• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2809-2818
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• 2022

In this investigation work, liquid-liquid extraction (L.L.E) through three distinctive frameworks have been examined for assurance of slip velocity (S.V), and characteristic velocity (C.V) in a non-center rotating column (N.C.R.C) with a wide extend of factors. Three double frameworks with distinctive interfacial tension comprising of toluene-water (high interfacial tension), n-butyl acetate-water (medium interfacial tension), and n-butanol-water (low interfacial tension) were investigated for tests. Two common relationships for the expectation of S.V and C.V, including phase stream rates, rotor speed, column geometry additionally physical properties, are displayed. The recommended relationships were compared with test information gotten from the writing and the display examination. Findings of this study, the present proposed correlations are more accurate than those previously reported.

• 대한기계학회논문집B
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• 제39권7호
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• pp.549-555
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• 2015

적외선 카메라를 이용한 입자추적유속계(IR-PTV)를 활용하여 물-공기 분리유동 시 계면속도를 측정하는 기법을 개발하였다. $3-5{\mu}m$ 파장대의 적외선은 물에 대해 $20{\mu}m$ 이하의 침투 깊이를 가지므로 입자추적유속계 기법에 활용 시 물-공기 계면 근처에 존재하는 추적입자들의 이동속도를 선택적으로 측정할 수 있다. IR-PTV 기법의 측정 정확도를 검증하기 위하여 물에 잘 뜨는 스티로폼 입자를 이용하여 $10^{\circ}$ 기울어진 경사면에서 공기-물 분리유동 시 계면속도를 측정하여 비교한 결과 5% 이내의 오차를 보이면서 잘 일치하였다. 개발한 기법을 이용하여 획득한 실험결과로부터 공기 속도가 증가함에 따라 계면속도가 비례하여 증가하는 것을 관찰하였으며 이는 계면전단력의 증가에 의한 것으로 해석된다.

• 비파괴검사학회지
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• 제30권6호
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• pp.578-586
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• 2010

This paper describes a theoretical model and acoustic analysis of hysteresis of contacting surfaces subject to compression pressure. Contacting surfaces known to be nonlinear and hysteretic is considered as a simple spring that has a complex stiffness connecting discontinuous displacements between two solid contact boundaries. Mathematical formulation for 1-D interfacial wave propagation between two contacting solids is developed using the complex spring model to derive the dispersion relation between the interface wave speed and the complex interfacial stiffness. Existence of the interface wave propagating along the hysteretic interface is studied in theory and discussed by investigating the solution to the dispersion equation. Unlike the linear interface without hysteresis, there can exist only one distinct mode of interface waves for the hysteretic interface, which is anti-symmetric motion. The anti-symmetric mode of interface wave propagates with the velocity faster than the Rayleigh surface wave but less than the shear wave depending on the interfacial stiffness. If the contacting surfaces are compressed so much that the linear interfacial stiffness is very high, the hysteretic stiffness does not affect the interface wave velocity. However, it has an effect on the speed of interface wave for a loosely contact surfaces with a relatively low linear stiffness. It is also found that the phase velocity of anti-symmetric wave mode converges to the shear wave velocity in despite of the linear stiffness value if the hysteretic stiffness approaches 0.5.

• Korean Chemical Engineering Research
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• 제53권3호
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• pp.315-320
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• 2015

Characteristics of gas-liquid mass transfer and interfacial area were investigated in a bubble column of diameter and height of 0.102 m and 2.5 m, respectively. Effects of gas and liquid velocities on the volumetric gas-liquid mass transfer coefficient ($k_La$), interfacial area (a) and liquid side true mass transfer coefficient ($k_L$) were examined. The interfacial area and volumetric gas-liquid mass transfer coefficient were determined directly by adopting the simultaneous physical desorption of $O_2$ and chemical absorption of $CO_2$ in the column. The values of $k_La$ and a increased with increasing gas velocity but decreased with increasing liquid velocity in the bubble column which was operated in the churn turbulent flow regime. The value of $k_L$ increased with increasing gas velocity but did not change considerably with increasing liquid velocity. The liquid side mass transfer was found to be related closely to the liquid circulation as well as the effective contacting frequency between the bubbles and liquid phases.

• 한국유체기계학회 논문집
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• 제17권3호
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• pp.33-40
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• 2014

In this study, a new model for calculating the liquid film thickness and condensation heat transfer coefficient in a vertical condenser tube is proposed by considering the effects of gravity, liquid viscosity, and vapor flow in the core region of the flow. In order to introduce the radial velocity profile in the liquid film, the liquid film flow was regarded to be in Couette flow dragged by the interfacial velocity at the liquid-vapor interface. For the calculation of the interfacial velocity, an empirical power-law velocity profile had been introduced. The resulting liquid film thickness and heat transfer coefficient obtained from the proposed model were compared with the experimental data from other experimental study and the results obtained from the other condensation models. In conclusion, the proposed model physically explained the liquid film thinning effect by the vapor shear flow and predicted the condensation heat transfer coefficient from experiments reasonably well.

• 대한기계학회논문집A
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• 제25권7호
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• pp.1055-1063
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• 2001

When the interfacial crack of isotropic/orthotropic bi-materials is propagated with constant velocity along the interface, stress and displacement components are derived in this research. The dynamic photoelastic experimental hybrid method for the bimaterial is introduced. It is assured that stress components and dynamic photoelastic hybrid developed in this research are valid. Separating method of stress components is introduced from only dynamic photoelastic fringe patterns. Crack propagating velocity of interfacial crack is 69∼71% of Rayleigh wave velocity of epoxy resin. The near-field stress components of bonded interface of bimaterial are similar with those of pure isotopic material and two dissimilar isotropic bimaterials under static or dynamic loading, but very near-field stress components of bonded interface of bimaterial are different from those.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.111-116
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• 2000

A semi-infinite interfacial crack propagated with constant velocity in two bonded anisotropic strip under out-of-plane clamped displacements is analyzed. The asymptotic stress and displacement fields near the crack tip are obtained, where the results get more general expressions applicable not only to isotropic/orthotropic materials but also to the extent of the anisotropic material having one plane of elastic symmetry for the interfacial crack. The dynamic stress intensity factor is obtained as a closed form, which is decreased as the velocity of crack propagation increases. The critical velocity where the stress intensity factor comes to zero is obtained, which agrees with the lower value between the critical values of parallel crack merged in the material 1 and 2 adjacent to the interface. The dynamic energy release rate is also obtained as a form related to the stress intensity factor.

• 한국산업융합학회 논문집
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• 제6권4호
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• pp.291-298
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• 2003

Interfacial crack problems between fiber and matrix in composite materials are discussed. A series of interfacial crack initiation and propagation experiments are conducted using the biaxial loading device for various mode-mixes. Normal crack opening displacement (NCOD) is measured near crack front by a crack opening interferometry and used for extracting fracture parameters. From mixed mode interfacial crack initiation experiments, large increase in toughness with shear components is observed. Initial velocity of crack propagation is very dependent upon the mode-mixes. It increased with positive mode-mix due to the increase of stress singularities ahead of crack front and decreased with negative mode-mix resulting from the increase of the degree of compressive stress behind the crack front. Crack propagation was less accelerated with positive mode-mix than the negative mode-mix.

• 대한기계학회논문집A
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• 제25권3호
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• pp.434-442
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• 2001

When the interfacial crack of two dissimilar isotropic bi-materials is propagated with constant velocity along the interface, stress and displacement components are derived in this research. The dynamic photoelastic experimental hybrid method for bimaterial is introduced. It is assured that stress components and dynamic photoelastic hybrid method developed in this research are valid. Separating method of stress component is introduced from only dynamic photoelastic fringe patterns. Crack propagating velocity of interfacial crack is 80∼85% (in case of aluminum, 24.3∼25.9%) of Rayleigh wave velocity of epoxy resin. The near-field stress components of crack-tip are similar with those of pure isotropic material under static or dynamic loading, but very near-field stress components of crack-tip are different from those.

• 대한기계학회논문집A
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• 제25권6호
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• pp.949-958
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• 2001

A semi-infinite interfacial crack propagated with constant velocity in two bonded anisotropic strips under out-of-plane clamped displacements is analyzed. Using Fourier integral transform the problem is formulated and the Wiener-Hopf equation is derived. By solving this equation the asymptotic stress and displacement fields near the crack tip are obtained, where the results get more general expressions applicable not only to isotropic/orthotropic materials but also to the extent of the anisotropic material having one plane of elastic symmetry for the interfacial crack. The dynamic stress intensity factor is obtained as a closed form, which is decreased as the velocity of crack propagation increases. The critical velocity where the stress intensity factor comes to zero is obtained, which agrees with the lower value between the critical values of parallel crack merged in the material 1 and 2 adjacent to the interface. Using the near tip fields of stresses and displacements, the dynamic energy release rate is also obtained as a form of the stress intensiy factor.