• International Journal of Naval Architecture and Ocean Engineering
• /
• 제11권1호
• /
• pp.435-447
• /
• 2019

Energy Flow Finite Element Analysis (EFFEA) is a promising tool for predicting dynamic energetics of complicated structures at high frequencies. In this paper, the Energy Flow Finite Element (EFFE) formulation of complicated Mindlin plates was newly developed to improve the accuracy of prediction of the dynamic characteristics in the high frequency. Wave transmission analysis was performed for all waves in complicated Mindlin plates. Advanced Energy Flow Analysis System (AEFAS), an exclusive EFFEA software, was implemented using $MATLAB^{(R)}$. To verify the general power transfer relationship derived, wave transmission analysis of coupled semi-infinite Mindlin plates was performed. For numerical verification of EFFE formulation derived and EFFEA software developed, numerical analyses were performed for various cases where coupled Mindlin plates were excited by a harmonic point force. Energy flow finite element solutions for coupled Mindlin plates were compared with the energy flow solutions in the various conditions.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2007년도 정기총회 및 학술발표대회
• /
• pp.163-167
• /
• 2007

For numerical analysis of a tidal flow, a two-dimensional hydrodynamic model is developed by solving the nonlinear shallow-water equations. The governing equations are discretized explicitly with a finite difference leap-frog scheme and a first-order upwind scheme on adaptive hierarchical quadtree grids. The developed model is verified by applying to prediction of tidal behaviors. The calculated tidal levels are compared to available field measurements. A very reasonable agreement is observed.

• Tribology and Lubricants
• /
• 제3권1호
• /
• pp.39-46
• /
• 1987

Frictional loss in turbulent regime is abnormally increased compared with in laminar regime. Thus the consideration of temperature rise across fluid film is significant in analysis and conventional isothermal theory loses its usefulness for performance prediction. This paper proposes to the three-dimensional thermohydrodynamic analysis of finite journal bearings operating under turbulent condition using two-equation model($\kappa-\varepsilon$ model) proposed by Hassid & Poreh. The equations are solved numerically by finite difference method. We make the analysis applicable even at large eccentricity when back flow of the lubricants occurs and axial flow is no longer ignored compared to circumferential flow.

• Journal of Mechanical Science and Technology
• /
• 제15권12호
• /
• pp.1750-1756
• /
• 2001

Three-dimensional and unsteady flow analysis is a practical target of high performance computation. As recently advances of computers, a numerical prediction by the large eddy simulation (LES) are introduced and evaluated for various engineering problems. Its advanced methods for the complex turbulent flows are discussed by several examples applied for aerodynamic designs, analysis of fluid flow mechanisms and their interaction to complex phenomena. These results of time-dependent and three-dimensional phenomena are visualized by interactive graphics and animations.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문초록집
• /
• pp.352.2-352
• /
• 2002

In this paper, Power Flow Analysis (PFA) method has been applied to the prediction of vibration energy density and intensity of coupled shell structures in the medium-to-high frequency ranges. To consider the wave transformation at joint between shell elements, power transmission and reflection coefficients are investigated for various joint angles, and here Donnell-Mushtari thin shell theory has been used. (omitted)

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.358-361
• /
• 2008

A study is made of thermal plume flow model for the development of helicopter simulator over the forest fire. For numerical analysis, the Boussinesq fluid approximation and line fire model, which is assumed by the shape of forest fire spreading, are adopted. Comparing 3-D full numerical solutions with 2-D similarity solution, it has been built a new model that is capable of temperature prediction along the symmetric vertical axis in both cases of laminar and turbulent flows.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 1998년도 춘계 학술대회논문집
• /
• pp.162-167
• /
• 1998

A computer code has been developed for the analysis of 2D viscous flow with free surface. VOF method and higher order upwind scheme have been employed for the accurate prediction of free surface motion. Surface tension effect and axisymmetric flow can be computed by the present code.

• 대한환경공학회지
• /
• 제33권3호
• /
• pp.191-195
• /
• 2011

본 연구의 목적은 낮은 전단흐름조건에서 편모 운동성이 박테리아의 거동 특성에 미치는 영향을 파악하는데 있다. 대다수의 미생물은 편모를 이용하여 수용액 내에서 운동할 수 있는 능력을 가지고 있으며, 이러한 운동성은 수계나 수처리 시스템에서 미생물의 거동에 있어서 중요한 역할을 한다. 그러나 현재까지 병원성 미생물의 이동 현상과 관련된 연구에서 편모에 의한 운동성은 거의 고려되지 않고 있는 실정이다. 본 연구에서는 미세유체장치를 이용하여 전단흐름이 낮은 조건에서 E. coli의 거동 특성을 파악하고자 하였다. 실험을 통하여 유속이 작은 경우에 E. coli는 포물선의 형태의 궤적들을 그리며 이동하는 것을 알 수 있었으며, 벽면 근처에서는 상류로 헤엄쳐 올라간다는 것을 파악하였다. 또한 유속과 종횡비(aspect ratio)에 따른 궤적의 변화를 분석하였는데, 유속이 작을수록 포물선 형태의 궤적을 그리게 되며, 길이가 짧을수록 보다 작은 회전 반경을 그리며 운동하는 것을 관찰할 수 있었다.

• 한국항공우주학회지
• /
• 제47권12호
• /
• pp.831-840
• /
• 2019

플러시 대기자료 측정장치는 비행체 표면에서 측정되는 압력 데이터를 이용하여 대기자료를 예측한다. FADS는 돌출된 프로브가 없으므로 고성능 항공기, 스텔스 비행체 및 극초음속 비행체에 적합하다. 본 논문에서는 구-원추 형상을 갖는 비행체에 대해서 아음속부터 초음속 비행까지 대기자료를 예측할 수 있는 FADS의 교정 절차와 계산 알고리즘을 제시한다. 표면 압력 데이터 측정을 위해 노즈부 표면에 5개 플러시 압력공들을 마련하였다. 유동각 예측과 압력 관련 변수의 예측을 분리하는 개념이며, 아음속 유동의 포텐셜 유동해와 극초음속 유동의 수정 뉴톤식을 결합한 압력모델을 사용한다. 교정 압력 데이터는 Euler 방정식을 푸는 전산유체역학 코드를 만들어서 마흐수 0.5 ~ 3.0의 범위에서 구축하였다. 비행 마흐 수 0.6~3.0, 받음각과 옆미끄럼각은 각각 -10° ~ +10°의 범위에서 여러 비행조건에 대해서 테스트를 수행하였다. 예측된 대기자료는 받음각, 옆미끄럼각, 마흐수, 자유류 정압이며 참고 데이터와 비교하여 정확도를 분석하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.1378-1385
• /
• 2008

The probability of landslide hazards was predicted to natural terrain around the stone relics of Jinjeon-saji area, which is located in Yangyang, Kangwon Province. As the analysis results of field investigation, laboratory test and geology and geomorphology data, the effect factors of landslides occurrence were evaluated, and then the landslides prediction map was made up by use of prediction model considering the effect factors. The susceptibility of stone relics induced by landslides was investigated as the grading classification of occurrence probability using the landslides prediction map. In the landslides prediction map, the high probability area of landslides over 70% of occurrence probability was 3,489m3, which was 10.1% of total prediction area. If landslides are occurred at the high elevation area, the three stories stone pagoda of Jinjeon-saji (National treasure No.122) and the stone lantern of Jinjeon-saji (Treasure No.439) will be collapsed by debris flow.