• Title/Summary/Keyword: Residual flow

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An Incompressible Flow Computation by a Hierarchical Iterative and a Modified Residual Method (계층적 반복과 수정 잔여치법에 의한 비압축성 유동 계산)

  • Kim J. W.
    • Journal of computational fluids engineering
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    • v.9 no.3
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    • pp.57-65
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    • 2004
  • The incompressible Navier-Stokes equations in two dimensions are stabilized by a modified residual method, and then discretized by hierarchical elements. The stabilization is necessary to escape from the Ladyzhenskaya-Babuska-Brezzi(LBB) constraint and hence to achieve an equal order formulation. To expedite a standard iterative method such as the conjugate gradient squared(CGS) method, a preconditioning technique called the Hierarchical Iterative Procedure(HIP) has been applied. In this paper, we increased the order of interpolation within an element up to cubic. The hierarchical elements have been used to achieve a higher order accuracy in fluid flow analyses, but a proper efficient iterative procedure for higher order finite element formulation has not been available so far The numerical results by the present HIP for the lid driven cavity flow and others showed the present procedure to be stable, very efficient and useful in flow analyses in conjunction with hierarchical elements.

Numerical Simulation of Pipe Flow with an Obstacle by applying Turbulent Models (난류모형을 적용한 장애물이 있는 파이프내의 유동장 수치시뮬레이션)

  • Kwag Seung- Hyun
    • Journal of Navigation and Port Research
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    • v.29 no.6 s.102
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    • pp.523-528
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    • 2005
  • The flow analysis is made to simulate the turbulent flow in the pipe with an obstacle. The models used are k-$\epsilon$, k-$\omega$, Spalart-Allmaras and Reynolds. The structured grid is used for the simulation The velocity vector, the pressure contour, the change of residual along the iteration number and the dynamic head are simulated for the comparison of four example cases. For the analysis, the commercial code is used.

Electrokinetic-Fenton 기법에 의한 phenanthrene으로 오염된 토양의 처리

  • 김정환;김강호;한상재;김수삼
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2001.09a
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    • pp.51-54
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    • 2001
  • This research was carried out to evaluate feasibility of using an Electrokinetic-Fenton(EK-Fenton) technique to treat hydrophobic organic pollutant(phenanthrene) from soils. Experiment examined the effect by introducing a continuous flow of a 3.5% hydrogen peroxide solution at the anode. An electric gradient of 1V/cm was applied to enhance the saturated flow in the soil cell for a period of 11 days. After 11 days or 1 pore volume, overall concentration of residual phenanthrene in the soil cell was 11% and residual phenanathrene concentration in the soil was found to increase with toward the cathode. This results indicated that Fenton-like reaction catalyzed by mineral surface was effective in oxidizing phenanthrene. This results also showed that hydrogen peroxide was effectively transported into the soil by electroosmotic flow as well as by diffusion.

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A study on the synthesis and mechanical properties of WC/C multilayered films (WC/C 다층박막의 합성 및 기계적 특성에 관한 연구)

  • 명현식;한전건
    • Journal of the Korean institute of surface engineering
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    • v.35 no.3
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    • pp.121-126
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    • 2002
  • WC/C multilayered films were deposited by arc ion plating and magnetron sputter hybrid system with various $C_2$H$_2$ flow rates and bias voltages. The coatings have been characterized with respect to their chemical composition (Glow Discharge Optical Emission Spectroscopy), hardness(Knoop micro-hardness), residual stress(Laser beam bending) and friction coefficient(Ball on disc type wear test). Deposition rate, microhardness and residual stress of WC/C films were observed to increase with increasing the $C_2$$H_2$ flow rates. The highest hardness and residual stress were measured to be 26.5 GPa and 1.1GPa for, WC/C film deposited at substrate bias of -100V. WC/C multilayered film was obtained very low friction coefficient(~0.1).

Characteristics of Tidal Current and Tidal Residual Current in the Archipelago Around Aphae Island in the Southwestern Waters of Korea (한국 서남해 압해도 주변 다도해역의 조류 및 조석잔차류 분포)

  • Choo, Hyo-Sang;Kim, Dong-Sun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.2
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    • pp.179-187
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    • 2018
  • In order to understand the flow of currents around Aphae Island and the surrounding Archipelago, the numerical model experiments on tidal currents and tide-induced residual currents were carried out. Dominant semidiurnal tidal currents have a reversing form and flow along the narrow channels of the archipelago. During periods of flood, currents flow from the west of Hwawon Peninsula to the archipelago to the northwest together with the currents flowing from the channels at Palgeum Island to Amtae Island and Amtae Island to Jeung Island. Ebb currents flow from the northwest archipelago to the channel of Amtae Island and Jeung Island as well as Amtae Island to Palgeum Island, further flowing south between Palgeum Island and Hwawon Peninsula. Flood currents are separated from east and west at the southern coast of Aphae Island, but flow south from both the west and east of Aphae Island to the channel found between Palgeum Island and Hwawon Peninsula at ebb. Flow speed is high between Amtae Island and Aphae Island where the flows meet and join. Lee wakes or topographical eddies are formed around the islands due to the high speed of the currents flowing along the narrow channel in the archipelago, manifesting as a tide-induced residual current. A weak cyclonic wake and anti-cyclonic eddy both exist at the west and northwestern coast of Aphae Island individually. The speed of the tide-induced residual current become slow on account of the wide littoral zone at exists around Aphae Island.

Prediction of Residual Layer Thickness of Large-area UV Imprinting Process (대면적 UV 임프린팅 공정에서 잔류층 두께 예측)

  • Kim, Kug Weon
    • Journal of the Semiconductor & Display Technology
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    • v.12 no.2
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    • pp.79-84
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    • 2013
  • Nanoimprint lithography (NIL) is the next generation photolithography process in which the photoresist is dispensed onto the substrate in its liquid form and then imprinted and cured into a desired pattern instead of using traditional optical system. There have been considerable attentions on NIL due to its potential abilities that enable cost-effective and high-throughput nanofabrication to the display device and semiconductor industry. Although one of the current major research trends of NIL is large-area patterning, the technical difficulties to keep the uniformity of the residual layer become severer as the imprinting area increases more and more. In this paper, with the rolling type imprinting process, a mold, placed upon the $2^{nd}$ generation TFT-LCD glass sized substrate($370{\times}470mm^2$), is rolled by a rubber roller to achieve a uniform residual layer. The prediction of residual layer thickness of the photoresist by rolling of the rubber roller is crucial to design the rolling type imprinting process, determine the rubber roller operation conditions-mpressing force & feeding speed, operate smoothly the following etching process, and so forth. First, using the elasticity theory of contact problem and the empirical equation of rubber hardness, the contact length between rubber roller and mold is calculated with consideration of the shape and hardness of rubber roller and the pressing force to rubber roller. Next, using the squeeze flow theory to photoresist flow, the residual layer thickness of the photoresist is calculated with information of the viscosity and initial layer thickness of photoresist, the shape of mold pattern, feeding speed of rubber roller, and the contact length between rubber roller and mold previously calculated. Last, the effects of rubber roller operation conditions, impressing force & feeding speed, on the residual layer thickness are analyzed with consideration of the shape and hardness of rubber roller.

Radionuclide Urodynamic Studies in Patients with Bladder Outlet Obstruction (방사성핵종 요류역학검사를 이용한 하부요로폐색의 평가)

  • Lee, Jae-Tae;Kim, Kwang-Won;Sohn, Sang-Kyun;Chung, Jin-Hong;Lee, Kyu-Bo;Whang, Kee-Suk;Yoon, Yeo-Deuk;Sohn, Houng-Gyu;Chung, Sung-Kwang
    • The Korean Journal of Nuclear Medicine
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    • v.24 no.1
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    • pp.24-28
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    • 1990
  • Various urodynamic studies have been used in patients with bladder outlet obstruction in order to evaluate the degree of obstruction, the results of therapy and postprostatectomy conditions. Radionuclide urodynamic study was performed in 27 patients with bladder outlet obstruction and 30 normal controls. The parameters evaluated were voiding time, 50% voiding time, average flow rate, peak flow rate, corrected peak flow rate, ejection fraction of the bladder and residual urine. Voiding time, 50% voiding time and residual urine of patients were significantly larger than controls and average flow rate, Peak flow rate, peak corrected flow rate and ejection fraction were significantly lower in patients. This method was noninvasive procedure for determining of voiding parameters and it avoids the extraexamination needs to determine the residual urine.

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INVERSE MINIMUM FLOW PROBLEM

  • Ciurea, Eleonor;Deaconu, Adrian
    • Journal of applied mathematics & informatics
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    • v.23 no.1_2
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    • pp.193-203
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    • 2007
  • In this paper we consider the inverse minimum flow (ImF) problem, where lower and upper bounds for the flow must be changed as little as possible so that a given feasible flow becomes a minimum flow. A linear time and space method to decide if the problem has solution is presented. Strongly and weakly polynomial algorithms for solving the ImF problem are proposed. Some particular cases are studied and a numerical example is given.

Effect of Chewlical Transport on Stability of Earth Embankment

  • Ahn, Tae bong
    • Geotechnical Engineering
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    • v.12 no.3
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    • pp.109-126
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    • 1996
  • In this study, the chemical fluid considered is sodium chloride sloutions. The concentrations for the sodium chloride solutions are varied from 0 to 20%. A series of lab oratory triaxial tests are performed on the cylindrical specimens of sand bentonite mixture with different (5, 10, 15%) sodium chloride content solutions. Deformation(elastic modulus, E) and strength (cohesion, c', and angle of friction, f') parameters are obtained from the triaxial tests and they are expressed as functions of conf'ming pressure and sodium chloride solution concentrations. The stress-strain-strength behavior based on the above strength parameters is introduced to the finite element method with a residual flow procedure (RFP). By integrating a slope stability (limit equilibrium) procedure in the finite element method, factors of safety with time are computed.

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A three dimensional numerical model of tide and tidal current in the bay of Cheonsu in Korea

  • Moon Seup Shin;Tet
    • Proceedings of the Korea Water Resources Association Conference
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    • 1998.05a
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    • pp.632-637
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    • 1998
  • The purpose of this study of this study is to find tide and tidal current variation by three dimensional numerical model of tide and tidal current in the bay of Cheonsu in Korea. On the basis of the observed data on water temperature and salinity data and wind data of summer(July) in the bay of Cheonsu in Korea, water circulation in the bay of Cheonsu is investigated with use of a robust diagnostic numerical model, including calculated co-range and co-tidal charts of M2 tide are similar to the observed ones. The residual flow Pattern at the surface layer during summer formed clockwise circulation in the front coastal the dike of the Sosam A zone(Ganwor island) and Taeju island. The residual flow pattern at the 15m layer during formed clockwise circulation in the front Taeju island. The residual flow Pattern at the surface layer formed anti-clockwise circulation in the upper Sangmok and Naepasu island.

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