• Journal of Magnetics
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• 제18권3호
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• pp.321-325
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• 2013

The problem of mixed convection in a differentially heated lid-driven square cavity filled with Cu-water nanofluid under effect of a magnetic field is investigated numerically. The left and right walls of the cavity are kept at temperatures of $T_h$ and $T_c$ respectively while the horizontal walls are adiabatic. The top wall of the cavity moves in own plane from left to right. The effects of some pertinent parameters such as Richardson number (ranging from 0.1 to 10), the volume fraction of the nanoparticles (ranging 0 to 0.1) and the Hartmann number (ranging from 0 to 60) on the fluid flow and temperature fields and the rate of heat transfer in the cavity are investigated. It must be noted that in all calculations the Prandtl number of water as the pure fluid is kept at 6.8, while the Grashof number is considered fixed at 104. The obtained results show that the rate of heat transfer increases with an increase of the Reynolds number, while but it decreases with increase in the Hartmann number. Moreover it is found that based the Richardson and Hartmann numbers by increase in volume fraction of the nanoparticles the rate of heat transfer can be enhanced or deteriorated compared to the based fluid.

• 한국가시화정보학회지
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• 제18권3호
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• pp.42-51
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• 2020

This study performs a numerical simulation of lid driven rectangular cavity flow with different aspect ratios of k = 0.5 to 4 under Reynolds 100, 1,000, 10,000 by using multi-relaxation time (MRT) Lattice Boltzmann Method (LBM). In order to achieve better convergence, well-posed boundary conditions in the domain should be defined such as no-slip condition on side and bottom solid wall surfaces and uniform horizontal velocity on the top of the cavity. This study focuses on the flow inside different shape of rectangular cavity with the aim to observe the effect of the Reynolds number and aspect ratio on the flow characteristics and primary/secondary vortex formation. In order to validate the study, the results have been compared with existing works. The result shows that the Reynolds number and the aspect ratio both has substantial effects on the flow inside the lid-driven rectangular cavity.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1071-1075
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• 2003

In a closed square cavity filled with a liquid, a cooled the upper horizontal wail and a heated the lower horizontal wall, the flow isn't generated under the ground-based condition when Rayleigh number is lower than 1700. In such case the flow phenomena near an air bubble under a cooled horizontal wall were investigated. The temperature and the flow fields were studied by using the Thermo-sensitive Liquid-Crystal and the image processing. The qualitative analysis for the temperature and the flow fields were carried out by applying the image processing technique to the original data. Injecting bubble at the center point of upper cooled wall, the symmetry shape of two vortexes near an air bubble was observed. The bubble size increased, the size of velocity and the magnitude of velocity increased. In spite of elapsed time, a pair of two vortexes was the unique and steady-state flow in a square cavity and wasn't induce to the other flow in the surround region.

• 한국음향학회지
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• 제16권1호
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• pp.76-80
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• 1997

Hofler 타입의 열음향 냉장시스템에 있어서 음향학적 공진특성을 해석하고, 공진특성이 냉장성능에 미치는 영향을 시스템의 제작 및 냉장 실험을 통하여 확인하였다. 열음향 냉장시스템의 공진특성을 결정하는 주요 인자는 공명구(cavity)와 가는 관, 그리고 굵은 관으로 구성되는 공명기의 특성과, 구동 스피커의 특성, 그리고 스피커 후면부의 음향학적 특성이며, 다시 스피커의 전기적 특성과 결합되어 전기적 공진특성이 정해진다. 또한 공명기에서 발생하는 벽-효과(wall effect)를 통한 감쇠로 인하여 공진특성이 둔해진다. 제작된 열음향 냉장시스템에 대한 해석 및 실험결과 전체 공진특성은 공명기에 의하여 결정되지만 후면부의 강성과 감쇠로 인하여 공진특성이 상당히 둔화되고, 냉장실험 결과 정확한 공진특성의 유지가 냉장성능에 큰 영향을 마침을 확인하였다.

• 한국임상수의학회지
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• 제17권1호
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• pp.275-278
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• 2000

A 3-year-old yorkshire terrier was examined because of the green-like vaginal discharge. Abdominal ultrasonographs revealed dead fetuses in the abdominal cavity. Surgical exploration revealed fetuses located in the region of the uterine wall, the omentum, the ileum, and the upper right side of the liver respectively. Fetal structures were removed and an ovariohysterectomy was performed. The abdominal cavity was flushed with warm saline and then the incision closed. These fetuses were at different stages of development. It was suggested that the development of the fetuses apparently continued in extrauterine pregnancy until the blood supply became inadquate for further growth.

• Journal of applied mathematics & informatics
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• 제7권3호
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• pp.801-812
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• 2000

Two-dimensional slow viscous flow on infinite half-plane past a perpendicular infinite cavity is considered on the basis of the Stokes approximation. Using complex representation of the two-dimensional Stokes flow, the problem is reduced to solving a set of Fredholm integral equations of the second kind. The streamlines and the pressure and vorticity distribution on the wall are numerically determined.

• 한국자기학회지
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• 제13권3호
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• pp.127-132
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• 2003

자성유체의 자연대류는 부력 이외에 자기체적력이 존재하기 때문에 뉴턴유체와 다르다. 본 연구에서는 좌측 및 우측 벽면이 고온 및 저온으로 설정된 정방형 케비티 공간내에서 자성유체의 자연대류를 실험하였다 실험은 열전대에 의한 온도측정과 감온액정에 의한 가시화를 실시하였다. 그 결과 케비티 공간내 자성유체의 전열특성 및 외부에서 가하는 자장의 방향과 세기에 따라 자연대류가 제어됨을 알 수 있었다.

• 대한두개안면성형외과학회지
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• 제20권6호
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• pp.347-353
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• 2019

Most orbital surgeons believe that it's difficult to restore the primary orbital wall to its previous position and that the orbital wall is so thin that cannot be firmly its primary position. Therefore, orbital wall fractures generally have been reconstructed by replacing the bony defect with a synthetic implant. Although synthetic implants have sufficient strength to maintain their shape and position in the orbital cavity, replacement surgery has some drawbacks due to the residual permanent implants. In previous studies, the author has reported an orbital wall restoring technique in which the primary orbital wall fragment was restored to its prior position through a combination of the transorbital and transantral approaches. Simple straight and curved elevators were introduced transnasally to restore the orbital wall and to maintain temporary extraorbital support in the maxillary and ethmoid sinus. A transconjunctival approach provided sufficient space for implant insertion, while the transnasal approach enabled restoration of the herniated soft tissue back into the orbit. Fracture defect was reduced by restoring the primary orbital wall fragment to its primary position, making it possible to use relatively small size implant, furthermore, extraorbital support from both sinuses decreased the incidence of implant displacement. The author could recreate a natural shape of the orbit with the patient's own orbital bone fragments with this dual approach and effectively restored the orbital volume and shape. This procedure has the advantages for retrieving the orbital contents and restoring the primary orbital wall to its prior position.

• Restorative Dentistry and Endodontics
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• 제29권2호
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• pp.170-176
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• 2004

목적 : 본 연구에서는 '전단접착강도 시험법에서 cohesive failure를 줄일 수 있는 것으로 소개된 metal iris를 사용하면, 실제의 1급 와동에서보다 복합 레진과 와동벽의 결합이 없어서 C-factol 적게 작용하고 계면에 발생하는 수축 응력이 감소됨으로써, 임상에서보다 높은 결합력 값이 보고될 것이다.'라는 가설을 검증하기 위하여 dentin ilia를 사용하여 전단접착강도를 측정하였다. 방법 : 64개의 대구치를 4군으로 구분하여 metal iris와 dentin iris군으로 구분하고, 그 각각을 ONE-STEP과 ALL-BOND 2의 두 군으로 나누었다. bonding agent를 적용하고. iris를 고정한 후, 복합 레진을 충전하여 시편을 완성하였다. 이 때 dentin iris의 경우 내면에도 bonding agent를 적용하여 와동벽과의 결합이 발생하게 하였다. 전단접착강도는 24시간 후 측정하였고, 파절의 양상은 주사전자현미경과 입체광학현미경을 이용하여 결정하였다. 결과 : 전단접착강도 측정법에서 iris 법을 이용함으로써 cohesive failure를 줄일 수 있다. 전단접착강도 측정법은 adhesive 두께가 얇은 경우에 와동벽의 영향을 받는다.

• 소성∙가공
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• 제15권1호
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• pp.15-20
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• 2006

The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filling difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation for both the conventional molding and the RTR molding processes.