서울 : 延世大學校 : 1983

김윤호 1983 국내석사

균열 크기 및 위치를 고려한 가스터빈 압축기 블레이드의 유한요소해석

김윤호 한국해양대학교 대학원 2020 국내석사

발전 효율 향상을 위한 장시간 가동 및 발전용 압축기 내부의 가혹한 하중 조건은 압축기 블레이드의 결함을 유발하며, 하나의 블레이드 파손은 발전시스템에 연쇄적인 피해를 입혀 발전 효율 하락 및 경제적 손실을 발생시킨다. 따라서 압축기 블레이드의 손상을 조기에 감지하는 것이 필요해졌으며, 이를 위해 균열이 압축기 블레이드에 미치는 영향을 파악하는 것이 중요해졌다. 본 연구에서는 실제 발전기의 압축기 내부의 블레이드와 유사한 조건을 모사하여 유한요소해석을 진행한다. 블레이드의 균열 위치와 길이를 다양하게 모사하여 이에 따른 응력 분포와 수준이 변화하는 것을 관찰함으로써 균열의 변화에 따른 압축기 블레이드의 상태 변화를 파악하며 이를 토대로 균열이 압축기 블레이드에 미치는 영향을 연구 및 분석함으로써 균열의 상태에 따른 블레이드의 정적 거동을 파악하고 파손 가능성을 예측하고자 한다. 또한 블레이드 팁에 3개의 절점을 지정하고 균열의 위치에 따른 절점의 변위차를 분석하고 이를 균열의 위치에 따른 블레이드의 굽힘 및 거동과 연관지어 고찰한다. 구조해석 이후에는 진동해석을 수행하고, 균열의 위치와 길이가 압축기 블레이드의 고유진동수 변화에 미치는 영향을 고찰한다. 균열의 상태에 따른 고유진동수의 변화 양상을 블레이드의 동적 특성과 연계하여 연구하며 그 결과를 바탕으로 파손 가능성이 있는 압축기 블레이드의 정보를 수집하고자 한다.

공기극 유동 특성이 고분자 전해질 연료전지 성능에 미치는 영향

김윤호 서울시립대학교 2011 국내박사

본 연구에서는 PEMFC 스택의 성능을 증가시키기 위한 방법으로서 스택 자체의 전기 화학적 특성 또는 유동 구조의 개선을 통해서가 아닌 스택을 구동하는데 필요한 BOP 시스템의 변경을 통해 스택의 성능을 향상시키는데 초점을 맞추었다. 또한 의료용 냉장고를 개발함에 있어 전원 시스템을 PEMFC 시스템을 적용하여 BOP 시스템을 최적화 하고자 하였다. 첫째, 개방형 공기극 채널 형상의 스택을 선정하여 측면으로부터 공급되는 공기극의 헤더 형상을 변화시켜 스택 성능의 변화 양상을 분석하였다. 크게 4가지의 헤더 형상을 모델링하여 수치해석과 실험을 병행하였으며, 실험결과 수치적으로 가장 좋은 유동 분포를 보인 헤더에서 기본 헤더 형상보다 스택의 성능이 약 8% 정도 상승하는 결과를 보였다. 이는 스택 자체의 설계 변경이 아닌 BOP 시스템의 설계 사양이 스택의 성능에 큰 영향을 미친다는 것을 역으로 보여주는 결과이다. 둘째, 공기극 유동 공급 방법으로서 일반적인 균일 유동에서 벗어나 균일 유동에 가진 유동을 적용함으로서 가지 유동에 의한 스택 성능 변화를 분석하였다. 일반적으로 가진 유동은 열 및 물질 전달을 효과적으로 증진시키기 때문에 채널 내에서의 공기의 열 및 물질 전달의 균일 및 증가시키기 위한 방법으로서 가진 유동을 적용하였다. 실험 결과 공기극에 가진 유동을 적용함에 따라 스택의 출력은 큰 폭으로 증가하였고 더불어 전류 한계 영역도 크게 증가하였다. 이는 채널 내에서의 온도 분포 및 산소의 분압 분포가 개선된 결과이다. 가진 유동 효과는 공기극 유량이 증가함에 따라 그 증가량이 감소하였고, 전체적인 스택의 효율 또한 조금 감소하였다. 그러나 효율의 증가폭에 비해 스택 출력의 상승폭이 매우 크기 때문에 공기극의 유량이 적은 운전 조건에서는 매우 큰 효과를 볼 수 있다. 이상의 연구 결과는 모두 스택의 성능을 향상시키는데 스택 자체의 설계 개선이 아닌 BOP 시스템의 설계 변경에 의한 결과이다. 즉 연료전지 전체 시스템을 고려할 때 BOP 시스템의 적절한 설계 및 최적화는 매우 중요한 요소라고 할 수 있다. 따라서 본 연구에서는 BOP 설계의 최적화에 따른 시스템 성능을 분석하기 위해 휴대 의료용 냉장고에 PEMFC 시스템을 적용하여 그 성능을 평가하였다. 개발된 PEMFC 시스템을 분선한 결과, 배터리 충전 모드에서의 배터리 충전 전력량, BOP 소비 전력량 그리고 외부 부하량을 변화시켜 BOP 효율을 계산한 결과, 외부 부하 및 PEMFC 스택 출력량이 증가함에 따라 BOP 효율이 증가하였다. 즉 PEMFC 스택을 구동하는데 있어서 BOP 시스템은 저전력 구간보다는 고전력 구간에서 상대적으로 높은 효율로 운전됨을 확인하였다. In the present study, a 10-cell PEMFC stack with straight type cathode flow channels is employed to investigate the effect of inlet air flow header configuration on the overall fuel cell performance. Four different types of inlet flow headers are considered and the flow patterns according to the air inlet flow header configuration are numerically obtained. The computed result for a modified header predicts about 8.5% improvement in the air flow distribution at 10-cell cathode channel inlets. Experiments are also carried out to confirm the numerical findings by measuring actual air flow distributions and the polarization curves of the PEMFC stack. The effect of cathode flow pulsation on the performance of a 10-cell proton-exchange membrane fuel cell is investigated. An acoustic woofer generates a pulsating flow, which is added to a unidirectional flow supplied from a compressed air tank. By adding the flow pulsation, the fuel cell power output and the limit current dramatically increase while the fuel cell efficiency slightly decreases, As the pulsation amplitude increases, the improvement in fuel cell performance is more pronounced. The performance enhancement shows no obvious dependency on a pulsation frequency change from 10 to 30 Hz. The cathode flow pulsation effect is more distinct at low cathode flow rates. A portable medical refrigerator powered by proton-exchange membrane fuel cell (PEMFC) system and cooled by thermoelectric cooler (TEC) cooling module is developed. The TEC cooling module consists of four TECs, heat sink for cold and hot side, and air cooling fans for both sides. The power consumption and cooling capacity of TEC cooling module are 63 W and 11.5 W, respectively. The PEMFC system consists of an air-cooled stack combined the oxidant and coolant flow, a hydrogen supply subsystem with metal hydride canister, and a control unit subsystem for the management of the system with DC-DC converter and battery. To analyze the performance of PEMFC system, the power consumption of balance of plant (BOP) components, power charging consumption of battery, and power output of PEMFC stack is measured by according to the external load rates. When the power output of PEMFC stack is increased from 50 W to 200 W, the BOP efficiency of PEMFC system is increased from 25% to 67%, respectively. Key Words : PEMFC(Proton Exchange Membrane Fuel Cell), BOP(Balance of Plant), Cathode Flow Rate, Cathode Flow Pulsation, Efficiency

Control of Force Turn-Off Direct Frequency Changers for VSCF Systems : 김윤호

김윤호 Univ. of Texas at Arlington 1987 해외박사

항공기의 전원은 가변속 기계적인 동력에서 일정주파수의 출력을 발전시켜야 한다. 본 논문에서는 이러한 가변속 제어에 사용될 수 있는 강제전류주파수 변환기의 제어 에 대해서 고찰하였다. 특히 강제전류주파수 변환기의 입력역률제어 방식, 고조파 제 어, 주파수제어등에 적합한 여러가지의 변조방식을 제안 하였으며 여기에 필요한 실현 방법등에 대해서 검토하였다.

MBSR(mindfulness-based stress reduction)과 사섭법(四攝法)을 활용한 명상수업 프로그램의 적용

김윤호 동국대학교 2018 국내석사

This research was intended to develop a meditation program using MBSR program for the purpose of stress relief, in addition to one of the Buddha’s teaching which is Catur-Samgraha-Vastu(四攝法, the four expedient means by which bodhisattvas embrace beings and lead them to liberation). Amidst rapid social development, the modern people are increasingly interested in the true meaning of life and happiness, but simultaneously are living without giving a second thought about such issues. Following the reasons, in the religious counselling, particularly in terms of Buddhist counselling, this research aims to reject undulated religious faith and guide people to the correct path of religious faith whilst searching for a suitable way of religious practice which will cause less religious hostility from ordinary people to practice. The content of this research in MBSR embodies five forms of meditation, sitting meditation, walking meditation, eating meditation, hatha yoga, and body scan, followed by forms of religious practices such as utilising Catur-Samgraha-Vastu including sharing compassion, bows, Posadha, writing wills, experience of mirroring, and arranged to divide these practice into five sessions, In addition, before the meditation program started and after practicing the above explained religious practices for five sessions, thirty-nine middle aged female participants were measured of their rates in happiness and negativity, quality of domestic relationship and satisfaction of their marriage life in order to study the successfulness of the Buddhist meditation program. As the findings were revealed from the participants, after undertaking five sessions of meditation classes the negativity rate significantly decreased and the marriage satisfaction rate had increased. The results reflect the participant’s level of stress relief and the change of mind towards their partners through the meditation program, which simultaneously correlates the result that the participants had realised their state of mind by themselves and took a positive approach to the change. On the other hand, rates of happiness and the quality of domestic relationship were very minimal which is believed to be because of the time limit the meditation program has in enabling the effects to family members who live separately and thus studying the quality of domestic relationship was not substantially meaningful. The explanation behind the minimal change in happiness is believed to be because the average participants who were able participate in the program already possessed a stable eoonomical and psychological state along with the leisure of having enough time. If the above research was to be throughly edited and thus successfully completed and enabled into the meditation program, it is hoped that not only will the quality of domestic relationship be cured but education, organisations and individuals will also be able to participate regionally for a method into enhancing the quality of life.

인라인스케이트의 활동이 건강체력 및 기능체력에 미치는 영향 : 초등학교 1학년 학생을 중심으로

김윤호 국민대학교 교육대학원 2010 국내석사

This research, activity inline skating school boys in grades 1 to physical fitness and functional fitness could affect any comparisons, to analyze the effect of promoting a more accurate is aimed to provide. Inline skating activities, more than 10 months and one grade school boys and a special group of 27 who does not exercise one grade elementary school boys and 27 men divided body composition, exercise capacity was measured. Attribute mean and standard deviation of measured data to obtain the difference between independent samples T test to test was conducted. Results of this study conducted the following conclusions were obtained. this study For a more healthy physical, strength, back strength, sit-ups, harvard step test, trunk flexion were measured and there were subtle differences(P< .01). All aspects of physical health showed slight differences. Second, For more information on physical features of the measured side step, sargent jump, stork stand portion in both groups, there were slight differences.(P< .01) When you see the results of aggregates in-line skating activities of one grade of elementary school students, They show a positive impact on their motor ability to exercise As a result of exercise capacity and body composition as a positive factor to increase the exercise can be recommended for children, and Children's physical growth and balanced development is thought to be a good exercise. 본 연구는 인라스케이트 활동이 초등학교1학년 남학생의 건강체력 및 신체조성에 어떠한 영향을 주는지 비교 · 분석하여 인라인스케이트의 활동이 초등학교 1학년 남학생에게 미치는 영향을 정확하게 제시하는데 목적을 두고 있으며, 인라인스케이트 활동을 10개월 이상 활동한 초등학교 1학년 남학생27명의 활동군과 특별한 운동을 실시하지 않는 초등학교 1학년 남학생 27명을 비활동군으로 나누어 건강체력과 기능체력을 측정하였다. 측정한 데이터는 요인별 평균과 표준편차를 구하여 그 차이를 검증하기 위해 독립표본 T검정을 실시하였다. 본 연구를 실시한 결과 다음과 같은 결론을 얻게 되었다. 첫째, 건강체력을 알아보기 위하여 측정정한 근력, 근지구력, 심폐지구력, 유연성,은 활동 집단과 비활동 집단 간에 유의한 차이가(P < .01) 있는 것으로 나타났다. 건강체력의 측면 모두 유의한 차이를 나타냈다. 둘째, 기능체력을 알아보기 위하여 측정한 민첩성, 순발력, 평형성 부분에 있어서 활동 집단과 비활동 집단 간의 유의한 차이가(P < .01) 있는 것으로 나타났다. 이상의 결과를 종합해 볼 때 인라인스케이트의 활동이 초등학교1학년 학생들의 건강체력과 기능체력에 긍정적인 영향을 미치는 것을 알 수 있으며, 이는 건강체력과 기능체력에 긍정적인 요인을 증가시키는 운동으로서 아동들에게 추천할 수 있으며, 아동들의 균형 있는 신체 발육과 발달에 좋은 운동이 될 것으로 사료된다.

저소득 국가의 경제성장 결정요인에 관한 연구 : ODA 활용 부문을 중심으로

김윤호 조선대학교 2015 국내석사

This study aims to check the result of an analysis of aids according to the purpose, unlike preceding studies dealing with aids and economic growths, which have analyzed the sum of the entire aids and the impacts on the economic growths. Most preceding studies were conducted simply on the efficacy of official development assistance (ODA) on the economic growth using its sum total, but as recently, studies subdividing the sectors of ODA have begun and analyses have been in progress, and yet, the results of the analyses differ depending on each study, so a question about the effectiveness of assistance still remains. This study first reviewed related theories, carrying out a literature review of the domestic and overseas preceding studies of the economic growth and built empirical analysis models based on the theoretical background reviewed. As for the empirical analysis models, three models were set up by differing the categories of ODA, and in all three models, dependent variable included GDP per each economically active person by country, while independent variables included the GDP to investment ratio, a production element representing material capital and the ratio of economically active population to the entire population, a production element representing human capital, and the rate of accessibility to hygienic facilities to the entire population, based on the idea that the improvement of hygienic facilities will increase productivity. In order to check the effects of the infrastructure sector in ODA on the economic growth, which was the main focus of analysis in this study, by differing the categories of ODA, the amount of the ODA executed per each economically active person was included as an independent variable in the first model; the amounts executed for social infrastructure and service and economic infrastructure and service were added as independent variables to the second model; and the amounts executed for the representative sub-sectors of social infrastructure and service, such as education, health care and drinking water sectors were included as independent variables in the third model. To sum up the results of an empirical analysis, the effects of the total amount of the entire assistance on the economic growth was not obvious. In contrast, in the results of the analysis that divided aids by two fields, it was found that the values of the coefficients in social infrastructure and service sector of the bilateral aids was statistically significant, and when the categories of the aids were subdivided further and the effects of the representative sub-fields of social infrastructure service were analyzed, it was found that education field had positive (+) effects on the economic growth and health field had negative (-) effects. Although we couldn't confirm the effects of the all ODA sectors, this study was an appropriate attempt in that it considered the characteristics of each aid and analyzed the effects of the aids on the economic growth according to their characteristics and purposes.

BSC 퍼지-DEA모형을 이용한 한우 비육농가의 효율성 분석

김윤호 忠北大學校 2011 국내박사

In today's open economy system, the management environment of Korean farms changes rapidly to require more competitiveness. Korean cattle farms should confront this environmental changes. The efficient cattle farms can survive and grow continuously, but the inefficient farms which does not make efforts to be efficient or does not eliminate inefficient factors to be confronted with a serious crisis. DEA(Data Envelopment Analysis) model is a methodology for performance analysis. It is a set of LP technique used to construct empirical production frontiers and evaluates the relative efficiency of DMU(Decision Making Units) with multiple inputs and outputs by given input-output data. The DEA model is particularly very useful when a form of the production function of a DMU like an cattle farm is not known. It has also advantages that can evaluate the relative efficiency by using survey real data without trying to unify or modify units for measured data, and can provide the extend of inefficiency factors of DMUs, which is especially useful information required to improve efficiency. The assumptions underlying DEA are that all the data assume the form of specific numerical value and require a consistent and/or homogeneous operating environment. However, in real world problem as cattle farms system, the input-output data may be imprecise. Another problem in the classical DEA is its low discriminating power when evaluated DMUs are insufficient or inputs-outputs are too many relative to the number of DMUs. To resolve these problems, this study take to incorporate fuzzy set theory with classical DEA. The fuzzy set theory has been proposed as a way to quantify imprecise and vague data in DEA model. Fuzzy-DEA model enables the result to have a higher discrimination, a meaningful interpretation and comparison of the efficiency among DMUs. Simultaneously, the result of DEA offer decision makers bench-marking informations that can help to transform inefficient farms into efficient farms. The summarized results of this study are as follows: To begin with, to derive the similarities among farms, farms for feasibility study limited a total of above fifty head of cattle in management scale, However, the nationwide investigations for farms make them have the differences in management and geographical conditions, to cope with this problem, we conduct cluster analysis before starting in DEA. Farms are classified into two cluster(Ⅰ: 11 farms, Ⅱ: 31 farms, respectively). This study verified t-test with the efficiency values between the cluster analysis model and united one. At the 10% significance level, it was rejected that the efficiency values between the cluster model and united one are not significantly different. Therefore, the model was deduced with statistics to be difference for efficiency value, and farms, in the end, have the similarities in clusters separated. Second, one of the problems in DEA is that the efficiency value depends on selected input and output indicators. It is subject that's selecting an appropriate index. This study chose 2 output and 6 input indicators through a check list of management in fattening korean cattle made with BSC. This study takes six input indicators as rating of pedigree registration, feed and labor cost of 10kg weight gain, automatic facilities, feeding & management, and quality assurance and takes two output ones as annual income and rating of above B1 grade. To test whether a selected model appraise the Korean cattle farms suitably, we toke variables with low correlation between output and input variables, made a model with these variables removed, evaluated the performance with the reduced model and verified the Wilcoxon Rank Sum Test with the ranking value between the reduced model and raw one. the raw model selected at the 5% significant level was deduced with statistics to be suitable. Third, this study introduces the fuzzy logic into DEA formulation to deal with the qualitative and heterogeneous variables so that the performance of cattle farms from different and uncertainty conditions can be assessed. This approach can deal with both quantitative and qualitative or linguistic fuzzy variables. The basic idea is to transform the fuzzy DEA model into a crisp LP problem by applying an alternative cut approach. Therefore, the problem is expressed to an interval programming. In this procedure, instead of comparing the equality(or inequality) of two interval, a variable is defined in the interval, not only satisfies the set of constraints, but also maximizes the efficiency value. We show that for the special case, in which fuzzy membership functions of fuzzy data are of trapezoidal types, possibility DEA models become LP models of Lertworasirikul et al.(2003). The fuzzy DEA in this study demonstrates a high discrimination in DEA applications compared to classical DEA. Forth, the greatest advantage of DEA model is that it offers decision-makers a benchmarking information that can help to transform inefficient farms into efficient farms. If a farm is classified with inefficient farm, the farm receives weight from reference group to ameliorate his management. For example, A13 in group I at Input-oriented BCC model, supposing variability to scale, is classified into inefficient farm. This farm has to benchmark A3, A6, A37, A39 to be transformed into efficient farm. Specifically, at fixed output levels, A13 makes rating of pedigree registration have to ameliorate more 22% than current levels, needs to find ways to reduce feed and labor that cost to gain 10kg, needs to reduce the salse age, and needs to improve a wide variety of activities (automatic facilities, feeding & management, and quality assurance). Finally A13 needs to enlarge farm scales since being set on IRS. One of the main contribution of this study is to develop a systematic efficiency evaluation process which utilizes not only the concept of the classical efficiency evaluation, but also various other concepts such as BSC based efficiency assessment, classifying farms with cluster analysis, scale efficiency analysis, ranking of farms with fuzzy DEA, and validity analysis of DEA model. Our study enables us to overcome the limitation that many of previous DEA related models for cattle farms have focussed on just crisp efficiency evaluation which presents only the result of efficiency evaluations.

Fisetin antagonizes cell fusion, cytoskeletal organization and bone resorption in RANKL-differentiated murine macrophages

김윤호 한림대학교 대학원 2014 국내석사

Osteoclastogenesis is comprised of several stage s including progenitor survival, differentiation to mononuclear preosteoclasts, cell fusion to multinuclear mature osteoclasts, and activation to osteoclasts with bone resorbing activity. Botanical antioxidants are now being increasingly investigated for their health-promoting effects on bone. This study investigated that fisetin, a flavonol found naturally in many fruits and vegetables, suppressed osteoclastogenesis by disturbing receptor activator of nuclear factor (NF)-B ligand (RANKL)-mediated signaling pathway and demoting osteoclastogenic protein induction. Nontoxic fisetin at ≤10 M inhibited the induction of RANK, tumor necrosis factor receptor associated factor 6 (TRAF6) and the activation of NF-B in RANKL-stimulated RAW 264.7 macrophages. In RANKL-differentiated osteoclasts cell fusion protein of E-cadherin was induced, which was dampened by fisetin. The formation of tartrate-resistance acid phosphatase-positive multinucleated osteoclasts was suppressed by adding fisetin to RANKL-exposed macrophages. It was also found that fisetin reduced actin ring formation and gelsolin induction of osteclasts enhanced by RANKL through disturbing c-Src-proline-rich tyrosine kinase 2 signaling. Fisetin deterred preosteoclasts from the cell-cell fusion and the organization of the cytoskeleton to seal the resorbing area and to secret protons for bone resorption. Consistently, the 5 day-treatment of fisetin diminished RANKL-induced cellular expression of carbonic anhydrase II and integrin 3 concurrently with a reduction of osteoclast bone-resorbing activity. Therefore, fisetin was a natural therapeutic agent retarding osteoclast fusion and cytoskeletal organization such as actin rings and ruffled boarder, which is a property of mature osteoclasts and is required for osteoclasts to resorb bone.

웹사이트 광고의 접속과 상호작용에 영향을 미치는 요인에 대한 연구

김윤호 경성대학교 멀티미디어정보예술대학원 2001 국내석사

The web site advertisement's effct course incluedes a process of an active user's spontaneous contact with website to interact actively differently from unilateral way of mass media's effect course which cause passive interaction. That means, the effect course is caused by interactivity with Web site aside from it's primary advertisenment promtion. The most important distictive feature in Internet is interaction. Active receiver of web site is, differently from passive user of mass media, can control information of product through interaction. Therefore, this study, will analyze consumer's two kinds of act. They are website contact and the promotion cause that affects interactive operation, motive of internet use, mass factor and message factor. And the reseacher will clarify user's variables and the relationship among composition variables. The result showed that the highest influential fact that cause website advertisement contact is web finder and E-mail(3.66%). In case of web finder(3.66%), the result showed same result with previous study but in E-mail(3.66), there showed unexpected result. Also, it showed that mass media advertisement(2.25%), mass media news(2.37%) are highly dependent on mass media. This proves that internet is not yet an individual mass media but has a supplementary relationship traditional mass media The result of interactive reaction, that is to say, with staying in special web site opening of web page this interactive action measure on information design perception mass factor in detail recreation perception , when seeing site, I feel good' (3,03%), infrmation perception provides 'because it provides proper product information(2.83%), in design perception 'because graphic design is good' (2.82) This is proved in refernce study coincide content. Internet is information media and because of many floating typed users �� 새 internet's special chracter, they are understood as those who are interested in recreational fact and design interact. Beased on theses, we can see that there are many factors in website contracts and interactive reaction. Therefore, there need a particualr effect. The debating points are as following. First, web managers will have to mobilize various ways to inform their web sites. There need to develop not only exsiting web finder engine but diverse ways which combine traditional media. Second, by using interior intention and exterior intention it needs to induce people to products and service by adding gift certificate or recreational factor attract non object oriented web floaters. Third, with design and recreation which is factors of media induce users' intention and provide proper information. Fourth, according to contact and interactive reaction's degree there shows a different feature in usage of promotion between heavy user and light user, contact motive. web site perception, participation level. So, when establishing advertisement strategy, a different approach is required between heavy user and light user. Finally, website advertisement is, differnetly from mass media advertisement, it will have to realize marketing which coincide with costomer's request and use's using frequencies by using website production with various variables and mixing high level message factors.