불확실성을 포함하는 조립작업을 위한 컴플라이언스 기반 펙인홀 전략

학위논문 (박사) -- 서울대학교 대학원 : 융합과학기술대학원 융합과학부(지능형융합시스템전공), 2020. 8. 박재흥.The peg-in-hole assembly is a representative robotic task that involves physical contact with the external environment. The strategies generally involve performing the assembly task by estimating the contact state between the peg and the hole. The contact forces and moments, measured using force sensors, are primarily used to estimate the contact state. In this paper, in contrast to past research in the area, which has involved the utilization of such expensive devices as force/torque sensors or remote compliance mechanisms, an inexpensive method is proposed for peg-in-hole assembly without force feedback or passive compliance mechanisms. The method consists of an analysis of the state of contact between the peg and the hole as well as a strategy to overcome the inevitable positional uncertainty of the hole incurred in the recognition process. A control scheme was developed to yield compliant behavior from the robot with physical contact under the condition of hybrid position/force control. Proposed peg-in-hole strategy is based on compliance characteristics and generating the force and moment. The peg is inserted into the hole as it adapts to the external environment. The effectiveness of the proposed method was experimentally verified using a humanoid upper body robot with fifty degrees of freedom and a peg-in-hole apparatus with a small clearance (0.1 mm). Three cases of experiments were conducted; Assembling the peg attached to the arm in the hole fixed in the external environment, grasping a peg with an anthropomorphic hand and assembling it into a fixed hole, and grasping both peg and hole with both hands and assembling each other. In order to assemble the peg-in-hole through the proposed strategy by the humanoid upper body robot, I present a method of gripping an object, estimating the kinematics of the gripped object, and manipulating the gripped object. In addition to the cost aspect, which is the fundamental motivation for the proposed strategy, the experimental results show that the proposed strategy has advantages such as fast assembly time and high success rate, but has the disadvantage of unpredictable elapsed time. The reason for having a high variance value for the success time is that the spiral trajectory, which is most commonly used, is used. In this study, I analyze the efficiency of spiral force trajectory and propose an improved force trajectory. The proposed force trajectory reduces the distribution of elapsed time by eliminating the uncertainty in the time required to find a hole. The efficiency of the force trajectory is analyzed numerically, verified through repeated simulations, and verified by the actual experiment with humanoid upper body robot developed by Korea institute of industrial technology.펙인홀 조립은 로봇의 접촉 작업을 대표하는 작업으로, 펙인홀 조립 전략을 연구함으로써 산업 생산 분야의 조립작업에 적용할 수 있다. 펙인홀 조립작업은 일반적으로 펙과 홀 간의 접촉상태를 추정함으로써 이루어진다. 접촉상태를 추정하기 위해 가장 널리 쓰이는 방법은 힘 센서를 사용하는 것인데, 접촉 힘과 모멘트를 측정하여 접촉상태를 추정하는 방식이다. 만약 이러한 센서를 사용하지 않을 수 있다면, 하드웨어 비용과 소프트웨어 연산량 감소 등의 장점이 있음은 자명하다. 본 논문에서는 힘 센서 혹은 수동 컴플라이언스 장치를 사용하지 않는 펙인홀 전략을 제안한다. 홀에 대한 인식 오차 혹은 로봇의 제어 오차를 극복하기 위하여 먼저 펙과 홀의 접촉 가능 상태를 분석하고 로봇의 컴플라이언스 모션을 위한 제어 프레임워크를 디자인한다. 전략은 컴플라이언스 특징에 기반하며 펙에 힘과 모멘트를 생성시킴으로써 조립작업을 수행한다. 펙은 외부환경에 순응함으로써 홀에 삽입된다. 제안한 전략은 낮은 공차를 갖는 펙인홀 실험을 통해서 그 유효성이 검증된다. 펙과 홀을 로봇팔과 외부환경에 각각 고정된 환경에서의 실험, 인간형 로봇핸드를 이용하여 펙을 잡아서 고정된 홀에 삽입하는 실험, 그리고 테이블에 놓인 펙과 홀을 각각 로봇핸드로 파지하여 조립하는 총 세 가지의 실험을 수행하였다. 핸드로 펙을 파지하고 조작하기 위하여, 파지 방법과 핸드를 이용한 물체 조작 알고리즘을 간략히 소개하였다. 제안한 전략의 성능을 실험적으로 분석한 결과, 높은 조립 성공률을 갖는 대신 조립시간이 예측할 수 없는 단점이 나타나 이를 보완하기 위해서 렌치 궤적 또한 제안하였다. 먼저 가장 일반적으로 사용되는 나선 힘 궤적을 이용했을 때 조립 성공시간의 분산이 큰 이유를 확률개념을 이용해 분석하고, 이를 보완하기 위한 부분적 나선 힘 궤적을 제안한다. 제안한 힘 궤적이 나선 힘 궤적에 비해 갖는 성능의 우수성을 증명하기 위하여 수치적 분석, 반복적 시뮬레이션, 그리고 로봇을 이용한 실험을 수행하였다.1 INTRODUCTION 1 1.1 Motivation: Peg-in-Hole Assembly 1 1.2 Contributions of Thesis 2 1.3 Overview of Thesis 3 2 COMPLIANCE BASED STRATEGY 5 2.1 Background & Related Works 5 2.2 Analysis of Peg-in-Hole Procedure 6 2.2.1 Contact Analysis 7 2.2.2 Basic Idea 9 2.3 Peg-in-Hole Strategy 12 2.3.1 Unit Motions 12 2.3.2 State of Strategy 13 2.3.3 Conditions for State Transition 15 2.4 Control Frameworks 18 2.4.1 Control for Compliant Behavior 18 2.4.2 Friction Compensate 20 2.4.3 Control Input for the Strategy 25 2.5 Experiment 29 2.5.1 Experiment Environment 29 2.5.2 Fixed Peg and Fixed Hole 31 2.5.2.1 Experiment Results 31 2.5.2.2 Analysis of Force and Control Gain 36 2.5.3 Peg-in-Hole with Multi Finger Hand 41 2.5.3.1 Object Grasping 42 2.5.3.2 Object In-Hand Manipulation 44 2.5.3.3 Experiment Results 49 2.5.4 With Upper Body Robot 50 2.5.4.1 Peg-in-Hole Procedure 52 2.5.4.2 Kinematics of Grasped Object 54 2.5.4.3 Control Frameworks 54 2.5.4.4 Experiment Results 56 2.6 Discussion 59 2.6.1 Peg-in-Hole Transition 59 2.6.2 Influential Issues 59 3 WRENCH TRAJECTORY 63 3.1 Problem Statement 64 3.1.1 Hole Search Process 64 3.1.2 Spiral Force Trajectory Analysis 66 3.2 Partial Spiral Force Trajectory 70 3.2.1 Force Trajectory with Tilted Posture 70 3.2.2 Probability to Three-point Contact 76 3.3 SIMULATION & EXPERIMENT 78 3.3.1 Simulation 78 3.3.2 Experiment 83 4 CONCLUSIONS 90 Abstract (In Korean) 102Docto

가상 당김, 여절단 국소화 및 4차원 칼라비-야우 다양체의 도널드슨-토마스 이론

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 수리과학부, 2022. 8. 김영훈.The main purpose of this dissertation is to generalize Manolache's virtual pullbacks and Kiem-Li's cosection localization to Donaldson-Thomas theory of Calabi-Yau 4-folds. The three main applications are Lefschetz principle, Pairs/Sheaves correspondence, and a foundation of surface counting theory. A secondary purpose is to revisit virtual pullbacks and cosection localization via the Kimura sequence for Artin stacks, derived algebraic geometry, and algebraic cobordism. We also prove Graber-Pandaripande's torus localization formula in full generality.이 학위 논문의 주요 목적은 가상 당김과 여절단 국소화를 칼라비-야우 4차원 다양체의 도널드슨-토마스 이론으로 확장하는 것입니다. 이차적인 목적은 가상 당김과 여절단 국소화를 아틴 스택의 교차이론, 파생 대수 기하학 및 대수적 코보디즘을 이용하여 일반화하는 것입니다.Abstract i Introduction 1 I Virtual intersection theory 17 1 Intersection theory 18 1.1 Intersection theory for schemes 18 1.2 Intersection theory for Artin stacks 25 1.3 Algebraic cobordism 29 2 Virtual pullbacks 35 2.1 Intrinsic normal cones 36 2.2 Perfect obstruction theories 47 2.3 Virtual pullbacks and virtual cycles 52 3 Cosection localization 65 3.1 Cone reduction 66 3.2 Reduced virtual cycles 72 3.3 Cosection-localized virtual pullbacks 75 II Donaldson-Thomas theory of Calabi-Yau 4-folds 83 4 Virtual pullbacks in DT4 theory 84 4.1 Local models 86 4.2 Symmetric obstruction theories 97 4.3 Square root virtual pullbacks 108 5. Cosection localization in DT4 theory 118 5.1 Cone reductions 119 5.2 Reduced virtual cycles 122 5.3 Cosection-localized virtual cycles 125 6 Applications to enumerative geometry 131 6.1 Moduli spaces, virtual cycles, and invariants 131 6.2 Lefschetz principle 140 6.3 Pairs/Sheaves correspondence 142 6.4 Counting surfaces on Calabi-Yau 4-folds 146 III Generalizations 148 7 Torus localization via equivariant virtual pullbacks 149 7.1 Equivariant virtual pullbacks 149 7.2 Localization of virtual cycles 159 8 Cosection localization via (-1) -shifted 1-forms 163 8.1 Three reductions 164 8.2 Localized virtual cycles 167 9 Virtual cycles in algebraic cobordism 170 9.1 Limit algebraic cobordism 170 9.2 Virtual pullbacks 176 9.3 Cosection localization 184 9.4 Torus localization 189 A Kimura sequence for Artin stacks 193 A.1 Kimura sequence for Artin stacks 193 A.2 Chow lemma for Artin stacks 197 Abstract (in Korean) i Acknowledgement (in Korean) ii박

환경요인이 기주식물 쥐방울덩굴과 초식동물 꼬리명주나비 유충에 미치는 영향

학위논문 (박사) -- 서울대학교 대학원 : 사범대학 과학교육과(생물전공), 2021. 2. 김재근.기후변화가 진행됨에 따라 나타나는 빠른 환경 변화로 인해 곤충을 포함한 생물다양성의 위기가 도래할 가능성이 높다. 생태계 내에서 곤충의 생태학적·생물학적인 가치를 생각해 볼 때, 기후변화가 곤충에 미칠 수 있는 영향을 구체적으로 규명하기 위한 연구가 필요하다. 이러한 관점에서 식물은 곤충에 주요한 영향을 미칠 수 있는 요인이므로 기후변화에 대한 식물의 반응을 이해하기 위한 노력이 선행되어야 한다. 지금까지 이를 해결하기 위한 연구가 다수 진행되었으며, 이를 토대로 기후변화로 인한 식물의 반응과 그로 인한 곤충 군집의 변화에 대한 가설이 제안되었다. 그러나, 기후변화는 복잡한 환경 요인의 변화를 동반하며 그에 대한 식물의 반응 또한 종의 특성에 따라 다른 양상으로 나타날 수 있어, 기후변화에 대한 현재의 주요 예측은 여전히 더 많은 실험적 증거와 증명을 필요로 한다. 특히, 기후변화가 식물과 곤충의 상호작용에 미치는 영향에 주요한 변화를 일으킬 것으로 예상되는 강수 빈도의 증가와 식물과 곤충의 계절성에 대한 연구는 여전히 미진한 실정이다. 따라서, 본 연구에서는 우리나라 고유종인 쥐방울덩굴(Aristolochia contorta)과 이를 유일한 기주식물로 활용하는 특이적 초식 곤충인 꼬리명주나비(Sericinus montela)를 활용하여 환경 요인이 식물-곤충 상호작용에 미치는 영향을 파악하고자 하였다. 환경 요인이 식물의 생육과 방어 작용에 미치는 영향과 그로 인해 나타나는 초식 곤충의 생육 변화의 관계를 규명하기 위하여 본 연구에서는 세 가지의 주요한 실험을 실행하였다. 우선, 다양한 환경 요인의 기주식물에 대한 영향의 가능성을 타진하기 위하여 쥐방울덩굴의 서식지에 대한 현장 조사를 수행하였다. 또한, 이산화탄소 농도의 상승과 강수 빈도의 증가가 식물의 생육과 방어 작용에 미치는 영향 및 초식 곤충에 대한 연쇄적인 효과를 파악하고, 기후변화에 따라 나타나는 식물-곤충 상호작용 변화의 계절적인 동태를 파악하기 위하여 상부개방형온실(open-top chamber)을 활용한 두 개의 메조코즘 실험을 진행하였다. 줄기 길이와 잎의 수를 측정하여 식물의 생장 양상을 관찰하였으며, 초식 곤충의 상대생장률(relative growth rate)을 기반으로 기후변화에 따른 식물의 반응이 곤충에 미치는 영향을 파악하였다. 추가적으로, 식물의 잎의 영양 가치를 평가하기 위하여 탄소: 질소 비율(C: N ratio)과 1차 대사산물을 분석하였고, 식물 잎에서 나타나는 화학적 반응을 비교하기 위하여 2차 대사산물을 분석하였다. 현장 조사 결과, 쥐방울덩굴의 생육은 다양한 생물적 요인과 비생물적 요인에 영향을 받을 수 있는 것으로 드러났다. 특히, 초식 곤충으로 인한 섭식 스트레스와 종간 경쟁으로 인한 스트레스, 토양 내 양이온 함량이 주요한 요인으로 확인되었다. 기후변화에 따른 식물의 반응의 관점에서는, 이산화탄소 농도의 상승이 식물의 광합성을 억제하여 생육을 감소시키고 식물의 방어 작용은 증진시켰다. 이러한 증진된 식물의 방어 작용에 따라 초식 곤충의 생육은 억제되었다. 이와 달리, 강수 빈도의 증가는 이러한 높은 농도의 이산화탄소의 영향을 부분적으로 완화하여, 초식 곤충의 생장을 증가시켰다. 더불어, 이러한 이산화탄소 농도의 상승과 강수 빈도의 증가가 잎의 영양 가치와 식물의 상시 방어(constitutive defense)에 미치는 영향은 시기에 따라 다르게 나타났다. 증가된 강수 빈도는 영양 가치를 증진시켰으며, 이러한 영향은 식물의 생육 기간의 중간에 가장 크게 나타났다. 반면, 상승된 이산화탄소 농도는 영양 가치를 감소시키고 상시 방어를 증진시켰으며, 식물의 생육 기간의 종료 시기에 가장 크게 확인되었다. 이러한 시기적으로 일치하지 않는 변화에 따라 특이적 초식 곤충과 비특이적 초식 곤충의 생장 양상 또한 계절적 변동을 나타낸 것으로 보인다. 결론적으로, 강수 빈도의 증가보다 이산화탄소 상승이 미치는 더 주요한 영향을 미치는 것을 고려해볼 때, 기주식물의 질과 양이 모두 감소할 수 있으며, 이에 따라 그것을 이용하는 특이적 초식 곤충의 생장도 억제될 수 있을 것으로 생각된다. 이러한 결과는 기후변화가 곤충 군집에 부정적인 영향을 미칠 것이라는 기존에 제시된 가설과 같은 결과를 예상하지만 그 과정은 다르게 나타날 수 있음을 시사한다. 그러나, 기후변화로 인한 환경 변화가 시기적으로 다른 영향을 미친다는 것을 고려해볼 때, 강수 빈도의 증가가 초식 곤충의 생활사 중 특정 시기의 생장을 증가시킴으로써 이산화탄소 증가의 부정적인 효과를 일부 상쇄할 수 있을 것으로 판단된다. 뿐만 아니라, 본 연구의 결과는 식물-곤충 상호작용에서 식물의 종특이적인 반응과 기존에 고려되지 않았으나 주요한 영향력을 가지고 있을 수 있는 환경 요인을 고려함으로써, 기후변화가 식물과 초식 곤충의 상호작용에 미치는 영향을 종합적으로 이해하는 데에 기여할 것으로 예상된다. 또한, 식물과 곤충의 생활사적 특성을 고려하는 것을 통해 기후변화 환경에서 식물-곤충 상호작용 변화의 더욱 정확한 예측을 가능하게 할 것으로 기대된다.It is quite obvious that the future biodiversity, including entomofauna, would be at risk by rapid environmental changes as climate change progresses. Considering the ecological and biological values in the ecosystem, the attempt to understand the plant responses to climate change is preferentially needed to be examined because of its significant consequences on insect family. Although there have been many researches, the effects of climate change on plant-herbivore interactions in the context of cascading effects from plants to herbivores are still unclear. In particular, the significance of increased precipitation frequency and the seasonality of plant and herbivore have not received sufficient attention yet. Here, I tried to address these gaps by conducting three major researches using a native plant (Aristolochia contorta) and its specialist herbivore (Sericinus montela). First, a field survey in natural habitat of A. contorta was conducted to investigate possible effects of various environmental factors on the host plant. Second, I performed two mesocosm experiments using open-top chambers (OTCs) to examine the effects of elevated CO2 and increased precipitation frequency on plant growth and defenses and consequences to specialist herbivores, and to figure out the seasonality of those effects of two environmental factors. I observed the growth of plant based on stem length and leaf number, and measured the relative growth rate (RGR) of herbivores to assess the cascading effects of plant responses to herbivores growth performance. I further investigated C: N ratio and primary metabolites as parameters of nutrient value, and analyzed secondary metabolites as parameters of plant chemical defenses. According to field survey, the growth period of A. contorta could be affected by various biotic and abiotic factors, particularly herbivorous and interspecific competitive stress, and cations in soil. In addition, elevated CO2 impeded growth with decreased photosynthesis ability, and increased resistance in plants. In contrast, increased precipitation frequency partly ameliorated the negative effects of high CO2. Growth performance of specialist herbivore decreased under elevated CO2 condition as a consequence of increased resistance in plants. Furthermore, elevated CO2 and increased precipitation frequency had different effects on nutrient value and constitutive defenses of host plant in distinct temporal variations. That is, positive effects of increased precipitation on nutrient value were significant in the middle of plant growing season, whereas negative effects of elevated CO2 on both of nutrient value and constitutive defenses were remarkable in the late of growing season. The unconformable variations of food quality seemed to be responsible for the seasonality of specialist and generalist herbivore. In conclusion, this research suggests both the quantity and quality of host plants would decline because of significant CO2 effects, and the growth performance of its specialist herbivore might be threatened as climate change progresses. That is, different scenario but the same predictions of climate change effects on entomofauna is suggested. Nevertheless, considering the seasonality of effects of elevated CO2 and increased precipitation frequency, less danger of herbivorous insect may be expected because of the ameliorating effect of increased precipitation frequency to high CO2 at a certain emergence timing in their life cycle. Additionally, the findings of this research can contribute to enable comprehensive understanding of climate change effects on plant-herbivore interaction, with the consideration of significant variable environmental factor under climate change and species-specific characteristics. This study also highlighted the ecological implications of seasonal dynamics for precise of future plant-herbivore interaction under climate change.Abstract i Contents iv List of figures viii List of tables xii Chapter 1. Introduction 1 1.1. Plant-herbivore interaction and secondary metabolites 1 1.2. Climate change and plant-herbivore interaction 4 1.3. Aristolochia contorta and Sericinus montela as experimental models for plant-herbivore interaction 8 1.4. Purpose of research 11 Chapter 2. Biotic and abiotic effects on the growth and reproduction of Aristolochia contorta 14 2.1. Introduction 14 2.2. Methods 16 2.2.1. Study sites and survey method 16 2.2.2. Soil analysis 19 2.2.3. Statistical analysis 19 2.3. Results and Discussion 20 2.3.1. Regional growth characteristics of A. contorta 20 2.3.2. Effects of environmental factors on growth speed of A. contorta 23 2.3.3. Effects of environmental factors on flowering and fruting of A. contorta 26 2.4. Conclusion 30 Chapter 3. Reduced host plant growth and increased tyrosine-derived secondary metabolites under climate change and negative consequences on its specialist herbivore 31 3.1. Introduction 31 3.2. Material and Methods 35 3.2.1. Plant material 35 3.2.2. Experimental design 36 3.2.3. Growth measurement 40 3.2.4. Carbon and nitrogen analysis 40 3.2.5. Secondary metabolite extraction and instrumental UPLC conditions 41 3.2.6. Photosynthesis and chlorophyll measurement 42 3.2.7. Measurement of relative growth performance of Sericinus montela 44 3.2.8. Statistical analysis 45 3.3. Results 46 3.3.1. Differences of the plant growth among experimental groups varied according to organs 46 3.3.2. Photosynthesis inhibition by long-term exposure to elevated CO2 concentration in Aristolochia contorta 52 3.3.3. Reduced growth performance of a specialist herbivore caused by decreased food quality of host plant under climate change 54 3.4. Discussion 60 3.5. Conclusion 66 Chapter 4. Seasonality of host plant responses to climate change and consequent effects on plant-herbivore interactions 68 4.1. Introduction 68 4.2. Material and Methods 71 4.2.1. Plant material 71 4.2.2. Experimental design 72 4.2.3. Measurement of relative growth performance of specialist and generalisth herbivore 75 4.2.4. Carbon and nitrogen analysis 76 4.2.5. Primary metabolites measurement 77 4.2.6. Phytohormone and secondary metabolites analysis 78 4.2.7. Statistical analysis 80 4.3. Results 81 4.3.1. Different seasonal variations in relative growth performance of specialist and generalist herbivore 81 4.3.2. Seasonal dynamics in leaf nutrient value related to unconformable variations in soluble sugars and free amino acids 86 4.3.3. Increased secondary metabolites for constitutive defenses in late growth period 90 4.3.4. Seasonal dynamics of JA inducibility but no differences in induced responses in secondary metabolites according to plant growing season 94 4.4. Discussion 98 4.4.1. The seasonality of nutrient value and defenses in plants and relative growth performances of specialist and generalist herbivore 98 4.4.2. Effects of elevated CO2 and increased watering frequency on the seasonality of host plant and specialist and generalist herbivore 101 4.5. Conclusion 107 Chapter 5. General conclusions 109 References 113 Abstract in Korean 134 Appendices 137 Appendix 1. The blueprint of an open-top chamber 137 Appendix 2. Response curve for the exact quantification of AA1 and AA2 139 Appendix 3. Primary metabolites analysis method 140 Appendix 4. Phytohormone analysis method 142 Appendix 5. Secondary metabolites analysis method 144Docto

수경재배 파프리카의 비파괴적 식물 내부 전기전도도 측정

학위논문 (박사)-- 서울대학교 대학원 : 농업생명과학대학 식물생산과학부(원예과학전공), 2018. 8. 손정익.The electrical properties of plant stems represent physiological activities in-cluding water and ion transport. Plant responds to changes in environmental condition, which can be reflected in internal electrical conductivity of plant stems (ECps). Therefore, monitoring of ECps may help understand the plant physiological changes related to environmental stress. Because direct and stable measurement of ECps was very difficult, complicated, and expensive, the ECps could not be easily adapted to monitor plant responses to stressed environmental conditions. The objectives of this study were to develop a stable and simple measuring method of internal ECps and investigate the re-lationship between the ECps and environmental factors in greenhouse. Two electrodes with three needles were inserted into both sides of paprika stem to monitor paprika ECps and stable ECps was acquired. Environmental fac-tors such as temperature, irradiance, and relative humidity were recorded and compared with the ECps. The ECps was positively correlated with light intensity and temperature (R2=0.642 and 0.815, respectively), while nega-tively correlated with relative humidity (R2=-0.416). The ECps was predicted using a regressed equation describing environmental data, and the predicted ECps corresponded well to measured ones. The ECps was higher during the day than at night, which was attributed to higher daytime water content in the stems. The ECps was better correlated with water content than ion con-centrations in the stem. To use ECps for monitoring of paprika responses to environmental stress, relationship of ECps with plant physiological responses was established. The relationships between ECps and photosynthetic re-sponses of paprika as well as sap flow were evaluated. Monitoring of papri-ka ECps relative to various environmental conditions such as low irradiance and water shortage showed that plant responses to environmental stress could be explained by changes in ECps. High ECps was related to high pho-tosynthetic rate, stomatal conductance, and transpiration rate. Sap flow of the plant was also associated with ECps, with a correlation coefficient of 0.606. However, the sap flow reflected only water flux, while ECps was de-termined by both water and ion contents in stem of paprika. Comparison of measured and predicted ECpss could be used to detect unusual cultivation conditions of paprika. Plant responses to water shortage could be reflected on lower ECps compared with predicted value. Therefore, continuous moni-toring of ECps can be used to detect plant responses to water stress. In order to use this method in the field, it will be necessary to test and develop field application techniques through further experiments such as comparison with sap flow.INTRODUCTION 1 LITERATURE REVIEW 5 Measurement of plant internal electrical conductivity 5 Plant responses to stress 8 Literature Cited 15 CHAPTER I. Non-destructive measurement of internal electrical conductivity of paprika and its relation to environmental fac-tors 21 Abstract 21 Introduction 23 Materials and Methods 28 Results and Discussion 37 Literature Cited 54 CHAPTER II. Evaluation of plant stress conditions in paprika by comparing internal electrical conductivity, photosynthetic re-sponse, and sap flow 58 Abstract 58 Introduction 60 Materials and Methods 63 Results and Discussion 67 Literature Cited 82 CONCLUSION 87 ABSTRACT IN KOREAN 89Docto

Formation Mechanisms and Suppression Method of Weld Defects in CO2 Laser Welding of Primer-coated Steel for Shipbuilding

Laser are now established as industrial tool that cut, weld, drill and modify the surface properties of materials. Laser-processes offer many advantages over conventional processes e.g. speed, quality, and increased production. The use of zinc-coated steel in automobile industries as well as in various industry fields has increased due to low price and high corrosion resistance. Recently the laser welding technology has been considered the application for shipbuilding structure. However, when this technology is applied to primer-coated steel, good quality weld beads are not easily obtained. Because that the primer-coated layer caused the spatter, humping bead and porosity, that are main part of the weld defects, attributed to the powerfully vaporizing pressure of zinc. We were performed experiment with objectives of understanding spatter and porosity formation mechanism and producing sound weld beads in 6mmt primer coated steels by a CO2 CW laser. The effects of welding parameterswere investigated in the bead shape and penetration depth in bead and lap welding. Laser welding of zinc-coated steel in lap joint leads to a problem that is related to the low boiling point of zinc(907 oC) compared with high melting point of steel(1530 oC). When the keyhole penetrates at the interface between the two sheets in lap joint, the layer rises to a very high temperature. At this temperature, the zinc vapour pressure is so high that it explodes out of the melt pool and generated the spatter and humping bead. Namely serious effects of primer-coated position was lap side rather than surface. Therefore, introducing a small gap clearance in the lap position, the zinc vapor could escape through it and sound weld beads can be acquired. And mechanism of porosity formation has searched by analysis the composition of inner surface of porosity and the vaporizing particle according to weld conditions. There is a lot of zinc in inclusion of inner surface of porosity. But there is not zinc in dimple structure. These results are indicated that the porosity was formed by zinc vaporized pressure. Then, the dynamic behaviors of laser-induced plasma and spatter phenomena were photographed by high speed video camera during CO2 CW laser welding with gap or no-gap clearance. Laser-induced plasma has been accompany with the vaporizing pressure of zinc ejecting from keyhole to surface of primer coated plate. In result, the weld defects such as spatter, porosity and humping bead have formed. This dynamic behavior of plasma was very unstable and this instability was closely related to the unstable motion of keyhole during laser welding. Therefore, as observing the behavior of plasma, it should be estimated how the keyhole was fluctuated and the weld defect was formed.defocused distance, welding speed, coated thickness, coated positionAbstract 1. 서론 1 1.1 연구 배경 1 1.2 연구 목적 3 2. 이론적 배경 5 2.1 용융아연도금강판의 적용현황과 특성 5 2.1.1 용융아연도금강판의 적용현황 5 2.1.2 용융아연도금강판의 피막조직 6 2.1.3 용융아연도금강판의 내식성 8 2.2 산업용 레이저의 발진 원리와 특성 13 2.2.1 레이저의 발진 원리 13 2.2.2 산업용 레이저의 특성 19 3. 실험 장치 및 방법 28 3.1 실험재료와 CO2 레이저 용접법 28 3.1.1 실험재료 28 3.1.2 CO2 레이저 용접장치와 용접방법 30 3.2 용접금속부의 기공과 증발입자의 조성 분석방법 36 3.2.1 용접금속내 기공의 조성 분석방법 36 3.2.2 증발입자의 포집 및 조성 분석방법 36 4. 실험 결과 및 고찰 38 4.1 Primer 코팅강판의 용입 및 용접결함의 특성 38 4.1.1 집광광학계의 비초점 거리변화에 따른 용입특성 39 4.1.2 용접속도 및 primer코팅조건에 따른 용접특성 49 4.2 Lap welding에 있어서 용접특성에 미치는 primer코팅조건 및 gap간극의 영향 79 4.2.1 Primer 코팅위치 및 코팅두께에 따른 용접특성 비교 79 4.2.2 용접특성에 미치는 gap간극의 영향 89 4.3 용접금속부의 기공과 증발입자의 조성 104 4.3.1 용접금속부의 강제파단에 의한 기공의 조성분석 105 4.3.2 비드표면에 형성되는 부유물질의 성분분석 113 4.3.3 증발입자의 조성분석 117 4.4 레이저 용접현상의 고속도 계측 121 4.4.1 고속도 비디오 카메라를 이용한 용접현상의 계측방법 121 4.4.2 Gap간극의 유무에 따른 유기플라즈마와 스패터의 동적 거동 123 4.5 기공 및 스패터의 발생 메카니즘과 억제방법 127 5. 결론 130 참고문헌 13

implant 시술로 인한 하치조 신경의 손상에 의한 변화와 치료 및 그 예후 (종설)

학위논문 (석사)-- 서울대학교 대학원 : 치의학과, 2012. 2. 황순정.본 논문에서는 임상 적용 이후 많은 임상적 연구와 그에 대한 연구가 이루어진 치과 임플란트에 대한 합병증 중 하나인 하치조 신경 손상에 대하여 손상 시 신경의 변화와 치료 및 그 예후에 대해 알아 보기 위하여 1942년부터 2011년까지의 보고된 문헌들을 고찰을 하였다. 본 논문의 고찰결과 다음과 같은 사실을 알 수 있었다. 하치조 신경은 하악관공 통과하여 섬유성 속에 둘러 쌓여 하악관을 따라 설측에서 협측으로 가로 지르며 전치부로 주행하면서 이신경과 절치신경으로 나누어지게 된다. 하치조 신경은 2개로 갈라지는 주행경로, 방사선상 보이지 않는 하악관과 하악공 등 사람에 따라 주행 경로가 다양하고, 실제로 하악관은 하나의 관이 아니라 해면골로 이루어져있고 이것을 작은 신경들이 주행하고 있어 임플란트 식립시 손상이 일어나기 쉽기 때문에 더욱 주의가 필요하다. 임플란트 시술에 의한 하치조 신경 손상은 임플란트 식립시 드릴에 의한 손상, 식립체의 의한 손상, 연조직 손상에 따른 신경 손상 등에 일어나며 신경진탕, 축삭단열, 신경속단열로 구분이 된다. 이러한 신경 손상 후 신경의 변화는 임상적으로 조직학적으로 나누어진다. 임플란트 식립 후 임상적으로 하치조 신경의 손상에 따른 감각이상, 감각저하, 감각과민, 감각부전, 감각소실 등의 감각장애 발병률은 0~40%로 보고된다. 조직학적으로는 하치조 섬유가 손상되면 삼차신경절 내의 신경세포체의 염색질소용해와 원위부에서 waller 변성이 일어나 축삭이 재생되고 섬유가 재생된다. 신경손상의 회복은 신경손상의 종류에 따라 달라지게 되는데 신경 압박은 4개월, 신경 절단은 8개월로 신경압박에서 감각 회복이 빠르다. 술 후에 감각 회복에 있어서도 압박이 절단 보다 회복이 빠르다. 하치조 신경 손상 시 치료 방법은 크게 비외과적인 방법과 외과적인 방법이 있다. 임플란트가 하악관을 침범시 임플란트는 반드시 제거 하고 다음과 같이 비외과적인 방법으로 약물요법과 이학요법을 시행한다. 약물 요법으로는 스테로이드와 NSAIDs를 3주간 투여하여하는 것이 권유되며 동통조절을 위한 항경련제와 항우울성 약물요법은 빨리 시행하는 것이 효과적인 것으로 보고가 되고 있다. 이러한 비외과적인 치료법을 통해 3개월 동안 감각저하의 개선이 없는 경우에는 문합술, 감압술, 신경이식술과 같은 외과적 방법을 시행하도록 추천되고 있다.This paper addresses the issue of changes to the inferior alveolar nerve caused by complications associated with dental implants. It represents a cumulative summary of research materials on the topic from 1942 to 2011. From this research, we found the following results: The inferior alveolar nerve is surrounded with fibrous tissue and travels through the mandibular foramen and along the mandibular canal from the lingual side to the buccal side, then travels separately to the anterior incisor nerves and to the mental nerves. The inferior alveolar nerve exhibits a variety of anatomical eccentricity such as the possibility of a second inferior alveolar nerve, and the potential invisibility of the mandibular canal and mandibular foramen in radiographics. In fact, the mandibular canal is not a single canal but consists of a number of cancellous bones, and is home to so many smaller nerves that it is highly sensitive to damage caused by the placement of an implant. Inferior alveolar nerve injury by implant placement can be caused by drilling for the implant placement, the placement of the body itself, or soft tissue damage. Such injury may be classified as neuropraxia, axonnotmesis or neurotmesis. The changes to the nerve after injury may be analyzed clinically and histologically. After implant placement, the clinical incidence of paresthesia, hypoesthesia, hyperesthesia, dyesthesia and anesthesia caused by inferior alveolar nerve injury is reported to be within the range of 0 to 40%. Histologically, after the fibers of the inferior alveolar nerve are damaged, chromatolysis of the cell body in the trigeminal ganglion as well as waller degeneration in the distal end occur, after which the nerve fibers regenerate. The recovery period of injuries to the inferior alveolar nerve depends on the type of injury. Nerve compression recovers faster at around 4 months, and nerve amputation takes longer, around 8 months. Sensory recovery from nerve compression after surgery is faster than that of nerve amputation. There are surgical and nonsurgical methods for the treatment of inferior alveolar nerve injuries. When an implant penetrates the mandibular canal, it must be surgically removed and followed up with medicament and physiological treatments. Medicament that includes the administration of steroids and NSAIDs for 3 weeks is suggested. The use of antidepressants and anticonvulsants for pain control has been reported to be more effective the sooner after surgery that they are administered. If the patient shows no improvement after these treatments, surgical methods such as anastomosis, decompression and nerve grafts are suggested by a majority of authors.Maste

The three critical factors of post merger integration : Renault Samsung case

Thesis (master`s)--서울대학교 대학원 :경영학과 국제경영전공,2002.Maste

Temper-rolling and Annealing Texture in Columnar Grains of Silicon Steel Sheets

MasterTexture evolution by strain annealing process was studied using 0.5% silicon steel sheets of which structure was mostly composed of columnar grains and showed 65~75% of (100)texture. The specimen of columnar grains were prepared by annealing Fe-Si sheets at 1000？C for 10min in the vacuum level of 3.5x10-1 and the hydrogen flow rate of 100ml/min. Development of (100)texture composed with columnar grains by α→γ→α transformation has been investigated. These specimens were temper-rolled and annealed for the study of strain induced boundary migration (SIBM). The method of evolution by columnar grains is one of the most effective ways to research SIBM because each grain is equally strained by temper-rolling without the restriction of grain boundaries. It was clearly shown that (310)//ND, (611)//ND, and (321)//ND grains tend to rotate toward (100)//ND. The rotation by temper-rolling depends on the initial orientation. It was found that Taylor factor is proportional to the stored energy measured by Vickers hardness

정상인에서 산동과 인위적 근시유발시 망막 광역치의 변화

학위논문(석사)--서울대학교 대학원 :의학과 안과학전공,1995.Maste

The Critical Assessment of Heterogeneous Outcome of CEO Hubris

학위논문 (박사)-- 서울대학교 대학원 : 경영학과, 2014. 2. 박철순.This dissertation aims to examine and explore the research area of CEO hubris. Research from the institutional theory explains the homogenous aspects of organization, however, lacks the explanations of heterogeneous behavior. This paper attempts to explain the heterogeneous behavior through CEO hubris. Thus, I conducted one empirical study and one review paper based on CEO hubris. First study is based CEO hubris and institutional theory through corporate social responsibility. It argues that CEO hubris does not follow the norm on corporate social responsibility due to arrogant and simple minded behavior of CEO hubris characteristics. Rather than following the norm of corporate social responsibility from institutional pressure, the degree of corporate social responsibility from CEO hubris will either be very high or very low. Furthermore, internal control mechanisms using ratios of outside board of directors and foreign ownership as a moderating variable is used for this research. Second study is a review paper based on CEO hubris, overconfidence, CEO celebrity, and narcissism. This paper attempts to clarify the confusion of similar perspectives by exploring and investigating a comprehensive review of the related theories by looking into the origin, definition, cause and outcome.OVERALL INTRODUCTION………………………………………1 STUDY 1 CEO HUBRIS AND INSTITUTIONAL PRESSURE: CORPORATE SOCIAL RESPONSIBILITY ……………………7 Abstract………………………………………………………………4 Introduction …………………………………………………………5 Theory and Hypothesis…………………………………………10 Method………………………………………………………………23 Results………………………………………………………………30 Discussion…………………………………………………………33 Conclusion…………………………………………………………37 STUDY 2 REVIEW PAPER: ANTECEDENTS AND OUTCOMES OF CEO HUBRIS ……38 Abstract.……………………………………………………………39 Introduction ………………………………………………………40 CEO Hubris: The Phenomenon………………………………42 Overconfidence, CEO Celebrity and Narcissism………51 Limitations and Future Research……………………………71 Conclusion…………………………………………………………73 OVERALL CONCLUSION…………………………………………74 REFERENCES………………………………………………………77 국문초록……………………………………………………………107 Tables Descriptive Statistics and correlations of Study...………96 Results of Deviation Median Regression Analysis………97 Results of KEJI Regression Analysis ………………………98 Antecedents and Outcomes of CEO Hubris...................99 Antecedents and Outcomes of Overconfidence…………100 Antecedents and Outcomes of CEO Celebrity……………101 Antecedents and Outcomes of Narcissism…................102 Figures Research Model…………………………………………………105 Summary Model of Antecedents and Outcomes of CEO Hubris………………………………………………………………106Docto