연료전지 적용을 위한 방향족 탄화수소 기반 고분자 전해질 막의 제조와 특성 및 막 전극 접합체의 성능

유성관 전북대학교 일반대학원 2022 국내박사

The aim of the thesis is to develop a high performance, enhanced physicochemical properties, and low-cost hydrocarbon polymer membrane for polymer electrolyte fuel cells (PEMFCs). First work is the synthesis of block copolymers by using a perfluorinated fluorenyl functional group on sulfonated poly(arylene ether) (SPAE) with inorganic fillers to improve the chemical, physical stability, and fuel cell performance of PEM. The structural and thermal stability of the pristine sulfonated poly(arylene ether) polymer membrane was investigated by using Field-Emission Scanning Electron Microscopy (FE-SEM) and thermal gravimetric analysis. Furthermore, in order to improve the chemical, physical, and electrochemical performance of pristine SPAE. Various concentrations of inorganic materials (graphene oxide (GO) and phosphotungstic acid (PWA)) was added into the SPAE matrix, which greatly improved ionic conductivity by promoting the formation of ion clusters in the polymer membrane. Notably, chemical and physical properties were greatly improved by combining the polymer matrix with inorganic fillers of GO and PWA. The optimized SPAE/GO/PWA with 0.7wt% GO and 36wt% PWA polymer nanocomposite membrane shows a higher water uptake value of about 52% at 90 oC as compared to other prepared polymer composite membranes and also increases the swelling ratio of the optimized polymer composite membrane by about 11% with good dimensional stability. The optimized SPAE/GO/PWA composite membrane with 0.7wt% GO and 36wt% PWA demonstrated a high proton conductivity of 186.3 mS·cm-1 at 90°C and 100% relative humidity (RH). The optimized polymer composite membrane based PEMFC display peak power density of 193.3 mW·cm−2 at 70°C under 100% RH. Therefore, this work provides a new pathway to the development of inorganic filler incorporated polymer nanocomposites membranes for fuel cell applications. Second work is the development of a phosphoric acid-doped polybenzimidazole (PA-PBI) based proton exchange membrane for high-temperature PEMFC applications. In this study, single cell performance observed at various temperatures and flow rates without humidification using the phosphoric acid-doped PBI membrane. The as-prepared membrane shows the improved unit-cell performance according to operating condition. We also measured the power density, membrane resistance, charge-transfer resistance, and mass-transfer resistance of a PA-PBI membrane based HT-PEMFC operating at 120–160°C with pure H2 and reformed H2 as anode fuel. In particular, the peak power density was achieved to 0.39 and 0.24 W·cm-2 by using pure H2 and reformed H2 respectively, at 160°C. These results demonstrated that the higher temperature improve the ionic conductivity, electrochemical reaction and gas diffusion rate of the PA-PBI membranes. The PA-PBI based HT-PEMFC's durability was tested at 4.8 A and 160 °C for 500 hours. These results were able to be observed clearly through the change in cathode flow rate of hydrocarbon polymer electrolyte based HT-PEMFC, which is a promising material to replace the Nafion membrane in fuel cells.

기계부품 접촉구동부의 에너지절약형 마찰처리 수식 모델 개발에 관한 연구

유성관 호서대학교 대학원 2003 국내석사

앞으로의 기계산업 및 21세기를 주도할 기술분야로 주목받고 있는 정보통신, 우주항공, 바이오 등 미래 첨단 기술들의 기반과 핵심은, 무엇보다도 나노 부품 및 시스템의 제작과 그에 대한 특성/신뢰성 평가기술에 있음은 당연할 것이다. Tribology는 이러한 제품의 신뢰성과 직결되는 마찰(friction), 마멸(wear), 윤활(lubrication), 표면공학(surface engineering)과 관련된 학문 및 기술을 말하며, 본 논문은 이 Tribology의 일환으로 기계접촉 구동부에서 일어나는 마찰·윤활 현상에 대한 마찰수식모델을 개발하는데 그 목적이 있다. 접촉 구동부의 동력전달이 효과적으로 이루어지기 위해서는 접촉 구동부 사이의 마찰경계조건을 정확히 수식모델화 하는 작업이 필요하다. 하지만 기존의 수식모델은 요소에 국한되어 접촉 구동부의 실제 조건과 상당한 차이를 보이고 있으며, 경험에 의한 데이터에 의존하고 있는 실정이다. 본 논문에서는 접촉 구동부의 마찰조건을 정확히 해석하고 마찰수식모델을 정립하였으며, 개발된 마찰수식모델의 실제사례에 적용시켜 보았다. 앞으로 광범위한 영역으로 적용되고 계속적인 연구가 이루어진다면 표면마찰이 일어나는 모든 기술 수준에 있어서 많은 발전이 이루어질 것으로 사료된다. 나아가 설비 플랜트에 보다 큰 효율과 성능을 제공하고 낮은 고장률과 현저한 비용절감을 초래할 것이며, 결국 소성가공 산업에 있어서 많은 에너지와 비용을 절감할 수 있을 것으로 사료된다. This paper is concerned with analysis of the friction phenomenon in machine part contact problem. In order to accomplish the analysis of the friction problems, it is necessary that the friction boundary condition between dies and worked materials should be worked out the accurate numerical friction models. But, the existing numerical models may be have large different from the actual conditions. In this paper, accurate analysis of the friction problems for surface roughness should be subjected. It should develop accuracy of the numerical friction models and potentialize application to the high speed forming work in forming processes. Therefore, the results should improve accuracy and cause energy saving for forming processes. Finally, it should develop the manufacturing industry in our country.

대학에서 ERP 회계교육의 효율적인운영 방안

유성관 원광대학교 산업경영대학원 2010 국내석사

정보통신 기술의 발달로 인해 지식혁명의 본격화, 기술혁신의 가속화, 정보화의 급진전 등으로, 세계는 점차 경쟁이 심해지게 되었다. 이로 인해 기업에서는 합리적인 의사결정을 하기 위하여 각 부문에서 만들어지는 단편적인 정보가 아닌, 기업 전체에 관련되어 산출되는 회계정보와 적시성을 요구하게 되었다. 이러한 환경하에서 기업에서 기업의 자원을 각 부문이 아닌, 전사적으로 통합관리해 주는 전사적자원관리(Enterprise Resource Planning : ERP)를 도입하게 된 것이다. ERP는 영업에서 생산출하에 이르는 기업의 모든 업무과정을 컴퓨터를 이용해 유기적으로 연결, 실시간으로 관리할 수 있도록 해주는 최신 경영시스템으로 볼 수 있다. 그러나 ERP를 도입하고자 하는 기업에서도 ERP 프로그램을 담당하는 실무자를 확보하기가 어려운 실정이며 이는 학교에서의 ERP 교육을 통하여 실무요원의 양성이 절실하다. 따라서 본 연구는 ERP교육에 관한 여러 연구사례들을 문헌을 통하여 정리․분석하여 현재 실시중인 ERP 교육의 문제점을 도출하여, ERP 교육의 효율적인 운용방안에 모색하였고, 그에 대한 내용은 다음과 같다. 첫째, 단순히 ERP 프로그램의 사용 방법에 대한 지도가 아닌, ERP 프로그램의 운영 원리에 대한 수업도 비중 있게 실시해야 한다. 둘째, 실무교육 강화를 위해 일반 전산실이 아닌 전용 회계실무실습실을 운영하여야 한다. 셋째, 교육과정에 있어서 ERP에 대한 이론은 최소화하여 활용측면에 비중을 두고, 사용능력을 습득시켜야 한다. 그리고 기초 학문으로 회계원리에서 세무회계, 원가회계의 개념까지 학생들이 충분히 이해 할 수 있도록 해야 한다. 넷째, ERP 교과목 관련 자격 제도를 전문분야에서 필요한 지식과 기술을 갖추었음을 공식적으로 인정하는 자격증으로써 자리잡게 하고, 이를 학점으로 인정해 주는 방안도 모색해야 한다. 다섯째, 현장실습과의 연계를 강화로, 산업체 현장의 직무경험을 전문교과 이수 단위로 인정하는 방안을 모색과 함께, 이수결과가 자격증 취득에도 유리하도록 한다. 마지막으로, e-learning 강화를 통해 조직원들에게 경쟁자들보다 앞서서 빠르게 지식을 부여함으로써 급변하는 환경에 대응할 수 있도록 한다. The progress of information and telecommunication technology has brought with it realization of intellectual revolution, acceleration of technical innovation and rapid advance of informatization, by thus increasingly intensifying international competition in all aspects of the society. Under these circumstances, companies are forced to demand for timely accounting information over all, not fragmentary, sectors of their business in order to make decisions in a reasonable manner. In response to such needs, companies have taken measures to introduce Enterprise Resource Planning (ERP) which will control the resources of business not from the standpoint of individual section but from the overall view of an enterprise. ERP may be defined to be an up-to-date management system that enables a company to control in real time all of its business processes ranging from sales through production to delivery by means of organically networked computers. In reality, however, it is hard for the companies intending to introduce ERP to find personnel to be assigned for ERP programming, a situation that calls upon educational institutions to start conducting ERP curriculum in order to train administrative workforce to be engaged practically in the field. This paper is therefore aimed at seeking methods of effectively operating ERP curriculum by reviewing and analyzing examples of studies from the concerned literature and deriving the issues from ERP education conducted currently. The suggestions could be summed up as follows: First, a depth class for teaching operational principles of ERP programs should be conducted in addition to the class for simple use of ERP programs. Second, an exclusive room for accounting practice should be set aside to reinforce practical training. Third, theoretical education of ERP should be minimized in the curriculum but a focus should be placed instead on its utilization in a try to help students enhance the ability to use it. Moreover, students should be taught fully of fundamental steps from the accounting principles to the concepts of tax accounting and cost accounting as well. Fourth, ways should be found to recognize publicly the proficiency in the ERP-related fields as a series of qualifications which must then be considered when rating academic grades. Fifth, approaches should be made to approve on-the-job experiences in the industrial field as completion of professional courses needed to acquire credits for professional subjects of the curriculum and to give advantage when winning qualifications. Lastly, e-learning should be intensified to let members of organizations have edge over competitors by providing them with the knowledge required to cope with the rapidly changing environment.

Characterization and functional analysis of RING-type E3 ubiquitin ligases in drought stress response in arabidopsis

유성관 Graduate School, Yonsei University 2021 국내박사

The sedative nature of plants confines the ability to evade the adverse environment. Environmental or abiotic stress includes a range of harmful conditions including drought, heat, cold, freezing, radiation or toxic chemicals. Among them drought/dehydration stress has been proven to account for more than a half portion of global crop yield loss by abiotic stress. Drought/dehydration stress causes two deteriorate secondary effects in plant cells. One is the loss of water-potential, leading to osmostress. The representative defensive mechanism against the water-loss is ABA (abscisic acid)-mediated drought stress response. The key result of ABA-signaling is the stomata closure to prevent the excess loss of water. The ABA-mediated stomatal closure is a complex process involving a set of gene expressions, protein modifications, and even a change in cytoskeletons. The other secondary stress is the proteotoxic stress, a state that proteins lose their native folded structures. The misfolding of proteins, namely proteooxicity, could be induced not only by dehydration but also by heat, high salinity, or toxic chemicals such as heavy metals. The consequent accumulation of misfolded proteins is a serious threat to a plant, for a cell with defected proteins are suffered from the lack of normal function of proteins and the formation of random protein aggregations. Interestingly, ubiquitination and consequent degradation of proteins have been shown to be involved in defense responses against the various deleterious effects caused by dehydration. Ubiquitination is a well-conserved eukaryotic process in which small molecules named ubiquitin are attached to target proteins mainly designated to degradation through proteasome complex or autophagy. Three classes of enzymes named E1 ubiquitin activating enzyme, E2 ubiquitin conjugating enzyme, and E3 ubiquitin ligase generally act in coordination during the ubiquitination. Among them E3 ubiquitin ligase have been largely studied for it is E3 ligase that directly interacts with the substrate proteins thus decide the specificity and function of ubiquitination. In fact, there are more than 1,500 genes known to encode E3 ubiquitin ligases in Arabidopsis genome. Although lines of studies have revealed the decisive roles of E3 ubiquitin ligases in drought stress response in plants, yet many genes are still to be investigated. In this thesis, I present three defensive mechanisms against the drought stress mediated by different RING-type E3 ligases regarding the disparate secondary effects of dehydration. i) JUL1 is responsible for normal stomatal closure by regulating guard cell microtubule depolymerization upon drought stress and consequent ABA-signaling. ii) DRR1 is involved in ameliorating the accumulation of dehydration-induced insoluble ubiquitinated protein aggregates. iii) AtAIRP1 interacts with a nucleus cargo protein AtKPNB1 during the ABA-mediated drought stress response in Arabidopsis. In chapter I, JUL1 E3 ubiquitin ligase was investigated in regard to ABA-mediated stomatal closure. The loss-of-function mutants of JUL1 showed compromised response to ABA treatment during the germination stage. Interestingly, the confocal microscopy and microtubule-interaction assays revealed that JUL1 was a microtubule-associated protein (MAP). Subsequent phenotypic assay showed that the guard cells of jul1 mutant plants were less responsive to ABA and other secondary messengers such as calcium ions and reactive oxygen species (ROS). The fluorescent tagging of tubulins showed that the ABA-induced depolymerization of guard cell microtubules were seriously inhibited in jul1 mutants. Consequently, the loss-of-function plants of JUL1 were more susceptible to drought stress and lost water more rapidly than the wild-type plants. In chapter II, the role of an E3 ligase in regulation of dehydration-induced misfolded protein accumulation was addressed. DRR1 was screened for responsiveness toward ABA and dehydration treatment. RNA interference (RNAi) and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 techniques were employed to generate the loss-of-function plants of DRR1. The suppression of DRR1 resulted in compromised tolerance against dehydration stress. However, canonical ABA-signaling such as germination retardation, stomatal closure, and water-loss rates were not affected by the lack of DRR1. Rather, DRR1 loss-of-function proteins showed hypersensitivity to proteotoxic stress caused by azetidine-2-carboxylic acid (AZC) treatment. Accordingly, the dehydration- and proteotoxicity-induced accumulation of insoluble ubiquitinated proteins were more salient in DRR1 loss-of-function plants. The reduced activity of proteasome complex was also observed in DRR1 knockdown and knockout plants in both drought- and AZC-treated samples. The last chapter introduces the interaction of an E3 ubiquitin ligase AtAIRP1 and a nucleus cargo protein AtKPNB1 in the ABA-signaling pathway. AtAIRP1 and AtKPNB1 were previously reported as a positive and a negative regulator of ABA-mediated drought stress response, respectively. Yeast-two-hybrid assay and subsequent interaction experiments revealed that AtAIRP1 and AtKPNB1 interacts both in vitro and in vivo. Target ubiquitination assay showed that AtKPNB1 was ubiquitinated by AtAIRP1. Subsequent genetic assays employing atairp1/atkpnb1 double transgenic knockout mutants confirmed the epistatic relation of AtAIRP1 and AtKPNB1. The insensitive ABA-mediated germination retardation, defected stomata closing and drought-susceptibility of atairp1 mutants was recovered in the double mutants.

쿠팡 리뷰 유용성과 상품매출에 영향을 미치는 요인 분석 : FCB grid model을 기준으로

유성관 연세대학교 정보대학원 2021 국내석사

신종 코로나바이러스(코로나19)가 발생한 이후 비대면 소비가 활성화되면서 온라인 쇼핑 이용률이 크게 증가하였다. 온라인 쇼핑에서 많은 소비자들은 상품에 대한 정보를 얻기 위해 온라인 리뷰를 이용한다. 온라인 리뷰는 소비자에게 특정 상품 또는 서비스를 이용한 경험이 있는 소비자가 해당 상품이나 서비스에 대한 이용 경험, 의견, 평가 등을 기입한 정보를 제공함과 동시에 기업들이 소비자들과 정보를 공유할 수 있는 소통의 장을 제공하였다. 하지만 정보통신기술의 발달로 매 순간 수많은 양의 온라인 리뷰가 생산되면서 소비자는 유용한 정보를 찾는 과정에 많은 정보탐색 시간 및 비용이 소모되고 있다. 그래서 어떤 리뷰가 소비자들에게 유용한지에 대한 연구는 꼭 필요하다. 따라서 본 연구는 상품군에 따라 유용한 리뷰에 영향을 미치는 요인을 분석했다. 상품을 분류하기 위해 FCB Grid 모델을 활용하였으며, 최종적으로 4가지(고관여-이성, 고관여-감성, 저관여-이성, 저관여-감성) 상품군을 정의하였다. 각 상품군에 따라 리뷰 속성(리뷰어 실명, 리뷰어 명성, 날짜, 평점, 길이, 이미지, 감성점수)이 리뷰의 유용성에 미치는 영향을 비교하였다. 더 나아가 각 상품군에 따라 리뷰 속성(유용성, 리뷰의 수, 평점, 감성점수)이 상품매출에 미치는 영향이 어떻게 다른지 비교하였다. 본 연구결과는 리뷰의 유용성 및 상품매출에 영향을 미치는 요인이 상품군에 따라 서로 다르다는 것을 볼 수 있었다. 고관여-이성 상품군의 경우, 5가지의 독립변수(리뷰의 길이, 리뷰어의 실명, 리뷰어 명성, 날짜, 감성점수)가 리뷰의 유용성에 영향을 미치는 것으로 나타났다. 또한, 상품 매출에 영향을 미치는 요인은 유용성과 리뷰의 수인 것으로 나타났다. 고관여-감성 상품군의 경우, 5가지의 독립변수(리뷰의 길이, 날짜, 리뷰의 평점, 이미지 리뷰, 감성점수)가 리뷰의 유용성에 영향을 미치는 것으로 나타났다. 또한, 1가지의 독립변수(유용성)가 상품의 매출량에 영향을 미치는 것으로 나타났다. 저관여-이성 상품군의 경우, 7가지의 독립변수(리뷰의 길이, 리뷰어의 실명공개 여부, 리뷰어 명성, 리뷰 작성날짜, 리뷰의 평점, 이미지 리뷰, 리뷰의 감성점수)가 리뷰의 유용성에 영향을 미치는 것으로 검증됐다. 또한, 1가지의 독립변수(리뷰의 수)가 상품의 매출량에 영향을 미치는 것을 확인할 수 있었다. 저관여-감성 상품군의 경우, 6가지의 독립변수(리뷰 길이, 리뷰어의 실명공개 여부, 리뷰어 명성, 리뷰 작성날짜, 리뷰의 평점, 리뷰의 감성점수)가 리뷰의 유용성에 영향을 미치는 것으로 나타났다. 또한, 1가지의 독립변수(리뷰의 수)가 상품의 매출량에 영향을 미치는 것을 확인할 수 있었다. 본 연구의 결과를 토대로 시사점을 제시하였다. Since the outbreak of the novel coronavirus (Covid-19), non-face-to-face consumption has been activated, and the rate of online shopping has increased significantly. In online shopping, many consumers use online reviews to get information about products. However, with the development of information and communication technology, a large amount of online reviews are produced at every moment, and consumers are spending a lot of information searching time and money in the process of finding useful information. Research to analyze the attributes of reviews that are recognized as useful to consumers is essential. Therefore, this study analyzed the factors that influence the helpfulness of reviews according to product groups. To classify products, the FCB Grid model was used, and finally four product groups (high involvement-think, high involvement-feel, low involvement-think, low involvement-feel) were defined. This research compares the effect of review attributes on the helpfulness of reviews for each product group. Specifically, the following review attributes are used for this research: name of the reviewer, reputation of the reviewer, written date of the review, review ratings, length of the reviews, images, and sentiment scores of the reviews. Furthermore, we compared how the effect of review attributes (usefulness, number of reviews, rating, and sentiment score) on product sales was different for each product group. As a result of this study, it can be seen that the factors affecting the helpfulness of reviews and product sales are different for each product group. In the case of high involvement-think product group, five independent variables (review length, reviewer's real name, reviewer reputation, date, and sentiment score) were found to affect the helpfulness of reviews. In addition, it was found that the factors affecting product sales were helpfulness and the number of reviews. In the case of high involvement-feel product group, five independent variables (review length, date, review rating, image review, emotional score) were found to affect the helpfulness of reviews. In addition, it was found that one independent variable (helpfulness) affects the sales volume of products. In the case of low involvement-think product groups, 7 independent variables (review length, reviewer's real name disclosure, reviewer reputation, review writing date, review rating, image review, review's emotional score) were found to affect the usefulness of reviews. In addition, it was confirmed that one independent variable (number of reviews) influenced the sales volume of the product. In the case of the low involvement-feel product group, six independent variables (review length, reviewer's real name disclosure, reviewer reputation, review writing date, review rating, and emotional score of the review) were found to affect the helpfulness of reviews. In addition, it was confirmed that one independent variable (number of reviews) influenced the sales volume of the product. Implications were presented based on the results of this study.