• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.803-812
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• 2023

The subsea separator of an offshore plant for offshore oil and gas development performs the process of separating oil and gas from crude oil produced in the subsea. The oil-gas subsea separator can be divided into a gravity type that separates fluids by gravity and an in-line type that separates fluids using centrifugal force of density. In the case of the deep sea, the development of a small in-line type separator is required due to manufacturing cost and safety problems caused by water pressure. Therefore, in this study, the gas-liquid phase separation efficiency of the subsea separator was identified through the study of the multiphase flow characteristics of the in-line type separator. For the optimal design of the in-line type separator, the shape of the internal swirl element(ISE) was selected first, and the separation efficiency results for each section of the in-line type separator were analyzed. This study was conducted in parallel with experiments and numerical analysis, and it is expected that the reliability and efficiency of the in-line type separator will be improved through the results.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.2
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• pp.55-64
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• 2015

In this study, a 3-D flame cooling analysis is conducted to examine thermal safety for the flame deflector of the 75 tonf class propulsion test facility, and the safe discharge of the exhaust gas is assessed by using numerical results. The Mixture multiphase model is adopted for the simulation of heat transfer and phase exchange process between flame and cooling water, and the computational study using the single species unreacted model for the exhaust plume is carried out for the flame cooling. Numerical analysis predicts maximum temperature on the flame deflector wall for different water flow rates, and evaluates the safe minimum flow rate of water corresponding to the fire-resistant temperature for concrete.

• Journal of computational fluids engineering
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• v.16 no.2
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• pp.1-10
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• 2011

A new computational program, which is based on the CIP/CCUP(Constraint Interpolation Profile/CIP Combined Unified Procedure) method, has been developed to numerically analyse sloshing phenomena dealt as multiphase-flow problems. For the convection terms of Navier-Stokes equations, the RCIP(Rational function CIP) method was adopted and the THINC-WLIC(Tangent of Hyperbola for Interface Capturing-Weighted Line Interface Calculation) method was used to capture the air/water interface. To validate the present numerical method, two-dimensional dam-breaking and sloshing problems in a rectangular tank were solved by the developed method in a stationary Cartesian grid system. In the case of sloshing problems, simulations by using a improved MPS(Moving Particle Simulation) method, which is named as PNU-MPS(Pusan National University-MPS), were also carried out. The computational results are compared with those of experiments and most of the comparisons are reasonably good.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.975-980
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• 2001

Like composite material. the coil winding pack of the KSTAR (Korea Superconducting Tokamak Advanced Research) consist of multiphase element such as metallic jacket material for protecting superconducting cable, vacuum pressurized imprepregnated (VPI) insulation, and corner roving filler. For jacket material, four CS (Central Solenoid) Coils, $5^{th}$ PF (Poloidal Field) Coil, and TF (Toroidal Field Coil) use Incoloy 908 and $6-7^{th}$ PF coil, Cold worked 316LN. In order to analyze the global behavior of large coil support structure with coil winding pack, it is required to replace the winding pack to monolithic matter with the equivalent mechanical properties, i.e. Young's moduli, shear moduli due to constraint of total nodes number and element numbers. In this study, Equivalent Young's moduli, shear moduli, Poisson's ratio, and thermal expansion coefficient were calculated for all coil winding pack using Finite Element Method.

• Macromolecular Research
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• v.12 no.5
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• pp.443-450
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• 2004

We have studied the effects that inorganic zeolite powder have on structurally different copolymer [poly(propylene-co-ethylene)] and terpolymer [poly(propylene-co-ethylene-co-l-butene)] systems and the possibility of preparing suitable porous composite films. The impact strength and yield stress of the composites did not improve upon any further loading of zeolite, but the modulus increased gradually with respect to the filler loading. The experimental modulus of each of the two systems was compared with theoretical models. We performed a morphological study of the filler mixing efficiency and image analysis. The number-, weight-, and z-average air hole diameters were compared with respect to the draw ratio as well as the zeolite loading. The experimental results suggest that these two matrices can provide a new choice for preparing future multiphase polymeric porous films by stretching them unidirectionally. In particular, we suggest that a 40 wt% zeolite loading at a draw ratio of 4 is useful for porous film applications.

• Journal of Power Electronics
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• v.19 no.4
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• pp.858-868
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• 2019

With the widespread use of modern clean energy, lithium-ion batteries have become essential as a more reliable energy storage component in the energy Internet. However, due to the difference in monomers, some of the battery over-charge or over-discharge in battery packs restrict their use. Therefore, a novel multiphase interleaved converter for reducing the inconsistencies of the individual cells in a battery pack is proposed in this paper. Based on the multiphase converter branches connected to each lithium battery, this circuit realizes energy transferred from any cell(s) to any other cell(s) complementarily. This flexible interlaced converter is composed of an improved bi-directional Buck-Boost circuit that is presented with its own available control method. A simulation model based on the PNGV model of fundamental equalization is built with four cells in PSIM. Simulation and experimental results demonstrate that converter and its control achieve simple and fast equalization. Furthermore, a comparison of traditional methods and the HNFABC equalization is provided to show the performance of the converter and the control of lithium-based battery stacks.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.495-509
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• 2019

The objective of this study is to analyze the compressibility effects of multiphase cavitating flow during the water-entry process. For this purpose, the water-entry of a projectile at transonic speed is investigated computationally. A temperature-adjusted Tait equation is used to describe the compressibility effects in water, and air and vapor are treated as ideal gases. First, the computational methodology is validated by comparing the simulation results with the experimental measurements of drag coefficient and the theoretical results of cavity shape. Second, based on the computational methodology, the hydrodynamic characteristics of flow are investigated. After analyzing the cavitating flow in compressible and incompressible fluids, the characteristics under compressible conditions are focused upon. The results show that the compressibility effects play a significant role in the development of cavitation and the pressure inside the cavity. More specifically, the drag coefficient and cavity size tend to be larger in the compressible case than those in the incompressible case. Furthermore, the influence of entry velocities on the hydrodynamic characteristics is investigated to provide an insight into the compressibility effects on cavitating flow. The results show that the drag coefficient and the impact pressure vary with the entry velocity, and the prediction formulas for drag coefficient and impact pressure are established respectively in the present study.

• Bulletin of the Korean Mathematical Society
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• v.49 no.2
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• pp.319-327
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• 2012

The equations of a multifluid interpenetration mix model are analyzed. The model is an intermediate mix model in the sense that it is defined by partial pressures but only a single global pressure and a single global temperature. It none-the-less avoids the stability difficulty. It is shown that the model is hyperbolic so that it is mathematically stable.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.3-8
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• 2001

LBM은 분자 운동을 직접 모사하지 않고 통계 역학적 원리에 기초하여 주어진 격자 구조 아래서 입자들의 단순 이동, 충돌 과정의 반복에 의해 유동을 모사하는 방법이다. 이미 다양한 열유동 현상들에 대한 응용 결과가 발표되었으며 병렬화, 단순한 프로그래밍 등의 장점으로 인해 앞으로 연소, 다상 유동, micro/nano 스케일 유동 등의 해석에 많은 가능성을 지니고 있다. 아직 국내에서는 이에 대한 소개가 제대로 이루어지지 못해 관련 분야의 연구자들이 충분한 관심을 갖고 있지 않은 것으로 생각되어 본 논문에서 LBM 방법에 대한 개략적인 소개를 시도하였다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.32-35
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• 2002

In order to characterize the migration of DNAPL in rock fractures, the dynamic macromodified invasion percolation (DMMIP) model, that is able to reflect the viscous force of groundwater in a fracture network, is suggested. DMMIP simulations are verified against the laboratory expenments, which shows a good qualitative and quantitative agreement.