Characterization of Solution Processes for Small Molecule Organic Light-Emitting Diode

조민준 성균관대학교 일반대학원 2013 국내석사

Solution-processed organic light emitting diodes (OLED) have been demonstrated with small molecule by using three solution processes. Spin-coating, electrospray deposition process(ESD) and electrohydrodynamic (EHD) jetting are employed as the way for deposition method. Mostly, polymer host has been used for solution process with good film formation property. However, polymer host has some problem such as difficulty of purifying and low electroluminescence property. Therefore, 4,4'-N,N'-dicarbazolebiphenyl (CBP) which is typical small molecule based ink is used for spin-coating and electrospray method. For three solution processes, various process variables and materials properties were investigated including solvent effect, annealing conditions, ETL molecular structures and so on. In spin-coating process, electron transporting material, annealing conditions and solvent effect was investigated to get highly efficient OLED device. Since 2,2',2''-(1,3,5- Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)(TPBi) had low highest occupied molecular orbital and high thermal stability, efficiency dramatically increased with TPBi. And annealing conditions for both removing solvent and avoiding crystallization were studied. Proper annealing condition(60℃ for 1hour) could raise the current efficiency almost twice. In case of solvents, dichloroethane(DCE) showed good film formation and device performance because of high viscosity and appropriate boiling point. Consequently 46.22cd/A of efficiency was obtained in use of TPBi as an ETL, annealing in 60℃ for 1hour with DCE as a solvent. ESD process has potential of bulk production in comparison CBP. However, it was hard to form uniform thin film with CBP based ink because of aggolomerate phenomenon. This was from molecular structure of CBP which didn't have branch structure. To make uniform thin-film, derivatives synthesis of CBP structure was fulfilled by removing one carbazole group in CBP. Due to elimination of carbazole group which had high hole mobility, device performance was lower than original CBP based device. 5 devices were fabricated with varying the ratio of CBP and its derivatives. Finally, 23.45cd/A of efficiency was obtained when the ratio between derivates and CBP was 1:4. The result showed possibility of ESD process which can be an alternative of spin-coating With EHD process, patterning fine lines for high resolution OLEDs was fulfilled for large area display. EHD jet printing is strongly dependent on ink properties and process conditions such as applied voltage, pressure, distance nozzle and substrate, speed of the moving stage and surface properties. For characterization those dependences, instead of polymer, small molecule ink was used because polymer could not fill the lighting area and make stable jetting. Considering vaporization problem and nozzle clogging problem, dichloroethane and dichlorobenzene were selected as solvent. Fine line patterning trends were investigated by changing applied voltage, line motor velocity and distance between nozzle and substrate. As a result, up to 30um pattern was achieved and it could be a promising technology for solution process. It is expected that these solution processes can be a good alternative of vacuum deposition technology.

Quality Control System Using Wafer Limit Management Reflecting Interrelated Processes

Eun Soo Kim 고려대학교 대학원 2025 국내석사

Manufacturing must provide products for customers that meet a certain quality standard. Even under the same process conditions, the basic characteristics and the influence on the process of each product could be different. This leads to a distribution of characteristics in the final products, resulting in some degree of deviation. Therefore, to maintain a certain quality, it is necessary to manage process conditions and control deviations in product characteristics. In this study, we analyzed the wafer limit control management method and machine learning. We analyzed and compared the correlations between semiconductor manufacturing processes such as etching, lithograph, etc. The effect of wafer limit management was reliable when there was a high correlation between processes. Through highly correlated processes, abnormal wafers could be detected using a new indicator based on standard deviation. Compared to abnormal wafer detected through machine learning, it showed the same level of detection. The abnormal wafers detected by the new indicator could undergo additional care items, such as full wafer measurement, process compensation, and full wafer screening. With each wafer limit management rather than process limit management, even on abnormal wafer could be detected early and, as a result, quality cost could be minimized. 제조업은 고객에게 특정 품질 기준을 만족하는 제품을 제공해야만 한다. 하지만, 동일한 공정 조건에서도 각 제품의 기본 내재된 특성이 다르고 공정에 대한 영향 정도가 다를 수 있다. 이런 이유로 최종 제품의 특성은 분포와 어느 정도의 편차를 가지게 된다. 따라서 일정한 품질을 유지하기 위해서는 공정 조건을 관리하고 제품 특성의 편차를 관리해야 한다. 본 연구에서는 웨이퍼 한계선 관리 방법을 제안하고 머신 러닝으로 분석했다. 반도체 제조 공정(식각, 노광 등) 간 상관관계를 분석하여, 웨이퍼 한계선 관리는 높은 상관관계의 공정에서 효과가 있음을 확인했다. 높은 상관관계의 공정들로 표준편차를 기반으로 한 새로운 지표를 사용하여 비정상 웨이퍼를 감지했고 머신 러닝으로도 동일 수준의 검출을 확인했다. 새로운 지표로 검출된 비정상 웨이퍼는 전수 측정, 공정 보상, 전수 스크리닝 같은 추가 관리 항목을 진행할 수 있다. 단순히 공정별 한계선 관리가 아닌 각 웨이퍼 한계선 관리 방법을 통해 낱장의 비정상 웨이퍼를 조기에 검출할 수 있고, 이는 품질 비용을 최소화할 수 있을 것이다.

Application of Process Mining in Managerial Accounting : A Case Study of an Investments and Securities Firm

Jason Jihoon Ree Graduate School of UNIST 2011 국내석사

Business process mining techniques use event logs recorded from information systems to extract and discover useful process and organizational information. Over the past couple of decades, many new and powerful process mining techniques have been developed by researchers and software vendors. Although numerous case studies demonstrating the applicability of process mining have been emerging in literature, there has yet to be an application of process mining in the financial sector. In this paper, we explore the applicability of process mining of an investments and securities firm, more specifically investigating its managerial accounting processes. Using an assortment of process mining techniques available in the ProM framework, we examine and discover clear differences between the AS-IS model stated by the financial firm and the process model extracted from the event logs. This research aims to accomplish the following: a) add to the current process mining application literature by examining the applicability of process mining in the financial sector, b) utilize various process mining techniques to observe and assess process information in the specific managerial accounting case study of the monthly profit and loss computation process, c) identify the strengths of process mining and how they can supplement the weaknesses of business process reengineering, and d) address the possibility that event log data with insufficient case sizes needs to be addressed differently than past approaches with data with sufficient case sizes.

A Process Mining Based Approach to Complex Manufacturing Process Flow Analysis: A Case Study

SookYoung Son Graduate school of UNIST 2014 국내석사

With recent advances in IT infrastructure in manufacturing environments, a large amount of manufacturing data are collected and stored in a database at various stages of production. These data may include valuable information for manufacturing companies to improve their manufacturing processes. The method of manufacturing data analysis is crucial for understanding the manufacturing data. However, traditional manufacturing data analysis methods such as data mining, simulation, etc. have limitations for this purpose since those are difficult to provide overall process-level information. Therefore, in this thesis, a process mining based approach for analyzing complex manufacturing processes is proposed. Process mining is a useful tool for process-related knowledge acquisition since it enables users to derive not only manufacturing process models, but also several performance measures related to processes, resources, and tasks. This thesis suggests a framework for the manufacturing process analysis. To do this, it applies process mining techniques to perform four types of analysis, which are visualization of production flows, machine-to-machine inter-relationship analysis, machine utilization, and monitoring & diagnosis of task performance regarding yield rate and lead time. Furthermore, a case study is conducted to support the proposed framework with an event log of an electronic components manufacturing process.

Process design and analysis for the production of sustainable bioplastic

김현우 경희대학교 대학원 2022 국내석사

The use of plastic or synthetic polymer is getting accelerated as the global population grows. Most of the plastic has been produced from fossil fuel and it causes considerable concern about climate change and fossil depletion. Lignocellulosic biomass is a sustainable carbon source and can produce various fuels and chemicals by replacing conventional fossil fuel. Although many studies have been performed to produce bio-based plastic from lignocellulosic biomass, there is a limitation due to the fact that they mainly focused on the element technologies. However, for commercialization, the development of an integrated process is indispensable by designing a separation process. Therefore, in this Master’s study, we develop the integrated process producing bioplastic and biodegradable plastic monomers and analyze to estimate the feasibility and sustainability of the developed process. In Application Ⅰ, we propose a process for synthesis of 2,5-furandicarboxylic acid (FDCA), which is a monomer of bioplastic, from biomass-derived cellulose through catalytic conversion. Cellulose is dehydrated to 5-hydroxymethylfurfural and subsequently oxidized to FDCA. To reduce utility consumption, we designed a heat exchanger network for heat integration. The minimum selling price (MSP) of FDCA is determined to be $1,532/ton, which is comparable to the market price of terephthalic acid (TPA). Through the LCA, we quantify the environmental impact and figure out how to enhance the developed process in terms of sustainability viewpoints. In Application Ⅱ, we propose an integrated process for the production of lactic acid, which is a biodegradable plastic monomer, from lignocellulosic biomass through biochemical conversion. Biomass is produced to lactic acid via dry dilute acid pretreatment, biodetoxification, and simultaneous saccharification and fermentation. We conduct heat integration and reduce utility consumption mainly required in the separation subsystem. Our TEA reveals that the MSP of lactic acid is determined to be $1,498/ton, which is approximate to the market price of lactic acid ($1,526/ton). Further, we evaluate the proposed process via integrative analyses including pioneer plant, and uncertainty analyses to quantify the risk and uncertainty during the construction and fluctuation of market situation. Through the LCA, we found the major contributor to environment and suggest the method for improving the sustainability of the process.

Process Modelling of Fixed Bed Units for Adsorption and Sorption-enhanced Reaction Systems

하산, 무하마드 부산대학교 대학원 2024 국내석사

In industries, fixed bed unit operations are widespread, for example fixed bed adsorbers are used for gas separation. Similarly, catalytic reactions are also carried out in fixed bed reactors also known as packed bed reactors. The two phenomena can also be combined in a single fixed bed unit containing both adsorbent and catalyst and referred to as sorption-enhanced reaction processes (SERP). For thermodynamically limited reactions like steam methane reforming, SERP is known to improve methane conversion and hydrogen purity. As the applications of adsorption and SERP processes grow, performance evaluation of such processes becomes increasingly important. The performance of the fixed bed for only adsorption or SERP is evaluated using breakthrough curve. Process modelling and simulation can be an efficient tool to predict the breakthrough curves and hence to evaluate the performance of fixed bed systems. A well validated process model can also be used to test the fixed bed systems under a variety of process conditions, to understand the relationship between different process variables, and to find the optimal process variables for a given system. The goals of this thesis are: (1) to discuss the fundamentals of process modelling of fixed bed systems for adsorption and SERP applications; (2) to develop a framework for simulating such process models in a user-friendly manner; (3) to demonstrate the utility of process modelling for predicting the performance of adsorption-based separation processes. In the first chapter, the process model for fixed bed system for pure adsorption and SERP, developed from the first principles, is presented. The model has been packaged into BREAKLAB application, which offers a graphical user interface to run breakthrough simulations for multicomponent adsorption and sorption-enhanced steam methane reforming (SE-SMR) process in a user-friendly manner. First, the mathematical model for BREAKLAB has been discussed along with the different pure component and mixture isotherm models available in BREAKLAB. The use of BREAKLAB has been demonstrated by three case studies. The extension of the model to simulate pressure vacuum sing adsorption (PVSA) cycle for SE-SMR followed by process optimization was also carried out. In the second chapter, process modelling for adsorption was integrated with molecular simulations to screen the best zeolite for acid gas (H2S, CO2) removal from the ternary mixture of H2S, CO2 and CH4. The extended dual-site Langmuir-Freundlich isotherm model was used, and the isotherm parameters were validated using the mixture isotherm data generated from grand canonical Monte Carlo (GCMC) simulation. The process optimization was carried out for validated zeolites (APC-0, APC-2, and ATV-1) using modified Skarstrom PVSA cycle. Process optimizations revealed that APC zeolites demonstrate superior performance because of simultaneous removal of H2S and CO2. Economic optimization showed that the APC-2 is the optimal zeolite for energy-efficient acid-gas removal.

외란을 고려한 회분공정의 공정확인법

정경록 경북대학교 대학원 2025 국내석사

This study introduces an advanced process identification method for the batch processes which are faced with not only the deterministic disturbances but also repetitive disturbances. This method utilizes input-output data from two batches, processes this data, and applies it to an existing process identification technique for processes with deterministic disturbance. By treating time-varying dynamics as deterministic disturbances—characterized by a varying mean, low frequency, and some degree of trend—the method approximates the disturbance using a combination of Laguerre functions. Also, this approach effectively reduces the impact of repetitive disturbance and mitigates the effects of time-varying dynamics within a single batch. The simulation study demonstrates that the proposed process identification method provides accurate process model for various types of processes, even in the presence of both repetitive and deterministic disturbance. The method effectively mitigates the impact of repetitive disturbances. In contrast, the existing process identification method fails to estimate accurate process models, as it does not account for repetitive disturbances. The proposed process can be used to predict the next batch’s behavior based on the identified model and tuning parameters. By combining this predictive capability with optimization techniques, it is possible to determine the optimal tuning parameters for the subsequent batch. The method is also applicable to advanced controllers, such as model predictive control and model reference adaptive control, and can be used to assess control loop performance in control performance monitoring systems, ultimately enhancing the productivity of batch processes. * A thesis submitted to the Council of the Graduate School of Kyungpook National University in partial fulfillment of the requirements for the degree of Master of Science in December 2024

Process and structure design in laser-powder bed fusion technique for high-performance structures

Kim, Minkyeom Sungkyunkwan University 2022 국내박사

As laser-powder bed fusion (L-PBF) has got a spotlight due to its advantage of saving cost and time for building complex structures, the L-PBF have been widely studied for industrial applications. However, there still remain critical challenges and issues in the L-PBF technique in terms of quality assurance and low properties. During the process, a laser selectively melts spread powders layer-by-layer, and therefore there arise complex interactions between melt pool, particles, and previous tracks/layers because of rapid heating and cooling cycles. The process makes it hard to predict qualities and properties of as-built parts. Therefore, the desirable processing conditions in the L-PBF have been explored via a trial-and-error effort, which requires substantial cost and time. Therefore, in this study, a systematic and integrated method to design the process and high-performance additively-manufactured (AM) structures were suggested through an empirical and numerical modeling. Firstly, the effect of qualities and properties of as-built 17-4 PH stainless steel (SS) were investigated to empirically understand the process and explore the way to improve mechanical properties. Densification, thermal deformation, and anisotropic properties of as-built and heat-treated parts were comprehensively investigated. Secondly, the L-PBF process was optimized based on printability maps of 17-4 PH SS. The qualities, properties, resolution, and productivity were the considerations for determining the processing conditions in building complex structures with the desirable qualities and properties. Particularly, a microscale process was deeply investigated via a thermal-fluid simulation model Thirdly, the complex structures such as bio-inspired or meta-structures were manufactured with the optimum conditions for the L-PBF process. Multi-performances of the structures were carefully explored via several tests with respect to a lightweight, high specific stiffness/strength, noise/vibration reduction, heat dissipation, and thermal insulation. The works could give a guideline of the design of material-process-structures in the L-PBF, and therefore AM technique is expected to achieve technological advances by overcoming the aforementioned challenges. 본 연구에서는 금속 3D 프린팅 기법 중 하나인 Laser powder bed fusion (L-PBF)에서의 공정 및 후공정를 연구 및 설계하고, 이를 기반으로 새로운 구조물을 제작하여 실 산업에서의 L-PBF 활용 가능성을 보이고자 했다. 1. L-PBF 공정 및 후공정(열처리) 연구 L-PBF 공정에서 주요한 공정변수 중 하나인 레이저 파워와 스캔 속도에 따른 부품의 품질(상대밀도, 열변형)과 물성(경도, 인장 및 펀치 시험 물성)을 분석하였다. 이와 더불어 3가지 종류의 열처리 기법(열간등압성형가공, 용체화처리, 시효열처리)을 조합한 7종류의 열처리 기법에 따른 출력물의 품질 및 물성 개성/저하 정도를 분석하고, 산업에 활용 가능한 L-PBF 공정조건과 열처리 기법을 도출하였다. 2. 멀티스케일 L-PBF 공정 최적화 L-PBF에서 품질과 물성을 결정하는 주요한 공정조건들이 매우 많아 기존에는 작업자들이 시행착오방식으로 공정조건을 탐색하였다. 본 연구에서는 이를 극복하기 위해 다양한 요소(기공율, 해상도, 경도, 인장물성, 생산성)들을 고려하여 프린팅 가능한 맵을 제안하였다. 프린팅 맵은 마이크로스케일에서 매크로스케일에 이른 실험과 해석이 병행된 L-PBF 공정분석을 기반으로 구축하였다. 위 프린팅 맵을 기반으로, L-PBF 관련 종사자/엔지니어들이 요하는 다양한 품질 및 성능을 충족하는 L-PBF 공정조건을 설계할 수 있을 것이다. 3. 적층제조 기반 셀 구조 개발 미래 모빌리티에 대한 관심이 증대됨에 따라 미래모빌리티에서 요하는 다양한 성능(경량, 고강도/강성, 에너지 흡수, 진동/소음 저감 등)을 지닌 소재/구조에 대한 연구가 지속되고 있다. 하지만 기존의 소재 및 제조기법으로 제작된 구조들로는 대립되는 성능을 모두 충족시키기는 어렵다. 따라서 본 연구에서는 적층제조 방식을 활용하여 이를 극복할 수 있는 구조물 설계안을 제시하였다. 주제 2에서 최적화된 L-PBF 공정조건을 기반으로 경량, 고강성, 진동저감, 및 고방열 또는 단열 특성을 지닌 구조를 설계하기 위해, 다양한 메타구조와 생체모방 구조들의 특성들을 종합적으로 평가하여 탁월한 성능을 지닌 단위셀 구조들을 선정하였다. 위의 메타구조 및 생체모방 구조의 단위셀 설계 기술과 이를 구현하기 위한 공정 최적화 기술은 복합 성능을 요하는 다양한 미래 모빌리티 관련 산업군에 활용 가능할 것으로 사료된다.

The Effects of Note-Taking as Stimuli on Inner Speech in L2 Process Writing

박은희 전남대학교 2015 국내석사

Researchers of second language (L2) writing have adopted and tested first language (L1) writing research designs and emphasized the similarities between first language and second language composing processes (Arndt, 1987; Jacobs, 1982; Jones & Tetroe, 1987; Raimes, 1985; Zamel, 1983). These studies investigated how writers' L1 writing process transfers to and is reflected in L2 writing process. In line with this approach, the present study focuses on the process-oriented ESL writing and seeks to apply Vygotsky's concept of "inner speech" to the analysis of the ESL composing process. Thirty-three students (age range 13 to 15 years old) participated in this study. The participants were divided into two groups: the experimental group (N= 18) and the control group (N= 15). The participants in the experimental group were asked to take notes throughout the composition process (which included brainstorming, drafting, revision, and rewriting). The control group was given the task to write a composition process without note-taking. Immediately after the completion of the task, the participants from the experimental group were interviewed. The results of our study amount to the following conclusions: 1) Writers' writing mean score increased through process writing with note-taking and there was a significant difference between the experimental and the control groups; 2) Brainstorming as a prewriting stage correlates with the dimensions of L2 writing (Focus/Idea, Organization, Voice, Word Choice, Sentence, and Convention). Specifically, organization yielded a high correlation with brainstorming; at the same time, no significant correlation was observed with voice and sentence; 3) The students in the experimental group with note-taking instruction produced better scoring in their post-writing task. That is, the substantial difference between pre-writing and post-writing was shown in organization, while there was no difference in voice. This study implies that process writing has an important role in students' L2 writing. Furthermore, inner speech is emerged consistently, when the writing productions are produced in L2 process writing. Inner speech continues to develop in complex cognitive operations.

Business Value of Process Mining : Concepts, Contingencies, and Maturity

ASTRIA HIJRIANI 울산과학기술원 Ulsan National Institute of Science and Te 2026 국내박사