다양한 광추출 구조를 적용하여 향상된 유기발광다이오드의 광추출효율

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 재료공학부, 2018. 2. 김장주.Organic light-emitting diode (OLED) is promised lighting sources as lightings and display. In order for OLEDs to be utilized in the industry, the light extraction efficiency of OLEDs needs to be improved further. The light extraction structure for the display requires high light extraction efficiency improvement, low spectral change depending on the viewing angle, low pixel blur and high contrast ratio. In addition, fabrication process that does not damage the thin top electrode layer is required for top-emitting OLED (TEOLED). The light extraction structure for the lighting requires high light extraction efficiency improvement, low spectral change depending on the viewing angle, uniform emission pattern and high color quality. Bottom-emission OLED (BEOLED) are selected for lighting so, various light extraction method can be applied. High power efficiency and color quality are required to compete with other light sources, including LEDs. To enhance extraction efficiency, various light extraction methods have been reported such as, microlens array, photonic crystal, scattering film, corrugated device etc. Among various methods, fabrication of organic micro cone array by vacuum deposition has potential as light extraction structure for display because of damage-less fabrication method, high enhancement ratio and spectral stability. But, size of the organic structure needs to be reduced in order to meet the actual display manufacturing time. In addition, when the size of structure goes to nano, precise optical simulation is needed for calculating optimized structure. As light extraction structure for lighting vacuum nano hole array (VaNHA) has potential with electrical stability due to flat surface, high extraction efficiency in comibation with half-spherical lens. Green OLED with hexagonal VaNHA and half spherical lens was demonstrated to extract air, substrate and waveguide mode but, for uniform emission pattern, hexagonal pattern cant be applied in lighting. This thesis concerns two research topics: (1) extraction efficiency of TEOLED with organic nano lens array (NLA) for display, and (2) extraction efficiency and color quality of OLED with VaNHA for lightings. Our analysis shows that each method could reach the proper light extraction method for display and lightings. The paper consists of two parts as display and lighting. In Chapter 1, efficiency of OLED, the optical loss path, the light extraction methods, and finite difference time domain (FDTD) method are briefly reviewed. In Chapter 2, we first explain the process of calculating the optical property distribution of a top-emitting OLED with light extraction structure by FDTD method. We will discuss the computational complexity of the finite difference method, and compare it with the calculated value of the classical electromagnetic dipole model for the verification of the above calculation results. Next, the calculation results of the light extraction efficiency of the TEOLED with the hexagonal NLA are described. In Chapter 3, we discuss the TEOLEDs with organic nano lens array (NLA). Oragnic NLA can be fabricatied without damage to OLED, by organic vapor phase deposition (OVPD) method. Acheivable extraction efficiency of NLA was calculated by FDTD modelling. With simulation result, optimal distribution for extraction is suggested and with high refractive index material and height of NLA, higher extraction efficiency can be achieved than efficiency with organic material (n=1.8). TEOLED with NLA showed enhanced efficiency of 50% with low pixel blur and low spectral change with viewing angle. Blue emitting TEOLED with NLA also showed enhancement ratio of 1.5 with low spectral change with viewing angle. In Chapter 4, we discuss the white OLED with randomly distributed VaNHA with unprecedently high efficiency of EQE 78% and power efficiency of 164 lm/W. Random pattern consists of 3 kinds of pillars with different radius of 120, 150 190 nm. With combination of half-spherical lens, almost air, substrate and waveguide mode of light can be extracted. By mode analysis calculation, extractable light can be increased with thick distance from metal electrode and emitting dipole. By random distribution, white OLED with VaNHA showed uniform emission pattern and spectral stability with viewing angle. FDTD calculations were performed to investigate the origin of high light extraction efficiency enhancement of Si3N4 and air extraction structures. The larger the difference between the refractive index of the dielectric layer and the nano hole array, the larger the light extraction efficiency. In Chapter 5, we discuss the theoretically achievable color quality of white tandem devices with various light extraction structure. First, color quality according to the proportion of the emitting dyes was calculated which is ideal value whole photolumeniscent (PL) spectrum is extracted. In consideration of micro cavity, achievable color quality of device without light extraction layer, device with half spherical lens, device with high refractive index and lens, device with high refractive index substrate and lens and elongated distance with dipole and metal electrode. Simulation result is compared with experiment result and matched well. By based this model, highly efficient tandem OLED with high color temperature ( > 5,000 K) can be fabricated. The WOLEDs showed maximum EQEs of 45.6 and 79.4% and maximum LE of 48.9 and 94.0 lm/W for WOLED without and with lens, respectively.Chapter 1. Introduction 1 1.1. Efficiency of OLEDs 1 1.2. Optical loss modes in OLEDs 3 1.3. Light extraction method of OLEDs 5 1.4. Finite difference time domain method 9 Chapter 2. Optical simulation method of light extraction in top emitting organic light emitting diode using finite difference time domain method 13 2.1. Introduction 13 2.2. Methodology of optical analysis of light extraction 15 2.3 Result and Discussion 21 2.4 Conclusion 30 Chapter 3. Enhanced light extraction efficiency of top-emitting OLED by using nano lens array fabricated by organic vapor phase deposition method 31 3.1. Introduction 31 3.2. Optical simulation 34 3.3. Experiment 41 3.4 Result and Discussion 45 3.5 Conclusion 54 Chapter 4. Theoretically achievable light extraction efficiency of white organic light emitting diode with vacuum nano-hole array 55 4.1. Introduction 55 4.2. Experiment 58 4.3 Result and Discussion 62 4.4 Optical simulation for extraction of waveguide mode 76 4.5 Conclusion 81 Chapter 5. Theoretically achievable color quality of white tandem OLED with various light extraction layers 82 5.1. Introduction 82 5.2 Optical simulation for high color quality 87 5.3 Experiment 96 5.4 Result and Discussion 99 5.4 Conclusion 105 Appendix 106 Bibliography 115 초록 124 CURRICULUM VITAE 129 List of Publications 131 List of Presentations 133Docto

Enhancement of Light Extraction Efficiency of Organic Light Emitting Diodes using Spin-on Glass based Randomly Dispersed Nano-pillar Arrays

학위논문 (석사)-- 서울대학교 대학원 : 재료공학부(하이브리드 재료), 2013. 2. 김장주.Randomly dispersed nano-pillar array (RaDNA) was embedded between the transparent electrode and the glass substrate to extract lights confined inside organic light emitting diodes (OLED). The room-temperature nano-imprining lithography (RT-NIL) was employed for the fabrication of RaDNA. Spin-on glass was utilized as a material of the nano-pillar array for stable devices. The pillar arrays were planarized before fabrication of OLEDs using a high refractive index material (trialkoxysilane-capped PMMA-titania hybrid optical material) to reduce the leakage current. The RaDNA OLED showed 7% enhancement in normal direction and 19% enhancement of light extraction efficiency in an integrating sphere. The emission pattern of RaDNA device showed no variation of emission spectrum with azimuthal angle and viewing angle.Abstract i Contents iii List of Tables v List of Figures vi Chapter 1 Introduction 1 1.1 Organic light emitting diode: principle and limitation of efficiency 1 1.2 OLEDs with randomly dispersed nano-pillar array (RaDNA) 5 1.3 Spin-on glass for stable RaDNA OLEDs 9 Chapter 2 Fabrication and characterization of spin-on glass RaDNA substrate 12 2.1 Introduction 12 2.2 Fabrication of RaDNA substrate 13 2.3 Planarization of RaDNA substrate 16 2.4 Characterization of RaDNA substrate 18 Chapter 3 Application of SOG RaDNA substrate in green phosphorescent OLEDs 30 3.1 Design of green phosphorescent OLEDs 30 3.2 Fabrication of green phosphorescent OLEDs 33 3.3 Characterization of green phosphorescent OLEDs 35 Chapter 4 Conclusion 39 References 40 요약 (국문초록) 42Maste

습답 쇄토 작업에 대한 변속기 부하 특성에 관한 연구

학위논문(석사)--서울대학교 대학원 :농공학과 농업기계전공,1999.Maste

Development of Contractor’s Risk Response Plan for Procurement and Supply on EPC Projects: Steel Plant Cases

MasterDue to uniqueness of the plant construction industries, the importance of procurement management in the plant construction projects is increasing. But because most activities are related to procurement management performed by external stakeholders, the projects have been exposed to relatively large risks. Thus, for the success of the project, contractor needs more attention to procurement management in contracting stage of EPC project life cycleThe purpose of this study is to identify the major risk factors which are related to the procurement of EPC project, and to propose an efficient response plans for the success of the EPC project.Based on some study in this report, the results of study and analysis are summarized as follows.First, project risk management process and procurement process for plant project is analyzed based on reference papers. Second, the major risk factors in EPC projects for steel making plant were identified. Third, priorities of the main risk factors were determined utilizing P-I Matrix method. Fourth, the risk response plans, and the checklist for risk management on the project life-cycle were proposed. Fifth, a case study performed based on checklist proposed in this report for steel making plant and expert validation carried out in order to improve the credibility of the proposed process for possibility of plant business.The outcomes of this study are that (1) the development of the check-lists for identification of procurement risks and (2) effective risk response measurement for managing risk management process for steel making plants.Utilizing the proposed risk assessment tools, it is expected that the goals of the project (i.e. within budget, on time delivery and higher quality) improve project management competency for risk and will be substantially achieved for EPC projects

작용소 공간의 조건 C

학위논문(박사) --서울대학교 대학원 :수리과학부,2007.Docto

플라즈마 식각 공정에 대한 실시간 종말점 및 이상진단

Thesis(doctors) --서울대학교 대학원 :응용화학부, 2008.8.Docto

A Study of System and Practices of Pension for People of Merit in North Korea

본 논문은 국민연금연구원(2017)의 ｢북한 노후소득보장 제도 및 실태 연구｣의 일부 내용을 발췌, 수정한 것임.본 연구의 목적은 북한 원자료(법령과 사전)에 기초하여 북한 공로자년금 제도를 분석하고 북한이탈주민 인터뷰를 통해 공로자년금 실태를 파악함으로써 제도와 실태 간 일치수준을 탐색적으로 분석하는 것이다. 또한 북한 공로자년금 제도가 독립된 특수직역연금제도 또는 특별연금제도인지 아니면 통합된 연금제도 내의 부가급여 제도인지를 파악하고자 한다. 본 연구의 주요 연구방법은 1946년부터 2016년까지 공로자년금과 관련된 북한 법령과 북한 사전을 통한 공간문헌 분석 및 공로자년금을 경험한 북한이탈주민에 대한 질적 인터뷰이다. 주요 연구 결과는 다음과 같다. 첫째, 제도와 실태 간 일치 수준에 대한 분석결과, 완전 일치의 경우, 공민이면 누구나 공훈에 따라 공로자년금 대상이 될 수 있는 적용대상 기준, 년로년금 수급연령과 동일한 연령 기준, 공훈과 연동한 급여 수준, 일반 근로자보다 높은 급여수준, 통합 재정체계 및 통합 전달체계라고 할 수 있다. 부분 일치의 경우, 급여종류에 있어서 공로자년금과 공로자유가족년금은 확인되나 공로자로동능력상실년금은 확인되지 않는다는 점이다. 둘째, 공로자년금은 독립된 특수직역연금제도 또는 특별연금제도가 아니라고 할 수 있다. 재정과 전달체계가 기존 년금제도에 통합되어 있기 때문에, 통합된 하나의 제도 내에서 부가급여를 제공하기 위한 특별현금급여라고 해석될 수 있다. 본 연구를 통해 통일 후 연금제도 통합 시 북한 주민의 사회보장수급권과 재산권을 보장하고, 불필요한 행정심판 및 행정소송을 최소화하여 사회적 비용을 완화하기 위한 기초자료로 활용되기를 기대한다.The purpose of this study is to analyze the pension for people of merit based on the North Korean original data(laws and dictionaries) and to analyze the level of consensus between the system and actual situation by analyzing the actual condition of the beneficiary through interviews with North Korean defectors. In addition, through the analysis of the system and actual situation, it is aimed to understand whether the pension for people of merit is an independent pension system or an additional benefit system in the integrated pension system. The main research method of this study is the qualitative interview about North Korean refugees who have experienced the North Korean legislation related to the pension for people of merit from 1946 to 2016 and the analysis of the original document. The results of this study are as follows. First, as a result of the analysis of the level of agreement between the system and actual situation, in the case of perfect agreement, anyone who is a citizen can become eligible subject to merit pension according to the meritorious year, the same age as the old-age pension, pension level linked with merit, higher pay levels than ordinary workers, an integrated financial system and an integrated delivery system. In the case of partial agreement, the pension for people of merit and the survivors pension for people of merit are identified in the type of benefit, but the disability pension for people of merit is not confirmed. Second, the pension for people of merit is not an independent special pension system. Since the financing and delivery system is integrated into the existing pension system, it can be interpreted as a special cash benefit to provide additional benefits within an integrated system. Through this study, it is expected that the integrated pension system after unification will guarantee social security rights and property rights of the elderly in North Korea, and will minimize unnecessary administrative judgments and administrative litigation, and will be alleviate social costs using this basic data

Physical entertainment media using I/O coupling units

학위논문(석사) - 한국과학기술원 : 문화기술학제전공, 2006.2, [ 85 p. ]최근 활발히 이루어지고 있는 컴퓨팅 자원과 네트워크 인프라의 편재화는 미디어에 새로운 변화를 가져오고 있다. 이제까지 PC를 비롯한 정보기기에 집중되어 있던 디지털 콘텐츠가 물리적 현실 세계로 확산되는 움직임이 나타나고 있는 것이다. 본 연구에서는 디지털 콘텐츠와 물리적 미디어가 유기적으로 결합할 수 있는 가능성을 모색하고자, 입출력 일체화 개체인 ‘I/O 셀(Cell)’과 그 집합체인 ‘텐저블 게임 콘솔(Tangible Game Console)’을 개발하였다. I/O 셀은 여러 종류의 센서와 액츄에이터가 하나의 물리적 노드 내에 통합되어 있는 개체로, 이 I/O 셀 다수를 집적하면 다양한 크기와 용도의 엔터테인먼트 미디어를 구성하는 것이 가능하다. 그 중 하나로 개발된 텐저블 게임 콘솔은 일종의 센서-액츄에이터 네트워크로 셀들 사이의 연계를 통해 다양한 물리적 정보를 인식하고 표현할 수 있다. 텐저블 게임 콘솔은 기존 게임 콘텐츠의 주요한 표현 수단이었던 이미지와 텍스트 정보 대신에 물리적 정보를 통해 게임 콘텐츠를 구성하며, 조작대상과 조작수단이 일체화되어 있고, 또한 음악, 퍼즐, 액션 등 다양한 장르의 게임 콘텐츠가 적용 가능하다는 특징을 가지고 있다. 텐저블 게임 콘솔에서는 불, 바람, 물, 생명체 등의 물리적 현상을 형상/움직임/소리/빛 등을 통해 재현하며, 사용자는 이를 때리기/바람불기/흔들기/기울이기 등의 직접적인 조작을 통해 체험할 수 있다. 또한 물리적인 상호작용 과정이 일정한 게임 규칙을 가지고 구성되어 있어 지속성 있는 놀이 경험을 제공한다. 텐저블 게임 콘솔의 콘텐츠로는 표면 상에서 움직이는 벌레를 때리는 동작을 통해 자연스럽게 음악을 연주할 수 있는 <Beat Bug>, 다양한 물리적 방법을 동원하여 한 작은 생명체를 지켜내야 하는 <Saving A Life>, 두 사람 사이에 촉감을 전달하며 게임을 즐길 수 있는 <Touching & Touched> 등이 있다. 본 연구는 텐저블 게임 콘솔과 그 콘텐츠를 개발하고 평가함으로써, 디지털 콘텐츠와 물리적 요소가 유기적으로 결합된 새로운 엔터테인먼트 미디어의 가능성을 타진한다.한국과학기술원 : 문화기술학제전공