• Journal of Ocean Engineering and Technology
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• v.16 no.3
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• pp.1-7
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• 2002

In this paper, a numerical model to analyze the performance of a vertical slit-type wave absorber is developed under the assumption of inviscid water waves. The formulation combines the linear potential theory with a semi-empirical description of the eddy-shedding at a slit-type wave absorber. We investigated the reflection coefficients over a wide frequency range for a vertical slit-type wave absorber both with and without a solid rear wall. Model test was conducted at KRISO' s two dimensional wave tank to validate the theoretical results. It is found that the agreement between theoretical results and experimental data is surprisingly good. We found that the wave absorbing system using a vertical slit plate has sufficient potentials for breakwaters for ocean development.

• Journal of Mechanical Science and Technology
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• v.18 no.6
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• pp.1036-1041
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• 2004

A newly designed pressure-scanning slit viscometer is developed to combine an optical device without refraction while measuring blood viscosity over a range of shear rates. The capillary tube in a previously designed capillary viscometer was replaced with a transparent slit, which is affordable to mount optical measurement of flowing blood cells. Using a pressure transducer, we measured the change of pressure in a collecting chamber with respect to the time, p(t), from which the viscosity and shear rate were mathematically calculated. For water, standard oil and whole blood, excellent agreement was found between the results from the pressure-scanning slit viscometer and those from a commercially available rotating viscometer. This new viscometer overcomes the drawbacks of the previously designed capillary viscometer in the measuring whole blood viscosity. First, the pressure-scanning slit viscometer can combine an optical instrument such as a microscope. Second, this design is low cost and simple (i.e., ease of operation, no moving parts, and disposable).

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.497-500
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• 2006

An theoretical analysis on the electro-osmotic flow in a 2-dimensional slit, that is induced by an external electric field acting on the electrical double layers near the slit wall, was performed. Especially, although there were many studies on the interacting electrical double layers, it was found in this study that they have several physical or mathematical fallacies. To resolve these, the general solution on the charge-regulating slit with the height as a parameter was obtained. The results of this work can provide the electrokinetic solution of nanoscale slit with the electrical double layer interaction as well as that of microscale slit without the interaction and can be used as the benchmark of a numerical analysis and the reference of electrokinetic flow path design.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.123-127
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• 2007

The effect of axial slit wall of outer cylinder on Taylor-Couette flow was experimentally investigated. The axial slits were azimuthally located along the inner wall of outer cylinder and the number of slits was 6, 9 and 18. The radius ratio and aspect ratio of the experimental models was 0.825 and 48, respectively. We used PIV method to measure the flow field and applied refractive index matching method to resolve the image distortion due to the complex model geometry. The results showed the effect of slit on the flow transition is increased as the number of slit increased. When the model has 6 slits, there were hardly the effect of axial slit wall and the flow transition happened at the same Reynolds number of plain smooth wall model case.

• Steel and Composite Structures
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• v.25 no.4
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• pp.473-484
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• 2017

In this study a seismic retrofit scheme for a building structure was presented using steel plate slit dampers. The energy dissipation capacity of the slit damper used in the retrofit was verified by cyclic loading test. Genetic algorithm was applied to find out the optimum locations of the slit dampers satisfying the target displacement. The seismic retrofit of the model structure using the slit dampers was compared with the retrofit with enlarging shear walls. A simple damper distribution method was proposed using the capacity spectrum method along with the damper distribution pattern proportional to the inter-story drifts. The validity of the simple story-wise damper distribution procedure was verified by comparing the results of genetic algorithm. It was observed that the capacity-spectrum method combined with the simple damper distribution pattern leaded to satisfactory story-wise distribution of dampers compatible with the optimum solution obtained from genetic algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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• pp.889-894
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• 2007

The effect of the axial slit of outer cylinder on Taylor-Couette flow was experimentally investigated. The radius ratio and aspect ratio of the model was 0.825 and 48, respectively. The depth of slits was 5mm and total 18 slits were azimuthally located along the inner wall of outer cylinder. We used PIV method to measure the flow field and applied refractive index matching method to resolve the image distortion due to the complex model geometry. The results showed the axial slit did not affect the transition from laminar Couette flow to Taylor vortex. The effect of slit wall appeared when the Reynolds number is larger than Re=143 and the slit model shows the transition to turbulent Taylor vortex flow above Re=143.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.89-101
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• 2014

나노 규모의 좁은 공간에서는 분자들과 벽면과의 상호작용이 커서 분자들의 거동에 큰 영향을 준다. 이와 관련하여 최근에 나노슬릿 (nano-slit)이나 나노채널(nano-channel)과 같은 제한된 공간(confined geometry)에서 DNA의 구조적, 동역학적 거동에 관한 연구가 활발히 진행 중이다. 이러한 연구에서 모티브를 얻어 많은 입자들(spheres)로 이루어진 나노슬릿(nano-slit)사이에 Leonard-Jones potential을 따르는 용매분자들과 고분자가 들어있는 시스템을 구성하여 고분자의 동역학에 관해 연구하고자 하였다. 이때 슬릿(slit)은 약간의 탄성 포텐셜을 가지는 경우와 완전히 고정되어서 움직이지 않는 경우로 나누어 실행하였다. 더불어 고분자의크기, 용매의 종류, slit 사이의 간격 등의 변화가 고분자의 동역학에 어떤 영향을 주는지 살펴보았다. 이를 통해 환경적 조건에 따른 나노슬릿(nano-slit)에서 고분자의 움직임의 양상을 이해할 수 있었다.

• Journal of the Semiconductor & Display Technology
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• v.3 no.3
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• pp.41-44
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• 2004

The aim of this study is the confirmation of the coating uniformity affected by the surface tension and wall attachment angle in a slit-coater model. In this work, we use the commercial code (Fluent) to solve the two-phase flow formed with air and photo resist numerically. The results show that the surface tension is the most important factor to determine the coating efficiency in the view of coating uniformity, and the coating uniformity is 2% for our slit-coater model and conditions. To improve the coating uniformity, it is in need of minimization of the sidewall effect of slit-coater.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.6
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• pp.637-642
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• 2002

An arc-shaped line array slit has been used for the laser generation of focused Lamb waves. The spatially expanded Nd:YAG pulse laser was illuminated through the arc-shaped line array slit on the surface of a sample plate to generate the Lamb waves of the same pattern as the slit. Then the generated Lamb waves were focused at the focal point of which distance from the slit position is dependent on the curvature of slit arc. The proposed method showed better spatial resolution than the conventional linear array slit in the detection of laser machined linear defect and drill machined circular defect on aluminum plates of 2mm thickness. Using the focused waves, we could detect the linear defect and the circular defect with the improvement of spatial resolution. The method can also be combined with the scanning mechanism to get an image just like by the scanning acoustic microscope(SAM).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.11
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• pp.2260-2266
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• 2009

In this paper, the problem of electromagnetic coupling between a slit fed by a flanged parallel-plate waveguide (FPPW) and a nearby conducting strip parallel to the slit is studied as a simplified problem for a near-field scanning microscopy (NSM). The characteristics of the FPPW are investigated from the results for the variations of the equivalent slit admittance, the reactive powers near the slit inside and outside the FPPW, the magnitude and phase of the voltage reflection coefficient of the TEM wave. The performance of the proposed apparatus as an NSM is tested by examining the effects of various geometrical parameters such as guide height, slit width, strip width, distance between slit and strip, and the ratio of slit width to guide height on the magnitude and phase of the voltage reflection coefficient of the TEM wave. From the results for the voltage reflection coefficient against the strip offset from the slit, it is found that a slit in the FPPW with smaller guide height gives higher scanning resolution and the phase variation is more sensitive than the magnitude variation.