Monte Carlo simulation of minority carriers transport for the ALIPDE pixel sensors

Liu, Dan Graduate School, Yonsei University 2017 국내석사

CERN에 있는 ALICE(A Large Ion Collider Experiment) 실험을 위한 ITS (Inner Tracking System) 업그레이드가 진행 중 이다. Heavy flavored production과 quark-gluon plasma를 이해하기 위해서는 가속기에 고성능 particle detector가 필요하다. 이를 위해 Monolithic Active Pixel Sensor의 종류인 ALPIDE chip이 디자인 되었다. 대전 된 입자는 입자와 충돌 경로를 둘러싸고 있는 실리콘 원자 사이의 이온화 반응에 의해 생성 된 non-equilibrium carrier를 수집함으로써 픽셀에 의해 검출 될 수 있다. Detector 성능을 결정짓는 중요한 요소는 charge collection efficiency, charge collection time, radiation tolerance 이다. 센서의 주 감지 영역 인 epitaxial layer가 위의 성능을 결정짓는 중요한 층이다. 픽셀의 charge collection efficiency와 collection time을 향상시키기 위하여 epitaxial layer의 전압, 전극의 배치 등을 바꿔가며 시뮬레이션을 하였다. 이 논문에서는 (1) 실제 ALPIDE 센서를 참조하여 단일 픽셀구조와 5 X 5 행렬 구조를 만들고, (2) device 시뮬레이션을 통하여 electric field와 electric potential을 계산 한 후 (3) Monte Carlo 방법을 통해 carrier transport를 시뮬레이션 하였다. 시뮬레이션의 결과는 detector의 전압과 간격이 클수록 보다 큰 potential과 electric field 분포를 갖는다는 것을 보여준다. Radiation은 charge collection 성능을 아주 살짝 변화시킴을 보였다. Charge collection time 은 약 5 ns 이다. ITS (Inner Tracking System) upgrade for the ALICE (A Large Ion Collider Experiment) of the LHC (Large Hadron Collider) at CERN is underway. High performance particle detectors are required to work with the collider to understand heavy flavored production and quark-gluon plasma. ALPIDE chip which is a kind of Monolithic Active Pixel Sensors (MAPS) have been designed. The charged particles can be detected by the pixel by collecting non-equilibrium carriers which are generated by the ionization reaction between the charged particles and the silicon atoms surrounding the impingement path. The key performance parameters for the detectors are charge collection efficiency, charge collection time, radiation tolerance and so on. As the main sensitive area of the sensor, the epitaxial layer is the main object of this work. In order to improve the charge collection efficiency and collection time of the pixel, the epitaxial layer parameters such as different applied voltage, different spacing in the electrode and different radiation environment are simulated to understand the charge collection mechanism. In this paper: (1) using the real ALPIDE chip as a reference design for a single pixel and 5 × 5 matrix structure; (2) evaluating the static factors in sensors such as electric potential, electric field and depletion region based on the device simulation; (3) simulating the carriers transport by the Monte Carlo method. Simulation shows that detectors with large voltage and bigger spacing have a more attractive potential and electric field distribution. The radiation changes slightly the performance of the charge collection performance. The charge collection time is about 5 ns.

Research on the Digital Translation and Contextualized Application of Chinese Cultural Genes : A Case Study of the Jiangsu Section of the Yangtze River

LIU DAN 가천대학교 글로벌캠퍼스 일반대학원 2025 국내박사

As the profound carriers of China’s outstanding traditional culture, Chinese cultural genes possess high symbolic, structural, and transmissible value. Their digital translation and contextualized application play a significant role in promoting the creative transformation and innovative development of culture. In recent years, although China has actively advanced the cultural digitalization strategy—emphasizing the digital transformation and intelligent application of cultural resources—the implementation process still faces challenges, such as fragmented cultural information and contextual distortion, which weaken the expressive power and communicative depth of cultural genes. Additionally, the integration of digital technology and cultural content remains limited, with low degrees of technical adaptability, thereby hindering the creation of high-quality, immersive cultural experiences. In terms of contextualized communication, the practical application of cultural genes in cultural tourism, education, and the creative industries remains at an early stage, lacking systematic mechanisms and theoretical support. Thus, how to systematically conduct research on the digitalization of cultural genes by integrating theoretical logic and practical pathways constitutes the core issue of this study. This research, centering on the theme of "the digital translation and contextualized application of Chinese cultural genes," focuses on the typical cultural regions along the Jiangsu section of the Yangtze River. It aims to address the contemporary question of how to scientifically identify, precisely express, and effectively disseminate cultural genes. Under the Liu Dan Supervised by Prof. Xuehua Jin Dep. of Business Administration Graduate School of GachonUniversity strategic framework of “Digital China” and the ongoing implementation of the national “Cultural Digitalization Strategy,” it becomes urgent to construct an expressive mechanism and communication pathway that suit the digital era, as cultural genes embody the intrinsic spirit and historical memory of Chinese culture. This study establishes a systematic research framework through four dimensions: theoretical construction, mechanism analysis, pathway modeling, and practical evaluation. First, at the theoretical level, this study integrates meme theory, cultural semiotics, communication theory, and experience economy theory to define the connotation, characteristics, and mechanisms of digital communication of cultural genes. A theoretical framework of "cultural genes—digital translation—contextualized application" is developed to explore the expressive logic and cognitive mechanisms of cultural essence in the new media environment. Second, at the developmental mechanism level, it outlines the evolutionary stages of the digitalization of cultural genes, analyzing the triadic drivers of policy, technology, and market forces, and reveals the path from digital collection to integrative innovation. On this basis, by employing case study methodology, the research focuses on the digital expression practices in northern, central, and southern Jiangsu, constructing three types of translation and contextualization pathways: protective digital translation with immersive expression, diverse digital translation with situational reconstruction, and precise digital translation with experiential dissemination. These demonstrate the diversity of cultural expression paradigms and the adaptability of technological pathways. At the methodological and evaluative levels, this study further constructs a structural system for the digitalization of cultural genes, comprising four standards: content organization, translation expression, technical integration, and rights management. It also designs an evaluation framework based on five dimensions—authenticity, integrity, applicability, user experience, and social impact—offering an executable model for the digital governance of cultural heritage. In addition, the study proposes transferable strategic recommendations in areas such as platform construction, public engagement, and international communication, facilitating the coordinated evolution of cultural genes from datafication to visualization, interactivity, and industrialization. The findings indicate that the digital translation of cultural genes has evolved from early-stage information storage to stages of structural expression, symbolic reconstruction, and interactive dissemination. Its internal mechanisms rely not only on technological tools but also on systematic cultural logic. The digital expression of cultural genes exhibits hierarchical, polysemous, and variable characteristics, and effective translation requires multi-dimensional coordination among abstraction, symbol construction, technical embedding, and media adaptation. The differentiated practices across northern, central, and southern Jiangsu demonstrate that cultural digital translation strategies must be adapted to local contexts, with protective, precise, and diverse approaches each holding distinct value in varying cultural ecologies. The main innovations of this research lie in four aspects: theoretical construction, pathway exploration, methodological integration, and practical application. Theoretically, the study constructs a systematic framework based on the triadic structure of "cultural genes—digital translation—contextualized application," advancing interdisciplinary integration among cultural gene studies, digital humanities, and media technology. In terms of translation pathways, it proposes the matching relationships between three translation paradigms (protective, precise, and diverse) and three contextual application modes (immersive, situational, and experiential), thereby expanding and enriching the theory of cultural digitalization pathways. Methodologically, it integrates multi-source data, field investigations, and case analyses to form a comprehensive research loop covering technical analysis, user participation, symbolic construction, and communication mechanisms. Practically, it develops a quantifiable evaluation index system for the digitalization of cultural genes, offering institutionalized and standardized tools and practical support for the digital governance of cultural heritage based on authenticity, integrity, applicability, user experience, and social benefit.

The Implementation of Smart Home System Based on 3G and ZigBee in Wireless Network System

Liu Dan Chonnam National Univ. 2012 국내석사

Physical Properties and Transformations of Low-Dimensional Systems

Liu, Dan Michigan State University ProQuest Dissertations & 2019 해외박사(DDOD)

Evolving from the macroscopic scale to the nanometer scale, in particular by reducing the dimensionality, fundamental properties (such as electronic and mechanical properties) of certain systems exhibit dramatic changes, which not only give rise to a wide range of emergent phenomena, but also boost technology development including nanoelectronics, optoelectronics and catalysis. In this thesis, I utilized combined techniques including density functional theory (DFT), molecular dynamic simulations (MD), continuum elasticity approach, and the tight-binding model to conduct a systematic study on low-dimensional nanostructures regarding their electronic and mechanical properties as well as underlying microscopic transformation mechanisms between different structural allotropes.First, I briefly introduce the motivation and background of this thesis. Then, in Chapter 2, I describe the computational techniques, mainly the DFT approach, on which most of my thesis is based.In Chapters 3 and 4, I apply the continuum elasticity method to study the phonon spectrum of two-dimensional (2D) and one-dimensional (1D) systems. My results highlight advantages of the continuum elasticity approach especially for the flexural acoustic phonon modes close to the Γ point, which are otherwise extremely hard to converge in atomistic calculations that use very large supercell sizes.From Chapter 5 to Chapter 7, I focus on allotropes of group III, V and VI elements and study both their stability and microscopic transformation mechanisms from one allotrope to another. First, I predicted a stable phosphorus coil structure, which may form by reconstruction of red phosphorous, and which was synthesized by filling a carbon nanotube with sublimed red phosphorus. Second, I proposed two stable 2D allotropes of Se and Te. I also suggested and evaluated a promising fabrication approach starting from natural 1D structures of these elements. After considering low-dimensional charge neutral systems, I changed my focus to study the effect of net charge on the equilibrium structure. Considering a heterostructure of alternating electron donor layers an monolayers of boron, I have identified previously unknown stable 2D boron allotropes that may change their structure under different levels of charge transfer.From Chapter 8 to Chapter 10, I focus mainly on carbon-based nanomaterials and their properties. In Chapter 8, I proposed a way to enhance the density of states at the Fermi level in doped C60 crystals in order to increase their superconducting critical temperature to room temperature. In Chapter 9, I have investigated a shear instability twisted bilayer graphene using the tight binding model. This system is susceptible to very small structural changes, since it becomes superconducting in a very narrow range of twist angles near the 'magic angle'. In Chapter 10, I introduced the cause of an unusual negative Poisson ratio and a shape-memory behavior in porous graphene with an artificially designed pattern.In Chapter 11, I finally present general conclusions of my PhD Thesis.

Durability study of proton exchange membrane fuel cells via experimental investigations and mathematical modeling

Liu, Dan Virginia Polytechnic Institute and State Universit 2006 해외박사(DDOD)

In this dissertation, novel approaches to PEMFC durability research are summarized. These efforts are significantly different from most other studies on durability in that rather than focusing on chemical degradation, more attention is given to the mechanical aspects of the PEMFC system. The tensile stress-strain behavior of NafionRTM 117 (N117) and sulfonated poly(arylene ether sulfone) random copolymer (BPSH35) membranes is explored under ambient conditions, with respect to the effects of initial strain rate, counterion type, molecular weight and the presence of inorganic fillers. A three-dimensional "bundle-cluster" model is proposed to interpret the tensile observations, combining the concepts of elongated polymer aggregates, proton conduction channels as well as states of water. The rationale focuses on the polymer bundle rotation/interphase chain readjustment before yielding and polymer aggregates disentanglement/reorientation after yielding. In addition, the influence of uniaxial loading on proton conductivity of N117 and BPSH35 membranes is investigated. When the membranes are stretched, their proton conductivities in the straining direction increase compared to the unstretched films, and then relax exponentially with time. The behavior is explained on the basis of the morphological variations of hydrophilic channels, accompanied by the rotation, orientation and disentanglement of the copolymer chains in the hydrophobic domains, as illustrated with the help of our bundle-cluster model. Finally, the long-term aging of hydrogen-air PEMFCs is examined with a cyclic current profile and under constant current conditions. The end-of-period diagnosis is performed for both MEAs at 100h aging intervals, including a series of cell polarization, impedance and electrochemical experiments. The results demonstrate that hydrogen crossover is the most significant result of degradation for the MEA under cyclic aging mode due to the formation of pinholes at approximately 500-600h, and mass transport limitations are the major degradation sources for constant current mode. A phenomenological mathematical model is set up to describe the PEMFC aging process under both cyclic and constant conditions.

중국 대학생의 한국유학 선호도에 관한 연구

Liu Dan 충북대학교 2010 국내석사

Along the development of science and technology, the world has become a global village, more and more students tend towards studying abroad with the reform and open-door policy carried out since 1950' of last century. Studying abroad is a popular academic option for university students around the world. Most students study abroad for specific academic and professional objectives, pursuing educational opportunities that are not available at home, or seeking the quality and prestige of educational institutions in foreign countries. Others study abroad for less specific objectives, such as improving foreign language skills, acquiring knowledge about a foreign country through courses, as well as experiencing life in a foreign country. A lot of factors effect the students' choice in the selection of foreign countries, such as the economic conditions, individual competency, the educational strength of the universities, the cultural distance and so on, the students' preference plays an important role among these factors. In this study, the college students' preference on studying in Korea was investigated, the reliability and propriety were analyzed using SPSS and the "what-if" analysis was carried out using Amos. Three parts are included in this study: questionnaire design, questionnaire survey and statistic analysis. The questionnaire investigation was conducted in December, 2009. The college students joined in the study are from Heilongjiang University, Yanbian University, Jilin institute of chemical technology and Weifang College. 215 questionnaire were recollected totally. The investigation results indicated that: Firstly, South Korea trend, which is included in inner motivation, affects the awareness on the nation. The higher degree of goodwill, the higher awareness on Korea. Secondly, extrinsic motivation of studying abroad affects the awareness on the nation, low living expenses and low tuition enhance the Chinese students' awareness on Korea. Thirdly, the advise from others has effects on the chinese students' awareness to Korea, their awareness on Korea can be raised with the persuasion from their parents, teachers and friends. Fourthly, Korean educational level has no effects on the national awareness, because Chinese students scarcely understand Korean education, on the other way, Korean colleges make a poor advertising in this respect. Fifthly, the national awareness affects the Chinese students' preference on studying in Korea, the higher national awareness, the higher preference.

Research on the Performance of Chinese Private SMEs from the Perspective of Leadership

LIU DAN 가천대학교 일반대학원 2022 국내박사

ABSTRACT The ability of enterprise leadership is the soul of the enterprise and the core element that determines the enterprise performance. The personal characteristics, management ability and professional ability of enterprise leaders play a vital role in the development of the enterprises. Based on the data of Chinese private small and medium-sized enterprises, the paper analyzes their leadership and enterprise performance through empirical research. Explore what kind of leadership people will succeed,what elements leaders need to have to improve business performance, and how there is the impact of the company’s life cycle on business performance. Analyzing the influence of multiple dimensions on the enterprise performance of leadership through interviews and issuing questionnaires, a quantitative analysis of the data obtained from the recycling questionnaire was conducted to find out the leadership elements that have a significant impact on the enterprise performance, and provide a theoretical basis for the research of this paper. Therefore, this paper chooses the perspective of private enterprise performance research, by combining the current Chinese economic development environment and the background of dynamic changes, in different life cycles of the enterprises, to verify the influence of leader leadership on enterprise performance, and then by analyzing the factors that influence the leadership to get suggestions to guide enterprises so as to improve leadership to increase the level of enterprise performance. On this basis, this paper mainly studies and discusses the interrelationship between leadership, life cycle and enterprise performance, in which we put forward the following hypotheses: 1.Leadership is positively related to enterprise performance. 2.Laissez-faire leadership during the enterprise growth stage is positively related to enterprise performance. 3.Despotic leadership during enterprise prosperity stage is negatively related to enterprise performance. 4. Democratic leadership during the enterprise recession stage is negatively related to the enterprise performance. 5. Enterprise life cycle has a regulating effect on leadership affecting enterprise performance. To test the hypotheses, 500 valid questionnaires were issued, and 448 valid questionnaires were recovered. Through the reliability analysis, validity analysis test, descriptive statistics analysis, correlation statistics analysis and regression data statistics analysis that were performed on questionnaire statistics by SPSS25 & STATA16 system, and the analysis of 11 factors that influence the leadership, in which the indicators related to leadership can be obtained to help enterprise leaders find ways to improve leadership and promote the improvement of enterprise performance.

뉴미디어 시대 중국의 패션 관련 1인 미디어 운영전략 비교연구 : 리베카의 이상세계 및 심야발치를 중심으로

LIU DANRU 홍익대학교 대학원 2021 국내석사

중국 민간(사립)양로시설 거주노인의 생활만족도에 영향을 미치는 요인에 관한 연구 : 산동성(山東省) 제닝시(濟寧市)를 중심으로

劉丹 고려대학교 대학원 2015 국내석사

내부통제의 질과 회계정보품질간의 관계 연구

유, 단 부산대학교 대학원 2017 국내석사

회계정보의 이해관계자들의 경제적 의사결정에서 유용해야 한다. 회계정보의 질은 직접 정보사용자의 의사결정에게 영향을 미친다. 회 계정보를 적정하게 공시하고, 회계정보의 질을 제고하는 것은 재무회 계연구에 있어서 중요한 과제라고 할 수 있다. 현대 회계이론 분야에 서 회계정보의 질을 제고하려면 기업의 내부통제를 강화하고 완성해야 한다. 내부통제는 기업의 경영활동 중에 중요한 부분이고 실제 작업 비중도 갈수록 중요성이 증가하고 있다. 내부통제 수준을 제고하고 내 부통제평가를 강화하는 것은 매우 중요한 과제이다. 본 연구는 선행연구에 기초하여 내부통제 평가시스템을 구축하고, 내부통제시스템의 질과 회계정보 품질 간의 관련성을 연구하였다. 내부통제와 회계정보품질의 이론적인 배경을 통하여 내부통제와 회 계정보품질의 관련성을 이론적으로 연구하였다. 또한 내부통제의 질과 회계정보품질의 관련성을 실증적으로 분석하였다. 본 연구는 선행연구를 기본적으로 참고하고 COSO보고서와 내부통 제평가지도 및 내부통제에 관한 법규를 참조하여 리스크 관리를 위한 내부통제평가시스템의 문항을 개발하였다. 그리고 층계분석법((analytic hierarchy process))을 이용해서 내부통제평가 지수를 계산하였다. 본 연구에서 회계정보품질은 수정Jones모형을 사용하였으면서 재량적 발 생액으로 회계정보의 질을 측정하였다. 실증적인 자료 분석을 위해 2015년 중국 선전(深圳)증권거래소에 상 장된 A주식을 발행하는 기업을 대상으로 자료를 조사하였으며, 모든 데이터는 선전증권거래소와 CSMAR 데이터베이스의 자료를 이용하여 분석하였다. 본 연구의 연구결과는 다음과 같다. 첫째, 내부통제와 재량적 발생액은 음(-)의 관련성이 있었다. 즉, 내 부통제의 질이 좋을수록 이익조정 정도가 낮고, 회계정보품질이 높게 나타나고 자산의 규모가 클수록 이익조정 정도가 낮아지고 회계정보품 질이 높아진다고 볼 수 있다. 둘째, 내부통제환경과 재량적 발생액은 음(-)의 관련성을 있었다. 즉, 내부통제환경이 좋을수록 재량적 발생액이 낮아지고 회계정보의 질이 높아진다. 내부통제환경은 어느 정도에 회계정보품질을 제고함에 있어 서 도움을 되는 것으로 추정할 수 있다. 셋째, 내부통제평가지수 가운데 목표수립 지수와 재량적 발생액사이 에는 음(-)의 관련성을 있는 것으로 분석하였다. 기업의 일상에서 회계 목표가 상대적으로 명확하면서, 구체적인 회계정책과 내부통제가 유지 될 때 효율적인 운영이 가능할 것이다. 즉, 목표수립의 지수가 높을수 록 재량적 발생액이 낮아지고 회계정보의 질이 좋아질 수 있음을 확인 할 수 있었다. 넷째, 내부통제평가지수 가운데 위험평가 지수와 재량적 발생액 간 은 음(-)의 상관관계가 있었다. 기업은 일상 관리 중에 존재하는 위험 에 대해서 상응한 평가와 관리가 이루어지면 기업 경영관리에 유리한 도움이 될 수 있다. 즉, 회계정보의 질은 좋아질 수 있다. The most essential feature of accounting information is usefulness in the economic decision. The quality of accounting information has a direct effect on the decisions and consequences of decision-makers. However it is an undoubted fact that the quality of accounting information is becoming worse and worse. How to improve the quality of information disclosure and the quality of accounting information has become an important subject in the field of financial accounting. Now, all of theorists agree with that: in order to improve the quality of accounting information, we must pay more attention to the effectiveness of internal control, which has a great influence on the quality of accounting information. Internal control is an indispensable part of the company management activities and it becomes more and more important in the practical work. Therefore, many people have appealed for the improvement of internal control and enforcement of internal control assessment. On the basis of existed studies in theory circle, considering the deficiency of current researches, this thesis mainly focuses on the construction of internal control assessment system and the relationship between the quality of internal control and the quality of accounting information, hoping to provide new ideas for related studies. First, after reviewing the related theories on accounting information quality, this thesis takes the common theoretical basis of internal control and accounting information quality as starting point, and then analyzes the relationship between the two theoretically. This part of work can provide theoretical support for the later empirical study. Second, this thesis constructs the evaluation system of internal control using “COSO” and the “Guideline of internal control” for reference, adopts the AHP method to get the weight, and finally got the ICI index. Further more, this thesis chooses the Adjusted Jones Model to compute the control lable accrual profit, and uses it to measure the earning information quality. We also try to analyze the accounting information from the earning point. Third, this thesis studies the relationship between the quality of internal control and quality of accounting information by means of empirical analysis. Meanwhile it pays great attention to the environment of internal control-one of the most important aspects of internal control. The result indicates that the internal control has the opposite effect on accounting information and the environment of internal control plays an important role. Last, this thesis gives some advices on how to improve the internal control and draws the main conclusion based on the theoretical and empirical research and points out the deficiencies. It also forecasts the future of this research.