r=-0.309, p=0.006) and HOMA-IR (r=-0.321, p=0.004) in ESRD patients. In a multiple linear regression analysis adjusted for age, gender, waist to hip ratio (WHR), and HDL-cholesterol, HOMA-IR (β=-0.880, p=0.041) was an independent factor associated with serum ADPN level. Kaplan-Meier analysis revealed that patients with higher ADPN levels (≥15.8 μg/mL) had a significantly higher survival rate compared with lowers (<15.8 μg/ mL) (p=0.032). Cox proportional hazard model adjusted for age, WHR, creatinine, CRP, and previous CVD history revealed that serum ADPN level (HR, 0.899; 95% CI, 0.818-0.987; p=0.026) was an independent determinant of cardiovascular outcomes. Conclusion: These findings suggest that lower ADPN levels independently predict cardiovascular events in non-diabetic ESRD patients.ope

Effect of Alkaline Reduced Water on Small Intestineand Systemic Immune Responses in C57BL/6 Mice

의생명과학전공/석사[한글]알칼리환원수(alkaline reduced water, ARW)를 급이하였을 때 동물 생체 내의 면역 및 소장에 미치는 영향을 알아보고자 본 연구를 시행하였다. C57BL/6 마우스에 6주 동안 알칼리환원수를 급이한 후 혈액 내 염증 및 면역세포, serological parameter, 소장 내 cytokine, 그리고 비장에서의 cytokine 발현 정도를 정수물을 먹인 대조군과 비교하였다. 혈액 내 염증 및 면역세포 수에서 호산구(eosinophil, p<0.05)와 호중구(neutrophil, p<0.001)는 대조군에 비해 ARW군에서 유의하게 감소하였고, 림프구(lymphocyte, p<0.001)는 반대로 ARW군에서 유의하게 증가하였다. Serological parameter를 측정한 결과 glutamic pyruvic transaminase(GPT, p<0.01), creatine phosphokinase(CPK, p<0.01), blood urea nitrogen(BUN)과 creatinine(p<0.001)이 대조군에 비해 ARW군에서 유의하게 낮은 수치를 나타냈으며, Na과 Cl(p<0.001)은 대조군에 비해 ARW군에서 유의하게 높은 수치를 나타냈다. 또한 소장의 경우, ARW군의 tumor necrosis factor-alpha(TNF-α) 발현 정도가 유의성은 없었지만 대조군에 비해 뚜렷하게 증가하였고 interleukin-4(IL-4, p<0.05)의 발현이 대조군에 비해 유의하게 증가하였다. 비장에서의 cytokine mRNA 발현은 대조군과 ARW군 사이에 변화를 보이지 않았다. 본 연구의 결과 알칼리환원수를 급이하였을 때 혈액 내 염증 및 면역세포와 혈청학적 성상 및 소장 점막에 작용하여 면역세포, 혈청학적 성상 및 cytokine 발현에 영향을 주었다.이를 통해 알칼리환원수의 생체 내 면역반응과 장내 면역반응에 미치는 영향은 알칼리환원수의 효과에 대한 기전 규명과 함께 계속적인 연구가 필요함을 확인하였다. [영문]In this study, the effects of alkaline reduced water on small intestine and systemic immunity of a mouse were investigated. C57BL/6 mice were fed with conventional water (control group) or ARW (ARW group) for 6 weeks. Then the numbers of peripheral blood leukocytes, serological parameters and cytokine mRNA expression levels in small intestine and spleen of C57BL/6 mice were examined.Among the peripheral blood leukocytes, the numbers of eosinophils (p<0.05) and neutrophils (p<0.001) were decreased and those of lymphocytes (p<0.001) number were increased in the ARW group. In case of serological parameters, GPT (p<0.01), CPK (p<0.01), BUN(p<0.001) and creatinine (p<0.001) levels were decreased in ARW group, but Na and Cl levels were increased in the ARW group (p<0.001). In small intestine, the mRNA expression of IL-4 was significantly increased in the ARW group and the mRNA expression of TNF-α was also clearly induced compared with normal control group. To the contrary, the mRNA expressions of cytokines (IL-4, IL-5, TNF-α, IL-1β) in spleen were not significantly changed.In conclusion, when ARW was fed on mice, it is observed that it affects to blood components, intestinal mucosa and the cells related to immune system, serological parameters, and expression of cytokine. Further study in necessary about functional effects of ARW on small intestine and systemic immune response including mechanism identification.ope

바나듐 흐름전지용 이온교환막의 이온선택도 향상을 위한 술폰화 PEEK/미세다공성 티타노실리케이트 세공충진 복합막의 연구

학위논문 (석사)-- 서울대학교 대학원 : 재료공학부, 2016. 2. 곽승엽.Titanosilicate ETS-10 has a 3D ordered microporous structure which needs two minus charge of extra-framework cations. Optimum pore size of ETS-10 and unique pore properties are useful for ion selective permeation and proton conduction through micropore. First, nanocomposite membranes of sulfonated poly(ether ether ketone) (SPEEK) and microporous titanosilicate ETS-10 are prepared with various contents by solution casting to confirm the effect of titanosilicate as an additive for vanadium redox flow battery applications. The field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) images of the composite membrane showed the presence and the uniformity dispersion of ETS-10 in the SPEEK polymer matrix. The water uptake, ion exchange capacity, mechanical property, proton conductivity, vanadium ion permeability and VRB single cell tests of the composite membranes were characterized in detail. The proton conductivity of composite membranes with 1 wt% and 4 wt% ETS-10 loading is improved compared to neat SPEEK membrane. The vanadium permeability decrease as ETS-10 loading due to blocking effect of particles. The composite membrane with 4 wt% ETS-10 which have the highest ion selectivity showed the VRB single cell performance of coulombic efficiency (CE) 99%, voltage efficiency (VE) 80.0% and energy efficiency (EE) 79.2% at 80 mA cm-2 resulting from low vanadium permeability without proton conductivity loss. At same cell test condition, Nafion 117 membrane showed the cell performance of CE 98.8%, VE 72.4% and EE 71.4%. Furthermore, the composite membrane with 4 wt% ETS-10 exhibited high capacity retention and maintained efficiency during 100 cycles at 40 mA cm-2. The results indicated that ETS-10 particle is suitable as a permselective barrier for reducing vanadium crossover and improving cell performance. Second, to improve cycle performances of vanadium redox flow battery, PTFE-based SPEEK/ETS-10 nanocomposite membranes were prepared with various contents by pore-filling method. And same analysis were performed and characterized in detail. The thickness of pore-filled membranes are less than composite membrane series (70 m and 120 m respectively). The pore-filled membrane with 3 wt% ETS-10 showed the VRB single cell performance of CE 99.1%, VE 81.6% and EE 81.3% at 80 mA cm-2 which slightly higher than the best among composite membrane. Furthermore, the pore-filled membranes showed high capacity retention and maintained efficiency compared to Nafion 117 during 100 cycles at 40 mA cm-2. These results indicated that PTFE pore-filling method is effective for improving cyclability and cell performance.1. Introduction 1 2. Experimental 7 2.1. Materials 7 2.2. Synthesis of ETS-10 crystal 7 2.3. Preparation of SPEEK/ETS-10 membrane 8 2.4. Preparation of SPEEK/ETS-10@PTFE membrane 9 2.5. Characterization of ETS-10 10 2.5.1. Crystallinity of ETS-10 10 2.5.2. Morphology of ETS-10 11 2.6. Characterization of membrane 11 2.6.1. Membrane morphology 11 2.6.2. Physicochemical property 11 2.6.3. Mechanical strength 13 2.6.4. Proton conductivity 13 2.6.5. Vanadium permeability 13 2.7. Evaluation of membrane performance 15 2.7.1. VRB single cell test 15 3. Results and Discussion 22 3.1. Characterization of ETS-10 22 3.1.1. Crystallinity and morphology of ETS-10 22 3.1.2. Acid resistance of ETS-10 28 3.2. Characterization of SPEEK/ETS-10 membrane 30 3.2.1. Membrane morphology study 30 3.2.2. Physicochemical properties 33 3.2.3. Mechanical properties . 36 3.2.4. Proton conductivity 38 3.2.5. Vanadium permeability and ion selectivity 42 3.2.6. VRB single cell performance 47 3.3. Characterization of SPEEK/ETS-10@PTFE membrane 54 3.3.1. Membrane morphology study 54 3.3.2. Physicochemical properties 58 3.3.3. Mechanical properties 60 3.3.4. Proton conductivity 62 3.3.5. Vanadium permeability and ion selectivity 65 3.3.6. VRB single cell performance 70 4. Conclusions 77 5. References 80 6. KOREAN ABSTRACT 87Maste

Deoxycholic acid induced modulation of colon cancer cell invasiveness

의학과/박사[한글]고지방식이에 의하여 대장 내 농도가 증가하는 데옥시콜릭산(deoxycholic acid, DCA)은 대장에서 종양 촉진인자로 알려져 있으나, 대장암의 침습과 전이에 미치는 영향에 대하여는 알려진 바가 없다. 본 연구는 HT-29 대장암 세포주를 이용하여 데옥시콜릭산 투여 후 세포의 침습성 변화를 알아보고, 이를 매개하는 신호 전달 경로를 알아보고자 하였다.HT-29 대장암 세포주에 데옥시콜릭산을 시간 및 농도별(0～80μM)로 처리한 후 혈관내피성장인자와 저산소증유도인자-1α mRNA 발현에 대한 역전사 중합효소연쇄반응, 혈관내피성장인자 및 MMP-9에 대한 Western blotting, MMP-9의 활성화 여부를 평가하기 위한 zymography, 그리고 세포의 이동성 변화를 확인하기 위한 wound migration assay를 시행하였다. 또한 데옥시콜릭산 매개 대장암 세포주의 침습성 변화에 관여하는 신호 전달 경로를 알아보기 위하여 이전에 알려진 대장암 관련 신호전달 억제물질의 전처리 후 변화를 확인하였다.데옥시콜릭산은 저산소증유도인자 mRNA의 발현, 혈관내피성장인자 mRNA 및 단백 발현, MMP-9의 단백 발현과 효소 활성도, 세포의 이동성을 농도 의존적으로 증가시켰다. 데옥시콜릭산 자극 후 혈관내피성장인자 단백 발현의 증가는 COX- 2의 선택적 억제제인 NS-398, NF-kB의 억제제인 PDTC, 그리고 TUDC의 전처리로 억제되었다. 데옥시콜릭산 유도 MMP-9의 효소 활성도는 p38 MAPK 억제제인 SB203580, ERK 억제제인 U0126, 그리고 PDTC의 전처리로 억제 되었으며, 데옥시콜릭산에 의한 세포 이동성 증가는 protein kinase C의 억제제인 GF109203X의 전처리로 감소되었다.데옥시콜릭산은 대장암 세포주에서 여러가지 신호 전달 경로를 통하여 세포의 침습성과 혈관형성의 잠재능을 의미 있게 증가시킴으로써 대장암의 종양촉진 뿐만 아니라, 대장암의 침습과 전이를 촉진 할 가능성을 제시하였다. [영문]Deoxycholic acid(DCA), a secondary bile acid, has been long implicated to promote colon tumor growth and progression; however, the molecular mechanisms of its action are largely unknown. In this study, we investigated the effects of DCA on colon tumor cells(HT-29) proliferation, migration, and invasiveness. In addition, we assessed the effects of various signal inhibitors on DCA induced modulation of colon tumor cell invasiveness.HT-29 cells were incubated with either medium only(control) or DCA for 24～48 hr. Time courses of RT-PCR for vascular endothelial growth factor(VEGF) and hypoxia-induced factor(HIF)-1α mRNA expression, Western blotting for VEGF and matrix metalloproteinase(MMP)-9, zymography for MMP-9 activation, and wound- migration assay were determined after different concentrations of DCA(0～80μM) treatment. Moreover, these experiments were reassessed after pretreatments(2～6hr) of specific inhibitors of various signal pathways.DCA enhanced HIF-1α mRNA expression, VEGF mRNA and VEGF protein expre- ssion, MMP-9 protein expression/activation, and cell migration ability in a dose-dependent manner. DCA-induced VEGF protein expression was inhibited by pretreatment of NS-398(COX-2 inhibitor), PDTC(NF-kB inhibitor), or tauroursodeoxycholic acid(TUDC). DCA-induced cell migration ability was inhibited by pretreatment of GF109203X, a protein kinase C inhibitor. DCA-induced MMP-9 protein expression/activation was inhibited by pretreatment of SB203580, U0126, or PDTC.DCA significantly upregulates invasive and angiogenic potentials in human colon cancer cells through multiple signal transduction pathways.ope

경영성과의 회계적 측정치와 경영자 보상간의 관계 : 한국기업 경영자보상의 하방경직성을 중심으로

학위논문(석사)--서울대학교 대학원 :경영학과 경영학전공,2002.Maste

乾隆 46年(1781) 살라르族 新敎徒 叛亂의 社會的 背景

학위논문(석사)--서울大學校 大學院 :東洋史學科,1996.Maste