• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.05a
• /
• pp.240-243
• /
• 2001

괘도차량에 부착된 물분사추진기의 유동해석을 실험과 포텐셜해석 그리고 점성해석을 사용하여 그 결과를 비교하였다. 예인수조에서 여러 차량 전진속도에 대해서 임펠러 회전수를 조정하여 제트속도를 변화시키면서 덕트표면에서의 정압을 계측하였다. 이는 제트시스템의 효율을 추정하기 위함이고 관로를 통한 에너지분포를 알 수 있다. 점성유동해석을 위해 지배방정식은 비압축성 Navier-Stokes 방정식을 유한체적법을 사용하여 이산화하고 해석하였으며 난류영향은 표준 ĸ-$\varepsilon$난류모형을 사용하여 유동을 해석하고 실험결과 및 포텐셜 해석결과와 비교하였다.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3033-3038
• /
• 2007

In this research, Rayleigh instability of gas-liquid flow in annular pipe is studied in film boiling using viscous potential flow. Viscous potential flow is a kind of approximation of gas-liquid interface considering velocity field as potential including viscosity. A dispersion relation is obtained including the effect of heat and mass transfer and viscosity. New expression for dispersion relation in film boiling and critical wave number is obtained. Viscosity and heat and mass transfer have a stabilizing effect on instability and its effect appears in maximum growth rate and critical wave number. And the existence of marginal stability region is shown.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.6
• /
• pp.69-77
• /
• 2000

본 연구에서는 전기삼투 배수와 제타포텐셜과 상관성을 규명하고자 하였다. 실험으로 직경 10cm, 길이 16cm의 원형 압밀시료에 일정 전압경사법으로 1V/cm의 직류접압을 가하여 0, 500, 3000 ppm의 납농도와 0, 230, 2300, 23000 ppm의 염분농도에서 각각 12일 과 14일 동안 전지삼투 배수량을 측정하였고, 같은 농도에서 kaolinite 현탁액의 제타포텐셜을 pH2부터 14범위에서 측정하였다. 실험결과 제타포텐셜은 전해질 농도와 pH 변화에 의존적이고, 전기삼투 투수계수와 비례관계가 있음을 확인할 수 있었다. 제타포텐셜에 따른 전기삼투 배수량과 비교한 결과, 전해질 농도가 낮을수록 제타포텐셜은 음의 값은 크고, 전기삼투 배수량도 더 증가하였다.

• Geotechnical Engineering
• /
• v.12 no.2
• /
• pp.95-106
• /
• 1996

In this study, a constitutive model which can describe the anisotropic and plastic behaviors of natural cohesive soils, was developed based on anisotropic bounding surface theory. The model was fomulated by the concepts of the improved anisotropic bounding surface function, nonassociated flow rule with new plastic potential function, anisotropic hardening rule, and new mapping rule governing the plastic behavior inside bounding sutraface. Comparing with the results of Ku consolidation and triaxial shearing tests, the predictions by the proposed model agree quite well with real soil responses.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.2-2
• /
• 2009

전통적으로 선박 프로펠러의 설계에 사용되는 수치해석방법을 소개하고, 점성유동장에서 작동하는 프로펠러의 해석을 포텐셜 이론을 적용해서 수행하는 방법을 소개한다. 캐비테이션 해석 등 최근의 프로펠러 주위 유동의 해석에 CFD가 적용되는 예를 보이고, 프로펠러의 성능 검증을 위해 실제 선박에서 수행되는 실험의 예를 보이고자 한다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 1996.11a
• /
• pp.88-91
• /
• 1996

본 연구에서는 전기화학적 정화방법인 electrokinetic 정화기술을 이용하여 오염된 토양내에서 중금속을 제거하는 방안을 연구하였다. 이를 위하여 납을 혼합하여 오염시킨 점토시료에 대하여 정화가동시간, 공급전류, 오염농도를 다르게 하고 3가지의 향상기법을 적용시켜 정화실험을 실시하였다. 실험결과를 토대로 유입수 및 유출수의 PH, 오염토의 PH, 전기포텐셜, 유출수량, 전기 전도도 등 오염토의 물리화학적 성질변화를 구명하고 정화가동조건 및 향상기법적용에 따른 오염토내의 납 제거효과를 파악하였다. 본 연구를 통하여 electrokinetic 정화기술은 투수성이 낫은 점성토 토양내의 중금속을 제거하는데 매우 효과적인 것으로 판명되었다.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.1
• /
• pp.25-32
• /
• 2014

Recently supercavitating torpedo has been studied because of its high-speed performance as the next generation of underwater weapon systems. In this study, we present a numerical method based on the potential flow. Characteristic features of the shape of supercavities and drag forces are investigated. In addition, we introduce a viscous-potential method to compensate for the effects of viscosity. The results are compared with viscous calculations using a commercial package, FLUENT V13.

• Journal of Navigation and Port Research
• /
• v.28 no.3
• /
• pp.199-205
• /
• 2004

We have developed a composite grid method for the solution of the radiation problem We divide the domain into two different grids; one is a moving grid system and the other is a fixed grid system. This numerical method is applied to calculation of the radiation forces generated by the submerged plate oscillating near a free surface. The experimental data are compared with the numerical ones obtained by the present method and a linear potential theory. As a result, we can confirm the accuracy of the present method. Finally, Lie have evaluated the effect of nonlinear and viscous damping on the hydrodynamic forces acting on the submerged plate.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.1
• /
• pp.131-142
• /
• 2003

The characteristics of electroosmosis drainage in clayey soil were investigated, when an electrokinetic technique was applied for the purpose of separating heavy metals in contaminated ground. A series of laboratory tests, considering voltage, zeta potential, pH distribution, and current, were performed for a lead-contaminated kaolin. The results of laboratory tests were compared with numerical analysis of finite difference method. The 1311owing conclusions were obtained: The flow velocity in electroosmosis was very sensitive to the chemical and electrical characteristics of the clay. As the concentration of ion increases, the flow rate decreases and the amount of drainage also decreases as time elapses.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.16 no.1
• /
• pp.95-104
• /
• 2003

This paper deals with the analytic and FEM analyses of sloshing frequency response of incompressible, invicid and irrotational flow in two dimensional rectangular tank. We use Laplace equation based on potential theory as governing equation. For small amplitude sloshing motion, the linearized free surface condition was applied and the analytic solution as obtained by the separation of variables. To simulate the effect of the energy dissipation due to viscous damping, artificial viscous coefficient is introduced and the divergence of response at resonance frequencies may be avoided by this coefficient. This problem was solved by FEM using 9-node elements in order to predict the maximum amplitude of sloshing response. Numerical results of free surface height, fluid pressure and fluid force show good agreement with those by analytic solution. After verifying the test FEM program, we analyze the frequency response characteristics of sloshing to the fluid height.