이원자가 도핑된 그래핀 및 보론나이트라이드 촉매의 일산화탄소 수소화반응과 메탄 선택적 산화반응으로의 응용

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 화학생물공학부, 2018. 2. 정인.Enormous effort has been undertaken for the development of efficient catalyst to achieve low cost and high productivity of chemical process. As the outstanding influence of interrelation between metal and supports is revealed the support materials have been focused by many studies. Among various materials, graphene and boron nitride, which has graphene-analogous structure, have drawn massive attention due to many opportunities in heterogeneous catalysis. The studies referred to herein, contain design of effective catalysts by introducing heteroatoms into graphene and boron nitride. Optimizing the properties of a catalyst to obtain a desired level of catalytic activity is the goal of heterogeneous catalysis. Here, we tuned the catalytic activity via manipulating the electronic state of a catalyst, induced by facile doping method into graphene at metal/graphene system. Experimental results revealed that the electronic state of the catalyst was manipulated depending on the type, concentration, and doping structure of dopants. For CO hydrogenation reaction, the catalytic activities of metal/doped graphene catalysts were controlled toward increasing or decreasing way, up to 7.7 times, according to the electronic state of cobalt metal. It was revealed that change in the electronic state led to variations in the interactions between active metal and reactants by kinetic study and theoretical calculations, causing differences in catalytic performances. This strategy was proven to be applicable to not only transition metal and but also noble metal in other reaction such as 4-nitrophenol reduction. The selective oxidation of methane is one of the most attractive and challenging process in the chemical industry. Here, we synthesized boron nitride (BN)-based catalysts containing atomically dispersed Fe site by means of pyrolytic method. The isolated single Fe sites were distributed throughout defective BN which consists of the typical B3N3 hexagonal structure but randomly oriented layers. The unprecedented catalyst, Fe-embedded BN (0.8Fe-BN), exhibited remarkable methane conversion (27%) and formaldehyde selectivity (52%) at 873 K. In comparison with Fe nanoparticle, the single Fe site, which is coordinated to oxygen atoms in square-pyramidal structure, dominantly served as the crucial active site and contributed to the enhanced catalytic performance. These results may provide more opportunities for the use of BN materials for heterogeneous catalysis.1. Introduction 1 1.1 Graphene and boron nitride materials in heterogeneous catalysis 1 1.2 Effects of tunable electronic properties on catalytic activity 3 1.3 Design of single atom catalyst for selective oxidation of methane 3 1.4. Objectives 7 2. Tuning effects of electronic state in metal/graphene catalysts for the control of catalytic activity via N- and B-doping into graphene 42 2.1 Introduction 42 2.2 Experimental 45 2.2.1 Preparation catalysts 45 2.2.2 Characterization 45 2.2.3 Catalytic activity test 46 2.3 Results and discussion 48 2.3.1 Preparation and physicochemical properties of the catalysts 48 2.3.2 Electronic state of doped graphene and active metals 16 2.3.3 Reaction tests 19 2.3.4 Model reaction tests 22 3. Selective oxidation of methane over Fe-embedded boron nitride catalysts 38 3.1 Introduction 38 3.2 Experimental 41 3.2.1 Preparation of catalysts 41 3.2.2 Characterization methods 41 3.2.3 Measurements of catalytic performance 42 3.3 Results and discussion 44 3.3.1 Structural characterization 44 3.3.2 Atomically dispersed Fe species within boron nitride 48 3.3.3 Catalytic performance over Fe@BN catalysts 49 4. Summary and Conclusions 74 Bibliography 76 국 문 초 록 83Docto

자성나노입자를 이용한 발열에 의한 슈도모나스 애루지노사 PA01 생물막의 불활성화

Thesis(masters) --서울대학교 대학원 :협동과정 바이오엔지니어링전공,2010.2.Maste

위암세포주 NCI-N87의 면역회피와 전이에 있어서 인터루킨 18의 역할과 그와 관련된 기전

Thesis(doctors) --서울대학교 대학원 :의학과 (해부학 전공), 2009.8.Docto

(The)Process of R&D project-priority ordering and strategic information for R&D decision making derived from technology relation analysis in defense technology

학위논문(석사)--서울대학교 대학원 :협동과정 기술정책전공,2005.Maste

Systematic Assembly Planning System for Multi-item, Low-volume Manufacturing Company

오늘날 생산 내외적 요소의 영향으로 생산성 향상이 중심과제가 되고 있지만 다품종 소량생산 기업에서는 적극성을 보이지 못하고 있다. 그 이유는 제품의 다양성 및 복잡성으로 인한 조립 계획수립의 어려움과 경험 부족등을 들수 있다. 본 연구에서는 이들 기업이 어떻게 계획을 수립해야하는가를 각각의 계획기능에서 보여주고자 한다.Improvement of productivity becomes an more and more important issue in today's industries due to the domestic and exterior requirements, but most of small to medium size companies can not positively be coped with such situation. Main reasons are considered to be the difficulties of assembly planning arising from the variety and sophistication of products and the lack of planning experiences. In this study it was intended to show how to establish assembly plans with individual planning functions required in a manufacturing company.Improvement of productivity becomes an more and more important issue in today's industries due to the domestic and exterior requirements, but most of small to medium size companies can not positively be coped with such situation. Main reasons are considered to be the difficulties of assembly planning arising from the variety and sophistication of products and the lack of planning experiences. In this study it was intended to show how to establish assembly plans with individual planning functions required in a manufacturing company

Factors affecting DNA-DNA hybridization for the identification of mycobacterium species

역학 및 질병관리학과/석사[한글] 우리 나라의 Mycobacterium tuberculosis에 의한 폐 감염은 감소하였다가 최근에 다시 증가경향을 보이고 있으며, M.tuberculosis 이외의 균종(Mycobacterium other than M.tuberculosis, MOTT)에 의한 감염은 현저히 증가되고 있어서 그 중요성이 강조되고 있다. 즉, MOTT 균종의 빠른 동정은 분리된 균주가 감염균인지를 결정하는데 도움이 될 뿐 아니라 환자의 치료 방침을 정하는 근거가 된다. 따라서 M.tuberculosis 뿐 아니라 MOTT의 동정은 매우 중요한 일이다. 대부분의 Mycobacterium은 증식이 늦어 종래의 생화학적 동정 방법으로는 최소한 1개월 이상의 기간이 필요하다. 최근 분자 생물학적 방법을 쓰는 PCR이나 gene probe 동정방법이 시도되고 있으나, 이러한 방법들은 주로 M.tuberculosis, M.intracellulare, M.avium 등의 일부 균만을 동정할 수 있는 것이고 실제 30여종 이상이나 되는 MOTT 모두를 동정할 수는 없다. 1991년 Ku sunoki등은 4시간만에 Mycobacterium 22종을 동정할 수 있는 hybridization법을 보고하였다. Hybridization법의 성적은 nucleic acid의 상태, 반응 조건 및 검출방법에 따라서 달라지게 되는데 이들의 상세한 방법은 알 수 없다. 이에 이 연구에서는 사람의 검체에서 분리되는 Mycobacterium을 hybridization법으로 동정할 때 필요한 시약의 조성과 시험조건의 반응에 대한 영향을 검토하여 다음과 같은 결론을 얻었다. 1. TMB는 methanol에 용해시킬 때 가장 안정하였고 가장 높은 흡광도를 보였다. 2. TMB 0.3-0.6 mg/ml H^^2O^^2는 0.08-0.16 mM 농도일 때 HRP 반응 흡광도가 가장 높았다. 3. HRP 활성은 TMB 희석액이 pH 5.0인 CE 용액일 때 높았다. 4. Hybridization 용액 중 SSC 반응의 흡광도는 4 x SSC 용액을 사용할 때 가장 높았다. 5. 동정용 균주 DNA를 열처리하면 광선처리만 하는 경우 보다 흡광도가 높았다. 위 결과들과 일차 배양된 배지에서의 집락 형태와 함께 이용하면 임상검체에서 흔하게 분리되는 Mycobacterium의 균종을 쉽고 빠르게 동정할 수 있을 것이라는 결론을 얻었다. [영문] Pulmonary tuberculosis caused by to Mycobacterium tuberculosis remain very prevalent in Korea, while increase of infection due to Mycobacterium other than M. tuberculosis (MOTT) was reported. Clinical significance of M. tuberculosis and MOTT are quite different, requiring their accurate identification of Mycobacterium sp. by conventional biochemical methods usually require at least 4 weeks and the results are often equivocal. Identification by PCR and gene probe method are rapid, but among the more than 30 species of Mycobacterium only a few species such as M. tuberculosis, M. interacellulare and M. avium can be identified. A method of DNA-DNA hybridization for the identification of 22 species of Mycobacterium was reported, but the detailed is not known. The aim of the study was to compare the composition of reaentsand factors affecting DNA-DNA reaction hybridization for the species identification of Mycobacterium. The following results were obtained. 1. The stock solution of tetramethylbenzidine (TMB) was most stable and gave high optical density (O.D.) when prepared with methanol. 2. Optimal concentrations of TMB and H^^2O^^2 for horseradish peroxidase (HRP) were 0.3-0.6 mg/ml and 0.08-0.16 mM, respectively. 3. HRP reaction was highest with pH 5.0 citrate EDTA buffer. 4. Highest O.D. was observed with the hybridization solution consisting of 4 x SSC, 10% dextran sulfate, 100 ㎍ salmon DNA. 5. Heating of sample DNA before light treatment enhanced hybridization reaction. It is concluded from the study that with the above reagents and conditions, most of the commonly isolated Mycobacterium species can be identified with the colonies formed on the primary culture medium.restrictio

이중하이브리드조직화학 기법을 이용한 흰쥐 시상하부의 vasopressin 및 oxytocin mRNAs의 발현에 관한 연구

학위논문(석사)--서울대학교 대학원 :의학과 해부학전공,1997.Maste

Development of Real-time Grinding Process Monitoring and Analysis System

The success of the manufacturing process which involves grinding as one of the stages depends solely on the accuracy of the grinding process. Being the last stage of the manufacturing path, it is mostly done to provide the desired surface finish to the product. This makes the stage very crucial. To prevent the ruining of all the previous stages and efforts, the real-time monitoring of the grinding stage becomes necessary which will make a room for better production planning and avoidance of failure occurrence. Conventionally the quality is dependent on the machine behavior as well as the operator's skill. To make the process in par with the latest industry 4.0, real-time process monitoring of the grinding process with the use of a vibration sensor is considered. The developed system in the paper focusses on the monitoring of the process behavior and log the occurred changes. The hardware architecture and software modules are introduced in detail and the application of the developed system is demonstrated with the grinding of an automotive part. The developed system is convenient to use and very helpful in improving the overall productivity of the brake disc production facility by reducing the quality failures and hence saving the resources

Prediction of residual stress and deformation based on the temperature distribution in 3D-printed parts

Selective laser melting (SLM) is a promising additive manufacturing (AM) technique that has the potential to produce almost any three-dimensional (3D) metallic parts with complicated structures. During the SLM process, the thermal behavior of metal powder plays a significant role in maintaining the product quality during 3D printing. Furthermore, due to high heating and cooling rates within the selective laser melting (SLM) process, a high-temperature gradient forms in the heat-affected zone, which generates significant residual stresses within the fabricated parts. In this study, a thermo-mechanical coupling model was developed for studying thermal behavior, residual stress, and deformation during the SLM process of Ti6Al4V alloy. In the experiments, a TELOPS FAST-IR (M350) thermal imager was applied to determine the temperature profile of the melting pool and powder bed along the scanning direction during the SLM fabrication using Ti6Al4V powder. The numerically calculated results were compared with the experimentally determined temperature distribution. The comparison showed that the calculated peak temperature for single track by the developed thermal model was in good agreement with the experiment results. Through the simulation, an effective prediction method for investigating the effects of process parameters such as the laser power and scanning speed on the temperature distribution, residual stress, and deformation was established. The findings showed that the development of residual stress on the fabricated parts gradually increased throughout the SLM process, produced by a heat accumulation effect