헬름홀츠 방정식의 해석적 기저 함수를 이용한 컴팩트 유한 차분법

학위논문 (박사)-- 서울대학교 대학원 공과대학 기계항공공학부, 2017. 8. 이건우.본 논문에서는 헬름홀츠 방정식의 해석적 기저함수를 이용한 컴팩트 유한차분법을 유도한다. 해석적인 정보를 활용하는 본 방법은 수치적인 분산 오차를 크게 줄임으로써, 기존의 컴팩트 유한차분법에 비해 수치 시뮬레이션에 사용되는 파장 당 최소 격자 수를 낮출 수 있다. 이를 통해, 사용되는 격자 수를 늘리지 않고서도 높은 주파수 혹은 파수 영역에 대한 시뮬레이션을 가능하게 해주므로 계산량이 감소한다. 효율성과 정확성이 높은 본 컴팩트 유한차분법은 정규 격자를 이용한 계산량이 큰 응용 분야에 매우 적합하다. 제안된 방법의 효율성과 정확성을 확인하기 위해 수치적인 결과를 보이고 이를 비교한다. 또한, 비균질 매질에서의 지진파 전파에 본 방법을 적용해보고 본 방법의 지구물리 응용 분야에 대한 적용성을 가늠한다.Compact finite difference methods using local analytic basis functions for the Helmholtz equation are derived in this thesis. Compared to former compact finite difference methods, the proposed methods using the analytic information of the Helmholtz equation greatly reduce the numerical dispersion error so that the minimum number of grids per wavelength required in the numerical simulation can be lowered. This enables us to simulate the higher frequency/wavenumber range without increasing the number of grids, which reduces the computational costs. The proposed compact finite difference methods have great potential for numerically intensive applications using regular tensor product grids, because of their efficiency and accuracy. Some numerical results and comparisons are provided to verify the efficiency and accuracy of the proposed scheme. The proposed scheme is also applied to seismic wave propagation in heterogeneous media to assess its feasibility for geophysical applications.1. Introduction 1 1.1 Background and Importance 1 1.2 Previous Works 2 1.3 Objectives 5 1.4 Organization of the Thesis 5 2. Discretization using Analytic Basis Functions 7 2.1 Preliminaries 7 2.1.1 Helmholtz Equation 7 2.1.2 Finite Difference Operator 8 2.1.3 Naive Second Order Finite Difference Method 10 2.2 1D Compact Finite Difference Methods 11 2.2.1 3-Point Method 11 2.2.2 Alternative Derivation 12 2.3 2D Compact Finite Difference Methods 14 2.3.1 5-Point Method 16 3.3.2 9-Point Method 20 2.4 3D Compact Finite Difference Methods 23 2.4.1 7-Point Method 26 2.4.2 19-Point Method 26 2.4.2 27-Point Method 28 2.5 Source Amplitude Correction Functions 30 2.5.1 1D Source Amplitude Correction Function 30 2.5.2 2D Source Amplitude Correction Functions 33 2.5.3 3D Source Amplitude Correction Functions 39 3. Dispersion Analysis and Numerical Experiments 44 3.1 Plane Wave Analysis 44 3.1.1 2D Dispersion Curves 44 3.1.2 3D Dispersion Curves 54 3.2 Numerical Solutions with the Impulse Source 62 3.2.1 2D 9-Point Method for a Homogeneous Medium 62 3.2.2 3D 27-Point Method for a Homogeneous Medium 72 3.2.3 2D Seismic Wave Propagation in Homogeneous Media 82 4. Conclusions 86Docto

The Case of the Halal Food Complex in South Korea

본 연구는 글로벌시장에서 주목받는 할랄식품산업과 관련해 최근 한국 사회에서 구성된 할랄식품 담론과 실천을 고찰해보며 할랄식품의 글로벌화를 파악하려는 시도이다. 본문은 농림축산식품부가 익산할랄단지 조성계획을 철회하게 된 과정에서 벌어진 종교, 정치적 논쟁을 문화지리적 관점에서 분석해보았다. 이를 위해 행위자-네트워크이론의 네 단계 번역 과정(Callon, 1986)을 통해 익산할랄단지 조성과 철회의 사례를 둘러싼 행위자-네트워크의 동맹과 배반의 과정을 살펴보았다. 먼저, 익산할랄단지 조성이라는 행위자-네트워크의 결집을 주도한 농림축산식품부는 국제식품전시, 언론보도라는 효과적인 장치를 통해 신(新)시장개척, 혹은 건강한 음식이라는 할랄식품 담론을 생산하고 공유했다. 두번째로, 익산할랄단지 조성을 무산시킨 주도적인 주체는 극우주의적 성향을 띤 보수 기독교 단체로서, 그들은 기도회, 전단지, 서명운동 등을 효과적인 담론배포의 장치를 통해 할랄식품을 웰빙식품에서 테러식품으로 치환하였다. 그 과정에서 생성되고 유포된 할랄괴담에는 한국사회에서 무슬림에 대한 사회적 차별과 배제의 인식이 담겨있으며, 한국사회에 만연한 외국인혐오증을 반영하고 있다. 익산할랄단지의 조성과 철회는 식품과 종교, 혹은 경제와 문화라는 이분적인 메커니즘이 상호교차하고 있음을 보여주는 사례이다. 할랄식품은 인종과 종교를 둘러싸고 한국사회에서 벌어지는 일련의 문화전쟁을 촉발하는 일시적 촉매제로 작동하였으며, 웰빙식품을 위시한 신(新)시장개척담론에서 반이슬람정서를 드러내는 테러식품으로의 담론전환에 따라 인간-비인간 행위자들의 새로운 연결망이 교차되는 지점에서 그 행위성을 드러내고 있다. 이처럼 글로벌화는 단일한 방향이 아닌 다각적으로 교차하며, 지역의 문화적 맥락에서 교섭하는 모습을 보인다. 본 연구는 할랄식품에 대한 담론의 형성과 실천은 글로벌 시장의 요구에 부합하려는 노력의 일환으로 작동하지만, 동시에 한국 사회의 맥락에서 발생하는 문화적 충돌을 경험하며 상황적으로 구성되고 있다는 것을 드러내고 있다. 여전히 한국에서 할랄식품정책을 둘러싼 갈등적 상황은 차별과 배제라는 어려운 관문을 완전히 극복하지 못하고 있지만, 그럼에도 불구하고 행위자-네트워크에 내재된 새로운 동맹의 가능성은 무슬림 및 할랄식품에 대한 공존의 사회를 조성할 열린 가능성을 보여주고 있다. 따라서 본 연구는 향후 한국의 다문화사회가 이주자에 대한 혐오를 규정하는 차별을 타개하고 합리적인 태도를 취할 수 있는 가능성을 전망하며, 상호문화적 통합사회로 나아가는데 기여하고자 한다.;This study shows the globalization of halal food by examining the discourse and practice of halal food in Korean society about the halal food industry which is attracting attention in the global market. The paper analyzes, through the lens of cultural geography, the religious and political debate that occurred in the process of withdrawing the plan for constructing Iksan Halal Complex. The paper examines the process of alliance and betrayal of actor networks in the case of Iksan Halal Complex through the four step translation process of the actor - network theory (Callon, 1986). First, MAFRA, a leading actor in the establishment of Iksan Halal Complex actor networks, has produced and disseminated discourse on the healthy halal food through the effective use of devices such as international food exhibitions and media reports. Secondly, conservative Christian groups who are extreme rightist organizations and one of the leading actors in stopping the Iksan Halal Complex plan, transformed the image of healthy halal foods to terrorism by aptly using prayer meetings, flyers, and signature campaigns. Halal rumors distributed in the process contain social discrimination and exclusion of Muslims in Korean society, reflecting the prevalence of xenophobia in Korean society. The case of the creation and withdrawal of the Iksan Halal Complex shows that the bipartite mechanisms of food, religion, or economy and culture are mutually intertwined. Globalization is not single directional, but cross-cutting, multi-faceted and dynamic in the cultural context of the region. Halal food served as a catalyst for raising a series of cultural wars in Korean society around races and religions. Ultimately, the globalization of halal foods, while still trying to meet the demands of global markets, is still contextualized in the context of the Korean society. Although the conflict surrounding the halal food policy in Korea still has not overcome the difficult hurdles of discrimination and exclusion, new alliance embedded in the actor-network showed the possibility of creating a society of coexistence with Muslims and Halal food in Korea. Therefore, this study provides a clue for Korea to overcome the discrimination that defines the abhorrence in the multicultural society and take a reasonable attitude in the future.I. Introduction 1 A. Controversy of Halal Food Complex in South Korea 1 B. Research Questions and Purpose 3 C. Research Methodology 5 D. Placing the Researcher 9 E. Chapter Outlines 12 II. Literature Review 14 A. Halal Food and Standardization 14 B. Food Globalization and Commodification 19 C. Culture War and Islamophobia 22 III. Halal Food Globalization and the Development of South Korean Halal Market 25 A. Halal Food Globalization 25 1. Increase of Global Muslim Population 25 2. Trends of Global Halal Food Market 28 3. Halal Food Certification and Halal Regime 33 B. Development of Korean Halal Market 37 1. Formation of Korean Muslims and Muslim communities 37 2. Development of Muslim Enclave and Halal Market in Itaewon 44 3. Diversification of Distribution Network in Halal Food Market 48 C. Halal Food Export Strategies and Policies in Korea 55 1. Halal Food Industry and Export Promotion Policy 55 2. Halal Food Policy Stats 62 IV. Conflict, and Compromise: Halal Food Discourse and Practice in Korea 67 A. Halal Food Discourses Healthy or Terrorists 67 1. Halal Food Measure Announced by MAFRA in June 2015 68 2. Spread of SNS message for abandoning Iksan Halal Complex 71 B. Translation of Healthy Food Halal 72 1. Defining the Problem and the Actor 73 2. Actor Interessement and Positive Discourse of Halal Food 77 3. Replacement and Transformation of Halal Food Complex 81 4. Cracks in the Alliance and Transition of Halal Food Policy 84 C. Dissidence: Betrayals and controversies of Terrorists Food Halal 87 1. Forming New Alliance and Defining the Actors 87 2. Actor Interessement and Negative Discourse of Halal Food 90 3. Effective Interessement Device to Public Concerns 94 4. Expansion of fear and withdrawal of Halal Complex 97 D. Culture War and Xenophobia in Korean Multi-cultural Society 100 1. Necessity of Revising Halal Industry Fostering Policy 101 2. Korean Society Overcoming Hatred against Foreigners 104 V. Conclusion 107 Bibliography 112 Appendix 115 Abstract(in Korean) 12

기묘핵 ¹²C, 28Si 과 56Fe의 약붕괴에 관한 연구

Thesis (doctoral)--서울대학교 대학원 :물리학과,1998.Docto

Structural modification of membrane electrode assembly in polymer electrolyte membrane fuel cell

Thesis(masters) --서울대학교 대학원 :화학생물공학부,2008.2.Maste

Implementation of multiplier and accumulator using 8-bit log number system

MasterA multiplier and accumulator using a logarithmic number system was proposed to improve floating point hardware by removing hardware multiplier. This new type of multiplier and accumulator was implemented in FPGA by using Verilog code. The multiplier and accumulator in FPGA received 16-bit pcm data from the smartphone and successfully proceeded with multiply and accumulation. The multiplier and accumulator is made up of four blocks; a pcm to log converter, a log decoder, log multiplier, and a kulisch accumulator

IoT 센서 기반 헬스케어 모니터링을 위한 능동학습방법

학위논문(박사) - 한국과학기술원 : 전기및전자공학부, 2024.2,[iv, 63 p. :]This dissertation presents a comprehensive study on resource-efficient human activity recognition (HAR) with a novel active learning strategy for supporting IoT-based healthcare monitoring. The study first introduces a novel deep learning-based active learning method designed to address the challenges associated with data labeling in supervised model training for HAR. With an extension of a single autoencoder to a multiclass scheme, the proposed method exploits the unique pattern characteristics inherent to each activity class for preferentially identifying the most informative samples for labeling. In addition, the proposed method introduces a margin scoring criteria based on cosine similarity by comparing pattern characteristics of each activity class to strategically select samples for constituting an informative training dataset, thereby enhancing the effectiveness of the process of supervised learning and the overall performance of the human activity recognition model. The method demonstrates superior classification performance of the HAR model, outperforming existing selecting methods. Additionally, the proposed methodology shows exceptional performance in terms of efficiency, leading to a substantial reduction in labeling costs. This is achieved by strategically selecting fewer, but more informative samples, thereby maintaining the same level of performance with reduced labeled samples. This study contributes to the field of IoT-based healthcare monitoring, fostering advancements in human activity recognition. By efficiently curating informative training datasets, the proposed method increases the effectiveness of the learning process of HAR. Furthermore, this study presents a resource-efficient human activity recognition in IoT environments, addressing the challenge of resource requirements in the deployment of IoT-embedded devices. The proposed method embraces a structured framework that integrates several essential components, including feature extraction in different levels of hierarchy within time series data, as well as an advanced technique to leverage temporal relationships between each hierarchically extracted feature. Specifically, the proposed method efficiently exploits temporal causality in feature spaces, thereby the number of recurrent operations is significantly reduced. The proposed method demonstrates superior classification performance over existing methods, particularly with substantial reductions in computational complexity and model complexity across diverse datasets. In addition, the proposed method shows a significant reduction in inference time and energy consumption in scenarios of model deployment at IoT-embedded devices, which results in advantages such as exceptional resource efficiency of the proposed method in a resource-constrained environment. This research significantly contributes to the development of an efficient HAR model, ensuring the integrity and reliability of IoT-based monitoring applications.한국과학기술원 :전기및전자공학부

ANODIC ELECTRODE, UNITIZED REGENERATIVE FUEL CELL INCLUDING THE SAME, AND METHOD FOR PREPARING THE SAME

산화 전극, 이를 포함하는 일체형 재생연료전지, 및 이의 제조 방법이 개시된다. 본 발명의 예시적인 구현예들에 따르면, 나노와이어로 이루어진 격자 형태의 백금(Pt) 층 및 이리듐(Ir) 층을 교호적으로 포함함으로써, 귀금속 촉매의 높은 활성 표면적, 연료전지 모드 및 수전해 모드 모두에서의 향상된 효율, 및 향상된 물질 전달, 즉 반응물의 손쉬운 접근 및 생성물의 신속한 제거를 달성하는 산화 전극을 제공할 수 있다

Hierarchically Assembled Cobalt Oxynitride Nanorods and N-Doped Carbon Nanofibers for Efficient Bifunctional Oxygen Electrocatalysis with Exceptional Regenerative Efficiency

Oxygen-based electrocatalysis is an integral aspect of a clean and sustainable energy conversion/storage system. The development of economic bifunctional electrocatalysts with high activity and durability during reversible reactions remains a great challenge. The tailored porous structure and separately presented active sites for oxygen reduction and oxygen evolution reactions (ORR and OER) without mutual interference are most crucial for achieving desired bifunctional catalysts. Here, we report a hybrid composed of sheath-core cobalt oxynitride (CoOx@CoNy) nanorods grown perpendicularly on N-doped carbon nanofiber (NCNF). The brushlike CoOx@CoNy nanorods, composed of metallic Co4N cores and oxidized surfaces, exhibit excellent OER activity (E = 1.69 V at 10 mA cm(-2)) in an alkaline medium. Although pristine NCNF or CoOx@CoNy alone had poor catalytic activity in the ORR, the hybrid showed dramatically enhanced ORR performance (E = 0.78 V at -3 mA cm(-2)). The experimental results coupled with a density functional theory (DFT) simulation confirmed that the broad surface area of the CoOx@CoNy nanorods with an oxidized skin layer boosts the catalytic OER, while the facile adsorption of ORR intermediates and a rapid interfacial charge transfer occur at the interface between the CoOx@CoNy nanorods and the electrically conductive NCNF. Furthermore, it was found that the independent catalytic active sites in the CoOx@CoNy/NCNF catalyst are continuously regenerated and sustained without mutual interference during the round-trip ORR/OER, affording stable operation of Zn-air batteries