• Journal of the Korean Vacuum Society
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• v.3 no.4
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• pp.466-481
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• 1994

차세대 집적회로 제조공정에 있어 핵심기술인 선택적 단결정 실리콘 성장공정에 대한 이동현상, 열역학, 미시적 전산모사를 수행하여 다각적인 분석과 이해를 시도하였다. 첫째, 실리콘 단결정 성장 공 정에 가장 많이 사용되는 배럴 반응기를 대상으로 유한 요소법을 이용하여 이동현상적 이론연구를 수행 하였다. 반응기내의 기체속도 분포, SiH2Cl2 농도분포를 각각 구하였으며 압력, 기판온도, 총유량 HCl 유 량변화 등의주요공정변수가 증착율과 균일도 지수에 미치는 영햐을 고찰하였다. 이러한 연구를 통하여 저온, 저압, 총유량이 많고 첨가되는 HCl 유량이 작은 경우가 균일도 확보를 위하여 적합한 조업조건임 을 알수 있었다. 둘째 Si-H-Cl 계에 대한 열역학적 기체의 Cl/H비가 낮은 경우가 선택적 실리콘 증착 에 적합함을 알수 있었다. 셋째, Monte Carlo법을 이용한 선택적 실리콘 미세박막 성장패턴에 관한 이 론 연구를 수행하여 종횡비, 재방출, 표면확산에 따른 박막증착 패턴의 변화를 고찰하였으며 표면확산이 선택도 상실 현상의 중요한 원인이 될 수 있음을 발견하였다. 또한 최상의 선택도 확보를위해서는 낮은 부착계수와 낮은 표면확산계수를 유지해야 됨을 알수 있었다.

• Journal of Navigation and Port Research
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• v.30 no.5 s.111
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• pp.369-374
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• 2006

The flow analysis was made by applying the turbulent models in the complicated fuel chamber of engine. The $k-\varepsilon,\;k-\omega$, Spalart-Allmaras and reynolds stress models are used in which the hybrid grid is applied for the simulation. The velocity vector, the pressure contour, the change of residual along the iteration number, and the dynamic head are simulated for the comparison of four example cases. Computational results are compared with others. For the code's validation, 2-D bodies were simulated in advance by predicting the drag coefficients.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.3
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• pp.41-50
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• 1993

This paper compares various potential based panel methods for the analysis of two-dimensional hydrofoil. The strength of singularity on each panel is assumed to be constant or linear. Robin boundary condition as well as Neumann and Dirichlet boundary conditions are applied to various formulations to evaluate the accuracies of the methods. Pressures and lifts are computed for various two-dimensional hydrofoil geometries and are compared with the analytic solutions. Extensive studies are performed on the local errors near the trailing edge, known to be sensitive to the foil geometry with sharp trailing edge and high camber. Robin boundary condition with the perturbation velocity potential formulation shows the best accuracy and convergence rate.

• Membrane Journal
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• v.29 no.5
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• pp.284-291
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• 2019

In this study, for the improvement of flow pattern with the CDI module that had the larger electrodes, it was designed with the rectangular type which is gradually wider from the inlet. Based on this, both the flow pattern of feed solution and dead zone were observed and the internal pressure, streaming line and velocity vector distribution were analyzed through the computational flow dynamics and compared with the experimental results. For all flow rates of 10, 20, 30 mL/min, there were no dead zones and the flow patterns were maintained constant. Therefore, it may be possible that the larger electrodes are applied to the CDI process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.2
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• pp.66-71
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• 2021

A hydraulic quick coupler is a component used to easily connect or disconnect pipes or hoses that transfer high pressure fluid without leakage in various mechanical devices. In this study, to obtain an optimal design of a 3/8" hydraulic quick coupler, the effect of different shapes of the internal piston on the internal flow characteristics of the coupler was analyzed and evaluated through numerical analysis based on computational fluid dynamics. Subsequently, the optimal shape design of the internal piston was obtained by comparing the flow characteristics results such as velocity distribution, temperature distribution, and the pressure drop of the hydraulic quick coupler.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.84-90
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• 2022

Hydraulic coupling systems play an important role in easily connecting or disconnecting pipes or hoses that transmit high-pressure fluids without hydraulic oil leakage in hydraulic power transmission equipment. A flat-face hydraulic quick coupler is a recently developed product that can reduce environmental pollution by minimizing hydraulic oil leakage during connection and disconnection. In this study, the influence of the shape of the inner ring of a 3/8" flat-face hydraulic quick coupler on its internal flow characteristics was analyzed and evaluated by numerical analysis based on computational fluid dynamics. The flow velocity distribution, temperature distribution, and optimal shape design of the inner ring were obtained by comparing the results of the flow characteristics, such as the pressure drop.

• Membrane Journal
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• v.17 no.1
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• pp.67-79
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• 2007

Uniform microcapsules containing ionic model drugs were prepared by controlling various conditions of emulsification procedure using a lab-scale membrane emulsification system with a SPG (Shirasu porous glass) tubular membrane. We observed the effects of various emulsification parameters [concentration and molecular weight of polycaprolatone (PCL) polymer, transmembrane pressure and emulsifier concentration in disperse phase and continuous phase, stirring speed] on the mean size and size ditribution of microcapsules containing lidocaine hydrochloride (cationic drug), sodium salicylate (nonionic drug) and 4-acetaminophen (anionic drug) used as a model drugs. Also, release characteristics of a model drugs from PCL microcapsules were investigated. Controlling membrane emulsification parameters, uniform PCL microcapsules with about $5\;{\mu}m$ of the mean size were finally prepared. The release rate and the burst effect of microcapsules were decreased in condition of the acidic solution, but it was increased in condition of the base solution.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.268-275
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• 1993

A series of parametric investigations are performed in order to resolve the flow characteristic of a Quebec city stoker incinerator. The parameters considered in this study are five internal configurations of the Quebec city stoker itself and its modified ones, primary air velocity, the injection velocity and angle of the secondary air, and the reduction of the stoker exit area. A control-volume based finite-difference method by Patankar together with the power-law scheme is employed for discretization. The resolution of the pressure-velocity coupling is made by the use of SIMPLEC algorithm. The standard, two equation, k-$\varepsilon$ model is incorporated for the closure of turbulence. The size of recirculation region, turbulent viscosity, the mass fraction of the secondary air and pressure drop are calculated in order to analyze the characteristics of flow field. The results are physically acceptable and discussed in detail. The flow field of the Quebec city stoker shows the strong recirculation zone together with the high turbulence intensity over the upper part of the incinerator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.623-629
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• 2020

This study examined the airflow field around a gun port on the flight condition of gunfire to verify the aircraft performance and safety effects and gun gas rate, path according to the options of diverter configuration. The gun port diverter not only effectively lowered the heat generated by gunfire but also effectively discharged the gun gas upwards. The path of gun gas can be changed according to its configuration. According to the optional configuration of the rear-gun-port diverter, the flow rate, path, and pressure of the gun gas were analyzed during gunfire. An analysis of the internal velocity distribution and the temperature change of the gun port revealed a rapid decrease in flow rate through the rear diverter according to the option configuration. The forward flow rate showed a similar tendency with little change. This ensures that the gun gas generated during gunfire has a sufficient flow distance from the aircraft surface, regardless of the rear gun port diverter's optional configuration. The flow stagnation of gun gas according to the option configuration of diverter had a great influence on the internal temperature rise of a gun port.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.39-45
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• 2008

The most important elements in flexible pavement design criteria are stress and strain distributions. To obtain reasonable stress and strain distributions in pavements, moving wheel loads must be applied to analyze the pavement responses. In this study, finite element analysis was used to identify the three-dimensional states using the vehicle load into a constant-position / time-variable load (25, 50 and 80km/hr). In an elastic system, the strain is the same in both longitudinal and transverse directions under a single wheel. However, the same is not necessary in a viscoelastic system. Test results showed that the maximum values between transverse and longitudinal strains the bottom of asphalt concrete base layers under 25km/hr were were about 40 percent.