• International Journal of Fluid Machinery and Systems
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• 제3권4호
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• pp.342-351
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• 2010

During the operation of a hydro turbine the fluid mechanical pressure loading on the turbine blades provides the driving torque on the turbine shaft. This fluid loading results in a structural load on the component which in turn causes the turbine blade to deflect. Classically, these mechanical stresses and deflections are calculated by means of finite element analysis (FEA) which applies the pressure distribution on the blade surface calculated by computational fluid dynamics (CFD) as a major boundary condition. Such an approach can be seen as a one-way coupled simulation of the fluid structure interaction (FSI) problem. In this analysis the reverse influence of the deformation on the fluid is generally neglected. Especially in axial machines the blade deformation can result in a significant impact on the turbine performance. The present paper analyzes this influence by means of fully two-way coupled FSI simulations of a propeller turbine utilizing two different approaches. The configuration has been simulated by coupling the two commercial solvers ANSYS CFX for the fluid mechanical simulation with ANSYS Classic for the structure mechanical simulation. A detailed comparison of the results for various blade stiffness by means of changing Young's Modulus are presented. The influence of the blade deformation on the runner discharge and performance will be discussed and shows for the configuration investigated no significant influence under normal structural conditions. This study also highlights that a two-way coupled fluid structure interaction simulation of a real engineering configuration is still a challenging task for today's commercially available simulation tools.

• 대한임상검사과학회지
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• 제38권3호
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• pp.152-157
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• 2006

The purpose of this study was to evaluate the usefulness of the automated TB-PCR assay for the detection of Mycobacterium tuberculosis. The 807 cases were analyzed with their TB-PCR, AFB smear and culture in bronchial washing fluids, sputum and body fluids samples. The TB-PCR positive of the bronchial washing fluid, sputum and body fluids were 11.3%, 7.3% and 3.6%, respectively, in cases of AFB smear-negative and culture-negative. The sensitivity values of the bronchial washing fluid, sputum and body fluids were 93.3%, 100% and 50%, respectively, according to the culture result. The sensitivity of body fluids was lower than that of the bronchial washing fluid and sputum. The specificity values of the bronchial washing fluid, sputum and body fluids were 83.3%, 89.0% and 95.7%, respectively, according to the culture result. In conclusion, the automated TB-PCR assay proved to be a useful method for the detection of Mycobacterium tuberculosis in the bronchial washing fluid and sputum. But we think that there is still a need for us to study body fluids further.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2410-2414
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• 2008

Human heart valves diseased by congenital heart defects, rheumatic fever, bacterial infection, cancer may cause stenosis or insufficiency in the valves. Treatment may be with medication but often involves valve repair or replacement (insertion of an artificial heart valve). Bileaflet mechanical heart valves (BMHVs) are widely implanted to replace the diseased heart valves, but still suffer from complications such as hemolysis, platelet activation, tissue overgrowth and device failure. These complications are closely related to both flow characteristics through the valves and leaflet dynamics. In this study, the physiological flow interacting with the moving leaflets in a bileaflet mechanical heart valve (BMHV) is simulated with a strongly coupled implicit fluid-structure interaction (FSI) method which is newly organized based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (remeshing) in FLUENT. The simulated results are in good agreement with previous experimental studies. This study shows the applicability of the present FSI model to the complicated physics interacting between fluid flow and moving boundary.

• 한국자동차공학회논문집
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• 제20권4호
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• pp.76-81
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• 2012

In recent, there are tremendous efforts to apply co-generation concept in automobile to improve its thermal efficiency. The co-generation is basically a simple Rankine Cycle that uses the waste heat from the engine exhaust and coolant for heat source. In spite of developed nano technology and advance material science, the bulky co-generation system is still a big concern in automotive application. Therefore, the system should be effectively designed not to add much weight on the vehicle, but the capacity of the waste heat recovery should be still large. With such a goal in mind, the system thermal efficiency was investigated in terms of the system operation condition and working fluid. This paper provides a direction for the optimal design of the automotive co-generation system.

• 대한한방내과학회지
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• 제23권1호
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• pp.141-145
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• 2002

Diabetic Ketoacidosis(DKA), one of acute complications of diabetes mellitus(DM) occurs mostly in insulin dependent diabetes mellitus (IDDM) patients. Its clinical symptoms are hyperglycemia, ketonemia or ketonuria, metabolic acidosis, etc. The interaction of lack of insulin, excessive secretion of insulin antagonic hormone and dehydration cause body fluid loss and electrolyte, typical symptom of DKA as polyuria, polydipsia, nausea, vomiting, abdominal pain occur. As a result, prompt supply of fluid and insulin by intravenous injection should be conducted for treatment. It is still an emergent disorder whose mortality is still 10 to 15%, though is has decreased compared to the past. We treated a female patient who has DKA, had withdrawn insulin pump therapy. We report a case of DKA with a brief review of related literatures.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.170-176
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• 2007

It is time to prepare the phaseout of R134a, the current refrigerant, in automotive air conditioning system because the EC deadline has been coming with new platform vehicles in 2011 and all vehicles by 2017. Until now a high-pressure carbon dioxide($CO_2$) system is the leading replacement of R134a in European auto-makers but there is no firm agreement in the world automotive market. Recently three new fluids have been announced as the possibilities from Honeywell, DuPont and INEOS Fluor. The new alternative refrigerant should meet the requirements like non flammable, non toxic, no ozone depletion effect and low GWP(under 150 to meet EC regulation). The objectives of this paper are to review the fluid H from Honeywell, the more possible alternative refrigerant in 3 new fluids, compare the properties of R134a & fluid H and see the possibility as a replacement of R134a. In this experimental paper we ran and reviewed the cooling performance data in the bench system, the vehicle and the field test. We found the possibility of fluid H system to meet the R134a system performance with some hardware modifications but agreed that it is still needed to study about the long term safety, environmental effects, material compatibilities and so on.

• 한국가시화정보학회지
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• 제12권2호
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• pp.23-29
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• 2014

Although many studies have been done on an open-end capillary, the invasion into a closed end capillary is still novel in its investigation. In this research we have explored the fluid invasion in closed-end capillaries where the shape of the meniscus and the height of invasion were accompanied by gas compression inside the capillary. Theoretically, the one dimensional momentum balance equation shows the fluid oscillation. In the experiments, we have found the different phenomena, either the fluid oscillation with low frequency or no oscillation. This discrepancy is mostly caused by two factors. First, a continuous decrease of the advancing contact angle due to decreasing invasion velocity as increasing pressure inside the closed-end capillary reduces the invasion velocities. Second, the high shear stress within the entrance length region was generated by the plug like velocity profile.

• International Journal of Fluid Machinery and Systems
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• 제10권1호
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• pp.63-75
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• 2017

Many axial fans have circular arc blades with constant thickness. It is still a challenging task to calculate their performance, i.e. to predict how large their pressure rise and pressure losses are. For this task a need for cascade data exists. Therefore, the designer needs a method which works quickly for design purposes. In the present contribution a design method for such cascades consisting of circular arc blades with constant thickness is described. It is based on a singularity method which is combined with a CFD-data-based flow loss model. The flow loss model uses CFD-data to predict the total pressure losses. An interpolation method for the CFD-data are applied and described in detail. Data of measurements are used to validate the CFD-data and parameter variations are conducted. The parameter variations include the variation of the camber angle, pitch chord ratio and the Reynolds number. Additionally, flow patterns of two dimensional cascades consisting of circular arc blades with constant thickness are shown.

• 한국언론정보학보
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• 제45권
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• pp.151-186
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• 2009

본 연구는 지난 몇 십 년 동안의 문화제국주의 논쟁에서 가장 큰 쟁점들을 정리하고 평가 분석 해석하는데 중점을 두었다. 이들 쟁점의 하나는 국제적 문화 유동(교류)의 성격에 관한 것이었다. 이 교류에 대한 해석을 두고 문화제국주의가 끝났느냐 아니면 계속되고 있느냐 하는 이른바 ‘문화제국주의의 역전 현상’으로 이어졌다. 또 하나의 논쟁은 이러한 유동이 세계화의 연속이냐 아니면 지역화의 일환이냐, 또는 이 유동이 동질화를 불러일으키느냐 아니면 혼성으로 이어지느냐에 관한 것이었다. 대체적인 견해는 예전의 문화제국주의, 주로 1960년대와 1970${\sim}$1980년대식의 일방적인 문화제국주의는 존재하지 않지만, 여전히 초국적 미디어 기업에 의한 세계적 지배는 형태를 달리할 뿐 여전히 존재하고 있다는 것이다. 따라서 문화(미디어) 제국주의 논쟁에서는 국가 간의 문화교류를 어떻게 바라보고 있는가? 문화제국주의는 존재하고 있는가? 세계화는 어떻게 바라보아야 하는가? 세계화는 또 다른 이름의 제국주의인가? 결론적으로 국제적 문화 유동은 그렇게 간단한 것이 아니다. 자연 현상이나 인류의 진보도 마찬가지이지만, 어느 한 현상은 하나의 요소나 관계만으로 이루어지는 것이 아니다. 문화유동도 다양한 여러 현상과 관계 등이 관계하여 이루어지는 복합적인 것이다. 이는 외부와 내부의 모순, 문화 유동과 관계된 국가와 사회의 내부 외부 관계, 계급, 사회적 문화적 상황 등과 관련이 있다. 최근의 문화(미디어)제국주의 논쟁에서도 특정한 나라의 편성과 장르에서 지역화와 세계화가 맞물려 복합적으로 나타난다는 연구 결과가 나오고, 특정 프로그램과 문화에 대한 문화 해석이 그 나라의 문화와 양식에 맞게 변형되기도 한다는 연구 결과가 나오고 있다. 문화의 유동은 양면성이 있다. 어떤 시기나 어느 국가에서는 그것이 이롭거나 긍정적으로 작용하기도 하고 어떤 경우에는 해롭거나 부정적으로 작용하기도 한다. 국제적 문화 유동에서는 제국주의적인 요소와 세계화, 지역화, 동질화, 혼성이 동시에 작동하고 있다. 문화제국주의론이나 문화제국주의를 비판하는 양측 모두 동전의 한 면만을 보고 있다. 따라서 지금 이 시점에서 문화제국주의 현상이 끝났다고 결론 내리기는 어렵다. 왜냐하면 국제적 문화 유동에서 미국과 초국적 미디어 기업의 지배(영향력)는 계속되고 있기 때문이다. 다만 그 원인을 외부의 적으로만 돌려버리는 단선적인 문화제국주의가 아니라 복잡한 국제적 문화 유동의 과정을 밝혀 지배적 관계들(또는 과단한 영향력)을 밝혀내는 것이 중요하다.

• Wind and Structures
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• 제5권2_3_4호
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• pp.193-208
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• 2002

Previous studies have shown that Computational Wind Engineering (CWE) is still in its infancy and has a long way to go to become truly useful to the design practitioner. The present work focuses on more recent studies to identify progress on outstanding issues and improvements in the numerical simulation of wind effects on buildings. The paper reviews wind loading and environmental effects; it finds that, in spite of some interesting and visually impressive results produced with CWE, the numerical wind tunnel is still virtual rather than real and many more parallel studies - numerical and experimental - will be required to increase the level of confidence in the computational results.