• Particle and aerosol research
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• v.11 no.2
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• pp.37-46
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• 2015

Dust particles, which inflow to the subway mechanical ventilation and air conditioning(MVAC) chamber, contain a fair amount of iron compounds, approximately 25.2w/w%. This work attempted to capture those iron containing dust using magnetic filters. Average magnetization value of the test MVAC dust was 0.012 emu on 5,000 Oe, which could correspond sufficiently with the magnetic interaction. External permanent magnets provided with magnetization of iron mesh screen showing high gradient magnetic field(HGM). It resulted in the capture efficiency with 84.0 ~ 99.7% and 81.2 ~ 99.8% for $PM_{10}$ and $PM_{2.5}$ respectively. Magnetic capture was found to be closely associated with the magnetic intensity, mesh opening size and flow velocity.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.3
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• pp.395-404
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• 2003

Quantitative data of the temperature and velocity were obtained simultaneously by using liquid crystal tracer. PIV(Particle Image Velocimety) based on a grey-level cross-correlation method was used for visualizing and analysis of the flow field. The temperature gradient was obtained by applying the color-image processing to a visualized image, and a neural-network a1gorithm was applied to the color-to-temperature calibration. This simultaneous measurement was applied to the Rayleigh-Bernard convection. This paper describes the method, and presents the quantitative visualization of Rayleigh-Bernard convection and the effect of aspect ratio and viscosity. Also the experimental results were compared with the numerical results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.512-518
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• 1994

An experimental study is made on turbulent diffusion flames stabilized by a circular cylinder in a divergence flow. In this paper, stabilization characteristics and flame structure are examined by varying the divergence angle of duct and position of a circular cylinder. The fuel used is a commercial grade gaseous propane injected by two slit of rod. It is found that the positive pressure gradient greatly influences the eddy structure behind the rod. and that two different kinds of combustion patterns exist at the blowoff limit depending on the divergent angle of duct. They are distinguished by their wake structures: one associated with Karman vortex shedding, the other without it. Also, the blowoff velocity in the former is found to be higher than in the later.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.347-352
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• 2000

The pressure drop characteristics of R-22 and R-410A(a mixture of 50wt% R-32 and 50wt% R-125) flowing in a small diameter tube with 1.77[mm] inner diameter and 3.14[mm] outer diameter was investigated experimentally. the mass fluxes of refrigerants are ranged from 450 to $1050[kg/(m^2{\cdot}s)]$ and the qualites are varied from 0.05 to 0.95. The main experimental results were summarized as follows; The single-phase liquid friction factors for small diameter tubes are higher than those predicted by the Blasius equation. In case of two-phase flow, the pressure gradient of the small diameter tube increases with increasing mass velocity and vapor quality. The experimental data are not well correlated by predictions which were proposed for the large diameter tube.

• The KSFM Journal of Fluid Machinery
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• v.4 no.2 s.11
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• pp.29-34
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• 2001

Experimental and numerical studies are conducted to investigate the flow field over a NACA0012 airfoil with ground effects. In experiment, the ground is simulated by a moving belt system. From the comparison between the experimental and numerical results, it is concluded that the velocity gradient over the ground plane causes the increments in pressure coefficient on lower surface of the airfoil and reduces the suction peak at the leading edge.

• Korea-Australia Rheology Journal
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• v.20 no.4
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• pp.189-196
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• 2008

The pulsatile flow of blood through a stenosed artery under the influence of external periodic body acceleration is studied. The effect of non-Newtonian nature of blood in small blood vessels has been taken into account by modeling blood as a Casson fluid. The non-linear coupled equations governing the flow are solved using perturbation analysis assuming that the Womersley frequency parameter is small which is valid for physiological situations in small blood vessels. The effect of pulsatility, stenosis, body acceleration, yield stress of the fluid and pressure gradient on the yield plane locations, velocity distribution, flow rate, shear stress and frictional resistance are investigated. It is noticed that the effect of yield stress and stenosis is to reduce flow rate and increase flow resistance. The impact of body acceleration is to enhance the flow rate and reduces resistance to flow.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1148-1157
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• 2005

In the present study, the unsteady Hartmann flow of a dusty viscous incompressible electrically conducting fluid under the influence of an exponentially decreasing pressure gradient is studied without neglecting the ion slip. The parallel plates are assumed to be porous and subjected to a uniform suction from above and injection from below. The fluid is acted upon by an external uniform magnetic field which is applied perpendicular to the plates. An analytical solution for the governing equations of motion is obtained to yield the velocity distributions for both the fluid and dust particles.

• The Korean Journal of Rheology
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• v.6 no.2
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• pp.104-118
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• 1994

단섬유 보강 플래스틱 재료의 사출성형 충전공정에서 금형재의 유동장이 섬유 배향 상태를 형성하는데 중요한 역할을 할 뿐만 아니라 섬유의 배향상태가 역으로 유동장에 영향 을 미친다. 충전유동과 섬유 배향의 연계해석을 위하여 단섬유에 의한 추가적인 응력을 포 함하는 Dinh과 Armstrong의 이방성 구성방정식을 충전유동의 해석에 도입하였다. 평명방향 으로의 속도구배에 의한 응력을 고려하여 새롭게 유도된 압력 지배방정식과 에너지방정식을 유한요소법과 유한차분법을 이용하여 풀고 동시에 2차배향텐서의 변화방정식을 4차 Runge-kutta 방법을 이용하여 풀었다. 절점 게이트 주변의 확장유동영역과 라인게이트를 통한 수축유동영역에서 평면방향으로의 속도구배에 의한 응력이 유동장에 미치는 영향을 고 찰하였다. 확장유동영역에서는 평면방향으로의 속도구배에 의한 영향이 추가적인 유량으로 나타나면서 주어진 유량조건하에서 평면방향으로의 속도구배에 의한 응력을 고려하지 않은 경우보다 작은 압력구배를 나타냈다. 수축유동영역에서는 위와 반대의 결과를 보였다. 이러 한 경향은 섬유의 부피분율이증가하거나 모양비가 커짐에 따라 증가한다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.16 no.2
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• pp.125-135
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• 2012

The transient magnetohydrodynamic (MHD) generalized Couette flow with heat transfer through a porous medium of an electrically conducting, viscous, incompressible fluid bounded by two parallel insulating porous plates is studied in the presence of uniform suction and injection and a heat source considering the Hall effect. A uniform and constant pressure gradient is imposed in the axial direction and an externally applied uniform magnetic field as well as a uniform suction and injection are applied in the direction perpendicular to the plates. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of the Hall current, the porosity of the medium and the uniform suction and injection on both the velocity and temperature distributions is investigated.

• Proceedings of the KOSOMBE Conference
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• v.1990 no.05
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• pp.25-27
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• 1990

By designing the gradient pulses to be velocity compensated during one pulse cycle in SSFP (steady state free precession) imaging, the flowing spins can be maintained in the steady state. In the new SSFP sequence the flow signal which might be lost in conventional SSFP imaging sequences can be restored owing to the signal contribution from the preceding pulse cycles. By using the proposed SSFP sequence substantial restoration of the flow signal has been observed for the CSF (cerebro spinal fluid) of the human head.