그래핀/전도성 고분자 나노하이브리드 물질의 제조 및 센서로의 응용

학위논문 (박사)-- 서울대학교 대학원 : 화학생물공학부, 2016. 2. 장정식.Graphene/conducting polymer (CP) nanohybrid materials have attracted considerable attention, due to their synergetic effects, including enhanced surface area, charge carrier mobility, thermal/electrical conductivity, and chemical/mechanical stability. To synthesize the graphene/CP nanohybrid materials for using in electronic device applications, covalent and non-covalent synthetic methods have been introduced. Contrary to non-covalent method, covalent functionalization requires time-consuming and harsh conditions, because it needs firstly to introduce functional group on the surface of graphene and CPs. On the other hand, non-covalent functionalization offers facile way to obtain graphene/CP nanohbyrid materials through secondary bonding interactions, such as π–π interactions. In-situ synthetic method, as one of the non-covalent synthetic method, is very promising and powerful tool to design graphene/CP nanohybrids owing to getting uniform nanohbyrid materials. Furthermore, the morphology and shape of the graphene/CP nanohybrids can be controlled by selectively designing the morphology of starting materials (graphene or CP materials). In this study, various graphene/CP nanohbyrid materials are introduced by using in-situ synthetic method. The synthesized nanohybrid materials exhibit excellent electrical/chemical properties, enabling to be applied in sensor applications. Synergetic effects of graphene/CP nanohbyrid mateirals provide rapid response/recovery time, when using as a transducer in the sensing device. Furthermore, the enlarged surface area from graphene/CP nanohybrids can provide the improved interactions with target analytes, leading to the ultrasensitive sensing performance.1. INTRODUCTION 1 1.1. Background 1 1.1.1. Conducting polymers 1 1.1.1.1. Polypyrrole (PPy) 3 1.1.1.2. Poly(3,4,- ethylenedioxythiophene) (PEDOT) 6 1.1.1.3. Polyfuran (PF) 7 1.1.1.4. Polyselenophene (PSe) 8 1.1.1.5. CP nanomaterials 9 1.1.1.5.1 1D CP nanomaterials 11 1.1.1.5.1.1 Self-degradation method 12 1.1.2. Graphene 13 1.1.3. Graphene/conducting polymer nanohybrid mateirals 16 1.1.3.1. Non-covalent graphene-CP nanohybrids 18 1.1.3.2. Covalent graphene-CP nanohybrids 26 1.1.4. Sensor application 28 1.1.4.1. Chemical sensor 30 1.1.4.1.1. Hazardous and toxic gases sensor 31 1.1.4.2. Liquid-ion gated FET-type biosensor 33 1.1.4.2.1. H2O2 FET-type biosensor 35 1.1.4.2.2. Glucose FET-type biosensor 37 1.1.4.2.3. Hg2+ FET-type biosensor 38 1.1.4.3. Piezotronic sensor 39 1.2. Objectives and Outlines 42 1.2.1. Objectives 42 1.2.2. Outlines 43 2. EXPERIMENTAL DETAILS 45 2.1. RGO/PPy NT hybrid materials 45 2.1.1. Fabrication of polypyrrole nanotube embedded reduced graphene oxide transducer for field-effect transistor-type H2O2 biosensor 45 2.1.1.1. Prepartation of PPy NTs 45 2.1.1.2. Prepratation of RGO/PPy NT hybrids 46 2.1.1.3. Fabrication of RGO/PPy NT composite FET sensor 47 2.1.1.4. Characterization of RGO/PPy NT hybrids 48 2.2. RGO/C–PPy NT hybrid materials 49 2.2.1. Fabrication of carboxylated polypyrrole nanotube wrapped graphene sheet transducer for field-effect transistor-type glucose biosensor 49 2.2.1.1. Preparation of C–PPy NTs 49 2.2.1.2. Preparation of RGO/C–PPy NT hybrids 50 2.2.1.3. Fabrication of RGO/C–PPy NT composites FET sensor 51 2.2.1.4. Characterization of RGO/C–PPy NT hybrids 52 2.3. RGO/PF NT hybrid materials 53 2.3.1. Fabrication of reduced graphene oxide-polyfuran nanohybrid for High-performance Hg2+ FET-type sensors 53 2.3.1.1. Prepration of PF NTs 53 2.3.1.2. Prepration of RGO/PF NT hybrids 54 2.3.1.3. Fabrication of RGO/PF NT composite FET sensor 55 2.3.1.4. Characterization of RGO/PF NT hybrids 56 2.4. RGO/PSe nanohybrid materials 57 2.4.1. Fabrication of graphene/polyselenophene nanohybrid materials for highly sensitive and selective chemiresistive sensor 57 2.4.1.1. Preparation of RGO/PSe nanohybrid materials 57 2.4.1.2. Characterization of RGO/PSe nano hybrid materials 58 2.5. CVD graphene/PEDOT/P(VDF-HFP) nanohbyrid mateirals 59 2.5.1. Prepatation of CVD graphene/free-standing PEDOT nanofiber/P(VDF-HFP) nanohbyrid materials 59 2.5.1.1. Prepatation of CVD graphene/free-standing PEDOT nanofiber/P(VDF-HFP) nanohbyrid materials 59 2.5.1.2. Characterization of CVD graphene/PEDOT/P(VDF-HFP) nanohybrid materials 61 3. RESULTS AND DISCUSSION 62 3.1. Fabrication of polypyrrole nanotube embedded reduced graphene oxide transducer for field-effect transistor-type H2O2 biosensor. 62 3.1.1. Fabrication of RGO/PPy NT hybrid materials 62 3.1.2. Electrical performance of RGO/PPy NT hybrid materials 70 3.1.3. FET-type H2O2 biosensor based on RGO/PPy NT hybrid materials 73 3.2. Fabrication of carboxylated polypyrrole nanotube wrapped graphene sheet transducer for field-effect transistor-type glucose biosensor 80 3.2.1. Fabrication of RGO/C–PPy NT hybrid materials 80 3.2.2. Electrical performance of RGO/C–PPy NT hybrid materials 88 3.2.3. FET-type glucose biosensor based on RGO/C–PPy NT hybrid material 91 3.3. Fabrication of reduced graphene oxide-polyfuran nanohybrid for High-performance Hg2+ FET-type sensors 100 3.3.1. Fabrication of RGO/PF NT hybrid materials 100 3.3.2. Electrical performance of RGO/PF NT hybrid materials 106 3.3.3. FET-type Hg2+ biosensor based on RGO/PF NT hybrid materials 110 3.4. Fabrication of graphene/polyselenophene nanohybrid materials for highly sensitive and selective chemiresistive sensor 117 3.4.1. Fabrication of RGO/PSe nanohybrid materials 117 3.4.2. Fabrication of chemiresistive sensor based on RGO/PSe nanohybrid materials 127 3.4.3. Chemiresistive sensing performance of the RGO/PSe nanohybrid film 130 3.5. Fabrication of graphene/free-standing nanofibrillar PEDOT/P(VDF-HFP) hybrid device for wearable and sensitive human motion detective piezo-resistive sensor 135 3.5.1. Fabrication of CVD graphene/free-standing nanofibrillar PEDOT/P(VDF-HFP) nanohbyrid devices 135 3.5.2. Sensing performance of E-skin device 143 3.5.3. Practical application of E-skin device 147 4. CONCLUSIONS 156 REFERENCES 162 국문초록 180Docto

석면 금지 정책의 국제적 확산이 환경안전보건에 미치는 영향과 함의

학위논문 (박사)-- 서울대학교 보건대학원 : 보건학과 환경보건학 전공, 2013. 8. 백도명.Out of 143 countries that consumed asbestos between 2003 and 2007, only 44 have banned asbestos. This study tried to explain how asbestos ban policy adopted and spread globally, how it impact world asbestos produce, trade, consumption, and mesothelioma mortality, historically and the future. Chapter I provide a rational explanation of why some countries have banned asbestos while others have not, based on a synthesis that asbestos ban policy of a country will rely on a process of cognition of threats and exploration of safer alternatives. As we hypothesized that increased social cost of mesothelioma, capacity of health-related infrastructures, and policy diffusion from adjacent countries were related to asbestos ban adoption, published databases of asbestos ban years, mesothelioma mortality, country rankings in health care and human rights standings, and distribution of banning countries over 14 regions were analysed accordingly. The average mesothelioma death rate was significantly higher for countries with asbestos bans than in those with no ban. No-ban countries had less well-developed health-related infrastructures. Among European countries, there was a tendency toward geographical diffusion of asbestos ban policy from Nordic to Western and then other European countries over the years. Even though aberrant cases were also noted where bans were instituted even without mesothelioma database, these were rather exceptions than rules. Risk cognition is a complex process, but the presence of well-functioning health infrastructures, as well as the increased social cost of mesothelioma, that can make the plight of asbestos victims visible to the eyes of public and policy makers, may have contributed to this process. Asbestos ban policy from adjacent countries might have facilitated the adoption of alternative solutions. Chapter II describes the world production and consumption of asbestos and the trade of asbestos-containing products. Data was obtained from the British Geological Survey, U.S. Geological Survey and United Nations Commodity Trade Statistics data, and described mainly the status of the income level and states which ban asbestos. World asbestos production increased until the late 1970s and then decreased for 15 years, finally plateauing in the last 15 years. Crude asbestos consumption in developed countries decreasedhowever, they plateaued or even increased in middle- and low-income countries. Most asbestos-containing products except crocidolite are still traded among countries which ban asbestos. The banning of asbestos is complete when there are no exports or imports of asbestos-containing end products. Even in countries which ban asbestos, the monitoring of the trade of asbestos-containing products is required. Chapter III attempts to build a prediction model of mesothelioma mortality according to the consumption of asbestos. A mesothelioma mortality prediction model was constructed based on cumulative asbestos consumption quantities as the exposure level. In each country, annual age-sex specific mortality rates were calculated by dividing the number of mesothelioma deaths by the corresponding age-group population. We use a negative binomial regression model to predict mesothelioma deaths by cumulative asbestos exposure. The model estimated that the latent period for mesothelioma was about 45 years. Predicted world future mesothelioma deaths among males during 2015-2070 ranged from 748,329 to 764,052 per million population, depending on the expected level of asbestos consumption. World mesothelioma deaths will peak in late 2039 according to the model and then decline.Abstract i Ⅰ. Introduction 1 Ⅱ. Chapter 1 : Why some, but not all, countries have banned asbestos 4 Introduction 4 Materials and Methods 6 Results 12 Discussion 21 Ⅲ. Chapter 2 : World asbestos consumption and trade of asbestos containing products 29 Introduction 29 Methods 31 Results 36 Discussion 55 Ⅳ. Chapter 3 : Predictions of mesothelioma mortality based on asbestos consumption 60 Introduction 60 Materials and Methods 64 Results 69 Discussion 77 References 82 Appendix Tables 93 국문초록 119Docto

고형광성 시아노스틸벤 유도체를 기반으로 하는 새로운 광응답성 연성재료: 광물리적 특성 및 액정 거동에 대한 연구

학위논문 (석사)-- 서울대학교 대학원 : 재료공학부, 2013. 2. 박수영.Photo-responsive materials are promising research areas for a wide range of applications such as optical device, and photo-actuator. Especially, azobenzene, and stilbene based soft materials are commonly known for implementing such applications due to their fast and reversible photo-induced isomerization behavior. Despite those remarkable properties, the molecules show low or non-fluorescence behavior in solid state. In order to solve such problem, fluorescent dyes are attached in azobenzene or stilbene unit via covalent, secondary bonding interactions, or host-guest mixed systems. Nevertheless, at the current stage, there are only a few reports to be successfully demonstrated. To date, we have reported a novel class of α-cyano-substituted stilbenic derivatives exhibiting a unique and peculiar fluorescence behavior, that is, aggregation-induced enhanced emission (AIEE): it is virtually non-fluorescent in the monomer state in solution but becomes highly fluorescent upon self-assembly into supramolecules. Furthermore, the cyanostilbene unit in typical AIEE molecules has a multiple function of enabling AIEE-type molecule to undergo a trans-cis photoisomerization, as commonly observed in stilbene and azobenzene materials. However, so far, there is no report on fluorescence property in combination with photoisomerization behavior by using such molecules. Herein, we report on a demonstration of fluorescence patterning technique via photo-induced isomerization behavior in soft state, LC or soft crystal, based on cyanostilbene derivatives for the first time. The molecules consist of rigid cyanostilbene/dicyanodistrylbenzene(DCS) backbone which shows AIEE behaivor and photo-responsive characters with different lengths of flexible alkoxy chains. In this respect, to clearly understand thermotropic LC and optical property in solid state, we study the following issues: i) the role of –CN group, ii) the role of length of alkyl chain, and iii) understanding of the differences in photoisomerization behavior between cyanostilbene and DCS beackbone. The photo-isomerization behavior is monitored by change of UV-vis abosrbance spectra and confirmed the conversition ratio of trans to cis isomer by 1H NMR data. Based on such characters, we demonstrated a fabrication of fluorescence patterning. Furthermore, we have synthesized a new cyanostilbene based material, GCS, which forms columnar hexagonal LC phase at room temperature. Thin film of GCS was prepared by spin-coated method. Initially, as-prepared film looks like amorphous state with a high transparency. However, a partial crystallization in the film occurs subsequently. During overnight under dark at near RT (25~30 °C), it was transformed into the perfectly uniform crystalline film that had same crystal arrangement to GCS bulk powder. In crystalline state, GCS exhibits intense blue fluorescence. Interestingly, such crystalline film shows a soft character. To understand such property, we have carried out GI-XRD measurement. In soft state, GCS shows phase transition behavior via photoisomerization process. Thus, we successfully demonstrate highly fluorescent micro patterns via unique property, so-called photo-tirrgered mass migration behavior, with phase transition by using soft crystalline material. In this work, we propose a new mechanism of photo-triggered mass migration with phase transition, crystal to LC phase, for the first time.Abstract..........................................................................................................................................i Contents........................................................................................................................................iv List of Tables...............................................................................................................................vii List of Schemes..........................................................................................................................viii List of Figures..............................................................................................................................ix Chapter 1. Introduction...............................................................................1 1.1 Aggregation induced enhanced-emission (AIEE)...............................................................1 1.2 Liquid crystal........................................................................................................................3 1.3 Photo-induced isomerization................................................................................................3 1.4 Research objectives..............................................................................................................4 1.5 Bibliography.........................................................................................................................6 Chapter 2. Novel Photoresponsive Liquid Crystal System Based on Cyanostilbene Molecules with Aggregation-Induced Enhanced Emission (AIEE): Studies on Mesomorphism, Photochemical Phase Transition Behavior and Photophysical Property.....................................7 2.1 Introduction..........................................................................................................................7 2.2 Results and discussion.........................................................................................................9 2.2.1 Synthesis.......................................................................................................................9 2.2.2 Optical property...........................................................................................................15 2.2.3 Liquid crystal & crystallization property.....................................................................17 2.2.4 Photoisomerization......................................................................................................23 2.2.4.1 Solution state........................................................................................................23 2.2.4.2 LC state.................................................................................................................24 2.2.5 Demonstration of fluoresecence patterning via photoisomerization behavior............31 2.3 Conclusion..........................................................................................................................34 2.4 Experimental......................................................................................................................35 2.4.1 General Information....................................................................................................35 2.5 Bibliograrphy.....................................................................................................................36 Chapter 3. Highly Fluorescent Micro patterns via Phototriggered Mass Migration Behavior in Cyanostilbene-based Crystalline Thin Film…37 3.1 Introduction........................................................................................................................37 3.2 Results and discussion........................................................................................................40 3.2.1 Synthesis......................................................................................................................40 3.2.2 Liquid crystal & crystallization property.....................................................................43 3.2.3 Formation of soft crystalline film................................................................................45 3.2.4 Aggregation induced enhanced emission (AIEE) behavior.........................................47 3.2.5 Photo-induced isomerization behavior........................................................................49 3.2.5.1 Solution state........................................................................................................49 3.2.5.2 Crystalline state....................................................................................................51 3.2.6 Highly fluorescent micro patterns via phototriggered mass migration behavior in cyanostilbene-based crystalline thin film...................................................................56 3.3 Conclusion..........................................................................................................................61 3.4 Experimental.......................................................................................................................62 3.4.1 General Information....................................................................................................62 3.5 Bibliograrphy......................................................................................................................64 Abstract in Korean............................................................................................................66 List of Presentations..........................................................................................................69Maste

노동조합 활동가의 정신건강 : 우울증과 직무스트레스

학위논문(석사) --서울대학교 대학원 :환경보건학과,2008. 2.Maste

Dual-channel speech enhancement using determinant-based generalized sidelobe canceller

학위논문(박사) - 한국과학기술원 : 전기및전자공학부, 2023.2,[iv, 81 p. :]다양한 잡음 신호로부터의 영향을 줄이는 것은 신호 처리분야에서 매우 중요한 요소이다. 그렇기 때문에 잡음 제거에 관한 연구는 예로부터 지금까지 활발히 연구되고 있다. 스펙트럼 차감법부터 시작하여 최근에는 딥러닝 기반 잡음제거 기술까지 많은 연구들이 있었고 이러한 연구들은 사용 특징 벡터, 마이크 수, 녹음 환경 등에 따라 분류할 수 있다. 그 중, 마이크 수는 단채널과 다채널 시스템으로 구분할 수 있는데 잡음의 공간적 정보를 활용할 수 있는 다채널 잡음 제거 기법이 일반적으로 월등한 성능을 보여주었다. 다채널 환경 중에서도 2채널 환경은 특별한 케이스로 볼 수 있는데 최근 들어 모바일이나 차량환경 등의 수요가 늘어남에 따라 2채널 잡음제거의 필요성도 높아졌다. 하지만 2채널에 특화된 기술보다는 아직까지는 넓은 범위의 다채널 개념에서의 연구가 많이 수행되고 있다. 이런 이유로, 본 학위논문에서는 2채널 잡음제거에 특화된 연구를 수행하고자 한다. 2채널 기반의 알고리즘은 상대적으로 계산량이나 또는 하드웨어 비용 낮지만 우수한 성능을 보여준다. 특히, 2채널 기반의 알고리즘은 모바일 또는 보청기 환경에 적용되며 공간적 특성을 활용하여 우수한 성능을 보여준다. 하지만 공간적 특성은 반향 환경에서 변화되기 때문에 잡음 제거 성능 하락의 원인이 된다. 따라서 본 연구에서는 기존 연구들이 사용한 공간적 특성 외에 행렬식 기반의 통계적 특성을 이용하여 다양한 잡음 환경에서 강인한 방법을 제안한다. 제안한 방법은 고정식 빔형성의 출력과 행렬식 기반 마스크를 곱한 후 공간적 특성인 차단 행렬을 통해 적응적으로 남아있는 잔여잡음을 제거한다. 시뮬레이션 환경 및 실제 환경에서 테스트한 결과 제안한 방법은 기존의 공간적 특성 기반 및 행렬식 기반 잡음제거 방법보다 우수한 성능을 보여주었다.한국과학기술원 :전기및전자공학부