• 대한조선학회논문집
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• 제40권5호
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• pp.36-42
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• 2003

A CFD simulation technique has been developed to handle the unsteady body motion with large amplitude by use of overlapping multi-block grid system. The three-dimensional, viscous and incompressible flow around body is investigated by solving the Navier-Stokes equations, and the motion of body is represented by moving effect of the grid system. Composite grid system is employed in order to deal with both the body motion with large amplitude and the condition of numerical wave maker in convenience at the same time. The governing equations, Navier-Stokes (N-S) and continuity equations, are discretized by a finite volume method, in the framework of an O-H type boundary-fitted grid system (inner grid system including test model) and a rectangular grid system (outer grid system including simulation equipments for generation of wave environments). If this study, several flow configurations, such as an oscillating cylinder with large KC number, are studied in order to predict and evaluate the hydrodynamic forces. Furthermore, the motion simulation of a Series 60 model advancing in a uniform flow under the condition of enforced roll motion of angle 20$^{\circ}$ is performed in the developed numerical wave tank.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 춘계 학술대회논문집
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• pp.99-109
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• 1998

This paper describes the analysis of flow and aeroacoustic field around a car-like body. The governing equations, 3-D unsteady incompressible Navier-Stokes equations, are solved with the iterative time marching scheme. The Chimera grid technique has been applied to efficiently simulate the flow around the side-view mirror, After the flow field analysis has been converged, the aerodynamic noise analysis of the side-view mirror has been performed by solving Ffowcs Williams and Hawkings equation. From the present numerical simulation, the A- and C-pillar vortex are evidently shown and the aerodynamic noise level induced by the side-view mirror is predicted to about 100dB.

• 한국안전학회지
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• 제21권1호
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• pp.15-20
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• 2006

The finite element alternating method is a convenient and efficient method to analyze three-dimensional cracks embedded in an infinite or a finite body because the method has the property that the uncracked body and cracks can be modeled independently. In this paper the method was applied for fatigue crack growth simulation. A surface crack in a cylinder was considered as an initial crack and the crack configurations and stress intensity factors during the crack growth were obtained. In this paper the finite element alternating method proposed by Nikishkov, Park and Atluri was used after modification. In the method, as the required solution for a crack in an infinite body, the symmetric Galerkin boundary element method formulated by Li and Mear was used. And a crack was modeled as distribution of displacement discontinuities, and the governing equation was formulated as singularity-reduced integral equations.

• 대한조선학회논문집
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• 제28권1호
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• pp.19-26
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• 1991

난류유동 지배 방정식인 타원형 레이놀즈 방정식을 수치계산에 의해 계산하였다. 계산 대상으로는 실험결과가 많이 알려진 축 대칭 물체를 택하였다. 수치적으로 얻어지는 물체접합 좌표계를 사용하였고, 난류모형으로는 $\kappa-\varepsilon$모형으로써 경계면 근처의 복잡한 유동특성을 추정할 수 있도록 영역을 2개로 나누어 계산하는 2층모형(two-layer model)을 사용하였다. 입구면의 경계조건을 사용하여 물체의 중앙부 이후부터 계산을 수행하였다. 입구면에서의 속도와 난류량 등은 경계층 방정식을 풀어 얻어진 결과와 평판의 경계층 자료로부터 얻어진 결과를 사용하였으며, 이로부터 입구면 조건이 점성유동 해석 결과에 미치는 영향을 조사하였다.

• Advances in aircraft and spacecraft science
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• 제10권5호
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• pp.419-437
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• 2023

This paper presents the study of the effects of rigid-body motion simultaneously with the presence of the effects of temporal variation due to the existence of morphing speed on the aeroelastic stability of the two-stage telescopic wings, and hence this is the main novelty of this study. To this aim, Euler-Bernoulli beam theory is used to model the bending-torsional dynamics of the wing. The aerodynamic loads on the wing in an incompressible flow regime are determined by using Peters' unsteady aerodynamic model. The governing aeroelastic equations are discretized employing a finite element method based on the beam-rod model. The effects of rigid-body motion on the length-based stability of the wing are determined by checking the eigenvalues of system. The obtained results are compared with those available in the literature, and a good agreement is observed. Furthermore, the effects of different parameters of rigid-body such as the mass, radius of gyration, fuselage center of gravity distance from wing elastic axis on the aeroelastic stability are discussed. It is found that some parameters can cause unpredictable changes in the critical length and frequency. Also, paying attention to the fuselage parameters and how they affect stability is very important and will play a significant role in the design.

• 시큐리티연구
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• 제14호
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• pp.389-412
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• 2007

이 연구는 2005년 부산에서 개최된 APEC 행사의 안전활동 문제점을 도출하여 이를 토대로 향후 우리나라에서 개최될 국제회의 안전활동에 대한 제고방안을 모색해 보는데 그 목적이 있다. 이와 같은 목적을 달성하기 위하여 부산 APEC 행사에 직접 참여한 공안기관인 경찰, 소방기관의 공무원과 APEC 행사를 근거리에서 지원한 부산시 공무원을 대상으로 델파이방법에 의해 3차례에 걸쳐 의견을 수렴하여, 국제회의의 단계별 구성요소 및 문제점을 파악하고 구성요소별로 문제인식에 대한 통계처리를 실시하였다. 이와 함께 공안기관 전문가 4명과 1 : 1 면담결과를 통하여 국제회의 행사에 관한 안전활동 제고방안을 모색한 결과는 다음과 같다. 사전준비단계에서는 제 공안기관과 지자체의 사전협조로 안전활동에 대한 빈틈없는 기반을 강구하여야 한다. 현장활동단계에서는 각 기능별로 안전활동을 검토하고 지자체와 지속적인 보완작용이 필요하다. 실시단계에서는 공안기관과 지자체와의 긴밀한 협조에 의한 시너지효과로 안전역량을 제고해야 한다. 평가 및 수정단계에서는 행사종료 후 공안기관과 지자체가 합동으로 효율적인 평가시스템 탐색하여 차후 행사에 대비해야 한다.

• 품질경영학회지
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• 제22권1호
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• pp.179-187
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• 1994

This study suggests a data base scheme of region statistics whose demand has been rapidly increased as the local self-governing body is introduced in Korea. A program for the region statistics management(registration, reference, modification, deletion) is developed and it can be used by personal computer users.

• International Journal of Safety
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• 제2권1호
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• pp.17-22
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• 2003

In order to analyze general three dimensional cracks in an infinite body, the symmetric Galerkin boundary element method formulated by Li and Mear is used. A crack is modelled as distribution of displacement discontinuities, and the governing equation is formulated as singularity-reduced integral equations. With the proposed method several example problems for three dimensional cracks in an infinite solid, as well as their growth under fatigue, are solved and the accuracy and efficiency of the method are demonstrated.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1995년도 추계 학술대회논문집
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• pp.132-137
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• 1995

Numerical analysis is conducted on the deformation of free surface of magnetic fluid. Steady magnetic fields are induced by a circular current loop. Governing equations of magnetic fields are solved by using the concept of vector potential. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. The deformations of free surface of magnetic fluid are qualitatively clarified. And, the patterns of steady non-uniform magnetic fields induced by a circular current loop are quantitatively presented.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2002년도 춘계학술대회 논문집
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• pp.71-76
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• 2002

본 논문에서는 GIS Data구축 감리에 대한 내용정의와 수행방법 및 사례에 대해서 소개하고, 향후 GIS사업의 성공을 위한 GIS Data구축 감리의 역할에 대해서 설명한다.