• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1845-1852
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• 2001

This paper deals with the experiment to obtain quantitative information about conditions of the interface between a water drop and surrounding oil. Velocity distributions in very close region of the interface are measured by introducing a new illumination technique and a telecentric lens. It enables precise measurements of velocity distributions in the close region to the interface. Although the measured velocity distributions exhibit strong influence from the solid wall of an experimental tube, the coincidence of inner and outside velocities on the interface is clearly confirmed for the clean interface. The shearing stresses on the interface, which are proportional to the velocity gradient normal to the interface, clearly show conditions of contaminated interface, which can be divided into two parts. From front stagnation point to somewhere near a separation point, the distribution of shearing stresses is well coincide with that of the Hadamard's analytical solution, while the distribution on the latter part of the interface sows quite different feature, which is supposed to be strongly influenced by contamination of the surface.

• Structural Engineering and Mechanics
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• 제85권5호
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• pp.645-654
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• 2023

Based on first-order shear deformation theory, a wave propagation model of graphene platelets reinforced metal foams (GPLRMFs) circular plates is built in this paper. The expressions of phase-/group- velocities and wave number are obtained by using Laplace integral transformation and Hankel integral transformation. The effects of GPLs pattern, foams distribution, GPLs weight fraction and foam coefficient on the phase and group velocity of GPLRMFs circular plates are discussed in detail. It can be inferred that GPLs distribution have great impacts on the wave propagation problems, and Porosity-I type distribution has the largest phase velocity and group velocity, followed by Porosity-III, and finally Porosity-II; With the increase of the GPLs weight fraction, the phase- and group- velocities for the GPLRMFs circular plate will be increased; With the increase of the foam coefficient, the phase- and group- velocities for the GPLRMFs circular plate will be decreased.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.145-150
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• 2006

At the furnace top, the distribution of charging coke and ore is adjusted to control the reducing gas flow distribution in the furnace. It is necessary to predict operation condition of blast furnace according to the burden profile to judge whether charging is properly conducted In this study, We propose the model for predicting while layer structures whithin furnace when top burden profile was given. Layer structure of coke and ore could be predicted by top burden profile and solid velocity. Solid velocity is assumed as potential flow. Potential function distribution and timeline are also calculated using solid velocity field. The Calculation is conducted for different burden profile cases. As the result burden distribution and grid structure, which is deformed to match the layer structure in shaft and deadman profile. Gas flow was calculated using this grid, and calculated results are compared with each other.

• 한국기계기술학회지
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• 제13권2호
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• pp.55-61
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• 2011

This study analyzed on the characteristics of temperature distribution in an active regeneration DPF using computer simulation. In order to verify the boundary condition of analysis, results of temperature distribution in DPF are compared between experimental and computer simulation. Using this boundary condition, temperature distribution and filter's durability in DPF analyzed according to various operating conditions. The results of computational analysis are agreed well with experimental ones from the tendency of temperature distribution of axis and radius direction. The temperature increases and the axial temperature gradients in DPF according to velocity of exhaust gas are lowered as the high velocity of exhaust gas. But the temperature gradients of radius direction at exit side in DPF are grown as the high velocity of exhaust gas. The results according to inlet temperature of exhaust gas show that the increase ratios of temperature in DPF are grown as the high temperature of exhaust gas.

• Journal of Electrical Engineering and information Science
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• 제1권1호
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• pp.45-50
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• 1996

This paper mainly describes the wind load assumption of 765kV transmission towers. We analyzed wind velocity data a meteorological observatories to get the wind velocity of 50 years return period by using Gumbel I type extreme value distribution. By multi-correlative regression analysis method, wind velocity at no observation site was obtained. Reference dynamics wind pressure map was obtained from above analysis and the wind pressure was classified as three regio in high temperature season.

• 한국지형학회지
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• 제23권1호
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• pp.103-115
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• 2016

At present, an acoustic Doppler current profiler (ADCP) is one of the most suitable tools for measurement of three dimensional flow characteristics in the river. The data resulting from this approach can be used for flow visualization and velocity mapping together with post-processing software tools. Among them, 'adcptools' is the latest one and provides more realistic velocity distribution in the cross-section since it uses velocity along the beam direction. In this study, a flow analysis was made using the 'adcptools' for the Amazon River and the Han River dataset. Discharge was recalculated and accuracy of discharge and velocity was evaluated. Streamwise velocity distribution and secondary flow pattern in cross-sections were visualized. Geo-referenced velocity distribution was also mapped. A summary with future prospect of 'adcptools' for studies on fluvial geomorphology is briefly given.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1992년도 수공학연구발표회논문집
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• pp.55-66
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• 1992

수로단면의 유속분포가 균일하지 않으므로, 에너지 원리의 $\alpha$값과 운동량원리의 $\beta$값 각각에 미치나, 대부분 실무에서는 이들 값을 추정하는 어려움 때문에 통상 1로 가정하여 사용하고 있다. 본 연구에서는 실용적으로 이용할 수 있는 공식을 유도하고, 기존에 사용되고있는 Prandtl-Von Karman 공식과 비교 검토하였으며, 유속분포계수 공식을 유도하기 위하여, 수로 바닥과 수 표면까지도 포함한 전 영역에서 비교적 정확한 유속분포를 나타내는 Chiu의 유속공식을 사용하였다. 또한, 실용적목적을 위해 유속데이타 없이 유속분포 계수를 구하기 위해서 Manning공식과 Chiu공식을 사용하였으며, 실험실 및 현장데이타를 위의 연구에 적용 검증하였다.

• 공업화학
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• 제19권6호
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• pp.609-616
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• 2008

본 연구는 크기가 다른 두 종류의 입자를 가진 비(非)콜로이드성 현탁액의 평균 침강 속도를 예측하는 수치적 방법을 제공한다. 이 방법은 무수히 많은 입자들이 유체에 불규칙적으로 분포된 현탁액 시스템의 유체 속도, 온도 등의 물리량을 앙상블 평균의 개념을 사용해서 표현하는 유효 매체 이론에 기초한다. 본 연구에서는 Acrivos와 Chang[1]이 단일(單一) 입도 현탁액에 대해 제안한 모델을 이중(二重) 입도 현탁액에 응용한다. 구체적으로 방사 분포 함수(radial distribution function)에 대한 계산과 stream function을 이용하여 침강 속도를 계산하고 그 결과를 Davis와 Birdsell[2]과 Cheung 등[3]의 실험 결과와 비교하였다. 그 결과 본 연구의 모델에 의한 예측이 실험 결과와 일치하는 것으로 나타났다.

• 반도체디스플레이기술학회지
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• 제12권2호
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• pp.19-25
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• 2013

Extrusion is one of the most important operations in the polymer-processing industry. Balancing the distribution of flow through a die to achieve a uniform velocity distribution is the primary objective and one of the most difficult tasks of extrusion die design. If the manifold in a coat-hanger die is not properly designed, the exit velocity distribution may be not uniform; this can affect the thickness across the width of the die. Yet, no procedure is known to optimize the coat hanger die with respect to an even velocity profile at the exit. While optimizing the exit velocity distribution, the constraint optimization used in this work with allowable pressure drop in the die; according to this constraint we can control the pressure in the die. The computational approach incorporates three-dimensional finite element simulations software STAR-CCM+. These simulations are used with numerical optimization to design polymer coat hanger dies with pressure drop, uniform velocity and temperature variation across the die exit.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.370-377
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• 2002

Generally, the system of calculation for the multi-path ultrasonic flow meters can be divided into two methods by how to get the mean velocity, namely, weighting and direct method. Weighting-method derive the mean velocity through modeling in theoretical velocity profile. Direct-method derive the mean velocity though actual flow distribution. The system of calculation varies with maker's transducer configuration and integration method. Each system has merits and demerits. This paper describes the system of integration that calculates line velocity over cross-section of the circular pipe. Flow rate mr discussed in this paper is a difference between theoretical flow rate and integrated flow rate according to values of Reynolds number in symmetric flow field or theoretical flow rate and integrated flow rate according to rotated model in asymmetric flow field.