Overcoming the Common Challenges in Differential Gene Expression Analysis Studies

Huang, Yan ProQuest Dissertations & Theses University of Cali 2019 해외박사(DDOD)

The ability to analyze gene expression data has had a fundamental impact in the biological sciences and on our understanding of the causes and mechanisms of disease. However, a significant statistical challenge is posed by the combination of the small number of replicates together with the large number of genes leading to an undesirable level of misclassified genes when identifying genes with differential expression levels. When multiple gene expression data sets are generated under the same set of experimental conditions, the ques- tion arises as to how to efficiently combine this information. Several methods in the literature have been suggested to aggregate ranked data from multiple sources. We introduce a new classifier, underpinned by Bayesian principles, called Peer Reinforced Ranker (PR-Ranker) which uses density estimation to approximate the probability that a gene is differentially expressed given a collection of ranked lists.Our classifier is amenable to theoretical analysis when the number of genes and lists is large using the theory of large deviations. Under modest technical assumptions we show that asymptotically PR-Ranker has the smallest loss of any rank aggregation procedure. Moreover, we prove that other more ad hoc methods, such as Borda, have a strictly higher asymptotic rate of loss.While the theoretical results are asymptotic, we perform a series of simulation studies that demonstrate that our classifier outperforms existing methods on datasets of realistic size for biological data. Furthermore, we show that the outperformance is even greater when the lists exhibit varying levels of noise or when some sources are corrupted. PR-Ranker automatically adapts to varying data quality and efficiently combines the data from different sources. Finally we apply PR-Ranker to a gene expression data set in a preeclampsia study. The top ranked genes identified were known to be biologically relevant to preeclampsia and our method achieved a substantially higher Consistency Index than other rank aggregation procedures.

Combining Theory and Experiment in Pt-Based Catalysts Design for Energy Conversion

Huang, Jin ProQuest Dissertations & Theses University of Cali 2021 해외박사(DDOD)

Investigation of Structure-Mechanics-Property Relations in Heart Valve Tissues

Huang, Siyao North Carolina State University 2014 해외박사(DDOD)

The microstructure and the mechanical property of the heart valve are physically critical factors in modeling the valve tissue equivalent. The heart valve tissue has a complex microstructure primarily containing collagen fibers and valve interstitial cells (VICs). The extracellular matrix (ECM) of the heart valve tissue, where collagen is the main component, provides strength to support the structure of the tissue. The inhomogeneity of the collagen fiber architecture gives rise to the nonlinear anisotropic material property of the tissue. Besides, to respond mechanical loads, VICs mediate a series of bioregulations for ECM remodeling such as homeostasis, collagen synthesis, and collagen degradation through collagen fibers, which further result in changes of the material behavior corresponding to mechanical stimulation. Due to the inhomogeneous architecture of collagen fibers and randomly distributed cell population, the mechanical behavior of the heart valve tissue becomes more complicated during cardiac cycles. Heart valves open and close correctly and persistently during cardiac systole and diastole for blood circulation. It is a widely acknowledged health concern that heart valve diseases lead to defective structures and improper functions of heart valves to directly influence the blood circulation and the heart workload. To date, at least 250,000 people are suffering heart valve diseases in the United States, and the population keeps rising. Studies have indicated that heart valve diseases are caused by the disrupted tissue homeostasis under a variety of pathological conditions, resulting in alterations in heart valve microstructures, mechanical properties, and other biomechanical regulations. Severe collagen depletion is one of disordered tissue remodeling caused by matrix metalloproteinases (MMPs) that pathologically induces matrix destruction, changes the viscoelastic property of the heart valve tissue, further affects cellular regulations mediated by VICs, and even leads to heart valve diseases. With application of collagenase simulating collagen degradation by MMPs, this study focuses on characterizing stress-relaxation behaviors of fresh porcine heart valve tissues and collagenase-treated ones under different stretching conditions. Moreover, the collagen concentration is measured to provide biochemical information related to the mechanical stress relaxation. The results reveal the sensitivity of collagen fibers to proteolytic degradation. The decrease in the stress state of the heart valve tissue is associated with the stretching level and the collagenase concentration. Stress is further decreased after applying collagenase, and a larger stress drop results from a higher strain level and/or a higher collagenase concentration. Therefore, the current study provides important links between several factors: collagen degradation, activities of matrix metalloproteinases, collagen fiber directions, and mechanical stimulations. It is known that heart valves constantly experience different stress states during cardiac cycles; however, how these mechanical stimuli translate into extracellular matrix remodeling, cellular mechanotransduction, cell migration, and collagen synthesis are still unclear. Although the computational simulations of heart valve tissue have been widely studied via the homogenization of collagen fiber distribution or the simplified representation of the highly heterogeneous collagen fiber network excluding the cell population, the matrix-to-cell stress transfer is underestimated. Meanwhile, VIC regulations have been investigated from cells generally isolated from the matrix prior to adhesion molecule characterization; thus, tissue-cell mechanical interactions have not been fully characterized in the native in vivo environment in which they normally operate. To demonstrate heterogeneously distributed collagen fibers responsible for transmitting forces into cells, this study introduces a virtual experiment via an image-based finite element analysis incorporating a histological photomicrograph of a porcine heart valve tissue. Furthermore, the evolution of stress fields at both the tissue and cellular levels is reported to contribute toward refining our collective understanding of valvular tissue micromechanics while a computational tool is provided to further study of valvular cell-matrix interactions.

Analyzing ESG Practice of Chinese Energy SOEs in Southeast Asia under the Green Belt and Road Initiative : Focusing on Coal and Hydropower Sector

HUANG 서울대학교 대학원 2024 국내석사

In light of the increasing significance of Environmental, Social, and Governance (ESG) principles, the Belt and Road Initiative (BRI) has faced criticism for ESG risks. The study explores how Chinese state-owned enterprises (SOEs) implement Beijing’s ESG principles within the energy sectors of coal and hydropower in Southeast Asia. It assesses the alignment of these practices with Beijing's policies and examines whether these practices adhere to or deviate from the established guidelines. Incorporating a dual framework of Corporate Social Responsibility (CSR) and Corporate Social Opportunity (CSO), this research analyzes how corporate actions meet regulatory expectations and leverage opportunities for promoting sustainable development. The findings reveal certain efforts, including advancements in clean energy investments and infrastructure enhancements, which contribute positively towards environmental conservation and economic growth. However, significant discrepancies remain in adhering to local environmental laws, conducting thorough environmental assessments, and maintaining transparency, highlighting the need for more stringent and application of ESG standards. In addition, there is a significant need to enhance both the employment standards offered and the adequacy of compensation for land usage and the social impacts caused by these projects. Addressing these issues will enable Chinese SOEs to better meet their ESG commitments, ensuring that their projects are economically viable, socially responsible, and environmentally sound. Enhancing these aspects of ESG implementation will further align corporate actions with policy ambitions, improving the overall sustainability and acceptance of these international investments. Overall, the implementation of ESG policies by Chinese firms in the coal sector primarily reflects a traditional CSR approach, focused on damage control and compliance. This indicates a need for stronger integration of CSO principles to shift these engagements from merely reactive measures to proactive, strategic actions that foster long-term sustainability and community development. Similarly, the hydropower sector in Southeast Asia under the BRI shows alignments with both CSR and CSO, though these efforts remain limited. While there are instances of environmental management and community support, the sector still largely emphasizes reactive CSR measures over proactive CSO strategies. To achieve truly sustainable outcomes, a greater emphasis on integrating and balancing these approaches is needed, particularly in enhancing genuine community participation and ensuring fair compensation and resettlement practices. The study argues for an enhanced integration of CSO principles, recommending that Chinese SOEs shift towards more proactive and strategic engagements that deeply embed sustainability into corporate strategies and community interactions. By strengthening the balance between CSR and CSO, these enterprises can mitigate environmental and social risks while maximizing benefits to local communities, achieving more robust sustainable outcomes. Key words: Belt and Road Initiative; Energy Sector; ESG; CSR; CSO Student number: 2022-24903 환경, 사회, 경영(ESG)의 중요성이 높아짐에 따라 일대일로 (Belt and Road Initiative) 정책은 ESG 위험에 대한 비판을 받고 있다. 본 연구는 중국 국영기업(SOE)들이 동남아시아의 석탄 및 수력발전 에너지 부문에서 어떻게 녹색 일대일로의 ESG 정책을 구현하고 있는지에 대해서 탐구하고 중국 ESG 정책과 국영기업의 실제 관행 사이의 일치 여부를 조사하며 이러한 관행이 ESG 지침을 얼마나 준수하는지를 평가한다. 또한, 본 연구는 기업들의 ESG 행동이 사회적 책임(CSR)인지 사회적 기회(CSO)인지를 분석한다. 본 연구 결과에서는 그린 에너지 및 인프라 개선과 같은 긍정적인 노력이 있음에도 불구하고 여전히 중대한 격차가 존재한다는 것을 보여준다. 그래서 현지 환경 법규 준수, 철저한 환경 평가 실시 및 투명성 유지에 있어 상당한 차이가 있어 ESG 기준의 보다 엄격하고 일관된 적용을 강조하고 고용 기회의 질과 토지 사용에 대한 보상 적정성도 상당한 개선이 필요하다. 이러한 문제를 보안해야 중국 SOE들은 ESG 정책을 더 잘 이행하고, 정책 목표와 기업 행동을 더 잘 일치되게 하여 전반적인 지속 가능성과 수용성을 높일 수 있다. 중국 기업의 석탄 부문 ESG 정책 구현은 주로 피해 통제 및 준수에 중점을 둔 전통적인 CSR 접근 방식을 반영한다. 이는 이러한 방식을 단순히 반응적인 조치에서 장기적인 지속 가능성과 지역 사회 개발을 촉진하는 전략적 행동으로 전환하기 위해 CSO 원칙의 강력한 통합이 필요함을 시사한다. 마찬가지로, 일대일로 하 수력 기업들도 CSR과 CSO의 조화가 보이지만 CSO에 대한 노력은 여전히 제한적이다. 환경 관리 및 지역 사회 지원의 사례가 있지만, 기업들이 여전히 적극적인 CSO 전략보다 반응적인 CSR 조치를 강조한다. 진정으로 지속 가능한 결과를 달성하려면 이러한 접근 방식을 통합하고 균형을 맞추는 데 더 큰 비중을 두어야 한다고 제기한다. 본 연구는 CSO 원칙의 향상된 통합을 주장하며, 중국 SOE들이 지속 가능성을 기업 전략 및 지역 사회 상호 작용에 깊이 통합하는 보다 적극적이고 전략적인 관여로 전환할 것을 권장한다. CSR과 CSO 간의 균형을 강화함으로써 기업은 환경 및 사회적 위험을 완화하면서 지역 사회에 대한 이익을 극대화하여 더 강력한 지속 가능한 결과를 달성할 수 있다. Key words:녹색 일대일로; 에너지 부문; 환경, 사회, 경영(ESG); 사회적 책임; 사회적 기회

Modeling Diffusion Induced Stresses for Lithium-Ion Battery Materials

Chiu Huang, Cheng-Kai North Carolina State University 2014 해외박사(DDOD)

Advancing lithium-ion battery technology is of paramount importance for satisfying the energy storage needs in the U.S., especially for the application in the electric vehicle industry. To provide a better acceleration for electric vehicles, a fast and repeatable discharging rate is required. However, particle fractures and capacity loss have been reported under high current rate (C-rate) during charging/discharging and after a period of cycling. During charging and discharging, lithium ions extract from and intercalate into electrode materials accompanied with the volume change and phase transition between Li-rich phase and Li-poor phase. It is suggested that the diffusion-induced-stress is one of the main reasons causing capacity loss due to the mechanical degradation of electrode particles. Therefore, there is a fundamental need to provide a mechanistic understanding by considering the structure-mechanics-property interactions in lithium-ion battery materials. Among many cathode materials, the olivine-based lithium-iron-phosphate (LiFePO4) with an orthorhombic crystal structure is one of the promising cathode materials for the application in electric vehicles. In this research we first use a multiphysic approach to investigate the stress evolution, especially on the phase boundary during lithiation in single LiFePO4 particles. A diffusion-controlled finite element model accompanied with the experimentally observed phase boundary propagation is developed via a finite element package, ANSYS, in which lithium ion concentration-dependent anisotropic material properties and volume misfits are incorporated. The stress components on the phase boundary are used to explain the Mode I, Mode II, and Mode III fracture propensities in LiFePO4 particles. The elastic strain energy evolution is also discussed to explain why a layer-by-layer lithium insertion mechanism (i.e. first-order phase transformation) is energetically preferred. Another importation issue is how current rate (C-rate) during charging/discharging affects diffusion induced stresses inside electrode materials. For the experimental part we first conduct charging/discharging under different C-rates to observe the voltage responses for commercial LiFePO4 batteries. Then Time-of-Flight Secondary Ion Mass Spectrometry technique is applied to measure the lithium ion intensities in different C-rate charged/discharged samples. These experimental results could be used to support that a more significant voltage fluctuation under high C-rates is due to different lithium insertion mechanisms, rather than the amount of lithium ions intercalated into electrode materials. Thus the investigation of C-rate-dependent stress evolution is required for the development of a more durable lithium ion battery. In this dissertation, we extend the single particle finite element model to investigate the C-rate-dependent diffusion induced stresses in a multi-particle system. Concentration dependent anisotropic material properties, C-rate-dependent volume misfits and concentration dependent Li-ion diffusivity are incorporated in the model. The concentration gradients, diffusion induced stresses, and strain energies under different C-rates are discussed in this study. Particle fractures have been observed in many experimental results, in this study we further discuss the effect of the crack surface orientation on the lithium concentration profile and stress level in cathode materials. The results of this dissertation provide a better understanding of diffusion induced stresses in electrode materials and contribute to our fundamental knowledge of interplay between lithium intercalations, stress evolutions, particle fractures and the capacity fade in lithium-ion batteries.

Molecular scale materials assembly investigated by atomic force microscopy

조강래 ProQuest LLC UMI Dissertation Publishing 2011 국내박사

Climate variability and trend on interannual-to-centennial timescales from global observations and atmosphere-ocean model simulations

Paek, Houk ProQuest LLC UMI Dissertation Publishing 2013 국내박사

Canonical correlation between knowledge management system, e-learning system and the development of learning organizations in South Korea

유선주 ProQuest LLC UMI Dissertation Publishing 2013 국내박사

Modernization, revolution, and midwifery reforms in twentieth-century China

안병길 ProQuest LLC UMI Dissertation Publishing 2011 국내박사

한·중 산업화 시대 유랑소설 비교연구 : 황석영과 진응송(陳應松)의 작품을 중심으로

황첸 경희대학교 대학원 2020 국내석사

중한 양국의 산업화 추진으로 양국의 경제는 역사상 유례가 없이 빠른 속도로 발전해 왔다. 뿐만 아니라 양국의 문학도 이 시기에 커다란 성과를 거두었다. 특히 불합리한 인간관계와 부조리한 현실에 대한 질문과 대응을 모색하는 유랑 노동자제재 소설은 학계의 폭넓은 관심을 모았다. 본 논문은 산업화 사회 배경에서 한국 작가 황석영과 중국 작가 진응송 쓴 유랑소설을 대상으로 하여 비교 연구를 진행 하였다. 황석영과 진응송은 산업화시기의 대표 작가로 훌륭한 작품을 많이 창작하였다. 그 시기 사회에서 소외된 노동자들의 비참한 삶은 작품을 통하여 리얼하게 보여주었다. 본고에서 평행 연구의 방법을 사용하여 황석영의 「삼포 가는 길」, 「객지」과 진응송의 「태평개」, 「마스령혈안」등 4편 작품을 연구대상으로 선정하여 분석했고 이를 통해서 작가 의식을 검토 하였다. 우선 본고의 Ⅱ장에서는 한국과 중국의 산업화시기 사회 배경, 황석영과 진응송의 작품 세계를 살펴보았다. 그들의 문학은 형성된 배경, 즉 사회적인 요인을 탐구하여 그들의 작품 특징을 명확하게 규정하였다. 한국과 중국은 다 노동자를 희생한 대가로 산업화 과정을 진행했다. 그리고 중한 양국은 유사성과 비슷한 시대배경으로 공통점이 나타난다. 사회제도와 국정, 그리고 작가의 의식과 창작목적이 다르기 때문에 차이점도 존재한다. 본 논문의 Ⅲ장에서는 양국 유랑소설에 대한 비교 분석을 세 가지 측면에서 전개되었다. 즉 가난하고 궁핍한 생활상, 소외된 삶의 현실, 도덕과 원칙의 상실이다. 첫째, 가난하고 궁핍한 생활상이다. 즉 양국 농민들이 산업화로 인해 고향을 잃어버리거나 돈을 벌 꿈을 가지고 도시나 공사현장으로 왔지만 생활 형편이 농촌에 있을 때보다 좋아지지 않거나 더 악화되었고 결국은 도세에서 떠돌아다니는 유랑자로 전락할 수밖에 없었다. 하지만 두 작가 필하의 이런 유랑 노동자 인물들은 자기의 가난하고 궁핍한 생활상에 대한 반응이 차이점을 볼 수 있다. 황석영 필하 인물들은 적극적인 반항 정신을 가지고 있는 반면에, 진응송 소설에서 노동자들은 무기력으로 약탈을 순종하고 감내한다. 둘째, 소외된 삶의 현실이다. 즉 한국 유랑 노동자든 중국 유랑 노동자든 모두 도시에서 소외당하는 사람들이었다. 대부분 노동자들이 도시에 와서 도시 사람들이 하고 싶지 않은 일을 하고 돈도 도시 사람보다 적게 받지만 도시 사람들이 늘 그들을 낮춰보고 경멸했다. 하지만 한중 양국 작가 작품에 나타나 소외당하는 유랑자들은 자신과 같은 처지인 유랑자에 대한 태도가 같지 않다. 같은 소외당한 인물이지만 황석영의 소설에는 인물 사이에 인간애와 연대 의식을 나타낸 반면에 진응송 소설에는 유랑 노동자들은 자신의 불행만 인식하고 상대를 적대적인 존재로 여긴다. 셋째, 도덕과 원칙의 상실이다. 즉 양국 유랑 노동자들은 도시에서 각종 이유로 도덕이나 원칙을 버렸다. 황석영의 「객지」에서 동혁과 대위는 파업을 시도했지만 결국 실패하는 것에 자신의 이익 때문에 심술부린 노동자인 장씨와 종기는 큰 작 용을 했다고 할 수 있다. 진응송의 「마스령혈안」에서 '나'와 '구재'는 결국 돈을 빼앗기 위해 살인을 저지르는 지경에 이르렀다. 제 Ⅳ장은 결론으로 앞에 진행된 비교 연구 내용을 정리하여 황석영의 소설과 진응송의 소설의 작가의식을 분석했다. 황석영의 「삼포 가는 길」과 「객지」는 가혹한 현실 생활환경을 묘사하는 통시에 인물들이 선량한 본성과 긍정적인 반항정신을 완전히 잃지는 않았다. 리얼리즘적 작품이지만 이상주의적 정서도 갖고 있다고 생각한다. 저자는 작품을 통해 자신의 아름다운 소망을 전달하고 비참한 상황에서도 인간애를 잃지 않기를 호소하는 치유성이 있는 작품이다. 진응송의 「태평개」와 「마스령혈안」은 완전하고 철두철미한 현실주의 작품이다. 작품 속 인물들의 마지막 결말은 모두 극단적인 비극이어서 독자들이 조그만 희망도 느끼지 못한다. 진응송은 이런 철저한 비극을 통해 중국 사회를 풍자했다. 작가는 작품을 통해 우리는 모두 피해자이자 가해자이기도 한다는 생각을 전달하고 우리 스스로를 깊이 반성할 수 있게 한다. This thesis is a comparative study of the homeless novels written by Korean writer Huang Xiying and Chinese writer Chen Yingsong under the background of industrialized society. The works of the two writers truly show the tragic living conditions of the workers at the bottom of society during the industrialization period. This thesis uses a parallel research method to compare and analyze the four works of Huang Xiying's "Road to Senpu", "Kei Di", Chen Yingsong's "Taiping Dog", and "Ma Xi Ling Blood Case". The second chapter examines the social background of the industrialization period in South Korea and China, and the world of works of Huang Xiying and Chen Yingsong. The social factors that influenced the creation of the two writers were analyzed, and the characteristics of their works were analyzed. The third chapter develops a comparative analysis of the two writers' street novels from three aspects. That is, poor living conditions, marginalized living reality, loss of morality and principles. First, poor living conditions. That is, farmers in both countries lost their hometown or came to the city or construction site with the dream of making money because of industrialization, but their living conditions were not as good or worse than in the countryside, and they could only be reduced to homeless people. However, these street workers described by the two writers have different responses to their poor living conditions. Huang Xiying's characters have a spirit of active resistance, but in Chen Yingsong's novels, the workersare unable to obey and endure plunder. Second, the marginalized reality of life. Although the homeless workers of the two countries make a living in the cities, they cannot truly integrate into the life of the cities, and they are alienated and neglected by the urban people. However, the homeless workers appearing in the works of Chinese and Korean writers have different attitudes towards people in the same situation. In Huang Xiying's novels, the characters show a sense of love and jointness, while in Chen Yingsong's novels, the homeless worker only realizes his misfortune and regards the other party as a hostile existence. Third, the loss of morality and principles. Homeless workers in both countries have abandoned morality or principles in cities. In Huang Xiying's "Away Land", the protagonists tried to strike but failed because of betrayal by several people. In Chen Yingsong's "Ma Xi Ling Blood Case", the protagonist's moral loss was embarked on the path of murder. The fourth chapter summarizes the above comparative research contents, and analyzes the writer's consciousness of Huang Xiying's novel and Chen Yingsong's novel. Huang Xiying's "Road to Moriura" and "Keiji" describe that in the harsh real life environment, the characters have not completely lost their good nature and positive spirit of resistance. Although it is a realistic work, it also has idealistic feelings. The author conveys his good wishes through his works, and calls for not to lose the kind heart and human love in the tragic life situation. It is a healing work. Chen Yingsong's "Peace Dog" and "Ma Xiling Blood Case" are downright realistic works. The final endings of the characters in the works are extreme tragedies, leaving readers with no hint of hope. Chen Yingsong satirized Chinese society through this complete tragedy. 本论文以产业化社会背景下韩国作家黄皙暎和中国作家陈应松所作的流浪小说为对象进行了比较研究。两位作家的作品真实地展现了产业化时期社会底层劳动者的悲惨生活状况。本论文通过平行研究的方法,以黄皙暎的「去森浦的路」,「客地」和陈应松的「太平狗」,「马嘶岭血案」四篇作品为研究对象进行了比较分析。第二章考察了韩中两国产业化时期的社会背景,黄皙暎和陈应松的作品世界。研究了当时有哪些社会因素影响了两位作家的创作,并分析了他们作品的特征。第三章从三个方面展开对两位作家流浪小说的比较分析。即,贫穷的生活状态,被边缘化的生活现实,道德和原则的丧失。第一,贫穷的生活状态。即,两国农民因产业化而失去故乡或带着赚钱的梦想来到城市或施工现场,但生活状况却不如在农村时好或更糟,最终只能沦落为流浪者。但是,两位作家笔下的这些流浪工人,对于自己穷困的生活状态的反应却有不同之处。黄皙暎笔下人物具有积极反抗的精神,而陈应松小说中,工人们却无能为力地顺从和忍受掠夺。第二,被边缘化的生活现实。两国的流浪劳动者虽然在城市谋生,但是无法真正融入城市的生活,受到城市人的疏远与冷落。但是,出现在中韩两国作家作品中的流浪劳动者, 对与自己处境相同的人的态度却不尽相同。黄皙暎的小说中,人物之间表现出仁爱和连带意识,而陈应松的小说中,流浪工人只认识到自己的不幸,视对方为敌对的存在。第三,道德和原则的丧失。两国流浪劳动者在城市中抛弃了道德或原则。黄皙暎的「客地」中,主人公们试图罢工却因为几人的背叛导致了失败。在陈应松的「马嘶岭血 案」中,主人公道德沦丧走上了杀人的道路。第四章对以上比较研究内容进行了总结,并分析了黄皙暎的小说和陈应松的小说的作家意识。黄皙暎的「去森浦的路」,「客地」描写了在残酷的现实生活环境,中人物没有完全丧失善良的本性和积极的反抗精神。虽然是现实主义作品,但也具有理想主义情怀。作者通过作品传达自己的美好愿望,呼吁在悲惨的生活境遇中也不要失去善良的本心和人间爱,是一部具有治愈性的作品。陈应松的「太平狗」,「马嘶岭血案」是彻头彻尾的现实主义作品。作品中人物的最后结局都是极端的悲剧,令读者感受不到一丝希望。陈应松通过这种完全的悲剧,讽刺了中国社会。