Conceptual, preliminary and detailed design of an injection-molded fiber-reinforced plastic/metal hybrid automotive front subframe

Fonseca, João Henrique 서강대학교 대학원 2022 국내박사

The complete design of a recycled-carbon-fiber reinforced-plastic / metal hybrid (PMH) automotive front subframe is realized is realized via finite element (FE) analyses and multiple structural optimization techniques. The structure considers a low-cost recycled carbon fiber (rCF) and PMH technologies. The design is divided into three main steps: the conceptual, preliminary, and detailed design. Conceptual design aims at constructing and analyzing different ideas and approaches before the construction of the actual geometry. This stage is fairly important, since the design of PMH parts is normally complicated; testing the concepts helps predicting future issues in the design, building knowledge regarding the manufacturing process and unique material characteristics, and drawing a proper design approach for the actual product. In Part I, the design and evaluation of PMH front subframes are realized via the design of concept models and FE analyses. Firstly, the design of two PMH front subframe concepts is carried out. The initial design approach consists of creating a C-type and a hollow-type insert and modifying the plastic component according with insert type. Additionally, the design variables considered in the design process are the dimensions of insert, insert thickness, and inclusion of plastic ribs. The PMH front subframes are later evaluated by performance criteria, including weight reduction, stiffness, natural frequency, stress levels under endurance loads, and strength. The results showed that the integration of rCF with injection overmolding of metal inserts was able to promote weight reduction, where the hollow-type and C-type PMH front subframes achieved a weight reduction of 19 % and 16 % in comparison to the reference steel front subframe, respectively. Moreover, the PMH front subframes achieved the desired performance targets set by the evaluation criteria. The preliminary design stage deals with the construction of the initial product geometry and specifications of additional performance requirements. In Part II, the design is realized via combined optimization techniques and their injection molding (IM) suitability verified. Topology optimization (TO) and combined TO and free-size optimization (FSO) techniques are exploited in the design process to find the optimal rib configuration and location of metal inserts. A material exchange technique to account for fiber orientation elementwise is employed and the models analyzed in terms of functionality and producibility. The robust design procedure was shown to be effective in developing sCFRP (short-recycled-carbon fiber reinforced-plastic) and PMH parts while considering IM restrictions and plastic part design guidelines from the early design stages. The PMH model obtained the most outstanding results with the greatest balance between functionality and producibility, with a 36 % weight reduction from the steel baseline model. Although the sCFRP models achieved weight reduction over 50 %, they presented difficulties in simultaneously obtaining the required levels of stiffness, strength and producibility. Detail design refines the preliminary product geometry into a shape that is functionally acceptable and compatible with the IM process. In Part III, the design is carried out via composite size optimization, which considers specific IM design guidelines in order to improve part quality. The complete FE modeling is discussed, where thickness-dependent material properties of the reinforced plastic utilized in this study is automatically updated in the optimization process. In the optimization modeling, user-defined constraints are utilized to improve the efficiency of the algorithm. Moreover, a proper design guideline for the front subframe case is selected based on simulation results. With the procedure, the quality and IM suitability of the PMH subframe was significantly improved, while weight reduction was increased to 38 % with a further simplification of the model. The results of this study contribute to the efficient multimaterial design of PMH components in the auto industry and the advance of a new class of lightweight subframes with improved structural performance, fabricated by fast-capability manufacturing processes and low-cost carbon fibers.

Implementation and application of bionic digital brain for digital twin-cutting process

Jielin, Chen 영남대학교 대학원 2024 국내박사

A self-study: Pedagogical practices in a multicultural literature course

SanGregory, Mary Jo The Ohio State University 2009 해외박사(DDOD)

Given the reality of the changing demographics in today's classrooms, it is imperative that teacher candidates leave their teacher education programs prepared to teach in culturally diverse classrooms. Research shows that using multicultural literature can be an effective approach to teaching about diversity. Research also shows that the majority of teachers neither know much about multicultural literature, nor do they use it regularly in today's classrooms. This study sought to explore the efficacy of pedagogical practices that help teachers and teacher candidates acquire the knowledge, skills and professional dispositions necessary to identify and select authentic multicultural literature, and explore its use as part of a culturally relevant approach to teaching.

Research on the Cutting Force Modeling and Machinability of Electrical Discharge Assisted Milling Process

Moran, Xu 영남대학교 대학원 2023 국내박사

현재 제조 산업은 어려운 가공 재료 처리에 직면하고 있으며, 이러한 재료에는 단단한 합금, 세라믹, 복합 재료 등이 포함된다. 이러한 재료들은 우수한 성능과 특성을 가지고 있으며, 항공우주, 에너지, 자동차 및 기타 산업 분야에서 널리 사용되고 있다. 그러나 이러한 재료들은 높은 경도, 고온 내성 및 취성 때문에 기존의 방법을 사용하여 가공하기 어렵다. 단일 가공 기술만으로는 모든 요구 사항을 충족시키기 어려워 하이브리드 가공 기술의 발전을 촉발하였다. 이 접근 방식은 하이브리드 가공에서 서로 다른 공정들의 결합 또는 상호 강화를 활용하여 단일 공정을 적용할 때 발생할 수 있는 부정적인 영향을 효과적으로 회피하거나 줄이기 위한 것이다. 이러한 어려움을 고려하여 전기 방전 보조 밀링 (EDAM)이라는 혁신적인 하이브리드 가공 공정이 소개되었다. EDAM 공정은 먼저 전기 방전의 열 효과를 활용하여 가공 영역을 연화시키고, 이를통해 재료의 가공성을 향상시킨다. 그 후 고속 밀링을 통해 효율적인 가공이 수행된다. EDAM 하이브리드 가공 공정은 절삭 힘의 효과적인 감소, 표면 품질의 향상 및 공구 수명의 연장을 입증하였다. EDAM 방법의 가공성을 더 향상시키기 위해 유연한 전극 기반의 EDAM 가공 접근 방식이 제안되었다. 기존의 전극과 비교하여 유연한 전극과 EDAM 도구의 우수성이 강조되었다. 또한, 전기 방전 가공에서 발생하는 열원의 증가로 인해 재료 제거 메커니즘이 더욱 복잡해진다. 따라서 EDAM 가공과 관련된 물리적 프로세스에 대한 포괄적인 이해를 위해서는 하이브리드 온도 영역과 관련된 다중 영역 온도 분포 및 관련 메커니즘에 대한 연구가 필요하다. 따라서 하이브리드 온도 분야의 맥락에서 다중 온도 분포 및 관련 메커니즘에 대한 연구가 필요하다. 이러한 이해는 절삭 힘에 대한 이론 모델의 유도와 가공 품질의 정밀한 제어를 위한 이론적 지침을 제공함으로써 가공 품질의 정밀한 제어를 위한 이론적 지침을 제공한다. The current manufacturing industry is facing challenges in processing difficult-to-machine materials, such as tough hard alloys, ceramics, and composite materials. These materials possess exceptional performance and characteristics and are widely utilized in aerospace, energy, automotive, and other sectors. However, their high hardness, high temperature resistance, and brittleness make them difficult to be processed using conventional methods. Single processing techniques may not meet all the requirements, which has led to the development of hybrid machining. This approach leverages the combination or mutual enhancement of different processes in hybrid machining to effectively avoid or reduce the adverse effects that may arise when a single process is applied. In light of these challenges, a novel hybrid machining process called Electrical Discharge Assisted Milling (EDAM) has been introduced. The EDAM process first utilizes the thermal effect of electrical discharge to soften the machining zone, thereby improving the machinability of the material. Subsequently, high-speed milling is performed to achieve efficient machining. The EDAM hybrid machining process has demonstrated effective reduction in cutting forces, improvement in surface quality, and extension of tool life. To further enhance the machinability of the EDAM method, a flexible electrode-based EDAM machining approach has been proposed. By comparing it with a conventional electrode, the superiority of the flexible electrode in conjunction with EDAM tools is emphasized. Additionally, due to the increased thermal source from electrical discharge machining, the material removal mechanism becomes more complex. Therefore, a comprehensive understanding of the physical processes involved in EDAM machining necessitates research on the multi-field temperature distribution and relevant mechanisms in the context of hybrid temperature fields. This understanding will facilitate the derivation of theoretical models for cutting forces and the optimization of their parameters, ultimately providing theoretical guidance for the precise control of machining quality.

From Mutually Assured Destruction to Mutually Assured Stability : A Constructivist Rationale for Expanding Missile Defense

La Boon, David Joël 서울대학교 대학원 2019 국내석사

미국 국제 안보 자문 위원회는 2012년 8월 12일 미국 국무부는 현행 세계 질서 내 상호 확증파괴(MAD)의 지속 불가능성에 관한 보고서를 제출하였다. 세계화의 기술 확산 효과, 현재의 제지 이론과 기술진보 안에 선제공격을 위한 유인 협력과 투명성의 의욕을 꺾고, 보다 궁극적으로 잉여 핵 재고와 자산의 제거를 목표로 핵 안정도, 핵 확산 방지 또는 제재를 위한 것이다. 미국-러시아, 미국-중국의 전략적 관계는 전략적 안정성을 초석으로 전통적인 제지 이론에 의존하고 있다. 그러나 미국-북한, 미국-이란의 전략적 관계는 이 원칙과는 차이가 있다. 미국은 러시아, 중국과의 기존의 균형을 깨는 위험을 무릅쓰고, 이들 국가를 겨냥한 미사일 방어 정책을 추진하기로 결정했다. 이는 러시아와 중국의 새로운 현대화 프로그램을 통해 가설적상황이 현실화됨에 있다. 한편, 미국은 미사일 방어 계획의 범위와 깊이, 예산권한과 핵배치 능력을 강화시켰다. 이 논문은 왜 미국이 ‘상호 확증파괴’에서 핵 억제이론에 이어 ‘안정성 상호 확증안정성’까지 예상되는 불안정성과 전략적 국가들 간의 잠재적인 안보 딜레마에 봉착하는 지에 중점을 둔다. 이를 통해 이 논문은 미사일 방어 기술의 전략적 안정성을 야기하는 원인과 미국-중국, 미국-러시아의 전략적 안정이 불안을 초래하는 다른 요소들을 검토한다. 이 현상학적 연구는 1차와 2차 자료에 대한 텍스트 분석의 질적 접근법과 학계 및 국방 관리에 대한 심층적 개별 면담을 활용한다. 억지 이론의 이론적 토대로 현실주의 이론에 근거하여 미국의 핵문제에 대한 태도; 뿐만 아니라, 엠마누엘 애들러의 구도화한 가설과 스티븐 웨버의 구조상의 병렬을 검토하며 이 논문은 각자의 단점, 오해, 오인을 강조할 것이다. 예측된 불안정성에도 불구하고, 현실주의 이론이 미사일 방어망의 확장을 설명할 수 있는 능력을 재평가할 여지가 생긴다. 대신, 미국의 미사일 방어 추진에 영향을 미치는 요인의 분석을 위하여 알렉산더 웬트(Alexander Went)의 무정부(Anarchy)의 문화 유형학을 사용한다. 웬트의 이론적 구조 안에 기본 기능 및 잠재적 탄도를 설명하는 이해의 수단으로서 매크로 시스템 문화적 내면화를 사용할 것이다. 기술 확산의 과정들은 세계화의 급격한 변화로 구조 안에 대리인으로서 행동하고 정책화 되었다. 또한 행동 경제학, 사회 심리학 발견으로 인간의 합리성의 빈공간을 발견했다. 이 학술적 발견은 고전적 억지 이론을 재평가할 필요성을 강조한다. 따라서 이 논문은 다음의 목표를 추구한다. 먼저, 전략적 안정성의 진화와 보통 현실주의 이론 유지하는 것를 조사한다. 기존의 관련 연구들은 인간 행동의 설명을 요하는 주제 임에도 불구하고 현실주의 이론에 근거하여 사회 이론적인 모형보다는 빅 데이터 및 계량모형 연구가 선호되었다. 이 연구는 사회적 구성주의 이론적 분석으로 기존과는 다른 국제정치이론 방법론을 제안한다. 결론적으로 우리에게 가장 중요한 것은 무정부의 문화로서의 핵 억지력이라는 점을 모색하고자 한다. August 12, 2012, the International Security Advisory Board released a report to the U.S. Department of State on Mutually Assured Stability (MAS) outlining the unsustainability of Mutually Assured Destruction (MAD) as a nuclear posture within the current world order. This is due to: globalization’s effects on technological diffusion; incentives for preemptive strike within current deterrence theory paired with technological advances; disincentives for cooperation and transparency; but ultimately to facilitate the elimination of excess nuclear inventories, and to prevent and/or dissuade nuclear proliferation by minor and threshold states in order to provide a finality to nuclear stability. The U.S.-Russia and the U.S.-China strategic relationship are largely reliant on conventional deterrence theory as a cornerstone of strategic stability. However, the U.S.-Democratic People’s Republic of Korea relationship, as well as with other threshold nuclear states like Iran, both do not rely on these same principles. Thus, at first glance, the U.S. has chosen to pursue missile defense policies targeting these states at the risk of upsetting the U.S.-Russian and U.S.-China equilibria. This hypothetical became a reality through both Russian and Chinese strategic modernization programs currently underway. Yet, the U.S. has doubled down on its missile defense programs expanding their scope and depth, budgetary authority, and deployments. This thesis seeks an answer to why the U.S. would shift away from the logic of MAD embedded in deterrence theory, the cornerstone of strategic stability, and from which it struggled for decades throughout the Cold War to establish and maintain, to MAS in which it would face predicted instabilities and a potential security dilemma with strategic peer-powers? This phenomenological study utilizes a qualitative approach of textual analysis on primary & secondary sources. Through the examination of the theoretical foundations of deterrence theory and the U.S. nuclear posture based on Realism, this thesis will highlight shortcomings, misperceptions, and misidentifications. This will thereby provide space for the reevaluation of the Realism’s merits to explain the currently unfolding expansion of missile defense in spite of these predicted instabilities. Instead, this reclaimed space will be filled by Alexander Wendt’s Cultures of Anarchy typology to classify factors influencing the American push for missile defense by evaluating the level of macro-system cultural internalization as a means of understanding their underlying functionality, and potential trajectory within Wendt’s framework. The processes of technology diffusion spurred on by the exponentially growth of globalization have altered the structure within which agents act and policy is developed and deployed. Additionally, discoveries in the fields of behavioral economics and social psychology have produced research locating the margins of human rationality, which further emphasize the need for a reevaluation of classical deterrence theory. Thus, this thesis seeks several objectives. One is to detail in theoretical terms the evolution of strategic stability and explore the limitations of holding to the commonly held Realist position. In terms of Realism’s proponents, the rise of big-data and dominance of computational modeling have been privileged over social theoretical models despite their limitations in explaining human behavior. Instead, the study will provide room for a more equipped pre-existing international relations theory to be employed – Social Constructivism. Perhaps most practically important to us as a species though, this thesis seeks to provide a hard edge to the horizon of nuclear deterrence by employing the spectrum of anarchic logics.

Non-governmental organizations and Business Partnerships for strengthening Social Development in Mozambique : A case study of Mozal S.A.R.L

Conselho, Lara Marisa João Hankuk University of Foreign Studies. Graduate Sch 2014 국내석사

컴퓨터 기반 적응형 평가를 활용한 자기주도적 학습용 학습관리시스템(CB-LMS)의 개발과 적용

조현준 부산대학교 2006 국내박사

A Study on the Development and Application of Computerized Adaptive Testing Based Learning Management System(CB-LMS) for Self-Directed Learning Hyun-Jun Jo Department of Multimedia, Graduate School Pusan National University Advisor: Young-Hwan Kim. Ph. D. The purpose of this study was to develop an Computerized Adaptive Testing based Learning Management System(CB-LMS) and apply it to educational field with verifying its effects. To accomplish the research objectives, this study was advanced with Research I to design and develop CB-LMS and Research II to adopt CB-LMS to educational field and analyze the effects on SDL(Self-Directed Learning), learning motivation, and learning achievement. A. Study I: Design and development of CB-LMS Prior, the research methods on Study I are consisting of three ways: first, analyzing precedent study to clarify the concept and elements on SDL, learning motivation, LMS, e-Learning, and others, second, advancing an interviewing with developers and field experts related to LMS, and third, taking professional advice on the outcomes from a designing step through convening the meeting with experts and applying the subjects of the meeting to the designing step. With the research methods mentioned above, this study was firstly operated to carry out designing principles to draw out CB-LMS through analyzing staple designing principles on SDL and describing the principles of CB-LMS through analyzing the cases of the design under the relevant e-Learning circumstances. Secondly, this study derived designing strategies to design CB-LMS with the mentions on selected strategies in accordance with designing principles of CB-LMS. And then, core functions for the development of CB-LMS and User-Interface developed were carried out. Last, CB-LMS was developed based on the research outcomes. In sum, staple designing principles and strategies from Research are as following: 1. Utilizing CAT for encouraging SDL 1.1. Proving an opportunity of self-assessment through SPRT-typed CAT 1.2. Going abreast two types of assessment with SPRT-typed CAT and CBT following the learning condition 1.3. Analyzing questions mentioned at the assessment for taking notes on incorrect answers and helping the learners to retake a chance 1.4. Tracing and managing the assessment results and learning activities on CAT through LMS continuously 1.5. Setting the flexibility on the control of the questions through providing managing tools of an item pool 2. Using a learning contract and peer-tutoring group for encouraging SDL 2.1. Providing a function to conclude a learning contract with learners and setting a flexible part in the contract articles 2.2. Offering a tool for solving a problem caused at using each learning contents and CAT by collaboration of peer learners 2.3. Enabling the learners to monitor the status of peer-tutoring 3. Taking strategic access method to Implement self-regulated procedure for promoting self-examination of learners 3.1. Supporting the learners to monitor their performance on the learning contract by themselves 3.2. Providng the learners with a chance to revise self-assessment and the learning strategies 3.3. Enabling the learners and teachers to change the substances of learning contract depending on the status of learning 4. Applying adoptive reciprocal action to derive optimum performance of the learners 4.1. Giving adoptive feedbacks on learning activities through analyzing learning styles of the learners 4.2. Providing adoptive interface on learning activities through analyzing learning style of the learners 4.3. Having the teachers to improve the status of learning of the learners with practical feedbacks 4.4. Ensuring various reciprocal action between learners and learners, learners and teachers, learners and systems, and learners and contents 5. Proceeding self-determination and assessment brought by the learners priror to the assessment by the experts 5.1. Providing the learners with an opportunity to monitor on the status of their learning performance by themselves 5.2. Establishing a standard for the learners to compare their learning status with whole learning group's 5.3. Giving an opportunity to the learners to inquire the assessment on their performance brought by the teachers 5.4. Supporting the teachers to apply the assessment results on the learners' offline learning activities with the results of online activities 6. Establishing the circumstances of reciprocal action to enhance learning motivation of learners 6.1. Correlating the results of CAT and peer-tutoring with the Avatar system 6.2. Managing the avatar as step-by-step and separately with providing an opportunity to foster learning performance 6.3. Providing a reciprocal tool of synchronism and asynchronism among peer learners and teachers 6.4. Advancing qualitative assessment on mutual activities during reciprocal action B. Study II: Analyzing the effects of CB-LMS on the SDL, learning motivation, and learning achievements Study II was implemented with two groups consisting of learners without educational background who attended the class of 'Educational method and Education Engineering', which is one of teaching subjects of a university located in Busan in the 2nd semester, 2005. This research was advanced with a single team composed of 32 learners excluding inactive persons from two groups during 13 weeks. The inspection tool for this research was developed and adopted as web-based tool considering the effectiveness for the inspection and data processing. The tool consisted of 84 questions to measure capabilities of SDL, 31 for learning motivation, and 50 for learning achievements. Accordingly, the results of this study are summarized as following: First, CB-LMS brought positive influence on the capabilities of SDL. In particular, there was significant difference in a variable of recognition strategies in the step of meta-cognition. In addition, it was found out that positive effect on proficiency goal-oriented variables in the step of motivation. Second, CB-LMS delivered positive effects on attention and confidence, and satisfaction in relation to learning motivation of the learners. Particularly, there were noticeable effects on the attention and confidence and satisfaction. Third, it was proved that CB-LMS was effective to learning achievements. This did not only come from the side of learning achievements but also the capabilities of SDL and learning motivation. Thus, it is required to consider applying designing strategies of CB-LMS to web-based learning. Forth, following the results of the research, designing principles and strategies of CB-LMS brought positive effects on the capabilities of SDL, learning motivation, and learning achievements to learners. Therefore, it is needed to using designing principles and strategies for existing web-based class and designing LMS actively.

Understanding the changes in the ocean-atmosphere interactions in the western tropical Pacific and its impact

조현수 한양대학교 대학원 2017 국내박사

ABSTRACT Understanding the changes in the ocean-atmosphere interactions in the western tropical Pacific and its impact Hyun-Su Jo Dept. of Marine Sciences and Convergent Technology Graduate School of Hanyang University This study examined the physical processes to understand the changes in the ocean-atmosphere interactions in the western tropical Pacific [130-150˚E, 0-15˚N] across the late-1990s during the boreal spring (March-April-May) and its impact in terms of oceanic and atmospheric teleconnections by analyzing the observational dataset as well as simple model experiments. For the entire analyzed period (1980-2015), it is found that the relationship between sea surface temperature (SST) and precipitation shows a positive correlation in the western tropical Pacific during the boreal spring. That is, anomalous warm SST leads to low-level moisture convergence and it can induce more precipitation accompanied with deep convective cloud (DCC) as well as vertical motion in the western tropical Pacific. Subsequently, an enhanced DCC acts dampen the anomalous warm SST by reflecting an incoming solar radiation, which is indicative of a negative cloud-radiation feedback. In particular, it was found that the low-level moisture convergence, which is mainly due to SST gradients in the central tropical Pacific and eastern Indian Ocean, is able to sustain the DCC in the western tropical Pacific through large-scale atmospheric circulations. However, it was found that a positive correlation of SST-precipitation became statistically insignificant after the late-1990s. In addition, the mean SST in the western tropical Pacific became warmer and the amount of mean precipitation also were increased before and after the late-1990s. After 1999, the anomalous warm SST leads more precipitation along with low-level moisture convergence as well as the enhanced DCC in the western tropical Pacific, which is similar to before 1999. However, the low-level convergence played more active role to lead more precipitation, which was closely associated with SST gradients in the central tropical Pacific and the eastern Indian Ocean. This led to quickly dampen the anomalous warm SST through a negative cloud-radiative feedback, which is in contrast to before 1999. That is, an enhanced negative cloud-radiation feedback as well as strong low-level convergence acted to weaken a positive correlation of SST-precipitation in the western tropical Pacific, which might be associated with a climate shift in the western tropical Pacific across the-1990s. Further study examined the changes in the oceanic and atmospheric teleconnections across the late 1990s in the Pacific basin by analyzing the observations and simple model experiments. It was found that the changes in the ocean-atmosphere interactions in the western tropical Pacific across the late-1990s led to the changes of correlation in the tropical forcing and the East Asian precipitation through atmospheric teleconnections. In addition, the mechanism which was responsible for the western North Pacific climate shift as well as the changes in the relationship in the SST variability between the tropical Pacific and the North Pacific across the late-1990s was also suggested in terms of oceanic and atmospheric teleconnections.

La flexibilité du droit de l'Union européenne

Marciali, Sébastien Bruylant 2008 국내박사

Les droits politiques dans la jurisprudence de la Cour européenne des droits de l'homme

Lécuyer, Yannick Dalloz 2009 국내박사