• 한국산학기술학회논문지
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• 제10권10호
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• pp.2583-2588
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• 2009

본 논문에서는 반정현파 형태의 충격을 받는 HDD에 대한 충격해석을 수행하고, 그 타당성을 실험적으로 검증하였다. 일반적으로 센서를 이용한 제품의 충격실험을 통해서는 제한적인 정보만을 얻을 수 있지만, 컴퓨터를 이용한 해석기술은 제품의 파손현상을 규명하는데 필요한 보다 광범위하고 상세한 정보를 제공할 수 있는 장점을 가진다. 하지만, 이러한 해석결과는 여러 요인들에 따라 매우 민감하기 때문에 그 타당성을 검증하는 것이 중요하다. 따라서 본 연구에서는 200G/1ms의 전자기 충격실험과 300G/2ms의 낙하충격실험을 통하여 HDD의 조립단계별로 LS-DYNA를 이용한 유한요소해석의 신뢰성을 검증하였다.

• 동력기계공학회지
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• 제13권5호
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• pp.46-51
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• 2009

Recently, the shock resistance and dynamic characteristics of hard disk drives have become more important due to their highly increased storage density and miniaturization. In this study, we have developed an ANSYS/Mechanical/LS-DYNA based HDD vibration/shock simulation tool for design engineers. This simulation tool using ANSYS APDL can produce a parametric finite element modeling of HDD automatically and has GUI-based applications using the script program language Tcl/Tk. In the present tool, we adopt the reliable methodology of vibration/shock simulation, which is experimentally verified. It is expected that this simulation tool can make the repetitive computational efforts for the shock-proof design of HDD drastically reduced.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.156-163
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• 2010

A nonequilibrium molecular dynamics(NEMD) simulation method is developed and applied to study shock waves propagating through argon gas. In this simulation method, shock waves are generated by pushing a piston at a constant speed from one side of a simulation box filled with argon molecules. A linear relationship between piston speeds and shock speeds is observed. Thermodynamic properties including density, temperature, and pressure before and after the shock front are obtained from the simulations and compared with the well-known Rankine-Hugoniot equations based on ideal gases. The comparison shows an excellent agreement, indicating that this NEMD simulation method can be employed to investigate various physical properties of shock waves further.

• 천문학회보
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• 제44권2호
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• pp.66.1-66.1
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• 2019

We study cosmological shock waves in and around protoclusters at cosmic noon in the Horizon Run 5 Simulation (HR5), one of the world's largest hydrodynamic cosmological simulations. We select the local peaks of X-ray luminosity at z=2.5-3 in the HR5 lightcone volume as protocluster candidates. We find shock waves with Ms > 1.3 within the virial radii of the HR5 protocluster candidates by applying several shock-finding algorithms based on the Rankine-Hugoniot jump condition. We compare the properties of shock waves from different shock-finding algorithms.

• 한국정밀공학회지
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• 제20권1호
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• pp.187-195
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• 2003

The performance of shock absorber is directly related to the car behaviour and performance, both for handling and ride comfort. The displacement sensitive shock absorber has two modes of damping force (i.e. soft and hard) according to the position of piston. In this study, a mathematical nonlinear dynamic model is introduced to predict the performance of displacement sensitive shock absorber. Especially in this paper, the transient zone is considered and the simulation result is well fit with experimental data. And the vehicle dynamic characteristic of displacement sensitive shock absorber is presented using quarter car simulation model. The simulation results of frequency response are compared with passive shock absorber.

• 대한기계학회논문집B
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• 제29권8호
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• pp.921-926
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• 2005

In the idealized model problem of the interaction between a planar travelling shock and a symmetric vortex, the physics of shock distortion and quadrupole sound generation are well known to many researchers. However, the authors have distinguished the weak waves reflected and transmitted by the complicated photograph images obtained from a shock tube experiment. In this paper, we introduces a parametric study based on Navier-Stokes simulation and Rankin vortex model to see the difference of shock deformation shapes. Four combination of the strength of shock and vortex are respectively selected from a parameter plane of shock and vortex strength extended to the strong vortex region. The result shows clearly discernable wave morphology for the main parameters, which is not yet explicitly mentioned by other researchers.

• 한국시뮬레이션학회논문지
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• 제32권4호
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• pp.1-10
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• 2023

본 연구는 모델링 및 시뮬레이션을 이용하여 수중폭발 충격이 함정에 탑재되는 수직발사형 발사체에 전달될 때의 반응을 검토하고 발사체 보호를 위해 내충격성을 확보하는 방안에대한 것이다. 정확한 수학적 모델을 확보하기 위하여 유사 장비에 대한 동특성 시험을 수행하였으며 이를 기반으로 수학적 모델을 보완하였다. 그리고 보완된 수학적 모델에 이용하여 수직발 사체에 BV043 규격에서 정한 수중폭발에 의한 충격이 전달되는 상황을 시뮬레이션 하였다. 1차 시뮬레이션 결과 비행체의 구조물이 견딜 수 없는 충격이 전달되는 것을 확인하였으며, 링스프링 구조의 완충기를 사용하여 비행체를 보호하는 방안을 연구하였다. 또한 링스프링 완충기의 설계 변수를 변경한 여러 경우에 대한 시뮬레이션을 수행함으로써 링스프링 완충기가 함정탑재용 수직발사 비행체의 내충격성을 더 증가시킬 수 있음을 확인하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.426-432
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• 2004

Large-Eddy Simulation (LES) is applied for the simulation of compressible flat plate boundary with Reynolds number up to 5 X 10$^{5}$ . Numerical examples include shock/boundary layer interaction and boundary layer transition, aiming future application to the analysis of transonic fan/compressor cascades. The present LES code uses hybrid com-pact/WENO scheme for the spatial discretization and compact diagonalized implicit scheme for the time integration. The present code successfully predicted the bypass transition of subsonic boundary layer. As for supersonic turbulent boundary layer, mean and fluctuation velocity of the attached boundary, as well as the evolution of the friction coefficient and the displacement thickness both upstream and downstream of the separation region are all in good agreement with experiment. The separation point also agreed with the experiment. In the simulation of the shock/laminar boundary layer interaction, the dependence of the transition upon the shock strength is reproduced qualitatively, but the extent of the separation region is overpredicted. These numerical examples show that LES can predict the behavior of boundary layer including transition and shock interaction, which are hardly managed by the conventional Reynolds-averaged Navier-Stokes approach, although there needs to be more effort before achieving quantitative agreement.

• 한국안전학회지
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• 제22권2호
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• pp.41-46
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• 2007

This paper considers the electrical shock risk of the human body due to underwater leakage current in such places of public baths. Many submerged electric facilities in a public bath may create a severe electric shock hazard for the human body, since wet body in an accidentally energized bathtub can result in low electrical resistance through the human body for leakage or fault currents. Therefore a major consideration, in the context of electrical safety underwater, is the shock risk to the bather as a result of electric current flowing through the water in bathtub. To assess the electric shock risk and to analyze the potential distribution in a bathtub, 2 different situation cases are set up, then experimental and simulation methods are adopted. The validity of 2 cases of simulation and experiment data in a bathtub for electric distribution underwater are compared and analyzed. Also electric shock risk assessment underwater in a real public bathtub by simulation program package, Flux 3D, was conducted herein, and the results are presented and discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.557-560
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• 2002

In this study, simulation of weak shock waves are peformed by a two-dimensional thermal fluid or compressible fluid model of the lattice Boltzmann method. The shock wave represents an abrupt change in fluids properties, in which finite variations in pressure, internal energies, and density occur over the shock thickness. The characteristics of the proposed model with a simple distribution function is verified by calculation of the sound speeds, and the shock tube problem. The reflection of a weak shock wave by wedge propagating in a channel is performed. The results agree well with those by finite difference method or by experiment. In the simulation of unsteady shock wave diffraction around a sharp corner, we show a flow field of vortical structure near the comer.