• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.463-471
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• 2013

This paper presents design and control of electronic control suspension(ECS) equipped with controllable magnetorheological(MR) damper for passenger vehicle. In order to achieve this goal, a cylindrical type MR fluid damper that satisfies design specification of a middle-sized commercial passenger vehicle is proposed. After manufacturing the MR damper with design parameters, their field-dependent damping forces are experimentally evaluated and compared with those of a conventional damper. A quarter-vehicle MR ECS system consisting of sprung mass, spring, tire, controller and the MR damper is established in order to investigate the ride comfort performances. On the basis of the governing equation of motion of the suspension system, five control strategies(soft, hard, comfort, sport and optimal mode) are formulated. The proposed control strategies are then experimentally realized with the quarter-vehicle MR ECS system. Control performances such as vertical acceleration of the car body and tire deflection are evaluated in frequency domains on random road condition. In addition, performance comparison of WRMS(weighted root mean square) of the quarter-vehicle MR ECS system on random road are undertaken in order to investigate ride comfort characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.157-167
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• 2008

Through this study, the standard design guidelines for high speed train with power cars have been derived to meet the crashworthiness requirements of the Korean rollingstock safety regulation. The crashworthiness regulation requires some performance requirements for two heavy collision accident scenarios; a train-to-train collision at the relative speed of 36 kph, and a collision against a standard deformable obstacle of 15 ton at 110 kph. A standard high speed train composition was defined as 2PC-2ET-6T with 17ton axle load, similar to KTX-2 for the Honam express line. Using theoretical and numerical analyses, some crashworthy design guidelines were derived in terms of mean crush forces and energy absorptions for major crushable components. The derived design guidelines were evaluated and improved using one dimensional spring-mass dynamic simulation. It is shown from the simulation results that the suggested design guidelines can easily satisfy the domestic crashworthiness requirements.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.4120-4132
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• 2017

In this research, we implement a deformable object simulation system using OpenGL's shader language, GLSL4.3. Deformable object simulation is implemented by using volumetric mass-spring system suitable for real-time simulation among the methods of deformable object simulation. The compute shader in GLSL 4.3 which helps to access the GPU resources, is used to parallelize the operations of existing deformable object simulation systems. The proposed system is implemented using a compute shader for parallel processing and it includes a bounding box-based collision detection solution. In general, the collision detection is one of severe computing bottlenecks in simulation of multiple deformable objects. In order to validate an efficiency of the system, we performed the experiments using the 3D volumetric objects. We compared the performance of multiple deformable object simulations between CPU and GPU to analyze the effectiveness of parallel processing using GLSL. Moreover, we measured the computation time of bounding box-based collision detection to show that collision detection can be processed in real-time. The experiments using 3D volumetric models with 10K faces showed the GPU-based parallel simulation improves performance by 98% over the CPU-based simulation, and the overall steps including collision detection and rendering could be processed in real-time frame rate of 218.11 FPS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1813-1818
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• 2014

This paper presents the stability analysis of the haptic system including a human impedance using the Routh-Hurwitz criterion. The reflective force is computed from a virtual spring model and is transferred to a human operator using the first-order-hold method. The stability boundary conditions are induced and the relation among a virtual spring ($K_w$), the mass ($M_h$), the damping ($B_h$) and the stiffness ($K_h$) of a human impedance is analyzed. Hence the stability boundary of the virtual spring ($K_w$) is proposed as $K_w{\leq}54413{\sqrt{(M_h+M_d)(B_h+B_d)}}-0.486K_h$ when the sampling time is 1 ms. The average relative error is about 0.5% when the mathematical analysis results are compared with the results of the stability boundary model.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.143-150
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• 2000

A physical lumped parameter model is proposed for the time domain analysis of dam-reservoir system. The exact solution of transmitting boundary is derived for a semi-infinite 2-D reservoir of constant depth. The characteristics of the solution are examined in both frequency and the domains. Mass and damping coefficient are obtained from asymptotic behavior of the frequency domain solution. Further refinement to the lumped model is made by approximating the kernel function of the convolution integral in the exact solution. Finally a new physical lumped parameter model is proposed that consists of two masses, a spring and two dampers for each mode. It is demonstrated that new lumped parameter model of transmitting boundary can give excellent results.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.110-116
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• 2005

Linear dynamic simulations with one and two degrees of freedom were built from SIMULINK in MATLAB commercial program. Before starting the simulations, initial conditions and system parameters which are mass, spring constant and coefficient of damping are easily inputted by user through each pop-up window, and the conditions for the simulation including time step, analysis methodology and so on can be modified with ease. Also, as soon as the simulations are started, the windows for animations which shows deformed motions dynamically with real time are popped-up and the graphical results are shown in time and frequency domains, simultaneously, The results of the simulations were verified through some examples of textbooks of mechanical vibrations. It was found that the programs would help us to solve any kind of linear dynamic simulation for one and two degrees of freedom.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.398-398
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• 2016

A triboelectric generator uses the principles of static electrification and electrostatic induction to convert mechanical energy into useful electrical energy. In this work we study a single degree of freedom (SDOF) vibration type triboelectric generator that is initiated by a vibrating source at its base. The system is modeled in Abaqus and the design parameters are systematically explored by their effect on the output. The relationships between the parameters: input force, input frequency, mass, spring stiffness and gap between the plates, are analyzed. Finally, based on initial experiments, and simulation results, a design methodology is formulated. The methodology will provide guidance for application specific design of reliable and effective vibration type triboelectric generators.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.140-143
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• 2007

A continuing elevated bridge is replaced with mass-spring system model, and a part of the bridge is cut out as an analytical area. A viscous boundary is installed at both ends, and dynamic analyses are carried out changing the wave velocity of the viscous boundary, The result is compared with a result of a very long model corresponding to the solution with infinite length. A wave velocity is chosen so that the good performance of a viscous boundary is exhibited. The parametric analyses are carried out changing the model of various structural properties, and an approximation expression is suggested to obtain the wave velocity easily for setting a viscous boundary.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.98-103
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• 2002

In this paper, shock analysis was performed for coarse and fine mesh model using MSC/NASTRAN and ANSYS after substituting the foundation of deck mounted equipment of marine ship for mass-spring system. In order to determine input file in MSC/NASTRAN, dynamic response analysis was also performed using DDAM based on the calculation in the range of low frequency. It was confirmed that the coarse mesh model has the sufficient effective weight in a lower degree mode compared to fine mesh model.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.85-90
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• 2001

Recent general Press brake has many problems in cutting high accurate products in the progress of industry. Previous hand-operated press brake needs many pre-processing works to adjust bending ang1e and marking-off works to calculate bending length. Also, the hand-operating work makes many geometric errors and has difficulty for variety-mass production. To solve these problems, this paper proposes Computer Numerical Control (CNC) general press brake and development of servo-control system based on database for reduction of geometric errors and pre-processing work time and high accuracy bending work.