• Korean Chemical Engineering Research
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• 제49권2호
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• pp.230-237
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• 2011

본 연구에서는 혈관 내 인공 폐(intravenous lung assist device)를 개발하기 위하여 CFD를 사용하여 새로운 형태의 인공 폐 모형에 대한 유체의 흐름 특성을 모델링하였다. 모델링을 위하여 중공사(hollow fiber)는 무시하였으며 vertical type과 tangential type이 모델로 사용되었다. 유체의 흐름 특성을 예측하기 유체의 입출구로 1개로 하였을 때와 2개로 하였을 때 그리고 입출구를 관의 중심부(vertical)와 관 벽의 접선방향(tangential)에 위치하였을 때의 흐름 특성을 파악 하였다. 실험 결과, tangential type과 같이 원통의 접선 방향으로 유체의 입구와 출구를 설정할 경우 vertical type에서 나타나는 흐름이 없는 영역(정체층)을 제거할 수 있었다. 또한 tangential type은 와류형태의 흐름이 지배적이며 한쪽으로 편중된 흐름이 아닌 복잡한 형태의 흐름이 발생하는 것으로 나타났다. 또한 유체의 입출구가 2개일 때 유체가 편중된 흐름이 발생하지 않고 관 전체에 복잡한 형태로 흐름이 발생하는 것으로 나타났다. 실험 결과를 통하여 우리는 유체가 유입되는 입구와 출구가 tangential type이며 각각 2개일 때 유체의 흐름이 복잡하며 정체층이 발생하지 않는 흐름이 발생한다는 것을 확인할 수 있었다.

• 충청수학회지
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• 제11권1호
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• pp.163-172
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• 1998

In this paper, we will study properties of the Green's potential for the Green's function of B which is defined in [8]. In particular, we will investigate boundary behavior of some functions related with Green's function within tangential approach regions that were used in [4].

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.168-171
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• 2002

For laser-cutting rapid prototyping systems that fabricate objects with layers having a certain degree of thickness, it is necessary both to minimize surface distortion and to generate dynamically feasible laser cutting trajectories. An effective tangential layer cutting algorithm is developed for this requirements. An energy function is defined in terms of tangential line lengths and their distances. And the energy is minimized for the tangential lines to closely describe a layer suffice. Our method is applied to 3D model samples and the generated tangential lines effectively approximate layer surface and make laser trajectory smooth.

• 한국유체기계학회 논문집
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• 제2권3호
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• pp.59-66
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• 1999

In this study the effects of nozzle diameter on the performance characteristics for the tangential impeller-type water meter are studied experimentally. The nozzle is cut along the tangential direction of the inner case in the water meter. The nozzle shape is round and the number of nozzles used for the experimental study are 8. The performance characteristics are discussed for various nozzle diameters such as 3.1, 3.3, 3.5, 4.0, 4.5 and 5.0 mm. Among the tangential impeller-type water meters, the water meter with the nozzle diameter of 5.0 mm shows the least pressure loss and the instrumental error compared to the Korean Standards.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권4호
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• pp.226-234
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• 2004

A rapid Prototyping system that laser-cuts and laminates thick layers can fabricate 3D objects promptly with a variety of materials. Building such a system must consider the surface distortions due to both vertical-cut layers and triangular surfaces. We developed a tangential layer-cutting algorithm by rearranging tangential lines such that they reconstruct 3D surfaces more closely and also constitute smoother laser trajectories. An energy function that reflects the surface-closeness with the tangential lines was formulated and then the energy was minimized by a gradient descent method. Since this simple method tends to cause many local minima for complex 3D objects, we tried to solve this problem by adding a simulated annealing process to the proposed method. To view and manipulate 3D objects, we also implemented a 3D visual environment. Under this environment, experiments on various 3D objects showed that our algorithm effectively approximates 3D surfaces and makes laser-trajectory feasibly smooth.

• Journal of the Korean Wood Science and Technology
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• 제26권2호
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• pp.29-37
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• 1998

An image analysis program with the function of measuring various quantitative characteristics in the transverse surface of wood was developed using Delphi 2.0. Data on pore characteristics (conditions for image processing, proportion of pores in relationship to other elements, tangential diameter, area, tangential and radial diameter, x and y coordinates of pore center, and geometric coefficients) were saved in text file format. In addition, the pore area histogram in the tangential and radial directions was saved as a BMP (bitmap) type file. Analyses indicated that quantitative characteristics such as the relative radial distribution of pores in a growth ring, pore tangential area histogram, and proportion of pore in lumen area appear to be useful in separating four diffuse-porous woods and four ring-porous woods on the species level.

• 한국가시화정보학회지
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• 제16권2호
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• pp.45-52
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• 2018

The tangential and axial cyclones were fabricated using a 3D printer and the total collecting efficiency, cut-diameter, and pressure drop characteristics of the two types of cyclones with the same inlet area were investigated experimentally. The results show that the total collecting efficiency tends to increase as the inlet velocity increases. However, at a 20m/s condition of the tangential cyclone, the collected particles were re-entrained to the ascending vortex flow, resulting in a decrease of the total collecting efficiency. In the axial cyclone, the cross-sectional area is designed to increase at the inlet and the velocity is reduced, so that the re-entrainment effect does not appear in this study. The pressure loss of the tangential cyclone was larger than that of the axial cyclone. The cut-diameter tends to decrease with increasing the inlet velocity in two types of cyclones, except for the 20m/s condition of the tangential cyclone.

• 한국정밀공학회지
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• 제15권10호
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• pp.140-147
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• 1998

The dynamic behavior of elastically restrained beams under the action of distributed tangential forces is investigated in this paper. The beam, which is fixed at one end, is assumed to rest on an intermediate spring support. The governing equations of motion are derived from the energy expressions, and the finite element formulation is employed to calculate the critical distributed tangential force. Jump phenomena for the critical distributed tangential force and instability types are presented for various spring stiffnesses and support positions. Stability maps are generated by performing parametric studies to show how the distributed tangential forces affect the frequencies and the stability of the system considered. Through the numerical simulations, the following conclusioils are obtained: (i) Only flutter type instability exists for the dimensionless spring stiffness K $\leq$ 97, regardless of the position of the spring support. (ii) For the dimensionless spring stiffness K $\leq$ 98, the transition from flutter to divergence occurs at a certain position of the spring support, and the transition position moves from the free end to the free end of the beam as the spring stiffness increases. (iii) For K $\leq$ 10$^{6}$ the support condition can be regarded as a rigid support condition.

• Geomechanics and Engineering
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• 제10권2호
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• pp.125-135
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• 2016

Adhesion in geotechnical engineering is the interaction between cohesive soil and a solid surface which can cause clogging in mechanized tunnelling through clayey formations. Normal piston pull out and modified direct shear tests were performed on clayey soil samples to determine which type of adhesion stress, normal or tangential, could be most effectively measured. Measured values for normal adhesion ranged from 0.9 to 18 kPa. The range of tangential adhesion was 2.4 to 10 kPa. The results indicate normal adhesion results were more accurate than those for the modified direct shear test that measure tangential adhesion. Direct shear test on identical samples did not show any correlation between measured cohesion and normal adhesion values. Normal adhesion values have shown significantly meaningful variation with consistency index and so are compatible with the base of field clogging assessment criteria. But tangential adhesion and cohesion were not compatible with these assessment criteria.

• 폴리머
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• 제36권5호
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• pp.637-642
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• 2012

실리카로 충전된 SBR(styrene butadiene rubber)/BR(butadiene rubber) 합성고무 복합소재에 대해서 가공기기의 구조가 실리카 분산에 미치는 영향을 파악하기 위해 주사전자 현미경(SEM-scanning electron microscope)을 이용하여 컴파운드의 모폴로지를 관찰하였다. Internal mixer 내에서 intermeshing rotor와 tangential rotor에 의해 배합된 컴파운드를 비교한 결과, intermeshing rotor에 의해 가공되었을 경우 실리카 입자가 더 고르게 분산 및 분포되었음을 관찰하였다. Rotor의 geometry 차이에 의해 intermeshing rotor가 tangential rotor보다 더 큰 전단력(shear)을 컴파운드에 전달하여 실리카 입자를 효과적으로 분산 및 분배시킨 것으로 판단된다.