미국의 동아시아 지역 미사일방어 전략에 대한 분석 연구: 상호확증파괴 이론 및 세력전이 이론을 중심으로

학위논문 (석사) -- 서울대학교 대학원 : 국제대학원 국제학과(국제협력전공), 2021. 2. 신성호.2016년 7월 8일, 미국은 주한미군에 고고도미사일방어체계(사드, THAAD)를 배치하기로 한국 정부와 합의하였다. 이는 아시아태평양 지역에 지속적으로 자국의 미사일 방어(MD) 전력을 배치하고 운영하려는 미국의 방어전략의 일환이었다. 나아가 2019년에는 Airborne Laser, 우주기반 레이더 및 요격미사일 체계 등의 최첨단 미사일방어 무기체계를 개발하겠다는 계획을 발표하기도 하였다. 미국의 지속적인 미사일방어 전력개발은 많은 라이벌 국가, 특히 중국으로부터 큰 반향을 일으켰다. 미국은 자국 MD체계의 역내 배치가 안정을 불러올 것이라 주장하는 반면, 미국의 MD 기술개발 및 전진배치 정책은 중국 핵무기체계의 개발을 불러일으켰다는 비판에 직면해있다. 상호확증파괴(MAD) 이론은 MD의 배치가 핵무기의 절대적인 상호파괴력으로 보장된 안정성을 깨트릴 수 있다고 경고한다. 그렇다면 미국은 왜 지속적으로 동아시아에 MD 개발 및 배치 정책을 고수하고 있는 것인가? 위 질문에 답하기 위해, 그리고 동아시아 지역에서 미국의 MD전략의 이론적 배경을 이해하기 위해 본 논문은 Kyungkook Kang과 Jacek Kugler의 세력전이이론에 기반한 이론적 틀을 활용하려 한다. 이들은 방어적인 패권국이 도전국에 대해 강력한 전력우위를 유지하는 것이 최선의 선택이라 주장한다. 이 이론에 따르면, 도전국의 핵 전력이 패권국의 전력과 대등해지는 상황은 위험하며 불안정하기 때문에, 패권국은 최대한 자국에게 유리한 핵 전력 우위를 유지하려 하며, 이는 상호확증파괴이론과는 상반된다. 본 논문은 미국의 오바마 정부 및 트럼프 정부에서 행해진 일련의 동아시아 지역 미국의 MD관련 정책과, 여기에 대응하는 중국의 반응을 두 개의 케이스 스터디로 분류하여 위의 이론적 틀을 실제 사건에 대입하고 분석하였으며, 이를 통해 패권국인 미국은 도전국인 중국에 대해 절대적인 핵 전력 우위를 유지하기 위해 자국의 MD체계를 동아시아 지역에 배치 및 지속 기술개발을 하고 있다는 결론을 도출한다. 이러한 분석 결과는, 세력전이 이론에 기반한 MD 정책은 결론적으로 미국의 방어적 능력 강화에 여기에 대응하는 중국의 공세적 능력 강화라는 끊임 없는 핵 전력 경쟁 속에 새로운 안보 딜레마에 직면하게 될 것이라는 점을 시사한다.On July 8, 2016, the United States made an agreement with the South Korean government to deploy a Terminal High Altitude Area Defense (THAAD) battery to Korea. This was in line with the U.S. Missile Defense (MD) policy in the Asia-Pacific, which adopted a phase-adaptive approach to gradually deploy more advanced MD capabilities in the region. In January 2019, the United States announced that it will revive key development programs such as Airborne Laser and Space-based sensors/interceptors, further diversifying the MD capabilities of the United States. Continuous technological advances and forward deployment of U.S. Missile Defense have been met with severe backlash from its strategic rivals, most notably China. Despite U.S. argument that MD will ensure regional stability, U.S. pursuit of MD innovation and forward advances have only led to further modernization of Chinese nuclear arsenals. Why is the United States pursuing MD strategy in East Asia when according to Mutually Assured Destruction (MAD), this will only destabilize the established order of nuclear deterrence? What are the implications of pursuing an expansive MD strategy in East Asia? To answer these questions and provide an explanation of the U.S. Missile Defense strategy in East Asia, this paper employed the theoretical framework based on the power transition theory proposed by Kyungkook Kang and Jacek Kugler. These scholars argue that the optimal choice for the dominant power is to maintain a preponderant advantage over the challenger. Under this framework, a situation where the challenger has enough capacity to match the defender is dangerous and unstable, therefore the defender tries to maintain the advantageous distribution of nuclear power. With the application of this framework, this paper shows that contemporary U.S. missile defense strategy in East Asia provides strong empirical evidence in support of this argument. An assessment of the U.S. Missile Defense strategy in East Asia clearly shows that the United States views China as a challenger, as it plans to maintain an obvious nuclear advantage by establishing and further diversifying defensive capabilities, while also modernizing the U.S. nuclear inventory for possible attack options. The implications of these findings suggest that a U.S. missile defense strategy that follows the logic based on power transition theory will ultimately lead to a nuclear security dilemma, where the U.S. and its contender – China – will compete in a nuclear arms race.Abstract (English)……………………………………………………………..………….. i Table of Contents ………………………………………………………………………. iii I. Introduction …..……………………………………………………………...………….1 II. Literature Review …..………………………………………...…………...………….4 1. Political Realism ………………………………………...…………....……….…4 2. Deterrence Theory ……………………………………….…………....………….6 3. Mutually Assured Destruction (MAD) ……………………….……....………….8 4. MAD and Missile Defense ………………….…………...…………....………...12 III. Theoretical Framework …..…………………………………….……....………..15 1. Kang-Kuglers Adaptation of Power Transition Theory …...…....……………..16 IV. Research Design …..……………………………………………....……..………….24 1. Application of the Kang-Kugler Model ……………………………....……..….24 2. Potential Criticisms ……………………………..…………….……....…………24 1) US-China Nuclear Imbalance .…………………………………….…...24 2) The North Korea Factor …..……………………………..…….……..….25 V. Case Study .…………………………………….………………………….....……….27 1. The Obama Administration…………………………..……….….………...…….…...28 2. The Trump Administration ………....……...…............................……….…..….……42 VI. Implications …..…………………………………………..……….…….....……..…58 VII. Conclusion …..………………………………...………..……….…….....…………61 Bibliography …..………………………………………..……..……….…….....……….64 Abstract (Korean) …..……………………………………..…...….…….....……..…….69Maste

양 계면 결함제어 공정을 통한 고성능 및 고안정성 페로브스카이트 광전소자 구현

학위논문(석사) -- 서울대학교대학원 : 공과대학 재료공학부, 2023. 8. 박병우.Organic-inorganic hybrid Perovskite solar cells (PSCs) are in the spotlight as promising renewable energy devices due to their desirable properties. However, they face challenges concerning both power conversion efficiency (PCE) and long-term stability. The presence of surface defects in PSCs poses a major hurdle to achieving high efficiency and stability, as these defects cause nonradiative recombination and degradation. Thus, suppressing electronic defects in both interfaces between the charge carrier transport layers and the perovskite layer is essential to improve photovoltaic performance and the long-term stability of PSCs. Herein, a novel double-side surface passivation method using phenyltrimethylammonium iodide (PTMAI) salt is applied to remove electronic defects effectively. PTMA cation is a quaternary ammonium salt known for its resistance to water and thermal stress as an effective defect passivator. Moreover, the bulky nature of this cation helps to suppress ion migration through the perovskite layer toward interfaces between the perovskite and charge transport layer. As a result, double-side passivation with PTMAI contributes to the enhancement of the perovskite crystallinity with the relaxed nonuniform distribution of the local strain of the perovskite layer. Furthermore, this passivation method also achieves remarkable suppression of trap density, promoting the growth of larger grains and a smoother surface in the perovskite layer. Consequently, the efficiency of formamidinium lead iodide (FAPbI3) PSC is significantly improved by double-side passivation with PTMAI, achieving a PCE of 21.87%. Moreover, the passivated cell exhibited enhanced long-term stability, maintaining over 80% of its initial PCE after 1860 h and 1030 h under 60 ℃ and continuous 1 sun illumination, respectively.유기/무기 하이브리드 페로브스카이트 태양전지(PSC)는 탁월한 특성으로 인해 유망한 재생 에너지 소자로 각광받고 있다. 그러나 동시에 전력 변환 효율(PCE) 및 장기 안정성과 관련된 문제에 직면해 있다. PSC에서 표면 결함의 존재는 비발광 재결합 및 열화를 일으키기 때문에 높은 효율과 안정성을 달성하는 데 주요 장애물이 된다. 따라서 전하 캐리어 수송층과 페로브스카이트 층 사이의 두 인터페이스에서 전자 결함을 억제하는 것은 PSC의 광전지 성능과 장기 안정성을 향상시키는 데 필수적이다. 이 연구에서는 전자결함을 효과적으로 제거하기 위해 페닐트리메틸암모늄아이오다이드(PTMAI) 염을 이용한 새로운 양 계면 결함 제어 방법을 적용하였다. 페닐트리메틸암모늄(PTMA) 양이온은 효과적인 결함 제어 물질로서 물과 열에 대한 저항성이 있는 것으로 알려진 4차 암모늄 염이다. 또한, 이 양이온의 큰 부피는 페로브스카이트 층으로부터 페로브스카이트와 전하 수송층 사이의 인터페이스로 이온이 이동하는 것을 억제하는 데 도움이 된다. 그 결과, PTMAI를 사용한 양 계면 결함제어 방법은 페로브스카이트 층에 존재하는 국부적 응력의 불균일한 분포를 완화시켜 페로브스카이트 결정도의 향상에 기여한다. 또한 이 방법은 트랩 밀도를 현저하게 억제하여 페로브스카이트 층에서 결정 입자를 더 크게 성장시키고 표면을 더 매끄럽게 만든다. 결과적으로 PTMAI를 사용한 양 계면 결함 제어 방법으로 FAPbI3 태양전지의 효율이 크게 개선되어 21.87%의 최종적인 PCE를 달성하였다. 또한, 결함이 억제된 소자는 60 ℃의 온도 조건 하에서 1860 시간 그리고 1 Sun (AM 1.5 G)의 지속적인 광 조건 하에서 1030 시간 후에 초기 효율의 80% 이상을 유지하면서 향상된 장기 안정성을 달성하였다.Chapter 1. Introduction to Overview of Perovskite Photovoltaics. 1 1.1. Introduction to Solar Cells 1 1.2. Basic Structure of Perovskite Solar Cells 5 1.3. Advantages and Disadvantages of Perovskite Solar Cells 9 1.4. References 14 Chapter 2. Double-Side Passivation of Perovskite Solar Cells for High Performance and Stability 16 2.1. Introduction 16 2.2. Experimental Section/Methods 18 2.3. Results and Discussion 21 2.4. Conclusions 34 2.5. References 35 Abstract in Korean 38석

텍스트와 특징점 기반의 목적함수 최적화를 이용한 문서와 텍스트 평활화 기법

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2014. 8. 조남익.There are many techniques and applications that detect and recognize text information in the images, e.g., document retrieval using the camera-captured document image, book reader for visually impaired, and augmented reality based on text recognition. In these applications, the planar surfaces which contain the text are often distorted in the captured image due to the perspective view (e.g., road signs), curvature (e.g., unfolded books), and wrinkles (e.g., old documents). Specifically, recovering the original document texture by removing these distortions from the camera-captured document images is called the document rectification. In this dissertation, new text surface rectification algorithms are proposed, for improving text recognition accuracy and visual quality. The proposed methods are categorized into 3 types depending on the types of the input. The contributions of the proposed methods can be summarized as follows. In the first rectification algorithm, the dense text-lines in the documents are employed to rectify the images. Unlike the conventional approaches, the proposed method does not directly use the text-line. Instead, the proposed method use the discrete representation of text-lines and text-blocks which are the sets of connected components. Also, the geometric distortion caused by page curl and perspective view are modeled as generalized cylindrical surfaces and camera rotation respectively. With these distortion model and discrete representation of the features, a cost function whose minimization yields parameters of the distortion model is developed. In the cost function, the properties of the pages such as text-block alignment, line-spacing, and the straightness of text-lines are encoded. By describing the text features using the sets of discrete points, the cost function can be easily defined and well solved by Levenberg-Marquadt algorithm. Experiments show that the proposed method works well for the various layouts and curved surfaces, and compares favorably with the conventional methods on the standard dataset. The second algorithm is a unified framework to rectify and stitch multiple document images using visual feature points instead of text lines. This is similar to the method employed in general image stitching algorithm. However, the general image stitching algorithm usually assumes fixed center of camera, which is not taken for granted in capturing the document. To deal with the camera motion between images, a new parametric family of motion model is proposed in this dissertation. Besides, to remove the ambiguity in the reference plane, a new cost function is developed to impose the constraints on the reference plane. This enables the estimation of physically correct reference plane without prior knowledge. The estimated reference plane can also be used to rectify the stitching result. Furthermore, the proposed method can be applied to any other planar object such as building facades or mural paintings as well as the camera-captured document image since it employs the general features. The third rectification method is based on scene text detection algorithm, which is independent from the language model. The conventional methods assume that a character consists of a single connected component (CC) like English alphabet. However, this assumption is brittle in the Asian characters such as Korean, Chinese, and Japanese, where a single character consists of several CCs. Therefore, it is difficult to divide CCs into text lines without language model. To alleviate this problem, the proposed method clusters the candidate regions based on the similarity measure considering inter-character relation. The adjacency measure is trained on the data set labeled with the bounding box of text region. Non-text regions that remain after clustering are filtered out in text/non-text classification step. Final text regions are merged or divided into each text line considering the orientation and location. The detected text is rectified using the orientation of text-line and vertical strokes. The proposed method outperforms state-of-the-art algorithms in English as well as Asian characters in the extensive experiments.1 Introduction 1 1.1 Document rectification via text-line based optimization . . . . . . . 2 1.2 A unified approach of rectification and stitching for document images 4 1.3 Rectification via scene text detection . . . . . . . . . . . . . . . . . . 5 1.4 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 Related work 9 2.1 Document rectification . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.1 Document dewarping without text-lines . . . . . . . . . . . . 9 2.1.2 Document dewarping with text-lines . . . . . . . . . . . . . . 10 2.1.3 Text-block identification and text-line extraction . . . . . . . 11 2.2 Document stitching . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.3 Scene text detection . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3 Document rectification based on text-lines 15 3.1 Proposed approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.1.1 Image acquisition model . . . . . . . . . . . . . . . . . . . . . 16 3.1.2 Proposed approach to document dewarping . . . . . . . . . . 18 3.2 Proposed cost function and its optimization . . . . . . . . . . . . . . 22 3.2.1 Design of Estr(·) . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.2.2 Minimization of Estr(·) . . . . . . . . . . . . . . . . . . . . . 23 3.2.3 Alignment type classification . . . . . . . . . . . . . . . . . . 28 3.2.4 Design of Ealign(·) . . . . . . . . . . . . . . . . . . . . . . . . 29 3.2.5 Design of Espacing(·) . . . . . . . . . . . . . . . . . . . . . . . 31 3.3 Extension to unfolded book surfaces . . . . . . . . . . . . . . . . . . 32 3.4 Experimental result . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.4.1 Experiments on synthetic data . . . . . . . . . . . . . . . . . 36 3.4.2 Experiments on real images . . . . . . . . . . . . . . . . . . . 39 3.4.3 Comparison with existing methods . . . . . . . . . . . . . . . 43 3.4.4 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 4 Document rectification based on feature detection 49 4.1 Proposed approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.2 Proposed cost function and its optimization . . . . . . . . . . . . . . 51 4.2.1 Notations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 4.2.2 Homography between the i-th image and E . . . . . . . . . 52 4.2.3 Proposed cost function . . . . . . . . . . . . . . . . . . . . . . 53 4.2.4 Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 4.2.5 Relation to the model in [17] . . . . . . . . . . . . . . . . . . 55 4.3 Post-processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.3.1 Classification of two cases . . . . . . . . . . . . . . . . . . . . 56 4.3.2 Skew removal . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.4 Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4.4.1 Quantitative evaluation on metric reconstruction performance 57 4.4.2 Experiments on real images . . . . . . . . . . . . . . . . . . . 58 5 Scene text detection and rectification 67 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 5.1.1 Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 5.1.2 Proposed approach . . . . . . . . . . . . . . . . . . . . . . . . 69 5.2 Candidate region detection . . . . . . . . . . . . . . . . . . . . . . . 70 5.2.1 CC extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.2.2 Computation of similarity between CCs . . . . . . . . . . . . 70 5.2.3 CC clustering . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 5.3 Rectification of candidate region . . . . . . . . . . . . . . . . . . . . 73 5.4 Text/non-text classification . . . . . . . . . . . . . . . . . . . . . . . 76 5.5 Experimental result . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 5.5.1 Experimental results on ICDAR 2011 dataset . . . . . . . . . 80 5.5.2 Experimental results on the Asian character dataset . . . . . 80 6 Conclusion 83 Bibliography 87 Abstract (Korean) 97Docto

CMS를 활용한 도서관 웹사이트 발전 방향

1. 이용자 환경의 변화 멀티 디바이스 시대 2007년 아이폰의 등장 이후 스마트 기기의 성장이 급속하게 빠르게 나타남. 2017년 스마트폰을 이용한 모바일 트래픽이 전체 트래픽의 81%, 태블릿 포함 시 92%의 점유 예상(출처: CISCO) 스마트폰, 태블릿 등 휴대기기의 판매량이 급속하게 신장 2015년 태블릿 판매량이 PC/노트북 판매량을 추월할 것으로 예상(출처: IDC) 전자책, 멀티미디어 자료 등의 이용을 위한 도구로써의 스마트 디바이스의 활용도가 증가하는 추

Fully vacuum–processed perovskite solar cells with high open circuit voltage using MoO3/NPB layer

학위논문 (석사)-- 서울대학교 대학원 : 재료공학부, 2015. 2. 김장주.Recently, organic/inorganic hybrid (e.g. CH3NH3PbI3, CH3NH3PbI3-xClx) perovskite based solar cells attract large attention because of the remarkably high power conversion efficiencies. Most of the devices reported up to now have been fabricated using solution processes. One of the critical issues of the solution processed perovskite solar cells is the reproducibility coming from the difficulties in controlling the uniformity, pin-hole formation, sensitivity to moisture and air of the perovskite film. Vacuum evaporation has a potential for high reproducibility and controllability due to solvent free processes combined with controllable growth parameters in a clean and inert environment. Nevertheless, the fully vacuumprocessed perovskite solar cells have been rarely reported up to now. The other crucial issue is the charge transport materials, mainly hole transport materials(HTMs), to enhance the device performance. The widely used HTM, 2,2,7,7-Tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (spiro-OMeTAD) is not an optimized HTM for the CH3NH3PbI3 based solar cells, since spiro-OMeTAD possesses a few hundred meV higher HOMO level than valance band (VB) edge of CH3NH3PbI3. This thesis presents high efficiency perovskite solar cells with high open circuit voltage using full vacuum process employing molybdenum oxide (MoO3) and N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) as a new hole extraction layer. All the layers in the solar cells including the perovskite active layer, hole extraction layers and electron extraction layers were deposited in the vacuum process. Uniform crystalline perovskite layers were able to be grown on the NPB layer under optimized conditions. The grain size of the films were about 100 nm with the root mean square roughness of 9.7 nm. The solar cells employing the MoO3/NPB as the hole extraction layer resulted in a high open circuit voltage (VOC) of 1.12 V, which is one of the highest values reported up to now in perovskite solar cells. Due to the effective hole extraction and high VOC, the devices showed a maximum power conversion efficiency (PCE) of 13.7% with JSC of 18.1 mA/cm2, VOC of 1.12 V and FF of 0.68. It turned out missing one of the MoO3 or NPB layers resulted in much poor solar cell performance due to either the failure of the formation of ohmic contact with the ITO electrode (missing the MoO3 layer) or due to the lack of the electron blocking layer or poor crystallinity of the perovskite layer (missing the NPB layer). The vacuum processed perovskite solar cells showed relatively high reproducibility showing the average value of PCE of 11.1%. The JSC and VOC are distributed within 17.2 mA/cm2 ~ 19.5 mA/cm2 and 0.98 V ~ 1.12 V respectively, exhibiting small deviation within approximately 7% from the average values. The FF values show a relatively wide distribution, 0.39~0.68, hence causing the similar distribution of PCE values, 7.1%~13.7%. Still the variation of the performance of the solar cells fabricated using the vacuum process is fairly narrow compared to the normal solution processed perovskite solar cells. Further study is required to find out the origin of the variation of FF, thereby to enhance the better reproducibility. The vacuum processed perovskite solar cells showed hysteresis depending on sweep direction. The device with MoO3/NPB layer showed PCE of 12.1% with JSC of 18.1 mA/cm2, VOC of 1.09 V and FF of 0.62 in the forward scan direction whereas overall solar cell parameter decreased in the reverse scan direction showing PCE of 10.3% with JSC of 17.1 mA/cm2, VOC of 1.07 V and FF of 0.56. The origin of the hysteresis is important issue, however it has not been clearly figured out yet.Abstract i Contents ii List of Tables vi List of Figures vii Chapter 1. Introduction 1 1.1 Motivation and outline of thesis 1 1.1.1 Motivation 1 1.1.2 Outline of thesis 2 1.2 Perovskite solar cells 4 1.2.1 Material properties of the perovskite 4 1.2.2 Working principles of the perovskite solar cells 7 1.2.3 Charge extractions in perovskite solar cells 7 1.2.4 Methodes to fabricate the perovskite thin films 9 Chapter 2. Vacuum deposition of CH3NH3PbI3 12 2.1 Introduction 12 2.2 Behavior of CH3NH3I3 in the vacuum deposition 13 2.3 Co-deposition with PbCl2(CH3NH3PbI3-xClx) 16 2.4 Co-deposition with PbI2(CH3NH3PbI3) 19 2.5 Film characterizations 22 2.5.1 Absorbance & XRD patterns 22 2.5.2 Surface analyzes 26 Chapter 3. Hole extraction layers in the vacuum processed peorvskite solar cells 29 3.1 Introduction 29 3.2 Experiments 32 3.3 Function of the MoO3 layer 33 3.4 Function of the NPB layer 38 3.5 Device with MoO3/NPB layer 45 3.6 Conclusion 51 Chapter 4. Reproducibility of the vacuum processed peorvskite solar cells 52 4.1 Introduction 52 4.2 Histograms 53 4.3 Reproducibility analysis 55 4.4 Conclusion 62 Chapter 5. Hysteresis behavior of the vacuum processed perovskite solar cells 63 5.1 Introduction 63 5.2 J–V characteristics with the different scan directions 64 5.3 Plausible origins 69 5.4 Conclusion 70 Chapter 5. Summary and out look 71 Bibliography 75 초록 81 List of Awards 84 List of Publications 85Maste

The Impacts of Coeducation in High School on the College Scholastic Ability Tes

Park et al. (2012) examined the impacts of coeducation in high school on the college scholastic ability test using random assignment in Seoul high schools. However, the student random assignment in Seoul within a school district was performed only withinⅠ. 서 론 　Ⅱ. 선행연구 개관 　Ⅲ. 연구방법 　Ⅳ. 분석 결과 　Ⅴ. 결론 및 고찰 　참고문

The Impacts of Smoking Bans on Smoking in Korea

There is a growing concern about potential harmful effect of second-hand or environmental tobacco smoking. As a result, smoking bans in workplace become more prevalent worldwide. In Korea, workplace smoking ban policy become more restrictive in 2003 whenⅠ. 서 론 Ⅱ. 문헌 연구 Ⅲ. 한국의 금연정책들 Ⅳ. 실증분석 Ⅴ. 회귀분석 결과 Ⅵ. 추정의 안정성 확인 Ⅶ. 결 론 참 고 문

Optimization of Agricultural UTV Gearbox Housing Shape Using Structural-Acoustic Coupled Analysis

학위논문(석사) -- 서울대학교대학원 : 농업생명과학대학 바이오시스템공학과, 2021.8. 박영준.최근 친환경 농업 기계의 개발 및 보급에 대한 요구가 증가함에 따라 농업기계 파워트레인의 전동화가 빠르게 진행되고 있다. 전동화 된 농업용 UTV의 기어박스에서 발생하는 기어 물림으로 인한 고주파 순음은 탑승자 및 작업자에게 불쾌감을 주므로, 농업용 UTV의 진동과 소음의 성능 개선을 위해서는 기어박스에서 발생하는 방사 소음을 감소시켜야 한다. 본 연구에서는 하우징의 최적 설계를 통해 기어박스의 방사 소음을 저감하였다. 먼저 연구 대상인 농업용 UTV 기어박스에 대해 랩 테스트를 수행하여 기어박스의 진동/소음 성능과 기어박스의 주요 가진원을 파악하였다. 시험 결과로부터 기어박스 하우징의 진동 및 방사 소음 수준을 파악하였으며, 기어박스를 가진하는 주요 성분이 1단 기어 쌍에서 발생하는 기어의 전달 오차의 1차 하모닉 성분임을 확인하였다. 기어박스 하우징의 최적화를 수행하기 위하여 기어 시스템의 동역학 해석 모델과 구조-음향 연성 해석 모델을 개발하였다. 진동 및 소음 해석 결과, 주요 영역에서 시험 및 해석 결과가 진동은 0.1 dB 이내, 소음은 0.2 dB(A) 이내의 오차를 보여 모델이 신뢰성을 갖는다고 판단하였다. 개발된 구조-음향 연성 해석 모델을 바탕으로 위상 최적화를 수행하여 하우징을 최적 설계하였다. 하우징 주변의 음압 레벨을 목적 함수로 사용하여 위상 최적화를 수행하였으며, 방사 소음을 저감할 수 있는 하우징의 최적 형상을 도출하였다. 최적화 결과를 토대로 하우징 리브를 설계하였으며, 운행 영역에서 약 2.43 dB(A)의 방사 소음 개선 효과를 확인하였다.Recently, as the demand for the development and dissemination of eco-friendly agricultural machines increases, the electrification of agricultural machine powertrains is progressing. Since the high-frequency pure sound caused by gear meshing generated from the reducer of an electrified agricultural UTV causes discomfort to passengers and workers, it is necessary to reduce the radiated noise generated by the reducer in order to improve the NVH performance of the agricultural UTV. In this study, radiated noise of the gearbox was reduced through the optimal design of housing. First, a rig test was performed on the agricultural UTV reducer to estimate the NVH performance of the reducer and identify the main components with the reducer. As a result of the test, the vibration and radiated noise of the reducer housing were measured, and it was confirmed that the main component which excites the reducer is the first harmonic of the first gear pair. Afterwards, a gear system dynamic analysis model and a structural-acoustic coupled analysis model were developed for the optimization. As a result of the vibration and noise analysis, the test and analysis results in the main areas showed an error within 0.1 dB for the vibration and 0.2 dB(A) for the noise. Therefore, it was judged that the model had reliability. Finally, the housing was optimally designed by performing topology optimization based on the developed structural-acoustic coupled analysis model. As a result of performing topology optimization using the sound pressure level around the housing as an objective function, the material arrangement of the housing was found to reduce radiated noise. As a result of designing the housing ribs based on the optimization results, the effect of improving radiated noise by about 2.43 dB(A) was confirmed in the operation area.제 1 장 서론 1 1.1 연구 배경 1 1.2 연구 동향 3 1.2.1 기어박스 방사 소음 예측 3 1.2.2 기어박스 하우징 형상 최적화 4 1.2.3 요약 및 결론 6 1.3 연구 목적 7 제 2 장 기어 시스템의 진동 소음 특성 9 제 3 장 기어 시스템의 진동 소음 시험 13 3.1 연구 대상 UTV 기어박스 13 3.2 오더 분석 16 3.3 시험 장치 구성 19 3.4 시험 결과 21 제 4 장 기어 시스템의 해석 모델 개발 26 4.1 지배 방정식 26 4.2 동역학 예측 모델 32 4.3 방사 소음 예측 모델 40 제 5 장 하우징 형상 최적화 45 5.1 위상 최적화 45 5.2 하우징 형상 최적화 47 제 6 장 결론 53 참고문헌 55 Abstract 61석

Xylitol과 Sorbitol이 Lysozyme과 Peroxidase에 관련된 효소활성 및 Candidacidal 활성에 미치는 영향

학위논문 (박사)-- 서울대학교 대학원 : 치의과학과, 2015. 2. 고홍섭.The purpose of this study was to investigate what xylitol and sorbitol could affect on the enzymatic and candidacidal activities of lysozyme, the peroxidase system, and the glucose oxidase-mediated peroxidase system. Xylitol and sorbitol were added to hen egg-white lysozyme, bovine lactoperoxidase, glucose oxidase-mediated peroxidase, and whole saliva in solution and on the hydroxyapatite surface phases. The enzymatic activities of lysozyme, peroxidase, and glucose oxidase-mediated peroxidase were determined by measuring the turbidity of a Micrococcus lysodeikticus suspension, the rate of oxidation to 5,5-dithiobis-2-nitrobenzoic acid by hypothiocyanite, and the production of oxidized o-dianisidine, respectively. Candidacidal activities were determined by comparing colony forming units and calculating the percent loss of cell viability using Candida albicans ATCC 10231, 11006, and 18804. Both xylitol and sorbitol did not affect the enzymatic activity of hen egg-white lysozyme both in solution and on the hydroxyapatite surface phases, while both sugar alcohols inhibited the enzymatic activity of salivary lysozyme significantly in solution phase, but not on the surface phase. Both xylitol and sorbitol enhanced the enzymatic activities of both bovine lactoperoxidase and salivary peroxidase significantly by dose-dependent manner in solution phase, but not on the surface phase. Sorbitol, not xylitol, inhibited the enzymatic activity of glucose oxidase-mediated peroxidase significantly. Both xylitol and sorbitol did not affect the candidacidal activities of hen egg-white lysozyme, the bovine lactoperoxidase system, and the glucose oxidase-mediated bovine lactoperoxidase system. Conclusively, xylitol and sorbitol inhibited salivary lysozyme activity, but enhanced both bovine lactoperoxidase and salivary peroxidase activities significantly in solution phase. Xylitol and sorbitol were not additive to the candidacidal activities related with lysozyme and peroxidase.II. INTRODUCTION 1 II. REVIEW OF LITERATURE 3 III. MATERIALS AND METHODS 14 IV. RESULTS 20 V. DISCUSSION 23 VI. CONCLUSIONS 26 REFERENCES 27 FIGURES 44 TABLES 46 KOREAN ABSTRACT 52Docto