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김성윤(SㆍYㆍKim),김유택(YㆍTㆍKim),남청도(CㆍDㆍNam),이영호(YㆍHㆍLee),강호근(HㆍKㆍKang),김성동(SㆍDㆍKim) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-
The effect of break down of centrifugal pump due to entrained air has not been clarified yet. Thus, air-water two-phase flow experimental apparatus was installed to clarify the effect of break down. The performance results of a single-phase flow satisfied reappearance. Also, the heads coincided well impeller types.
강제대류계(强制對流系)에 있어서 막비등열전달(膜沸騰熱傳達)에 관한 연구(硏究)
김유택,권순석,정대인,Kim, Y.T.,Kwon, S.S.,Jung, D.I. 대한설비공학회 1991 설비공학 논문집 Vol.3 No.1
The aim of this study is to investigate the heat transfer characteristics in the transient cooling process of a high temperature wall. The slow transient cooling experiment was carried out with a copper block of high thermal capacity. The results of these experiments are as follows. 1. Temperature histories measured by the thermocouple, which is 0.99, 2.00, 2.99mm from the heat transfer surface showed monotonous during the cooling process. These variation are the curves of typical temperature histories in film-boiling, transition-boiling, and nucleate-boiling regions. 2. The temperature histories were measured by thermocouple installed in the copper block. The variations of the surface heat fluxes and surface temperature were computed from the numerical solution method TDMA from the measured temperature histories for radial position one dimensional heat transfer inverse problem. The boiling curves were found by the computed temperature histories. 3. The rewetting point which starts to change from film boiling to nucleate boiling is not connected with the mass velocity and it were found that the temperature of rewetting point indicated about $100^{\circ}C$. 4. The heat flux of rewetting point was about $10^5Kcal/m^2h$, at that time, the heat transfer coeficient indicated about $1000Kcal/m^2h^{\circ}C$ irrelevent to mass velocity. 5. The wall superheat decreases as the pressure increases. But I found that rewetting point appeared under higher condition in the wall temperature.
김유택(Y.T. Kim),이영호(Y.H.Lee) 한국해양대학교 해사산업연구소 1996 海事産業硏究所論文集 Vol.5 No.-
Underwater ram-jet is a powerful alternative to the conventional propulsion systems and is adequate to super-speed crafts in the future. This ram-jet having no moving parts in the water phase consists of a simple contoured duct. Many formulations and assumptions based upon thermo-fluid dynamics, continuity equation, Euler and Rayleigh equations, and the bubble motion equation are applied to predict ram-jet propulsion performances.
EAF dust가 함유된 붕규산염계 결정화 유리의 미세구조 분석
안영수,강승구,김유택,이기강,김정환,Ahn, Y.S.,Kang, S.G.,Kim, Y.T.,Lee, G.K.,Kim, J.H. 한국결정성장학회 2006 韓國結晶成長學會誌 Vol.16 No.2
붕규산염계 유리 프리트에 중금속이 다량 함유된 전기로 EAF dust(전기로 제강분진, 이하 더스트)를 $10{\sim}80wt%$ 범위로 첨가한 후 용융하여 유리 시편을 얻었다. 제조된 유리의 DTA분석 결과로부터 유리전이온도, $T_g$가 $550^{\circ}C$ 부근임을 확인하였고 이로부터 결정화에 필요한 열처리 조건을 $700^{\circ}C$/10 hr으로 정하였다. 더스트 첨가량이 70wt% 이상인 유리시편은 XRD 분석 결과 spinel 결정 피크만이 나타났으며, 결정화 시편의 경우, 더스트 첨가량이 40wt% 이상부터 spinel 결정이, 80wt% 부터는 spinet과 willemite 피크가 함께 검출되었다. XRD 분석으로는 결정상이 검출되지 않았던 조성의 유리시편에서도 aspect ratio=$0.7{\sim}1.0$인 수십 nm 크기의 결정상 존재가 SEM으로 확인되었고 결정화 시편에서도 더스트 함량이 l0wt%부터 결정상이 관찰되었다. 결정화 시편에서 관찰된 결정상은 그 형태와 분포가 첨가량에 따라 다양하고 비균일 하였으나 더스트 첨가량이 70wt%인 시편에서는 aspect ratio가 1에 가까운 6면체 형상을 나타내었다. Glassy specimen was obtained by melting and quenching a borosilicate glass frit miked with $10{\sim}80wt%$ EAF dust. The glass transition temperature, $T_g$ of glassy specimen was measured around $550^{\circ}C$ from the DTA curve and the eat treatment condition to crystallize a glassy specimen was selected as $700^{\circ}C$/1 hr. The spinel crystal peaks were found in XRD analysis for the glass containing dust > 70 wt%. For the glass-ceramics, however, the spinel peaks in a specimen containing dust > 40 wt%, and the spinel and willemite peaks in dust > 80 wt%. The crystals of several tens of nanometer with aspect ratio of $0.7{\sim}1.0$ were observed at a glassy specimen containing dust > 40 wt% by SEM which was not found by XRD analysis. For the glass-ceramics, the crystals were found in a specimen containing dust of even 10 wt% by SEM. The feature and distribution of crystals observed through the specimen for a glass-ceramics were diverse and not uniform. The crystals found in the glass-ceramics containing 70 wt% dust were hexahedral with an aspect ratio of around unity.
전현태(H. T. Jeon),남상현(S. H. Nam),최영도(Y. D. Choi),김유택(Y. T. Kim),이영호(Y. H. Lee) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
Small hydropower attracts attention because of its clean, renewable and abundant energy resources to develop. However, suitable draft-tube type is not determined yet because of its complicated internal flow and unstable turbine performance at the partial flow rate by the influence of the draft tube configuration. Therefore, it is necessary to study the influence of draft tube shape. The purpose of this study is to investigate the influence of the draft tube shape to its internal flow using CFD analysis. The results using two different computational models (draft tube without runner and draft tube with runner) are compared. The result which is computed without runner show that large secondary flow occurs at the curve area of the draft tube and the secondary flow goes out to the outlet of the draft tube. Another result which is computed with runner show that internal flow has complex flow in the whole flow field of the draft tube.
김성윤(S.Y.Kim),김정환(J.H.Kim),강호근(H.K.Kang),김유택(Y.T.Kim),남청도(C.D.Nam),이영호(Y.H.Lee) 한국마린엔지니어링학회 2004 한국마린엔지니어링학회 학술대회 논문집 Vol.2004 No.-
A numerical investigation was performed to determine the effect of airfoil on the optimum flap height and tip clearance using NACA00l5 Wells turbine. A Navier-Stokes code, FLUENT and CFX-TASCflow were used to calculate the flow field of the Wells turbine. The basic feature of the Wells turbine is that even though the cyclic airflow produces oscillating axial forces on the airfoil blades, the tangential force on the rotor is always in the same direction. Geometry used in definining the 3-D numerical grid is based upon that of an experimental test rig. This paper tries to analyze the optimum double flaps and tip clearances of Wells turbine with the numerical analysis.
김성윤(S. Y. Kim),이상일(S. L. Lee),김유택(Y. T. Kim),김성동(S. D. Kim),이용선(Y. S. Lee),이영호(Y. H. Lee) 한국유체기계학회 2004 유체기계 연구개발 발표회 논문집 Vol.- No.-
LabVIEW is mostly preferred to use in experiment, measurement and control as one of the useful thing in America and Europe. So, We tried performance experiment of a single-stage closed-type centrifugal pump by using the LabVIEW. The pump rpm and the shaft torque are measured by rpm sensor and torque sensor. The test pump's maximum rpm, head, ㎾ are 1,750m, 13m, and 1.5㎾, respectively. The casing is made up with transparency acrylic for confirmation the flow patterns. We installed experimental equipment for air water two phase flow. This paper tries to analyze the single-phase flow characteristics through this air water two phase flow experimental apparatus. The performance results of a single-stage closed-type centrifugal pump satisfied reappearance and coincide well with head and coefficients according to the change of rpm.