• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.69-72
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• 2004

The performance of the centrifugal fan in a vacuum cleaner is affected by the hydraulic loss, such as the friction loss, the recirculation loss and the impact loss etc., Those losses depend on the rotational speed of the impeller, the inlet and exit widths, the relative flow angles to the blade, the number of the blades and the geometry of the shroud and the diffuser. These parameters are complicatedly interrelated, so the experimental means in analyzing the fans are rather limited. In the present study, the flow analysis are done numerically by changing the relevant fan parameters. A commercial code, STAR-CD, is used for the calculations. It is seen from the analyses that the computational results agree well with the experimental results. The results obtained can be used for the basic design of a centrifugal fan.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.533-539
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• 1997

Pressure ripple of hydraulic vane pump results form flow ripple due to pump geometry and reverse flow through the discharge port due to compressibility of fluid and result in vibration and noise of connected hydraulic elements. In a ba;anced type vane pump, cam ring curve is important factor to influence the flow ripple. Therefore, to reduce the now ripple, it has been required that optimal selection of seal region by proper design of cam ring and each port position, and notches for preventing the excessive reverse flow. This paper has been performed analytical study of compression characteristics with major design parameter in side plate and cam ring, and examined into the role of notch and radius reduction ratio.

• 한국정밀공학회지
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• 제15권1호
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• pp.87-93
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• 1998

Pressure ripples of hydraulic vane pump results from flow ripples due to pump geometry and reverse flow through the discharge port due to compressibility of fluid and result in vibration and noise of connected hydraulic elements. In a balanced type vane pump, cam ring curve is important factor to influence the flow ripples. Therefore, to reduce the flow ripple, it has been required that optimal selection of seal region by proper design of cam ring and each port position, and notches for preventing the excessive reverse flow. This paper has been performed analytical study of compression characteristics with major design parameter in side plate and cam ring. and examined into the role of notch and radius reduction ratio.

• 대한기계학회논문집B
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• 제30권10호
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• pp.942-949
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• 2006

A lumped model is proposed to predict liquid ejection characteristics of a thermally driven inkjet print head. The model is based on a two-dimensional heat conduction equation, an empirical pressure-temperature equation and a nonlinear hydraulic flow-pressure equation. It has been simulated through the construction of an equivalent R-C circuit, and subsequently analyzed using SIMULINK and a circuit simulation tool, PLECS. Using the model, heating and cooling characteristics of the head are predicted to be in agreement with the IR temperature measurements. The effects of the head geometry on the drop ejection are also analyzed using the nonlinear hydraulic model. The present model can be used as a design tool for a better design of thermal inkjet print heads.

• 물과 미래
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• 제29권2호
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• pp.191-198
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• 1996

본 논문에서는 icing의 모양을 대표적으로 나타낼 수 있는 적절한 특성길이의 선정에 대해 서술하였다. 실험 자료를 분석한 결과, 어떤 하나의 길이 단위로 특성길이를 정의하기는 곤란하였다. 특히, glaze icing 의 경우에는 그 형상이 매우 복잡하여 특성길이를 결정하기가 매우 어려웠다. 그러나, 바람의 방향에 수직한 단면의 길이로 정의되는 icing 길이가 icing으로 인한는 하중을 나타내기에는 실린더 혹은 전선의 지름 보다는 더 적절한 특성길이라 판단된다.

• 한국기계가공학회지
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• 제12권6호
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• pp.101-108
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• 2013

An aircraft fuel hose is a kind of high pressure hose, and generally consists of a nipple, a socket, an inner tube, and a reinforcement layer to increase the tensile strength. Especially the nipple supports the other components in manufacturing stages such as the swaging or crimping processes however, the nipple also serves to prevent leakage in cases of hose engagement with a hydraulic system. To ensure the seal of the hose assembly, a beam seal fitting with metal-to-metal contact is usually adopted at the end of a nipple. Therefore, the geometry of the beam is an important parameter to be determined to make sure there is sufficient contact force. This study aims to investigate the effects of beam seal geometry on the contact force by changing the inclined angle and the thickness of the beam. The results reveal that the proper thickness and inclined angle of the beam seal are 0.45 mm and $8.5^{\circ}$, respectively.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.381-382
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• 2002

The Fluid film between the valve plate and the cylinder block was measured by use of a gap sensor and the mercury-cell slip ring unit under real working conditions. During the operating periods, experiments with discharge pressure, revolution speed, and valve geometry was carried out for the fluid film on the valve plate. To investigate the effect of the valve shape, we designed two valve plates each having a different shape; the first valve plate was a plane valve plate. while the second valve plate was a spherical valve plate. It was noted that these two valve plates observed different aspects of the fluid film characteristics between the cylinder block and the valve plate. The leakage flow rate and the shan torque were also investigated in order to clarify the difference between these two types of valve plates. From the results of this study. we found that the spherical valve plate estimated good fluid film patterns and performance more than the other valve plate in oil hydraulic axial piston pumps.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권5호
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• pp.475-486
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• 2016

Four-rotor dish-shaped unmanned underwater vehicles (FRDS UUVs) are new type underwater vehicles. The main goal of this paper is to develop a quick method to optimize the design of hydraulic support landing platform for the new UUV. In this paper, the geometry configuration and instability type of the platform are defined. Computational investigations are carried out to study the hydrodynamic performance of the landing platform using the Computational Fluid Dynamics (CFD) method. Then, the response surface model of the optimization objective is established. The intelligent particle swarm optimization (PSO) is applied to finding the optimal solution. The result demonstrates that the stability of landing platform is significantly improved with the global objective index increasing from 1.045 to 1.158 (10.86% higher) after the optimization process.

• 유공압시스템학회논문집
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• 제1권2호
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• pp.8-14
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• 2004

Abstract: In the oil hydraulic piston pumps the clearance between the valve plate and cylinder block plays an important role for volumetric and overall efficiency. Thus, adequate lubricational fluid film is needed for the interface. In this study, fluid film thickness is measured by a gap sensor and a slip ring under operational conditions to observe the behavior of the lubrication mechanism in detail. To investigate the effect according to the valve plate types in view of the fluid film, three different types were designed. Leakage flow rate and shaft torque were also measured to clarify the effect according to the valve plate types. A broad range of experiments were conducted to provide reasonable data on the effect of fluid film. In this experiments two main parameters were found, of which the one is the discharge pressure and the other is valve plate geometry. As a result, we found that the spherical valve plate could get more stable fluid film thickness, maintain good efficiency for high pressure range than the other types.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1478-1486
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• 2009

As a conventional line-fitting method, the Bouwer and Rice method has been popularly adopted to estimate the hydraulic conductivity of an aquifer through a slug test. Because a ventical cutoff wall is usually very compressible and features a small wall thickness, the Bouwer and Rice method should be carefully used for the vertical cutoff wall. In addition, a relatively impermeable layer, called a filter cake, formed at the interface between the cutoff wall and the natural soil formation makes it difficult to use the Bouwer and Rice method directly. In order to overcome such limitations, the original Bouwer and Rice method is modified by incorporating the concept of the flow net method. In this modification, the geometry condition of cutoff walls including the filter cake is effectively considered in evaluating the hydraulic conductivity of a vertical cutoff wall.